Levofloxacin Product Monograph

SUMMARY PRODUCT INFORMATION

INDICATIONS AND CLINICAL USE

LEVOFLOXACIN (levofloxacin) tablets are indicated for the treatment of adults with bacterial infections caused by susceptible strains of the designated microorganisms in the infections listed below.

Upper Respiratory Tract

Acute sinusitis (mild to moderate) due to Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella (Branhamella) catarrhalis.

Lower Respiratory Tract

Acute bacterial exacerbations of chronic bronchitis (mild to moderate) due to Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, Haemophilus parainfluenzae, or Moraxella (Branhamella) catarrhalis.

Community-acquired pneumonia (mild, moderate and severe infections) due to Staphylococcus aureus, Streptococcus pneumoniae (including penicillin-resistant strains), Haemophilus influenzae, Haemophilus parainfluenzae, Klebsiella pneumoniae, Moraxella (Branhamella) catarrhalis, Chlamydia pneumoniae, Legionella pneumophila, or Mycoplasma pneumoniae (see DOSAGE AND ADMINISTRATION, and CLINICAL TRIALS).

Nosocomial pneumonia due to methicillin-susceptible Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens, Escherichia coli, Klebsiella pneumoniae, Haemophilus influenzae or Streptococcus pneumoniae. Adjunctive therapy should be used as clinically indicated. Where Pseudomonas aeruginosa is a documented or presumptive pathogen, combination therapy with an anti-pseudomonal β-lactam is recommended.

Skin and Skin Structure

Uncomplicated skin and skin structure infections (mild to moderate) due to Staphylococcus aureus or Streptococcus pyogenes.

Complicated skin and skin structure infections (mild to moderate), excluding burns, due to Enterococcus faecalis, methicillin-sensitive Staphylococcus aureus, Streptococcus pyogenes, Proteus mirabilis, or Streptococcus agalactiae.

Urinary Tract

Complicated urinary tract infections (mild to moderate) due to Enterococcus (Streptococcus) faecalis, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, or Pseudomonas aeruginosa (see DOSAGE AND ADMINISTRATION and CLINICAL TRIALS).

Uncomplicated urinary tract infections (mild to moderate) due to Escherichia coli, Klebsiella pneumoniae, or Staphylococcus saprophyticus.

Acute pyelonephritis (mild to moderate) caused by Escherichia coli (see DOSAGE AND ADMINISTRATION and CLINICAL TRIALS).

Chronic bacterial prostatitis due to Escherichia coli, Enterococcus faecalis, or Staphylococcus epidermidis.

Appropriate culture and susceptibility tests should be performed before treatment in order to isolate and identify the organisms causing the infection, and to determine their susceptibility to levofloxacin. Therapy with levofloxacin may be initiated before the results of these tests are known; once results become available, appropriate therapy should be continued.

As with other drugs in this class, some strains of Pseudomonas aeruginosa may develop resistance fairly rapidly during treatment with levofloxacin. Culture and susceptibility testing performed periodically during therapy, will reveal not only the therapeutic effect of the antimicrobial agent, but also the possible emergence of bacterial resistance.

Geriatrics (≥ 65 years of age):

Drug absorption appears to be unaffected by age. Dose adjustment based on age alone is not necessary (see WARNINGS AND PRECAUTIONS; Special Populations and ACTION AND CLINICAL PHARMACOLOGY).

Pediatrics (< 18 years of age):

Safety and effectiveness in children under 18 years of age have not been established (see WARNINGS AND PRECAUTIONS; Special Populations).

CONTRAINDICATIONS

LEVOFLOXACIN (levofloxacin) tablets are contraindicated in persons with a history of hypersensitivity to levofloxacin, quinolone antimicrobial agents, or any other components of this

product. For a complete listing, see the DOSAGE FORMS, COMPOSITION AND PACKAGING section of the Product Monograph.

Levofloxacin is also contraindicated in persons with a history of tendinitis or tendon rupture associated with the use of any member of the quinolone group of antimicrobial agents.

WARNINGS AND PRECAUTIONS

General

The oral administration of levofloxacin increased the incidence and severity of osteochondrosis in immature rats and dogs. Other quinolones also produce similar erosions in the weight-bearing joints and other signs of arthropathy in immature animals of various species. Consequently, levofloxacin should not be used in pre-pubertal patients (see TOXICOLOGY).

Although levofloxacin is soluble, adequate hydration of patients receiving levofloxacin should be maintained to prevent the formation of a highly concentrated urine. Crystalluria has been observed rarely in patients receiving other quinolones, when associated with high doses and an alkaline urine. Although crystalluria was not observed in clinical trials with levofloxacin, patients are encouraged to remain adequately hydrated.

As with any antimicrobial drug, periodic assessment of organ system functions, including renal, hepatic, and hematopoietic, is advisable during prolonged therapy (see ADVERSE REACTIONS).

Musculoskeletal Effects

Ruptures of the shoulder, hand, Achilles tendon, or other tendons that required surgical repair or resulted in prolonged disability have been reported in patients receiving quinolones, including

Serious Warnings and Precautions

$ Levofloxacin has been shown to prolong the QT interval of the electrocardiogram in some patients (see WARNINGS AND PRECAUTIONS; Cardiovascular).

$ Serious hypersensitivity and/or anaphylactic reactions have been reported in patients receiving quinolone therapy, including levofloxacin (see WARNINGS AND PRECAUTIONS; Sensitivity/Resistance).

$ Seizures may occur with quinolone therapy. Levofloxacin should be used with caution in patients with known or suspected CNS disorders which may predispose to seizures or lower the seizure threshold (see WARNINGS AND PRECAUTIONS; Neurologic).

$ Levofloxacin should not be used in pregnant women unless the potential benefits outweigh the potential risk to the fetus (see WARNINGS AND PRECAUTIONS; Special Populations). $ For nursing mothers, a decision should be made to either discontinue nursing or discontinue the administration of levofloxacin, taking into account the importance of levofloxacin therapy to the mother and the possible risk to the infant (see WARNINGS AND PRECAUTIONS; Special Populations).

$ Levofloxacin is not recommended for children under the age of 18 years (see WARNINGS AND

PRECAUTIONS; Special Populations).

levofloxacin. Post-marketing surveillance reports indicate that this risk may be increased in patients receiving concomitant corticosteroids, especially the elderly. Levofloxacin should be discontinued if the patient experiences pain, inflammation, or rupture of a tendon. Patients should rest and refrain from exercise until the diagnosis of tendonitis or tendon rupture has been confidently excluded. Tendon rupture can occur during or after therapy with quinolones, including levofloxacin (see CONTRAINDICATIONS).

Sexually Transmitted Diseases

Levofloxacin is not indicated for the treatment of syphilis or gonorrhea. Levofloxacin is not effective in the treatment of syphilis. Antimicrobial agents used in high doses for short periods of time to treat gonorrhea may mask or delay the symptoms of incubating syphilis. All patients with gonorrhea should have a serologic test for syphilis at the time of diagnosis. Patients treated with antimicrobial agents with limited or no activity against Treponema pallidum should have a follow-up serologic test for syphilis after 3 months.

Cardiovascular

QT Prolongation

Some quinolones, including levofloxacin, have been associated with prolongation of the QT interval on the electrocardiogram and infrequent cases of arrhythmia. During post-marketing surveillance, very rare cases of torsades de pointes have been reported in patients taking levofloxacin. These reports generally involved patients with concurrent medical conditions or concomitant medications that may have been contributory. The risk of arrhythmias may be reduced by avoiding concurrent use with other drugs that prolong the QT interval including macrolide antibiotics, antipsychotics, tricyclic antidepressants, Class IA (e.g. quinidine, procainamide) or Class III (e.g. amiodarone, sotalol) antiarrhythmic agents, and cisapride. In addition, use of levofloxacin in the presence of risk factors for torsades de pointes such as hypokalemia, significant bradycardia, cardiomyopathy, patients with myocardial ischemia, and patients with congenital prolongation of the QT interval should be avoided (see DETAILED PHARMACOLOGY; Human Pharmacology; Studies Measuring Effects on QT and Corrected QT (QTc) Intervals).

Endocrine and Metabolism

Disturbances of Blood Glucose

Disturbances of blood glucose, including symptomatic hyper- and hypoglycemia, have been reported with the use of quinolones, including levofloxacin. In patients treated with levofloxacin, some of these cases were serious. Blood glucose disturbances were usually in diabetic patients receiving concomitant treatment with an oral hypoglycemic agent (e.g. glyburide/glibenclamide) or with insulin. In these patients, careful monitoring of blood glucose is recommended. If a hypoglycemic reaction occurs in a patient being treated with levofloxacin, discontinue levofloxacin immediately and initiate appropriate therapy (see DRUG INTERACTIONS, and ADVERSE REACTIONS). Serious hypoglycaemia and hyperglycemia have also occurred in patients without a history of diabetes.

Gastrointestinal

Clostridium difficile-associated disease

Clostridium difficile-associated disease (CDAD) has been reported with use of many antibacterial agents, including levofloxacin. CDAD may range in severity from mild diarrhea to

fatal colitis. It is important to consider this diagnosis in patients who present with diarrhea or symptoms of colitis, pseudomembranous colitis, toxic megacolon, or perforation of the colon subsequent to the administration of any antibacterial agent. CDAD has been reported to occur over 2 months after the administration of antibacterial agents.

Treatment with antibacterial agents may alter the normal flora of the colon and may permit overgrowth of Clostridium difficile. C. difficile produces toxins A and B, which contribute to the development of CDAD. CDAD may cause significant morbidity and mortality. CDAD can be refractory to antimicrobial therapy.

If the diagnosis of CDAD is suspected or confirmed, appropriate therapeutic measures should be initiated. Mild cases of CDAD usually respond to discontinuation of antibacterial agents not directed against Clostridium difficile. In moderate to severe cases, consideration should be given to management with fluids and electrolytes, protein supplementation, and treatment with an antibacterial agent clinically effective against Clostridium difficile. Surgical evaluation should be instituted as clinically indicated since surgical intervention may be required in certain severe cases (see ADVERSE REACTIONS).

Hepatic

Very rare post-marketing reports of severe hepatotoxicity (including acute hepatitis and fatal events) have been received for patients treated with levofloxacin. No evidence of serious drug-associated hepatotoxicity was detected in clinical trials of over 7,000 patients. Severe hepatotoxicity generally occurred within 14 days of initiation of therapy and most cases occurred within 6 days. Most cases of severe hepatotoxicity were not associated with hypersensitivity. The majority of fatal hepatotoxicity reports occurred in patients 65 years of age or older and most were not associated with hypersensitivity. Levofloxacin should be discontinued immediately if the patient develops signs and symptoms of hepatitis. (See ADVERSE REACTIONS, Post-Marketing Adverse Reactions.)

Immune

Hypersensitivity

Serious and occasionally fatal hypersensitivity and/or anaphylactic reactions have been reported in patients receiving therapy with quinolones, including levofloxacin. These reactions often occur following the first dose. Some reactions have been accompanied by cardiovascular collapse, hypotension/shock, seizure, loss of consciousness, tingling, angioedema (including tongue, laryngeal, throat or facial edema/swelling), airway obstruction (including bronchospasm, shortness of breath, and acute respiratory distress), dyspnea, urticaria, itching, and other serious skin reactions. Levofloxacin should be discontinued immediately at the first appearance of a skin rash or any other sign of hypersensitivity. Serious acute hypersensitivity reactions may require treatment with epinephrine and other resuscitative measures, including oxygen, intravenous fluids, antihistamines, corticosteroids, pressor, amines and airway management, as clinically indicated (see ADVERSE REACTIONS).

Serious and sometimes fatal events, some due to hypersensitivity and some due to uncertain etiology, have rarely been reported in patients receiving therapy with quinolones, including levofloxacin. These events may be severe, and generally occur following the administration of multiple doses. Clinical manifestations may include one or more of the following: fever; rash or

severe dermatologic reactions (e.g. toxic epidermal necrolysis, Stevens-Johnson syndrome); vasculitis; arthralgia; myalgia; serum sickness; allergic pneumonitis; interstitial nephritis; acute renal insufficiency or failure; hepatitis, including acute hepatitis; jaundice; acute hepatic necrosis or failure; anemia, including hemolytic and aplastic; thrombocytopenia, including thrombotic thrombocytopenic purpura; leukopenia; agranulocytosis; pancytopenia; and/or other hematologic abnormalities. The administration of levofloxacin should be discontinued immediately, at the first appearance of a skin rash or any other sign of hypersensitivity, and supportive measures instituted (see ADVERSE REACTIONS).

Neurologic

CNS and Psychiatric Effects

Convulsions and toxic psychoses have been reported in patients receiving quinolones, including levofloxacin. Quinolones including levofloxacin, may also cause increased intracranial pressure and central nervous system stimulation which may lead to tremors, restlessness, anxiety, lightheadedness, dizziness, confusion and hallucinations, paranoia, depression, nightmares, insomnia and, rarely, suicidal thoughts or acts. These reactions may occur following the first dose. If these reactions occur in patients receiving levofloxacin, the drug should be discontinued and appropriate measures instituted. As with all quinolones, levofloxacin should be used with caution in patients with a known or suspected CNS disorder that may predispose to seizures or lower the seizure threshold (e.g. severe cerebral arteriosclerosis, epilepsy), or in the presence of other risk factors that may predispose to seizures or lower the seizure threshold (e.g. alcohol abuse, certain drug therapies such as NSAIDs and theophylline, renal dysfunction). Levofloxacin should be used with caution in patients with unstable psychiatric illness (see DRUG INTERACTIONS, and ADVERSE REACTIONS).

Rare cases of sensory or sensorimotor axonal polyneuropathy affecting small and/or large axons resulting in paresthesias, hypoesthesias, dysesthesias and weakness have been reported in patients receiving quinolones, including levofloxacin. Levofloxacin should be discontinued if the patient experiences symptoms of neuropathy including pain, burning, tingling, numbness, and/or weakness or other alterations of sensation including light touch, pain, temperature, position sense, and vibratory sensation in order to prevent the development of an irreversible condition.

Renal

Safety and efficacy of levofloxacin in patients with impaired renal function (creatinine clearance ≤ 80 mL/min) have not been studied. Since levofloxacin is known to be substantially excreted by the kidney, the risk of toxic reactions to this drug may be greater in patients with impaired renal function. The potential effects of levofloxacin associated with possible increased serum/tissue levels in renal impaired patients, such as effect on QTc interval, have not been studied. Adjustment of the dosage regimen may be necessary to avoid the accumulation of levofloxacin due to decreased clearance. Careful clinical observation and appropriate laboratory studies should be performed prior to and during therapy, since elimination of levofloxacin may be reduced. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function. Administer levofloxacin with caution in the presence of renal insufficiency (See DOSAGE AND ADMINISTRATION; Recommended Dose and Dosage Adjustment, Patients with Impaired Renal Function, and DETAILED PHARMACOLOGY; Special Populations,

Renal Insufficiency).

Skin

Phototoxicity

Moderate to severe phototoxicity reactions have been observed in patients exposed to direct sunlight or ultraviolet (UV) light while receiving drugs in this class. Excessive exposure to sunlight or UV light should be avoided. However, in clinical trials with levofloxacin, phototoxicity has been observed in less than 0.1% of patients. Therapy should be discontinued if phototoxicity (e.g. skin eruption) occurs.

Special Populations

The safety and efficacy of levofloxacin tablets in children, adolescents (under the age of 18 years), pregnant women, and nursing mothers have not been established.

Pregnant Women: There are no adequate and well-controlled studies in pregnant women. Levofloxacin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus (see TOXICOLOGY).

Nursing Women: Levofloxacin has not been measured in human milk. Based upon data from ofloxacin, it can be presumed that levofloxacin can be excreted in human milk. Because of the potential for serious adverse reactions from levofloxacin in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother (see TOXICOLOGY).

Pediatrics (< 18 years of age): Levofloxacin is not indicated for the treatment of patients younger than 18 years of age. Quinolones, including levofloxacin, cause arthropathy in juvenile animals of several species (see TOXICOLOGY). The incidence of protocol-defined musculoskeletal disorders in a prospective long-term surveillance study was higher in children treated for approximately 10 days with levofloxacin than in children treated with non-fluoroquinolone antibiotics for approximately 10 days (see ADVERSE REACTIONS).

Geriatrics (≥ 65 years of age): The pharmacokinetic properties of levofloxacin in younger adults and elderly adults do not differ significantly when creatinine clearance is taken into consideration. However, since the drug is known to be substantially excreted by the kidney, the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection. It may also be useful to monitor renal function.

Elderly patients may be more susceptible to drug-associated effects on the QT interval (See WARNINGS AND PRECAUTIONS; Cardiovascular).

ADVERSE REACTIONS

Adverse Drug Reaction Overview

In North American Phase 3 clinical trials involving 7537 subjects, the incidence of treatment-emergent adverse events in patients treated with levofloxacin tablets was comparable to comparators. The majority of adverse events were considered to be mild to moderate, with 5.6% of patients considered to have severe adverse events. Among patients receiving multiple-dose therapy, 4.2% discontinued therapy with levofloxacin due to adverse experiences. The incidence of drug-related adverse reactions was 6.7%.

In clinical trials, the most frequently reported adverse drug reaction occurring in > 3% of the study population were nausea, headache, diarrhea, insomnia, dizziness and constipation.

Serious and otherwise important adverse drug reactions are discussed in greater detail in other sections (see WARNINGS AND PRECAUTIONS).

Clinical Trial Adverse Drug Reactions

Because clinical trials are conducted under very specific conditions the adverse reaction rates observed in the clinical trials may not reflect the rates observed in practice and should not be compared to the rates in the clinical trials of another drug. Adverse drug reaction information from clinical trials is useful for identifying drug-related adverse events and for approximating rates.

The data described below reflect exposure to levofloxacin in 7537 patients in 29 pooled Phase 3 clinical trials. The population studied had a mean age of 49.6 years (74.2% of the population was < 65 years), 50.1% were male, 71.0% were Caucasian, 18.8% were Black. Patients were treated with levofloxacin for a wide variety of infectious diseases (See INDICATIONS AND CLINICAL USE). Treatment duration was usually 3-14 days, the mean number of days on therapy was 9.6 days and the mean number of doses was 10.2. Patients received levofloxacin doses of 750 mg once daily, 250 mg once daily, or 500 mg once or twice daily. The overall incidence, type and distribution of adverse reactions was similar in patients receiving levofloxacin doses of 750 mg once daily, 250 mg once daily, and 500 mg once or twice daily.

Adverse reactions (characterized as likely related to drug-therapy) occurring in ≥1% of levofloxacin-treated patients is shown in Table 1 below.

Table 1. Common (≥1%) Adverse Reactions Reported in Clinical Trials with Levofloxacin

Less Common Clinical Trial Adverse Drug Reactions (<1%)

Less common adverse reactions occurring in 0.1 to <1% of levofloxacin-treated patients is shown in Table 2 below.

Table 2. Less Common (0.1 to 1%) Adverse Reactions Reported in Clinical Trials with Levofloxacin

a N = 7274

Rare (<0.1%) adverse reactions from Phase 3 studies include dyspnea and rash maculo-papular.

In clinical trials using multiple-dose therapy, ophthalmologic abnormalities, including cataracts and multiple punctate lenticular opacities, have been noted in patients undergoing treatment with other quinolones. The relationship of the drugs to these events is not presently established.

Crystalluria and cylindruria have been reported with other quinolones.

Abnormal Hematologic and Clinical Chemistry Findings

Laboratory abnormalities seen in > 2% of patients receiving multiple doses of levofloxacin: decreased glucose 2.1%

It is not known whether this abnormality was caused by the drug or the underlying condition being treated.

Pediatric Data

In a group of 1534 pediatric patients (6 months to 16 years of age) treated with levofloxacin for respiratory infections, children 6 months to 5 years of age received 10 mg/kg of levofloxacin twice a day for approximately 10 days and children greater than 5 years of age received 10 mg/kg to a maximum of 500 mg of levofloxacin once a day for approximately 10 days. The adverse reaction profile was similar to that reported in adult patients. Vomiting and diarrhea were reported more frequently in children than reported in adults. However, the frequency of vomiting and diarrhea was similar in levofloxacin-treated and non-fluoroquinolone antibiotic comparator-treated children.

A subset of 1340 of these children treated with levofloxacin for approximately 10 days was enrolled in a prospective, long term, surveillance study to assess the incidence of protocol-defined musculoskeletal disorders (arthralgia, arthritis, tendonopathy, gait abnormality) during 60 days and 1 year following the first dose of levofloxacin.

During the 60-day period following the first dose, the incidence of protocol-defined musculoskeletal disorders was greater in levofloxacin-treated children than in non-fluoroquinolone antibiotic comparator-treated children (2.1% v 0.9%, respectively [p=0.038]). In 22/28 (78%) of these children, reported disorders were characterized as arthralgia. A similar

observation was made during the 1-year period, with a greater incidence of protocol-defined musculoskeletal disorders in levofloxacin-treated children than in non-fluoroquinolone antibiotic comparator-treated children (3.4% v 1.8%, respectively [p=0.025]). The majority of these disorders occurring in children treated with levofloxacin were mild and resolved within 7 days. Disorders were moderate in 8 children and mild in 35 (76%) children.

Post-Market Adverse Drug Reactions

Table 3 lists adverse reactions that have been identified during post-approval use of levofloxacin. Because these reactions are reported voluntarily from a population of uncertain size, reliably estimating their frequency or establishing a causal relationship to drug exposure is not always possible.

Table 3: Postmarketing Reports of Adverse Drug Reactions

DRUG INTERACTIONS

Overview

Levofloxacin undergoes limited metabolism in humans and is primarily excreted as unchanged drug in the urine. The P450 system is not involved in the levofloxacin metabolism, and is not affected by levofloxacin. Levofloxacin is unlikely to alter the pharmacokinetics of drugs metabolized by these enzymes. Disturbances of blood glucose have been reported in patients treated concomitantly with levofloxacin and an antidiabetic agent. Therefore, careful monitoring of blood glucose is recommended when these agents, including levofloxacin, are co-administered. As with all other quinolones, iron and antacids significantly reduced bioavailability of levofloxacin.

Drug-Drug Interactions

Table 4- Established or Potential Drug-Drug Interactions

Proper name

Clinical comment Antacids, Sucralfate, Metal Cations, Multi-Vitamins

These agents should be taken at least 2 hours before or 2 hours after levofloxacin tablet administration

Theophylline

Theophylline levels should be closely monitored, and theophylline dosage adjustments made if appropriate, when levofloxacin is co-

administered. Adverse reactions, including seizures, may occur with or without an elevation in serum theophylline level (see WARNINGS AND PRECAUTIONS).

Warfarin

When these products are

administered concomitantly, prothrombin time, International Normalized Ratio (INR), or other suitable coagulation tests should be monitored closely, especially in the elderly patients.

Cyclosporine

No dosage adjustment is required for levofloxacin or cyclosporine when administered concomitantly.

Digoxin

No dosage adjustment for

levofloxacin or digoxin is required when administered concomitantly.

Probenecid and Cimetidine

Although the differences were statistically significant, the changes were not high enough to warrant dosage adjustment for levofloxacin when probenecid or cimetidine is co-administered.

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

The concomitant administration of a non-steroidal anti-inflammatory drug with a quinolone, including

levofloxacin, may increase the risk of CNS stimulation and convulsive seizures (see WARNINGS AND PRECAUTIONS; Neurologic and DETAILED PHARMACOLOGY: Animal Pharmacology).

Antidiabetic Agents

Careful monitoring of blood glucose is recommended when these agents, including levofloxacin, are co-administered.

Zidovudine

No dosage adjustment for levofloxacin appears to be required when co-administered with zidovudine.

Legend: C = Case Study; CT = Clinical Trial; T = Theoretical

Drug-Food Interactions

LEVOFLOXACIN may be taken with or without food.

Drug-Herb Interactions

Interactions with herbal products have not been established.

Drug-Laboratory Interactions

Some quinolones, including levofloxacin, may produce false-positive urine screening results for opiates using commercially available immunoassay kits. Confirmation of positive opiate screens by more specific methods may be necessary.

DOSAGE AND ADMINISTRATION

Dosing Considerations

The dosage of LEVOFLOXACIN (levofloxacin) tablets for patients with normal renal function (i.e. Cl_Cr > 80 mL/min) is described in the following dosing chart. For patients with altered renal function (i.e. Cl_Cr ≤ 80 mL/min), see the Patients with Impaired Renal Function subsection.

Recommended Dose and Dosage Adjustment

Patients with Normal Renal Function

Infection* Dose Freq. Duration**

500 mg q24h 7 days

Acute Bacterial Exacerbation of

Chronic Bronchitis

750 mg

q24h

5 days

500 mg q24h 7-14 days (10-14 days for severe infections)

Comm.-Acquired Pneumonia

750 mg*** q24h 5 days

Sinusitis 500 mg q24h 10-14 days 750 mg**** q24h 5 days Nosocomial Pneumonia 750 mg q24h 7-14 days Uncomplicated SSSI 500 mg q24h 7-10 days

Complicated SSSI 750 mg q24h 7-14 days Chronic Bacterial Prostatitis 500 mg q24h 28 days Complicated UTI 250 mg

750 mg‡

q24h

q24h 10 days

5 days Acute Pyelonephritis 250 mg

750 mg

q24h

q24h 10 days

5 days Uncomplicated UTI 250 mg q24h 3 days * DUE TO THE DESIGNATED PATHOGENS (see INDICATIONS AND CLINICAL USE). ** TOTAL THERAPY DURATION. When appropriate, patients may be converted from levofloxacin injection to an equivalent dose of levofloxacin tablets.

*** Efficacy of this alternative regimen has only been documented for infections caused by penicillin-susceptible Streptococcus pneumoniae, Haemophilus influenzae, Haemophilus parainfluenzae, Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila.

**** The efficacy of a regimen of 750mg daily for 5 days has been demonstrated to be non-inferior to a regimen of

500mg daily for 10 days. The 750mg daily 5 day regimen has not been compared to a regimen of 500mg daily for 11-14 days.

‡ The efficacy of this alternative regimen has been documented for infections caused by Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. Efficacy against infections caused by Enterococcus faecalis, Enterobacter cloacae, or Pseudomonas aeruginosa has not been demonstrated with this regimen.

Patients with Impaired Renal Function

On the basis of the altered levofloxacin disposition pharmacokinetics in subjects with impaired renal function, dose adjustment is recommended for patients with impaired renal function as given below (see ACTION AND CLINICAL PHARMACOLOGY, DETAILED PHARMACOLOGY; Special Populations, Renal Insufficiency and WARNINGS AND PRECAUTIONS; Renal).

Dosing recommendations for renally impaired patients are based on data collected from a clinical safety and pharmacokinetic study in renally impaired patients treated with a single 500 mg oral dose of levofloxacin. There is no clinical experience available in this patient population for the 250 mg dose or 750 mg dose. Pharmacokinetic modeling was used to determine a recommended dosing regimen which would provide equivalent drug exposures for which clinical efficacy has been demonstrated. The potential effects of levofloxacin associated with possible increased serum/tissue levels in renal-impaired patients, such as effect on QTc interval, have not been studied.

Renal Status Initial Dose Subsequent Dose

Acute Sinusitis / Acute Bacterial Exacerbation of Chronic Bronchitis / Community Acquired Pneumonia / Uncomplicated SSSI / Chronic Bacterial Prostatitis

Cl_Cr from 50 to 80 mL/min No dosage adjustment required Cl_Cr from 20 to 49 mL/min 500 mg 250 mg q24h Cl_Cr from 10 to 19 mL/min 500 mg 250 mg q48h Hemodialysis 500 mg 250 mg q48h CAPD 500 mg 250 mg q48h

Complicated UTI / Acute Pyelonephritis

Cl_Cr ≥ 20 mL/min No dosage adjustment required Cl_Cr from 10 to 19 mL/min 250 mg 250 mg q48h

Complicated SSSI / Nosocomial Pneumonia / Community Acquired Pneumonia / Acute Bacterial Exacerbation of Chronic Bronchitis/Acute Sinusitis/Complicated UTI/Acute Pyelonephritis

Cl_Cr from 50 to 80 mL/min No dosage adjustment required

Cl_Cr from 20 to 49 mL/min 750 mg 750 mg q48h Cl_Cr from 10 to 19 mL/min 750 mg 500 mg q48h Hemodialysis 750 mg 500 mg q48h CAPD 750 mg 500 mg q48h Uncomplicated UTI No dosage adjustment required Cl_Cr = creatinine clearances

CAPD = chronic ambulatory peritoneal dialysis

When only the serum creatinine is known, the following formula may be used to estimate creatinine clearance.

Men: Creatinine Clearance (mL/min)

= Weight (kg) x (140 – age) x 1.2

Serum creatinine (μmol/L)

Women: 0.85 x the value calculated for men.

The serum creatinine should represent a steady state of renal function.

Missed Dose

More than the prescribed dose of LEVOFLOXACIN should not be taken, even if a dose is missed.

Administration

LEVOFLOXACIN can be administered without regard to food. Doses should be administered at least 2 hours before or 2 hours after antacids containing calcium, magnesium, aluminum, sucralfate, metal cations such as iron, multi-vitamin preparations with zinc, or products containing any of these components.

OVERDOSAGE

In the event of an acute overdosage, the stomach should be emptied. The patient should be observed, including ECG monitoring (see ACTION AND CLINICAL PHARMACOLOGY; Studies Measuring Effects on QT and Corrected QT (QTc) Intervals), and appropriate hydration maintained. Treatment should be supportive. Levofloxacin is not efficiently removed by hemodialysis or peritoneal dialysis.

The administration of activated charcoal as soon as possible after oral overdose may prevent excessive increase of systemic levofloxacin exposure.

Levofloxacin exhibits a low potential for acute toxicity. Mice, rats, dogs and monkeys exhibited the following clinical signs after receiving a single high dose of levofloxacin: ataxia, ptosis, decreased locomotor activity, dyspnea, prostration, tremors, and convulsions. Doses in excess of 1500 mg/kg orally produced significant mortality in rodents.

For management of a suspected drug overdose, contact your regional Poison Control Centre.

ACTION AND CLINICAL PHARMACOLOGY

Mechanism of Action

Levofloxacin is a synthetic broad-spectrum antibacterial agent for oral administration.

Levofloxacin is the L-isomer of the racemate, ofloxacin, a quinolone antibacterial agent. The antibacterial activity of ofloxacin resides primarily in the L-isomer. The mechanism of action of levofloxacin and other quinolone antibacterials involves inhibition of bacterial topoisomerase II (DNA gyrase) and topoisomerase IV. Topoisomerases are essential in controlling the topological state of DNA, and are vital for DNA replication, transcription, repair and recombination.

Fluoroquinolones, including levofloxacin, differ in chemical structure and mode of action from other classes of antimicrobial agents, such as β-lactam antibiotics, aminoglycosides, and macrolides. Therefore, microorganisms resistant to these latter classes of antimicrobial agents may be susceptible to fluoroquinolones. For example, β-lactamase production and alterations in penicillin-binding proteins have no effect on levofloxacin activity. Conversely, microorganisms resistant to fluoroquinolones may be susceptible to other classes of antimicrobial agents.

Pharmacodynamics

Studies Measuring Effects on QT and Corrected QT (QTc) Intervals

Two studies have been conducted to assess specifically the effect of levofloxacin on QT and corrected QT (QTc) intervals in healthy adult volunteers. In a dose escalation study (n=48) where the effect on average QTc, after single doses of 500, 1000, and 1500 mg of levofloxacin, was measured between the baseline QTc (calculated as the average QTc measured 24, 20, 16 hours and immediately before treatment) and the average post-dose QTc interval (calculated from measurements taken every half hour for two hours and at 4, 8, 12 and 24 hours after treatment), an effect on the average QTc (Bazett) was –1.84, 1.55 and 6.40 msec, respectively. In a study which compared the effect of 3 antimicrobials (n=48) where the difference was measured between the baseline QTc (calculated as the average QTc measured 24, 20, 16 hours and immediately before treatment) and the average post-dose QTc interval (calculated from measurements taken every half hour for four hours and at 8, 12 and 24 hours after treatment), an effect on the average QTc was an increase of 3.58 msec after the 1000 mg dose of levofloxacin. The mean increase compared to baseline of QTc at C_max in these two trials was 7.82 msec and 5.32 msec after a single 1000 mg dose. In these trials, no effect on QT intervals compared to placebo was evident at any of the doses studied. The clinical relevance of the results of these studies is not known (see DETAILED PHARMACOLOGY; Human Pharmacology; Studies Measuring the Effects on QT and Corrected QT (QTc) Intervals).

Pharmacokinetics

The mean (± SD) pharmacokinetic parameters of levofloxacin determined under single and steady-state conditions following oral (p.o.) of levofloxacin are summarized in the following table.

Table 1.2 - Summary of Pharmacokinetic Parameters (mean ± SD)

C_max T_max AUC ^j CL/F Vd/F t_½ Cl_r Regimen N

(μg/mL) (h) (μg•h/mL) (mL/min) (L) (h) (mL/min) Single Dose

250 mg p.o. ^a 15 2.8 ± 0.4 1.6 ± 1.0 27.2 ± 3.9 156 ± 20 ND 7.3 ± 0.9 142 ± 21 500 mg p.o. ^a* 23 5.1 ± 0.8 1.3 ± 0.6 47.9 ± 6.8 178 ± 28 ND 6.3 ± 0.6 103 ± 30 750 mg p.o. ^cc 10 7.1 ± 1.4 1.9 ± 0.7 82.2 ± 14.3 157 ± 28 90 ± 14 7.7 ± 1.3 118 ± 28

Multiple dose

500 mg q24h p.o. ^a 10 5.7 ± 1.4 1.1 ± 0.4 47.5 ± 6.7 ^x 175 ± 25 102 ± 22 7.6 ± 1.6 116 ± 31 750 mg q24h p.o. ^cc 10 8.6 ± 1.9 1.4 ± 0.5 90.7 ± 17.6 143 ± 29 100 ± 16 8.8 ± 1.5 116 ± 28

500 mg p.o. single dose, effects of gender and age:

male ^e 12 5.5 ± 1.1 1.2 ± 0.4 54.4 ± 18.9 166 ± 44 89 ± 13 7.5 ± 2.1 126 ± 38 female ^f 12 7.0 ± 1.6 1.7 ± 0.5 67.7 ± 24.2 136 ± 44 62 ± 16 6.1 ± 0.8 106 ± 40 young ^g 12 5.5 ± 1.0 1.5 ± 0.6 47.5 ± 9.8 182 ± 35 83 ± 18 6.0 ± 0.9 140 ± 33 elderly ^h 12 7.0 ± 1.6 1.4 ± 0.5 74.7 ± 23.3 121 ± 33 67 ± 19 7.6 ± 2.0 91 ± 29

500 mg p.o. single dose, patients with renal insufficiency:

Cl_Cr 50-80 mL/min 3 7.5 ± 1.8 1.5 ± 0.5 95.6 ± 11.8 88 ± 10 ND 9.1 ± 0.9 57 ± 8 Cl_Cr 20-49 mL/min 8 7.1 ± 3.1 2.1 ± 1.3 182.1 ± 62.6 51 ± 19 ND 27 ± 10 26 ± 13 Cl_Cr <20 mL/min 6 8.2 ± 2.6 1.1 ± 1.0 263.5 ± 72.5 33 ± 8 ND 35 ± 5 13 ± 3 Hemodialysis 4 5.7 ± 1.0 2.8 ± 2.2 ND ND ND 76 ± 42 ND CAPD 4 6.9 ± 2.3 1.4 ± 1.1 ND ND ND 51 ± 24 ND ^a healthy males 18-53 years of age;

^c healthy male subjects 32-46 years of age;

^cc healthy male subjects 19-51 years of age;

^d including 500 mg q48h for 8 patients with moderate renal impairment (Cl_Cr 20-50 mL/min) and infections of the respiratory tract or skin; ^e healthy males 22-75 years of age;

^f healthy females 18-80 years of age;

^g young healthy male and female subjects 18-36 years of age;

^h healthy elderly male and female subjects 66-80 years of age;

^j AUC for 0-∞ reported, unless otherwise specified;

x AUC0-24 h;

^* Absolute bioavailability; F = 0.99 ± 0.08 from a 500 mg tablet and F = 0.99 ± 0.06 from a 750 mg tablet

ND = Not Determined

Absorption:

Levofloxacin is rapidly and essentially completely absorbed after oral administration. Peak plasma concentrations are usually attained 1 to 2 hours after oral dosing. The absolute bioavailability of a 500 mg tablet and a 750 mg tablet of levofloxacin is approximately 99% in both cases, demonstrating complete oral absorption of levofloxacin. Levofloxacin pharmacokinetics are linear and predictable after single and multiple oral dosing regimens. Steady-state conditions are reached within 48 hours following a 500 mg or 750 mg once-daily dosage regimen. The peak and trough plasma concentrations attained following multiple once-daily oral dosage regimens were approximately 5.7 μg/mL and 0.5 μg/mL after the 500 mg doses, and 8.6 μg/mL and 1.1 μg/mL after the 750 mg doses, respectively.

There was no clinically significant effect of food on the extent of absorption of levofloxacin. Oral administration with food slightly prolongs the time to peak concentration by approximately 1 hour, and slightly decreases the peak concentration by approximately 14%. Therefore, levofloxacin can be administered without regard to food.

The plasma concentration profile of levofloxacin after i.v. administration is similar and comparable in extent of exposure (AUC) to that observed for levofloxacin tablets when equal doses (mg/mL) are administered. Therefore, the oral and i.v. routes of administration can be considered interchangeable (see following figure).

Distribution:

The mean volume of distribution of levofloxacin generally ranges from 74 to 112 L after single and multiple 500 mg or 750 mg doses, indicating widespread distribution into body tissues. Levofloxacin reaches its peak levels in skin tissues (11.7 µg/g for a 750 mg dose) and in blister fluid (4.33 µg/g for a 500 mg dose) at approximately 3-4 hours after dosing. The skin tissue biopsy to plasma AUC ratio is approximately 2. The blister fluid to plasma AUC ratio is approximately 1, following multiple once-daily oral administration of 750 mg and 500 mg levofloxacin to healthy subjects, respectively. Levofloxacin also penetrates into lung tissues. Lung tissue concentrations were generally 2- to 5-fold higher than plasma concentrations, and ranged from approximately 2.4 to 11.3 µg/g over a 24-hour period after a single 500 mg oral dose.

Levofloxacin is 24 to 38% bound to serum proteins across all species studied. Levofloxacin binding to serum proteins is independent of the drug concentration.

Metabolism:

Levofloxacin is stereochemically stable in plasma and urine, and does not invert metabolically to its enantiomer, D-ofloxacin. Levofloxacin undergoes limited metabolism in humans, and is primarily excreted as unchanged drug (87%) in the urine within 48 hours.

Excretion:

The major route of elimination of levofloxacin in humans is as unchanged drug in the urine. The mean terminal plasma elimination half-life of levofloxacin ranges from approximately 6 to 8 hours following single or multiple doses of levofloxacin given orally or intravenously.

Special Populations and Conditions

Pediatrics: The pharmacokinetics of levofloxacin in pediatric patients have not been studied.

Geriatrics: There are no significant differences in levofloxacin pharmacokinetics between young and elderly subjects when the subjects’ differences in creatinine clearance are taken into consideration. Drug absorption appears to be unaffected by age. Levofloxacin dose adjustment based on age alone is not necessary.

Gender: There are no significant differences in levofloxacin pharmacokinetics between male and female subjects when the differences in creatinine clearance are taken into consideration. Dose adjustment based on gender alone is not necessary.

Race: The apparent total body clearance and apparent volume of distribution were not affected by race in a covariate analysis performed on data from 72 subjects.

Hepatic Insufficiency: Pharmacokinetic studies in hepatically impaired patients have not been conducted. Due to the limited extent of levofloxacin metabolism, the pharmacokinetics of levofloxacin are not expected to be affected by hepatic impairment.

Renal Insufficiency: Pharmacokinetic parameters of levofloxacin following oral doses of levofloxacin in patients with impaired renal function (creatinine clearance ≤ 80 mL/min) are presented in Table 1.2. Clearance of levofloxacin is reduced and plasma elimination half-life is prolonged in this patient population. Dosage adjustment may be required in such patients to avoid accumulation.

A dosage reduction is being recommended depending on the levels of renal insufficiency. Dosing recommendations are based on pharmacokinetic modeling of data collected from a clinical safety and pharmacokinetic study in renally impaired patients treated with a single 500 mg oral dose of levofloxacin (see WARNINGS AND PRECAUTIONS; Renal, and DOSAGE AND ADMINISTRATION; Recommended Dose and Dosage Adjustment, Patients with Impaired Renal Function).

Neither hemodialysis nor continuous ambulatory peritoneal dialysis (CAPD) is effective in removal of levofloxacin from the body, indicating supplemental doses of levofloxacin are not required following hemodialysis or CAPD.

Bacterial Infection: The pharmacokinetics of levofloxacin in patients with community-acquired bacterial infections are comparable to those observed in healthy subjects.

STORAGE AND STABILITY

LEVOFLOXACIN tablets should be stored at room temperature (15-30°C) in well-closed containers.

DOSAGE FORMS, COMPOSITION AND PACKAGING

Dosage Forms

LEVOFLOXACIN tablets are available as:

250 mg tablets: Pink, film-coated, oval-shaped, biconvex tablet with ‘LO 250’ on one side and “ ” on the other.

500 mg tablets: Peach-coloured, film-coated, oval-shaped, biconvex tablet with ‘LO 500’ on one side and “ ” on the other.

750 mg tablets: White to off-white, film-coated, oval-shaped, biconvex tablet with ‘LO

750’ on one side and “ ” on the other.

Composition

Each tablet contains either 250, 500 or 750 mg of levofloxacin (as levofloxacin hemihydrate) as the active ingredient and the following inactive ingredients: colloidal anhydrous silica, crospovidone, hydroxypropylcellulose, microcrystalline cellulose and sodium stearyl fumarate.

The film coatings contain:

250 mg: FD&C blue #1, FD&C red #40, FD&C yellow #6, iron oxide red, polyethylene glycol, polyvinyl alcohol, talc and titanium dioxide.

500 mg: iron oxide black, iron oxide red, iron oxide yellow, polyethylene glycol, polyvinyl alcohol, talc and titanium dioxide.

750 mg: polyethylene glycol, polyvinyl alcohol, titanium oxide and talc.

Packaging

LEVOFLOXACIN tablets are available in HDPE bottles of 50 and 100 tablets and PVC/PVDC foil blister packs of 10 tablets.

PART II: SCIENTIFIC INFORMATION

PHARMACEUTICAL INFORMATION

Drug Substance

Common name: Levofloxacin hemihydrate

Chemical name: (S)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H-pyrido[1,2,3-de]-1,4-benzoxazine-6-carboxylic acid hemihydrate

Molecular formula: C₁₈H₂₀FN₃O₄ • ½ H₂0

Molecular mass: 370.37

Structural formula:

N

F

N

1/2 H₂O

OH

O

O

O

N

H3C H

CH₃

Physicochemical properties

Solubility: Freely soluble in acetic acid; slightly soluble in water, methanol and ethanol

Melting point: 228°C - 230°C (decomposition)

pK_a values: pK_a1 = 5.33; pK_a2 = 8.07

CLINICAL TRIALS

Comparative bioavailability

A blinded, single-dose, randomized, two-way crossover, comparative bioavailability study of LEVOFLOXACIN 750 mg tablets against the Canadian Reference Product, Levaquin^TM (levofloxacin tablets, 750 mg), has been performed on 16 healthy adult volunteers (male and female) under fasting conditions. Statistical analysis was performed on data from 12 subjects (7 females and 5 males). A summary of the bioavailability data is presented in the table below.

^# LEVOFLOXACIN 750 mg Tablets ^† The reference product, Levaquin^® 750 mg Tablets (Janssen-Ortho Inc.) was purchased in Canada. ^§ Expressed as the arithmetic mean (CV%) only. * Calculated using the least-square means.

Acute Sinusitis

Study demographics and trial design

Table 2.1 – Summary of patient demographics for clinical trials in Acute Sinusitis

Study #

Gender

Male/female

152/237 CAPSS-232

115/191 M92-040

N93-006

^a Subjects enrolled and randomized to treatment.

^b 780 outpatient adults with clinically and radiologically determined acute maxillary sinusitis (ITT population)

Study Results

5 Day Treatment Regimen

Table 2.2 – Results of study CAPSS-232 in Acute Sinusitis

Endpoints

95% Confidence

Interval^c

Clinical Success Rate^a.b

(-4.8, 12.1)

Microbiologic Eradication Rate^d

(-9.7, 4.1)

^a Test-of-Curve visit 17 to 22 days after first dose of active study drug (7-12 days after last dose for 500 mg arm, 12-17 days after last dose for 750 mg arm) in microbiologically clinically evaluable population (subset of 462 patients where sinus samples were taken by sinus puncture).

_b Clinical success was defined as complete (cured) or partial (improved) resolution of pre-treatment signs and symptoms of ABS to such extent that no further antibiotic treatment was deemed necessary

^c Two-sided 95% CIs (with continuity correction) around the difference in response rates

^d Microbiologically evaluable population

Table 2.3 – Clinical Success Rates^a for Microbiologically Evaluable Population^b (CAPSS-232)

Pathogen

Comparator n/N (%)

Streptococcus pneumoniae

Haemophilus influenzae

Moraxella catarrhalis

^a Eradication rate for the three pathogens was the same as clinical success rate because microbiological success was presumed based on clinical success.

^b Subset of 462 patients where sinus samples were taken by sinus puncture

10-14 day Treatment Regimen

Table 2.4 – Clinical Success^a in Pivotal Acute Sinusitis Studies – Clinically Evaluable Subjects

Study Number

95% Confidence

Interval

M92-040

(-6.8, 4.6) N93-006

N/A ^a cured plus improved

Table 2.5 – Microbiologic Eradication in Pivotal Acute Sinusitis Studies – Microbiologically Evaluable Subjects

Study Number

95% Confidence

Interval

M92-040

N/A N93-006

N/A

Table 2.6 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (N93-006)

Pathogen Levofloxacin

n/N (%)

Haemophilus influenzae 35/36 (97.2) Streptococcus pneumoniae 32/32 (100.0) Staphylococcus aureus 31/33 (93.9) Moraxella (Branhamella) catarrhalis 14/15 (93.3)

Community Acquired Pneumonia

Study demographics and trial design

Table 2.7 – Summary of patient demographics for clinical trials in Community Acquired Pneumonia

Study #

Gender Male/female

148/108 CAPSS-150

162/133 K90-071

M92-075

^a Subjects enrolled and randomized to treatment.

^b 528 outpatient and hospitalized adults with clinically and radiologically determined mild to severe community-acquired pneumonia

Study Results

5 Day Treatment Regimen

Table 2.8– Results of study CAPSS-150 in Community Acquired Pneumonia

Endpoints

95% Confidence

Interval^c

Clinical Success Rate^a,b

(-7.0, 4.4) Microbiologic Eradication Rate^d

(-8.6, 7.0) ^a 7-14 days after last dose of active study medication for clinically evaluable population

^b success rates include the clinical response category of cured and improved

^c two-sided 95% CIs (with continuity correction) around the difference in response rates

^d 7-14 days after last dose of active study medication for microbiologically evaluable population

In the clinically evaluable population (31-38 days after enrollment) pneumonia was observed in 7 out of 151 patients in the levofloxacin 750 mg group and 2 out of 147 patients in the levofloxacin 500 mg group. Given the small numbers observed, the significance of this finding cannot be determined statistically.

Table 2.9 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (5-day regimen)

Pathogen Levofloxacin 750 mg

n/N (%)

Penicillin susceptible S. pneumoniae 19/22 (86.4)

Haemophilus influenzae 12/13 (92.3)

Haemophilus parainfluenzae 12/12 (100.0)

Mycoplasma pneumoniae 32/34 (94.1)

Chlamydia pneumoniae 20/22 (90.9)

Legionella pneumophila 12/12 (100.0)

7 to 14 day Treatment Regimen

In three North American clinical studies, of 655 patients treated with levofloxacin for community-acquired pneumonia, 45 clinically and microbiologically evaluable patients were defined as severely ill by study criteria and met American Thoracic Society criteria for severe community-acquired pneumonia (American Thoracic Society, 1993). Clinical success (cure and improvement) was achieved in 98% of these 45 patients. Data on the treatment of patients with severe Legionella pneumonia is limited to one patient.

Data on the treatment of community-acquired pneumonia due to penicillin-resistant S. pneumoniae is limited to 12 evaluable patients from the combined clinical trials database. Of these, 4 were considered to have been severe. All 12 patients achieved clinical success (see MICROBIOLOGY).

The following tables describe the results from the two pivotal trials for community-acquired pneumonia (7-14 day treatment regimen).

Table 2.10 – Clinical Success^a in Pivotal Community Acquired Pneumonia Studies – Clinically Evaluable Subjects

Study Number

95% Confidence

Interval

K90-071

(-10.7, -1.3) M92-075

N/A ^a cured plus improved

Table 2.11 – Microbiologic Eradication in Pivotal Community Acquired Pneumonia Studies – Microbiologically Evaluable Subjects

Study Number

95% Confidence

Interval

K90-071

(-17.1, -4.7) M92-075

N/A

Table 2.12 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (K90-071)

Pathogen Levofloxacin

n/N (%)

Comparator n/N (%)

Chlamydia pneumoniae 46/47 (97.9) 49/53 (92.5) Streptococcus pneumoniae 39/39 (100.0) 39/40 (97.5) Haemophilus influenzae 30/30 (100.0) 19/24 (79.2) Mycoplasma pneumoniae 19/19 (100.0) 22/22 (100.0) Staphylococcus aureus 10/10 (100.0) 9/9 (100.0) Haemophilus parainfluenzae 7/8 (87.5) 15/21 (71.4) Moraxella (Branhamella) catarrhalis 7/7 (100.0) 6/7 (85.7) Legionella pneumophila 5/5 (100.0) 3/4 (75.0) Klebsiella pneumoniae 3/3 (100.0) 8/8 (100.0)

Table 2.13 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (M92-075)

Pathogen Levofloxacin

n/N (%)

Chlamydia pneumoniae 71/75 (94.7)

Streptococcus pneumoniae 43/44 (97.7)

Haemophilus influenzae 38/39 (97.4)

Staphylococcus aureus 10/12 (83.3)

Moraxella (Branhamella) catarrhalis 11/11 (100.0)

Mycoplasma pneumoniae 10/10 (100.0)

Haemophilus parainfluenzae 8/9 (88.9)

Klebsiella pneumoniae 7/7 (100.0)

Legionella pneumonphila 4/5 (80.0)

Acute Bacterial Exacerbation of Chronic Bronchitis

Study demographics and trial design

Table 2.14 – Summary of patient demographics for clinical trials in Acute Bacterial Exacerbation of Chronic Bronchitis

Study #

Gender male/female

CAPSS-197

K90-070

124/124 M92-024

^a Subjects enrolled and randomized to treatment

^b From ITT population. Study subjects were characterized by FEV₁<50% predicted, or FEV₁ between 50% and 65% predicted, with ≥4 exacerbations in the preceding 12 months and/or the presence of significant co-morbidity. About half (48.2%) of the subjects were current smokers, with a mean pack-year history of 42.4.

Study Results

5 Day Treatment Regimen

Table 2.15 – Results of study CAPSS-197 in Acute Bacterial Exacerbation of Chronic Bronchitis

Endpoints

95% Confidence

Interval^d

Clinical Success Rate^a

(-7.8, 12.9)

Microbiologic Eradication Rate^e

(-13.9, 10.7)

^a 17 to 26 days after the first dose of study drug for clinical evaluable subjects

^b Success rates include the clinical response category of cured and improved

^c Difference in success rates

^d Two-sided 95% CIs (with continuity correction) around the difference (amoxicillin/clavulanate minus levofloxacin) in clinical success rates

^e Microbiologically evaluable population

Table 2.16 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population

Pathogen Levofloxacin

n/N (%)

Comparator n/N (%)

Staphylococcus aureus 4/5 (80.0) 3/5 (60.0) Streptococcus pneumoniae 16/18 (88.9) 10/13 (76.9) Haemophilus influenzae 25/30 (83.3) 20/20 (100.0) Haemophilus parainfluenzae 18/20 (90.0) 15/18 (83.3) Moraxella catarrhalis 10/12 (83.3) 16/19 (84.2)

7 day Treatment Regimen

Table 2.17 – Clinical Success^a in Pivotal Acute Bacterial Exacerbation of Chronic Bronchitis Studies – Clinically Evaluable Subjects

Study Number

95% Confidence

Interval

K90-070

(-6.5, 6.6) M92-024

(-6.8, 2.7) ^a Cured plus improved

Table 2.18 – Microbiologic Eradication in Pivotal Acute Bacterial Exacerbation of Chronic Bronchitis Studies

• Microbiologically Evaluable Subjects

Study Number

95% Confidence

Interval

K90-070

(-16.6, 1.3) M92-024

(-8.6, 2.5)

Table 2.19 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (K90-070)

Pathogen Levofloxacin

n/N (%)

Comparator n/N (%)

Haemophilus influenzae 21/21 (100.0) 17/24 (70.8) Moraxella (Branhamella) catarrhalis 18/19 (94.7) 8/8 (100.0) Haemophilus parainfluenzae 14/15 (93.3) 7/7 (100.0) Pseudomonas aeruginosa 8/10 (80.0) 11/14 (78.6) Streptococcus pneumoniae 9/10 (90.0) 6/7 (85.7) Staphylococcus aureus 8/9 (88.9) 2/3 (66.7)

Table 2.20 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (M92-024)

Pathogen Levofloxacin

n/N (%)

Comparator n/N (%)

Haemophilus influenzae 42/44 (95.5) 29/31 (93.5) Haemophilus parainfluenzae 27/27 (100.0) 30/32 (93.8) Moraxella (Branhamella) catarrhalis 25/25 (100.0) 29/32 (90.6) Streptococcus pneumoniae 14/16 (87.5) 10/10 (100.0) Staphylococcus aureus 10/10 (100.0) 34/35 (97.1) Pseudomonas aeruginosa 9/10 (90.0) 8/9 (88.9)

Nosocomial Pneumonia

Study demographics and trial design

Table 2.21 – Summary of patient demographics for clinical trials in Nosocomial Pneumonia

Study #

Gender Male/female

CAPSS-117

^a Subjects enrolled and randomized to treatment

Table 2.22– Results of study CAPSS-117 in Nosocomial Pneumonia

Endpoints

95% Confidence

Interval

Clinical Success Rate^a

(-9.9, 16.2) Microbiologic Eradication Rate^b

(-20.3, 8.3) ^a Success includes Cured and Improved; clinically evaluable population

^b overall microbiologic eradication rates by subject for microbiologically evaluable population

Table 2.23 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (CAPSS-117)

Pathogen

Comparator n/N (%)

Staphylococcus aureus

Pseudomonas aeruginosa

Haemophilus influenzae

Escherichia coli

Klebsiella pneumoniae

Serratia marcescenes

Streptococcus pneumoniae

Uncomplicated Skin and Skin Structure Infections

Study demographics and trial design

Table 2.24 – Summary of patient demographics for clinical trials in Uncomplicated Skin and Skin Structure Infections

Study #

Gender male/female

124/107 K90-075

67/69 L91-031

^a Subjects enrolled and randomized to treatment.

Study Results

Table 2.25 – Clinical Success^a in Pivotal Uncomplicated Skin and Skin Structure Infection Studies – Clinically Evaluable Subjects

Study Number

95% Confidence

Interval

K90-075

(-7.7, 0.7) L91-031

(-8.4, 3.3) ^a cured plus improved

Table 2.26 – Microbiologic Eradication in Pivotal Uncomplicated Skin and Skin Structure Infection Studies – Microbiologically Evaluable Subjects

Study Number

95% Confidence

Interval

K90-075

(-14.5, -2.7) L91-031

(-11.7, 5.1)

Table 2.27 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (K90-075)

Pathogen Levofloxacin

n/N (%)

Comparator n/N (%)

Staphylococcus aureus 87/87 (100.0) 76/87 (87.4) Streptococcus pyogenes 14/14 (100.0) 18/20 (90.0) Pseudomonas aeruginosa 7/8 (87.5) 10/10 (100.0)

Table 2.28 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (L91-031)

Pathogen Levofloxacin

n/N (%)

Comparator n/N (%)

Staphylococcus aureus 66/70 (94.3) 70/75 (93.3) Streptococcus pyogenes 17/18 (94.4) 12/13 (92.3) Pseudomonas aeruginosa 5/5 (100.0) 5/5 (100.0)

Complicated Skin and Skin Structure Infections

Study demographics and trial design

Table 2.29– Summary of patient demographics for clinical trials in Complicated Skin and Skin Structure Infections

Study #

Gender male/female LOFBIV-SSS-040

^a Subjects enrolled and randomized to treatment.

Table 2.30 – Results of study LOFBIV-SSS-040 in Complicated Skin and Skin Structure Infections

Endpoints

95% Confidence

Interval

Clinical Success Rate^a

(-13.3, 5.8) Microbiologic Eradication Rate^b

(-24.3, -0.2) ^a Success includes Cured and Improved; clinically evaluable population

^b overall microbiologic eradication rates by subject for microbiologically evaluable population

Table 2.31 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (LOFBIV-SSS-040)

Pathogen

Comparator n/N (%)

Staphylococcus aureus

Streptococcus faecalis

Streptococcus pyogenes

Proteus mirabilis

Streptococcus agalactiae

Pseudomonas aeruginosa

Complicated Urinary Tract Infection and Acute Pyelonephritis

Study demographics and trial design

Table 2.32 – Summary of patient demographics for clinical trials in Complicated Urinary Tract Infection (cUTI) and Acute Pyelonephritis (AP)

Study #

Gender male/female

207/330 CAPSS-349

117/168 L91-058

L91-059

^a Subjects enrolled and randomized to treatment. ^b Intent-to-treat population. Patients with AP complicated by underlying renal diseases or conditions such as complete obstruction, surgery, transplantation, concurrent infection or congenital malformation were excluded.

Study Results

5 Day Treatment Regimen

Table 2.33 – Clinical Success^a in Complicated Urinary Tract Infection (cUTI) and Acute Pyelonephritis (AP)

• Microbiologically Evaluable Subjects

Study Number

95% Confidence

Interval^b

CAPSS-349

(-3.8, 7.7) ^a Clinical success includes subjects who were cured or improved at the Posttherapy Visit

^b Two-sided 95% confidence interval around the difference (comparator minus levofloxacin).

Table 2.34 – Results of Study CAPSS-349 in Complicated Urinary Tract Infection (cUTI) and Acute Pyelonephritis (AP)

Primary

Endpoints

95%

Confidence Interval^g mITT Population^b,c

(-6.6, 6.9)

(-7.0, 9.8)

(-14.4, 7.6) Microbiologically Evaluable Population^d,e

(-2.5, 8.9)

(-3.4, 11.4) Microbiologic Eradication^a

(-7.1, 8.9) ^a At posttherapy visit (10-14 days after last active dose of levofloxacin and 5-9 days after last active dose of ciprofloxacin). ^b The mITT population included patients who had a clinical diagnosis of AP or cUTI and who had a positive (≥10⁵ CFU/mL) urine culture with no more than 2 uropathogens at Study Entry.

^c In the mITT population there were a limited number of patients treated with IV therapy (levofloxacin-8, comparator-9), with catheters (levofloxacin-4, comparator-5) and with bacteremia (levofloxacin-13, comparator-12). ^d The microbiologically evaluable population included patients with a confirmed diagnosis of cUTI or AP according to the protocol-specified inclusion criteria and with a known uropathogen with adequate growth (≥ 10⁵ CFU/mL) who met all other microbiologic evaluability criteria.

^e In the microbiologically evaluable population there were a limited number of patients treated with IV therapy (levofloxacin-4, comparator-3), with catheters (levofloxacin-3, comparator-3) and with bacteremia (levofloxacin-10, comparator-8). ^f Difference in eradication rates (comparator minus levofloxacin)

^g Two-sided 95% confidence interval around the difference (comparator minus levofloxacin) in microbiologic eradication rates.

Table 2.35 – Microbiologic Eradication Rates by Pathogen at Posttherapy Visit

Table 2.36 – Relapse Rates at Post-Study Visit^a

^a 33-40 days after the last active dose of levofloxacin and 28-35 days after the last active dose of ciprofloxacin

10 Day Treatment Regimen

Table 2.37 – Clinical Success^a in Pivotal cUTI and AP Studies – Microbiologically Evaluable Subjects

Study Number

95% Confidence

Interval

L91-058

(-7.6, 4.7) L91-059

(-9.2, 2.0) ^a cured plus improved

Table 2.38 – Microbiologic Eradication in Pivotal cUTI and AP Studies – Microbiologically Evaluable Subjects

Study Number

95% Confidence

Interval

L91-058

(-5.4, 6.0) L91-059

(-7.0, 2.8)

Table 2.39 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (L91-058)

Pathogen Levofloxacin

n/N (%)

Comparator n/N (%)

Escherichia coli 88/92 (95.7) 96/99 (97.0) Klebsiella pneumoniae 31/32 (96.9) 22/23 (95.7) Streptococcus faecalis 8/9 (88.9) 6/11 (54.5) Proteus mirabilis 13/14 (92.9) 5/5 (100.0) Pseudomonas aeruginosa 7/12 (58.3) 7/7 (100.0) Enterobacter cloacae 9/9 (100.0) 4/4 (100.0)

Table 2.40 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (L91-059)

Pathogen Levofloxacin

n/N (%)

Comparator n/N (%)

Escherichia coli 118/119 (99.2) 116/118 (98.3) Klebsiella pneumoniae 29/31 (93.5) 23/25 (92.0) Proteus mirabilis 11/11 (100.0) 9/9 (100.0) Streptococcus faecalis 4/8 (50.0) 6/8 (75.0) Pseudomonas aeruginosa 8/9 (88.9) 4/6 (66.7) Enterobacter cloacae 6/7 (85.7) 4/6 (66.7)

Uncomplicated Urinary Tract Infections

Study demographics and trial design

Table 2.41 – Summary of patient demographics for clinical trials in Uncomplicated Urinary Tract Infections

Study #

Gender Male/female

LOFBO-UTI-060

^a Subjects enrolled and randomized to treatment.

Study Results

Table 2.42 – Results of Study LOFBO-UTI-060 in Uncomplicated Urinary Tract Infections

Endpoints

95% Confidence

Interval

Clinical Success Rate^a

(-4.8, 2.6) Microbiologic Eradication Rate^b

(-8.7, 1.8) ^a Success includes Cured and Improved; microbiologically evaluable population

^b Overall microbiologic eradication rates by subject for microbiologically evaluable population

Table 2.43 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (LOFBO-UTI-060)

Pathogen Levofloxacin

n/N (%)

Comparator n/N (%)

Escherichia coli 125/127 (98.4) 131/138 (94.9) Klebsiella pneumoniae 10/11 (90.9) 8/8 (100.0) Staphylococcus saprophyticus 8/8 (100.0) 3/3 (100.0) Staphylococcus aureus 5/5 (100.0) 3/3 (100.0)

Chronic Bacterial Prostatitis

Study demographics and trial design

Table 2.44 – Summary of patient demographics for clinical trials in Chronic Bacterial Prostatitis

Study #

Gender Male/female

CAPSS-101

^a Subjects enrolled and randomized to treatment.

Study Results

Table 2.45 – Results of Study CAPSS-101 in Chronic Bacterial Prostatitis

Endpoints

95% Confidence

Interval

Clinical Success Rate^a

(-11.15, 9.34) Microbiologic Eradication Rate^b

(-8.98, 12.58) ^a Success includes Cured and Improved; mITT

^b Overall microbiologic eradication rates by subject for microbiologically evaluable population

Table 2.46 – Microbiologic Eradication Rates by Pathogen for Microbiologically Evaluable Population (CAPSS-101)

Pathogen

Comparator n/N (%)

Escherichia coli

Enterococcus faecalis

Staphylococcus epidermis

DETAILED PHARMACOLOGY

Animal Pharmacology

Pharmacodynamics

A summary of the major findings obtained from animal pharmacology studies with levofloxacin is presented below:

Table 2.47 – Summary of Major Nonclinical Pharmacological Effects of Levofloxacin

In mice, the CNS stimulatory effect of quinolones is enhanced by concomitant administration of non-steroidal anti-inflammatory drugs.

In vitro and in vivo studies in animals indicate that levofloxacin is neither an enzyme inducer nor inhibitor in the human therapeutic plasma concentration range; therefore, no drug metabolizing enzyme-related interactions with other drugs or agents are anticipated.

Human Pharmacology

Pharmacokinetics

Studies Measuring the Effects on QT and Corrected QT (QTc) Intervals

Two double-blind, placebo-controlled studies assessing the effect of levofloxacin on QTc intervals in healthy male and female volunteers 18-84 years of age were conducted. Each had a four-treatment crossover, single-dose study design. One study evaluated dose-response. The other was a comparative study that involved measuring the effects of doses of levofloxacin and two other fluoroquinolones. In this comparative study, subjects were given twice the doses of these antibiotics that are recommended for the treatment of otherwise healthy subjects with community-acquired pneumonia. In both trials, no effect on QT intervals compared to placebo was evident at any of the doses of levofloxacin studied (top panels of Figure A and Figure B).

Dose escalation study (Figure A): In this trial, the mean change in the average QTc interval (calculated from measurements taken every half hour for two hours and at 4, 8, 12 and 24 hours after treatment) from the baseline QTc (calculated as the average QTc measured 24, 20, 16 hours and immediately before treatment) was a decrease of 1.84 msec after treatment with 500 mg, and an increase of 1.55 msec after treatment with 1000 mg of levofloxacin and an increase of 6.40 msec after treatment with 1500 mg. The change in QTc interval at C_max (calculated using the Bazett formula) after treatment with 500 mg of levofloxacin was not significantly different from that measured after treatment with placebo. In this trial, the mean change in the QTc (Bazett) at C_max from baseline QTc (calculated as the average QTc measured 24, 20, 16 hours and immediately before treatment) was -3.20 msec after treatment with 500 mg of levofloxacin, 7.82 msec after treatment with 1000 mg of levofloxacin and 10.58 msec after treatment with 1500 mg of levofloxacin.

Comparative, placebo-controlled study (Figure B; only levofloxacin and placebo data shown): In this study, the mean change in the average QTc interval (calculated from measurements taken every half hour for four hours and at 8, 12 and 24 hours after treatment) from the baseline QTc (calculated as the average QTc measured 24, 20, 16 hours and immediately before treatment) was 3.58 msec after treatment with 1000 mg levofloxacin. In this study, the change in QTc (Bazett) at C_max from a baseline QTc (calculated as the average QTc measured 24, 20, 16 hours and immediately before treatment) was 5.32 msec after treatment with 1000 mg of levofloxacin.

Pharmacokinetics

Absorption

Levofloxacin is rapidly and essentially completely absorbed after oral administration. Peak plasma concentrations are usually attained 1 to 2 hours after oral dosing. The absolute bioavailability of a 500 mg tablet and a 750 mg tablet of levofloxacin is approximately 99% in both cases, demonstrating complete oral absorption of levofloxacin. Levofloxacin pharmacokinetics are linear and predictable after single and multiple oral dosing regimens. After single oral doses of 250 to 1000 mg of levofloxacin to healthy subjects, plasma concentrations increase proportionally with the dose as shown (mean ± SD):

Oral Dose Peak Plasma Concentration Area Under the Curve (mg)__ _ n___ (μg/mL)___ (AUC_0-∞, μg.h/mL)____

250 15 2.8 ± 0.4 27.2 ± 3.9

500 23 5.1 ± 0.8 47.9 ± 6.8

750 10 7.1 ± 1.4 82.2 ± 14.3

1000 10 8.9 ± 1.9 111.0 ± 20.8

Steady-state conditions are reached within 48 hours following 500 mg or 750 mg once-daily dosage regimens. The peak and trough plasma concentrations attained following multiple once-daily oral dosage regimens were approximately 5.7 and 0.5 μg/mL after the 500 mg doses, and 8.6 and 1.1 μg/mL after the 750 mg doses, respectively.

Oral administration with food slightly prolongs the time to peak concentration by approximately 1 hour and slightly decreases the peak concentration by approximately 14%.

Distribution

The mean volume of distribution of levofloxacin generally ranges from 74 to 112 L after single and multiple 500 mg or 750 mg doses, indicating widespread distribution into body tissues. Levofloxacin reaches its peak levels in skin tissues (11.7 µg/g for a 750 mg dose) and in blister fluid (4.33 µg/g for a 500 mg dose) at approximately 3-4 hours after dosing. The skin tissue biopsy to plasma AUC ratio is approximately 2. The blister fluid to plasma AUC ratio is approximately 1, following multiple once-daily oral administration of 750 mg and 500 mg levofloxacin to healthy subjects, respectively. Levofloxacin also penetrates into lung tissues. Lung tissue concentrations were generally 2- to 5-fold higher than plasma concentrations and range from approximately 2.4 to 11.3 µg/g over a 24-hour period after a single 500 mg dose. Levofloxacin also penetrates into cortical and spongiosa bone tissues in both the femoral head and distal femur. Peak levofloxacin concentrations in these tissues ranging from 2.4 to 15µg/g were generally attained by 2 to 3 hours after a single 500 mg oral dose.

In vitro, over a clinically relevant range (1 to 10 µg/mL) of serum/plasma levofloxacin concentrations, levofloxacin is approximately 24 to 38% bound to serum proteins across all species studied, as determined by the equilibrium dialysis method. Levofloxacin is mainly bound (approximately 21 to 30%) to serum albumin in humans. Levofloxacin binding to serum proteins is independent of the drug concentration.

Metabolism

Levofloxacin is stereochemically stable in plasma and urine, and does not invert metabolically to its enantiomer, D-ofloxacin. Levofloxacin undergoes limited metabolism in humans and is primarily excreted as unchanged drug in the urine. Following oral administration, approximately 87% of an administered dose was recovered as unchanged drug in urine within 48 hours, whereas less than 4% of the dose was recovered in feces in 72 hours. Less than 5% of an administered dose was recovered in the urine as the desmethyl and N-oxide metabolites, the only metabolites identified in humans. These metabolites have little relevant pharmacological activity.

Excretion

The major route of elimination of levofloxacin in humans is as unchanged drug in the urine. The mean terminal plasma elimination half-life of levofloxacin ranges from approximately 6 to 8 hours following single or multiple doses of levofloxacin given orally or intravenously. The mean apparent total body clearance and renal clearance range from approximately 144 to 226 mL/min and 96 to 142 mL/min, respectively. Renal clearance in excess of the glomerular filtration rate suggests that tubular secretion of levofloxacin occurs in addition to its glomerular filtration. Concomitant administration of either cimetidine or probenecid results in approximately 24% and 35% reduction in the levofloxacin renal clearance, indicating that secretion of levofloxacin occurs in the renal proximal tubule. No levofloxacin crystals were found in any of the urine samples freshly collected from subjects receiving levofloxacin.

Factors Influencing the Pharmacokinetics

Special Populations

Elderly

There are no significant differences in levofloxacin pharmacokinetics between young and elderly subjects when the subjects’ differences in creatinine clearance are taken into consideration. Following a 500 mg oral dose of levofloxacin to healthy elderly subjects (66 - 80 years of age),

the mean terminal plasma elimination half-life of levofloxacin was about 7.6 hours, as compared to approximately 6 hours in younger adults. The difference was attributable to the variation in renal function status of the subjects and was not believed to be clinically significant. Drug absorption appears to be unaffected by age. Levofloxacin dose adjustment based on age alone is not necessary.

Pediatric

The pharmacokinetics of levofloxacin in pediatric patients have not been studied.

Gender

There are no significant differences in levofloxacin pharmacokinetics between male and female subjects when the differences in creatinine clearance are taken into consideration. Following a 500 mg oral dose of levofloxacin to healthy male subjects, the mean terminal plasma elimination half-life of levofloxacin was about 7.5 hours, as compared to approximately 6.1 hours in female subjects. This difference was attributable to the variation in renal function status of the male and female subjects, and was not believed to be clinically significant. Drug absorption appears to be unaffected by the gender of the subjects. Dose adjustment based on gender alone is not necessary.

Race

The effect of race on levofloxacin pharmacokinetics was examined through a covariate analysis performed on data from 72 subjects: 48 white and 24 nonwhite. The apparent total body clearance and apparent volume of distribution were not affected by the race of the subjects.

Renal Insufficiency

Clearance of levofloxacin is reduced and plasma elimination half-life is prolonged in patients with impaired renal function (creatinine clearance =80 mL/min). Dosage adjustment may be required in such patients to avoid levofloxacin accumulation. Neither hemodialysis nor continuous ambulatory peritoneal dialysis (CAPD) is effective in removal of levofloxacin from the body, indicating supplemental doses of levofloxacin are not required following hemodialysis or CAPD (see ACTION AND CLINICAL PHARMACOLOGY; Pharmacokinetics, WARNINGS AND PRECAUTIONS; Renal, and DOSAGE AND ADMINISTRATION).

Plasma Ratio

Comparison of the expected steady-state AUC values^a in renally impaired patients relative to those in patients with normal renal function:

Creatinine Clearance

50-80 mL/min receiving

500 mg q24h

Creatinine Clearance

20-49 mL/min receiving

250 mg q24h

Creatinine Clearance <20 mL/min receiving 250 mg q48h AUC value relative to

patients with normal

renal function receiving

500 mg q24h

172% 183% 139%

AUC value relative to

patients with normal

renal function receiving

500 mg q12h

89%

94% 71%

^a Values were extrapolated from the mean levofloxacin plasma concentration-time data in subjects with normal renal function (n = 23) and subjects with impaired renal function (n = 3 for Cl_Cr 50 - 80 mL/min, n = 8 for Cl_Cr 20 -49 mL/min, and n = 6 for Cl_Cr <20 mL/min).

Urine Concentrations

The mean ± SD concentrations (µg/mL) of levofloxacin in the urine following a 500 mg p.o. dose of levofloxacin in subjects with impaired renal function are summarized as follows^a:

Collection Interval

Cl_Cr 50-80 mL/min

n^b = 3

Cl_Cr 20-49 mL/min

n = 8

Cl_Cr <20 mL/min n = 6

0__6 h 185±61.7 98.1±48.1 66.5±27.3 6__12 h 91.6±24.4 75.2±22.1 39.0±23.1 12__24 h 156±183 58.6±31.1 29.5±20.7 24__36 h 49.7±16.2 44.1±10.6 <25 36__48 h <25 <25 <25 ^a Limit of quantitation = 25 µg/mL

^b n = number of subjects

Expected steady-state urinary concentrations (µg/mL) of levofloxacin in renally impaired patients with the recommended adjusted dose regimen in the treatment of complicated UTI and acute pyelonephritis^a:

Collection Interval

Cl_Cr 50-80 mL/min receiving 250 mg

q24h

Cl_Cr 20-49 mL/min receiving 250 mg

q24h

Cl_Cr <20 mL/min receiving 250 mg q48h

0__6 h 161 103 54 6__12 h 61 76 29 12__24 h 40 58 24 24__36 h – – 23 36__48 h – – 16 ^a Values were extrapolated from the mean pharmacokinetic profiles in subjects with impaired renal function (n = 12 for Cl_Cr 50 - 80 mL/min, n = 8 for Cl_Cr 20 -49 mL/min, and n = 6 for Cl_Cr < 20 mL/min).

Hepatic Insufficiency

Pharmacokinetic studies in hepatically impaired patients have not been conducted. Due to the limited extent of levofloxacin metabolism, the pharmacokinetics of levofloxacin are not expected to be affected by hepatic impairment.

Bacterial Infection

The pharmacokinetics of levofloxacin in patients with serious community-acquired bacterial infections are comparable to those observed in healthy subjects.

HIV Infection

The pharmacokinetics of levofloxacin in HIV seropositive subjects (with CD4 cell counts ranging from 17 to 772) are comparable to those observed in healthy subjects.

Drug-Drug Interactions

The potential for pharmacokinetic drug interactions between levofloxacin and theophylline, warfarin, cyclosporine, digoxin, probenecid, cimetidine, sucralfate, zidovudine and antacids has been evaluated (see DRUG INTERACTIONS).

MICROBIOLOGY

Levofloxacin is the L-isomer of the racemate, ofloxacin, a quinolone antibacterial agent. The antibacterial activity of ofloxacin resides primarily in the L-isomer. The mechanism of action of levofloxacin and other quinolone antibacterials involves inhibition of bacterial topoisomerase II (DNA gyrase) and topoisomerase IV, enzymes required for DNA replication, transcription, repair, and recombination. In this regard, the L-isomer produces more hydrogen bonds and therefore, more stable complexes with DNA gyrase than does the D-isomer. Microbiologically, this translates into a 25- to 40-fold greater antibacterial activity for the L-isomer, levofloxacin, over the D-isomer. Quinolones rapidly and specifically inhibit bacterial DNA synthesis.

Levofloxacin has in vitro activity against a broad spectrum of gram-positive and gram-negative aerobic and anaerobic bacteria. Levofloxacin is often bactericidal at concentrations equal to or greater than the Minimum Inhibitory Concentrations (MIC). The in vitro activity of levofloxacin against clinical isolates is summarized in the following table.

Table 2.48 – In Vitro Activity of Levofloxacin against Clinical Isolates

* As with other drugs in this class, some strains of Pseudomonas aeruginosa may develop resistance fairly rapidly during treatment with levofloxacin.

** Data obtained for isolates from Complicated Skin and Skin Structure clinical studies, and literature, indicate the MIC value has increased for MRSA (see INDICATIONS AND CLINICAL USE for approved organisms). ‡

Based on NCCLS classification

Levofloxacin is not active against Treponema pallidum (see WARNINGS AND PRECAUTIONS; Sexually Transmitted Diseases).

Resistance

Resistance to levofloxacin due to spontaneous mutation in vitro is a rare occurrence (range: 10^-9 to 10^-10). Although cross-resistance has been observed between levofloxacin and other fluoroquinolones, some organisms resistant to other quinolones, including ofloxacin, may be susceptible to levofloxacin.

Susceptibility Tests

Susceptibility testing for levofloxacin should be performed, as it is the optimal predictor of activity.

Dilution Techniques

Quantitative methods are used to determine antimicrobial minimal inhibitory concentrations (MICs). These MICs provide estimates of the susceptibility of bacteria to antimicrobial compounds. The MICs should be determined using a standardized procedure. Standardized procedures are based on a dilution method^*1 (broth or agar) or equivalent with standardized inoculum concentrations and standardized concentrations of levofloxacin powder. The MIC values should be interpreted according to the following criteria:

For testing aerobic microorganisms other than Haemophilus influenzae, Haemophilus parainfluenzae, and Streptococcus pneumoniae:

MIC (μg/mL) Interpretation

≤ 2 Susceptible (S)

4 Intermediate (I)

≥ 8 Resistant (R)

For testing Haemophilus influenzae and Haemophilus parainfluenzae:^a

MIC (μg/mL) Interpretation

≤ 2 Susceptible (S)

^a These interpretative standards are applicable only to broth microdilution susceptibility testing with Haemophilus influenzae and Haemophilus parainfluenzae using Haemophilus Test Medium^*1.

The current absence of data on resistant strains precludes defining any categories other than “Susceptible”. Strains yielding MIC results suggestive of a “nonsusceptible” category should be submitted to a reference laboratory for further testing.

For testing Streptococcus pneumoniae:^b

MIC (μg/mL) Interpretation

≤ 2 Susceptible (S)

4 Intermediate (I)

≥ 8 Resistant (R)

^b These interpretative standards are applicable only to broth microdilution susceptibility testing using cation-adjusted Mueller-Hinton broth with 2-5% lysed horse blood.

A report of “Susceptible” indicates that the pathogen is likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable. A report of “Intermediate” indicates that the result should be considered equivocal, and, if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated. This category implies possible clinical applicability in body sites where the drug is physiologically concentrated or in situations where a high dosage of drug can be used. This category also provides a buffer zone which prevents small uncontrolled technical factors from causing major discrepancies in interpretation. A report of “Resistant” indicates that the pathogen is not likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable; other therapy should be selected.

Standardized susceptibility test procedures require the use of laboratory control microorganisms to control the technical aspects of the laboratory procedures. Standard levofloxacin powder should give the following MIC values:

Microorganism MIC (μg/mL)

Enterococcus faecalis ATCC 29212 0.25 - 2

Escherichia coli ATCC 25922 0.008 – 0.06

Escherichia coli ATCC 35218 0.015 – 0.06

Pseudomonas aeruginosa ATCC 27853 0.5 – 4

Staphylococcus aureus ATCC 29213 0.06 – 0.5

Haemophilus influenzae ATCC 49247 ^c 0.008 – 0.03

Streptococcus pneumoniae ATCC 49619 ^d 0.5 - 2

^c This quality control range is applicable to only H. influenzae ATCC 49247 tested by a broth microdilution procedure using Haemophilus Test Medium (HTM)^*1.

^d This quality control range is applicable to only S. pneumoniae ATCC 49619 tested by a broth microdilution procedure using cation-adjusted Mueller-Hinton broth with 2-5% lysed horse blood.

Diffusion Techniques

Quantitative methods that require measurement of zone diameters also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. One such standardized procedure^*2 requires the use of standardized inoculum concentrations. This procedure uses paper disks impregnated with 5 μg levofloxacin to test the susceptibility of microorganisms to levofloxacin. Reports from the laboratory, providing results of the standard single-disk

susceptibility test with a 5 μg levofloxacin disk, should be interpreted according to the following criteria:

For aerobic microorganisms other than Haemophilus influenzae, Haemophilus parainfluenzae, Streptococcus pneumoniae and Nisseria gonorrhoeae:

Zone Diameter (mm) Interpretation

≥ 17 Susceptible (S)

14-16 Intermediate (I)

≤ 13 Resistant (R)

For Haemophilus influenzae and Haemophilus parainfluenzae:^e

Zone Diameter (mm) Interpretation

≥ 17 Susceptible (S)

^e These interpretive standards are applicable only to disk diffusion susceptibility testing with Haemophilus influenzae and Haemophilus parainfluenzae using Haemophilus Test Medium^*

(HTM)².

The current absence of data on resistant strains precludes defining any categories other than “Susceptible”. Strains yielding zone diameter results suggestive of a “Nonsusceptible” category should be submitted to a reference laboratory for further testing.

For Streptococcus pneumoniae:^f

Zone Diameter (mm) Interpretation

≥ 17 Susceptible (S)

14-16 Intermediate (I)

≤ 13 Resistant (R)

^f These zone diameter standards for Streptococcus pneumoniae apply only to tests performed using Mueller-Hinton agar supplemented with 5% sheep blood and incubated in 5% CO₂.

Interpretation should be as stated above for results using dilution techniques. Interpretation involves correlation of the diameter obtained in the disk test with the MIC for levofloxacin.

As with standardized dilution techniques, diffusion methods require the use of laboratory control microorganisms to control the technical aspects of the laboratory procedures. For the diffusion technique, the 5 μg levofloxacin disk should provide the following zone diameters in these laboratory test quality control strains:

Microorganism Zone Diameter (mm) Escherichia coli ATCC 25922 29 - 37 Pseudomonas aeruginosa ATCC 27853 19 - 26 Staphylococcus aureus ATCC 25923 25 - 30 Haemophilus influenzae ATCC 49247^g 32 - 40 Streptococcus pneumoniae ATCC 49619^h 20 - 25

^g This quality control range is applicable to only H. influenzae ATCC 49247 tested by a disk diffusion procedure using Haemophilus Test Medium (HTM)^*2.

^h This quality control range is applicable to only S. pneumoniae ATCC 49619 tested by a disk diffusion procedure using Mueller-Hinton agar supplemented with 5% sheep blood and incubated in 5% CO₂.

* REFERENCES

1. 1.

   National Committee for Clinical Laboratory Standards: Methods for Dilution Antimicrobial Susceptibility Tests for

   Bacteria That Grow Aerobically, Fourth Edition, 1997.

2. 2.

   National Committee for Clinical Laboratory Standards: Performance Standards for Antimicrobial Disk Susceptibility

   Tests, Sixth Edition, 1997.

TOXICOLOGY

The potential toxicity of levofloxacin has been evaluated in acute, sub-chronic, carcinogenicity, mutagenicity, reproduction and teratology, and special toxicity studies.

Acute Toxicity

Table 2.49 – Summary of the acute toxicity studies

Signs of acute toxicity with metabolites (desmethyl and N-oxide) were similar to that of levofloxacin and were produced at doses significantly greater than would be encountered with therapeutic use.

Sub-Chronic Toxicity

Table 2.50 – Summary of the sub-chronic toxicity studies

Dosage = mg/kg/day; Clin Obs = clinical observations; Clin Path = clinical pathology; Micro = macroscopic and microscopic findings; NOAEL = No Observable Adverse Effect Level; NSF = No Significant Findings; TI = Therapeutic Index - relationship of toxic dose to the projected human dose (calculation based on maximum daily dose of 500 mg and body weight of 70 kg);

ALT = alanine aminotransferase; ALP = alkaline phosphatase; AST = aspartate aminotransferase; A/G = albumin/globulin;

fc = food consumption; wc = water consumption; bw = body weight;

RBC = red blood cells; WBC = white blood cells; retic = reticulocyte; PMN = neutrophil; M:E = myeloid:erythroid; K⁺

= potassium; Cl^-

= chloride; P = phosphorus; Fe = iron.

Carcinogenicity

Levofloxacin exhibited no carcinogenetic or tumorigenic potential after dietary administration of 10, 30 or 100 mg/kg/day for 2 years in a rat carcinogenicity study. The highest dose was 1.4 or 6.7 times the highest recommended human dose (750 mg) based on surface area or body weight,

respectively. The mean levofloxacin plasma concentration in the 2-year rat bioassay (at 100 mg/kg/day) was 34% of the human steady-state concentration after 500 mg b.i.d. dosing. In a 2-stage multiple organ carcinogenesis model in rats, levofloxacin at a dosage level of approximately 668 mg/kg/day in diet for 16 weeks did not promote the development of preneoplastic or neoplastic lesions after pre-treatment with a number of wide spectrum carcinogens.

Mutagenicity

Levofloxacin was not mutagenic in the following assays: Ames bacterial mutation assays (S. typhimurium and E. coli), CHO/HGPRT forward mutation assay, mouse micronucleus test, mouse dominant lethal test, rat unscheduled DNA synthesis and the mouse sister chromatid exchange (SCE) assays. It was positive in the in vitro chromosomal aberration (CHL cell line) and SCE assays (CHL/IU cell line).

Reproduction and Teratology

Table 2.51 – Segment I: Fertility and Reproductive Performance Studies

wc = water consumption; bw = body weight; fc = food consumption

^a In both studies, males (8 weeks old) were administered levofloxacin daily for 9 weeks prior to mating, throughout the mating period, and until necropsy. The females (11-12 weeks old) were treated daily for 2 weeks prior to mating, throughout the mating period, and for 7 days after copulation.

NOAEL = No Observable Adverse Effect Level.

Table 2.52 – Segment II: Teratogenicity

bw = body weight; wc = water consumption; fc = food consumption; inj. = injection ^a In both rat studies, the rats were dosed from Day 7 to Day 17 of gestation. NOAEL = No Observable Adverse Effect Level.

Table 2.53 – Segment III: Perinatal and Postnatal

NOAEL = No Observable Adverse Effect Level.

Special Studies

Arthropathic Potential

Levofloxacin and other quinolones have been shown to cause arthropathy in immature animals of most species tested (see WARNINGS AND PRECAUTIONS). In juvenile rats, 7 days of oral administration of 300 mg/kg/day levofloxacin results in blister and cavity formation in articular cartilage. In juvenile dogs (4 months old), 7 days of oral administration of 10 mg/kg/day levofloxacin produces blister formation, cavitation, and increased synovial fluid of diarthroidal joints. In young immature dogs (13 months old), blister formation and cavitation of the arthritic joint were observed in 1/3 dogs following oral administration of 40 mg/kg/day levofloxacin for 7 days.

In long-term multidose studies, arthropathy in rats was observed after oral administration of 800 mg/kg/day for 4 weeks, after intravenous administration at 60 mg/kg/day for 4 weeks and 90 mg/kg/day for 13 weeks. Arthropathic lesions were observed in 4-month-old dogs following 4 mg/kg/day intravenous administration for 2 weeks and in 7-8-month-old dogs following 10 mg/kg/day intravenous administration for 4 weeks. No arthropathy was observed following 2-week intravenous dosing at dosages up to 30 mg/kg/day in young adult dogs (18 months old).

Three-month old beagle dogs dosed orally with up to 40 mg/kg/day levofloxacin for 8 or 9 consecutive days, with an 18-week recovery period, exhibited musculoskeletal clinical signs by the final dose at dose levels ≥2.5 mg/kg (approximately 0.2-fold the pediatric dose based upon AUC comparisons). Synovitis and articular cartilage lesions were observed at the 10 and 40 mg/kg dose levels (equivalent to and 3-fold greater than the potential therapeutic dose, respectively). All musculoskeletal clinical signs were resolved by week 5 of recovery; synovitis was resolved by the end of the 18-week recovery period; whereas, articular cartilage erosions and chondropathy persisted.

Phototoxicity

When tested in a mouse ear swelling bioassay, levofloxacin exhibited phototoxicity similar in magnitude to ofloxacin but less phototoxicity than some of the other quinolones tested. A single oral administration of 800 mg/kg levofloxacin followed by UVA exposure has been shown to result in ear erythema and swelling.

Crystalluria

When tested in rats with 20, 60, 120 or 180 mg/kg of levofloxacin, crystalluria has been observed in some intravenous rat studies; urinary crystals are not formed in the bladder, being present only after micturition and are not associated with nephrotoxicity. Cardiac Effects Levofloxacin exhibits a weak interaction with the human HERG channel. The IC50 for levofloxacin in inhibiting human HERG K⁺ channel is 915 μM. At therapeutic doses of 250, 500, and 750 mg levofloxacin, the peak unbound plasma concentrations ranged from 6 μM for a single oral levofloxacin dose of 250 mg to 12 μM and 15 μM for 500 and 750 mg levofloxacin doses, respectively.

Studies in rabbit Purkinje fibers and studies in guinea pig right ventricular myocardium revealed no detectable effect on action potential duration with levofloxacin at concentrations up to 100 μM.

The potential for levofloxacin to induce torsades de pointes was examined in a canine model of chronic high-degree atrioventricular block. Oral administration of levofloxacin at 6 and 60 mg/kg induced no ventricular arrhythmias. Monophasic action potential duration (MAP90) was not significantly affected by levofloxacin 0.3 and 3.0 mg/kg IV.

REFERENCES

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3. 3.

   Niederman MS, Bass JB Jr, Campbell GD, Fein AM, Grossman RF, Mandell LA, Marrie

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4. 4. Tanaka M, Kurata T, Fujisawa C. Mechanistic study of inhibition of levofloxacin absorption by aluminum hydroxide. Antimicrobial Agents and Chemotherapy 1993; 37(10):2173-2178.
5. 5. Yamane N, Jones RN, Frei R, Hoban DJ, Pignatari AC, Macro F. Levofloxacin in vitro activity: results from an international comparative study with ofloxacin and ciprofloxacin. J Chemotherapy 1994; 6:83-91.
6. 6. Peterson LR, Cooper I, Willard KE, et al. Activity of twenty-one antimicrobial agents including L-ofloxacin against quinolone-sensitive and –resistant, and methicillin-sensitive and –resistant Staphylococcus aureus. Chemotherapy 1994; 40:21-25.
7. 7. Child J, Mortiboy D, Andrews JM, Chow AT, Wise R. Open-label crossover study to determine pharmacokinetics and penetration of two dose regimens of levofloxacin into inflammatory fluid. Antimicrobial Agents and Chemotherapy 1995; 39(12):2749-2751.
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