Apo-Risedronate (Apotex, 150 mg) Product Monograph

RECENT MAJOR LABEL CHANGES

TABLE OF CONTENTS

Sections or subsections that are not applicable at the time of authorization are not listed

RECENT MAJOR LABEL CHANGES .......................................................................................... 2

TABLE OF CONTENTS ............................................................................................................ 2

PART I: HEALTH PROFESSIONAL INFORMATION .................................................................... 4

1 INDICATIONS ............................................................................................................... 4

1.1 Pediatrics ..................................................................................................................... 4

1.2 Geriatrics ..................................................................................................................... 4

2 CONTRAINDICATIONS .................................................................................................. 4

4 DOSAGE AND ADMINISTRATION .................................................................................. 5

4.1 Dosing Considerations ................................................................................................ 5

4.2 Recommended Dose and Dosage Adjustment ........................................................... 5

4.4 Administration ............................................................................................................ 5

4.5 Missed Dose ................................................................................................................ 6

5 OVERDOSAGE .............................................................................................................. 6

6 DOSAGE FORMS, STRENGTHS, COMPOSITION AND PACKAGING ................................... 7

7 WARNINGS AND PRECAUTIONS ................................................................................... 7

7.1 Special Populations ................................................................................................... 10

7.1.1 Pregnant Women ...................................................................................................... 10

7.1.2 Breast-feeding ........................................................................................................... 10

7.1.3 Pediatrics ................................................................................................................... 10

7.1.4 Geriatrics ................................................................................................................... 10

8 ADVERSE REACTIONS ................................................................................................. 10

8.1 Adverse Reaction Overview ...................................................................................... 10

8.2 Clinical Trial Adverse Reactions ................................................................................ 11

8.3 Less Common Clinical Trial Adverse Reactions ......................................................... 13

8.4 Abnormal Laboratory Findings: Hematologic, Clinical Chemistry and Other

Quantitative Data ...................................................................................................... 13

8.5 Post-Market Adverse Reactions ................................................................................ 14

9 DRUG INTERACTIONS ................................................................................................. 14

9.2 Drug Interactions Overview ...................................................................................... 14

9.3 Drug-Behavioural Interactions .................................................................................. 14

9.4 Drug-Drug Interactions ............................................................................................. 14

9.5 Drug-Food Interactions ............................................................................................. 16

9.6 Drug-Herb Interactions ............................................................................................. 16

9.7 Drug-Laboratory Test Interactions ............................................................................ 16

10 CLINICAL PHARMACOLOGY ........................................................................................ 17

10.1 Mechanism of Action ................................................................................................ 17

10.2 Pharmacodynamics ................................................................................................... 17

10.3 Pharmacokinetics ...................................................................................................... 19

11 STORAGE, STABILITY AND DISPOSAL .......................................................................... 21

12 SPECIAL HANDLING INSTRUCTIONS ............................................................................ 21

PART II: SCIENTIFIC INFORMATION ..................................................................................... 22

13 PHARMACEUTICAL INFORMATION ............................................................................. 22

14 CLINICAL TRIALS ......................................................................................................... 23

14.1 Clinical Trials by Indication ........................................................................................ 23

14.2 Comparative Bioavailability Studies .......................................................................... 24

15 MICROBIOLOGY ......................................................................................................... 25

16 NON-CLINICAL TOXICOLOGY ...................................................................................... 25

17 SUPPORTING PRODUCT MONOGRAPHS ..................................................................... 27

PATIENT MEDICATION INFORMATION ................................................................................ 28

PART I: HEALTH PROFESSIONAL INFORMATION

1 INDICATIONS

APO-RISEDRONATE (risedronate sodium hemi-pentahydrate) is indicated for:

• the treatment of osteoporosis in postmenopausal women

Postmenopausal Osteoporosis: In the treatment of osteoporosis in postmenopausal women at risk of fracture, APO-RISEDRONATE prevent vertebral and nonvertebral osteoporosis-related (fragility) fractures and increase bone mineral density (BMD) at all measured skeletal sites of clinical importance for osteoporotic fractures, including spine, hip, and wrist.

Osteoporosis may be confirmed by the presence or history of osteoporotic fracture, or by the finding of low bone mass (e.g., at least 2 standard deviation [SD] below the premenopausal mean).

APO-RISEDRONATE may be considered in postmenopausal women who are at risk of developing osteoporosis and for whom the desired clinical outcome is to maintain bone mass and to reduce the risk of fracture.

Factors such as family history of osteoporosis (particularly maternal history), age, previous fracture, smoking, moderately low BMD, high bone turnover, thin body frame, Caucasian or Asian race, and early menopause are associated with an increased risk of developing osteoporosis and fractures.

Important Limitations of Use: The optimal duration of use has not been determined. Patients should have the need for continued therapy re-evaluated on a periodic basis. See 4 DOSAGE AND ADMINISTRATION.

1.1 Pediatrics

Pediatrics (<18 years of age): No data are available to Health Canada; therefore, Health Canada has not authorized an indication for pediatric use.

1.2 Geriatrics

Geriatrics (> 65 years of age): In risedronate sodium osteoporosis studies, 26 to 46% of patients were between 65 and 75 years of age and 10 to 23% were over 75 years of age. No overall differences in efficacy or safety were observed between these patients and younger patients (< 65 years) in the above osteoporosis studies. See 14 CLINICAL TRIALS.

2 CONTRAINDICATIONS

APO-RISEDRONATE is contraindicated in:

• Patients who are hypersensitive to this drug or to any ingredient in the formulation, including any non-medicinal ingredient or component of the container. For a complete listing, see 6 DOSAGE FORMS, STRENGTHS, COMPOSITION AND PACKAGING.
• Hypocalcemia. See 7 WARNINGS AND PRECAUTIONS.

4 DOSAGE AND ADMINISTRATION

4.1 Dosing Considerations

Patients should receive supplemental calcium and vitamin D if dietary intake is inadequate. See 7 WARNINGS AND PRECAUTIONS.

4.2 Recommended Dose and Dosage Adjustment

• The patient should be informed to pay particular attention to the dosing instructions as clinical benefits may be compromised by failure to take the drug according to instructions.
• Treatment of Postmenopausal Osteoporosis: The recommended regimen is 1 tablet of 150 mg once-a-month on the same calendar day each month, taken orally.
• Renal Impairment: No dosage adjustment is necessary in patients with a creatinine clearance ≥30 mL/min or in the elderly. Not recommended for use in patients with severe renal impairment (creatinine clearance < 30 mL/min).
• Pediatrics (<18 years of age): Health Canada has not authorized an indication for pediatric use.
• Geriatrics: No dosage adjustment is necessary in elderly patients. See 1.2 Geriatrics.

4.4 Administration

APO-RISEDRONATE tablets

• APO-RISEDRONATE should be taken on an empty stomach at least 30 minutes before consuming the first food, drink (other than plain water) and/or any other medication of the day. Food, medication or drink (other than plain water) can interfere with the absorption of APO-RISEDRONATE. (See 4.2 Recommended Dose and Dosage Adjustment and 9 DRUG INTERACTIONS).
• Each APO-RISEDRONATE tablet should be swallowed whole while the patient is in an upright position and with sufficient plain water (≥ 120 mL) to facilitate delivery to the stomach.
• Patients taking APO-RISEDRONATE should not lie down for at least 30 minutes after taking the medication. See 7 WARNINGS AND PRECAUTIONS.
• APO-RISEDRONATE tablets should not be chewed, cut, or crushed. See 7 WARNINGS AND PRECAUTIONS.
• Medications containing polyvalent cations (e.g. calcium, magnesium, aluminum, and iron) can interfere with the absorption of APO-RISEDRONATE. These medications should be administered at a different time of the day than APO-RISEDRONATE.
• The optimal duration of bisphosphonate treatment for osteoporosis has not been established. The need for continued treatment should be re-evaluated periodically based on the benefits and potential risks of APO-RISEDRONATE on an individual patient basis.

4.5 Missed Dose

Patients should be instructed that if they miss a 150 mg dose of APO-RISEDRONATE (1 tablet of 150 mg), and the next month’s scheduled dose is more than 7 days away, they should take the missed tablet in the morning after the day it is remembered. Patients should then return to taking their APO-RISEDRONATE 150 mg as originally scheduled.

If a dose of APO-RISEDRONATE 150 mg is missed, and the next month’s scheduled dose is within 7 days, patients should be instructed to wait until their next month’s scheduled dose and then continue taking APO-RISEDRONATE 150 mg. Patients should not take more than 150 mg of APO-RISEDRONATE within 7 days.

5 OVERDOSAGE

Decreases in serum calcium following substantial overdose may be expected in some patients. Signs and symptoms of hypocalcemia may also occur in some of these patients.

Milk or antacids containing calcium, magnesium, and aluminum may be given to bind APO-RISEDRONATE (film-coated tablets) and reduce absorption of the drug. In cases of substantial overdose, gastric lavage may be considered to remove unabsorbed drug if performed within 30 minutes of ingestion. Standard procedures that are effective for treating hypocalcemia, including the administration of calcium intravenously, would be expected to restore physiologic amounts of ionized calcium and to relieve signs and symptoms of hypocalcemia.

6 DOSAGE FORMS, STRENGTHS, COMPOSITION AND PACKAGING

Table 1 – Dosage Forms, Strengths, Composition and Packaging

Description

APO-RISEDRONATE 150 mg: Each light blue, oval, biconvex coated tablet, engraved “APO” on one side, “RIS150” on the other side contains risedronate sodium hemi-pentahydrate equivalent to 150 mg risedronate sodium. Available in bottles of 30 or 100 tablets and blister packs of 1 tablet.

7 WARNINGS AND PRECAUTIONS

General

Hypocalcemia and other disturbances of bone and mineral metabolism should be effectively treated before starting APO-RISEDRONATE therapy.

Adequate intake of calcium and vitamin D is important in all patients, especially in patients with Paget's disease in whom bone turnover is significantly elevated.

Detailed dosing instructions (see 4.2 Recommended Dose and Dosage Adjustment and 4.4 Administration) are provided to ensure correct dosing of each APO-RISEDRONATE therapy.

Gastrointestinal

Bisphosphonates may cause upper gastrointestinal (GI) disorders such as dysphagia, esophagitis, esophageal ulcer, and gastric ulcer (see 8.1 Adverse Reaction Overview). Since some bisphosphonates have been associated with esophagitis and esophageal ulcerations, to facilitate delivery to the stomach and minimize the risk of these events, patients should take APO-RISEDRONATE while in an upright position (i.e., sitting or standing) and with sufficient plain water (≥ 120 mL). Patients should not lie down for at least 30 minutes after taking the drug. Health professionals should be particularly careful to emphasize the importance of the dosing instructions to patients with a history of esophageal disorders (e.g., inflammation, stricture, ulcer, or disorders of motility).

Monitoring and Laboratory Tests

Osteonecrosis of the jaw: Prior to treatment with APO-RISEDRONATE, a routine oral examination should be performed. Patients with positive risk factors (e.g. cancer, chemotherapy, immunosuppression, angiogenesis inhibitors, head and neck radiotherapy, corticosteroids, poor oral hygiene, and diabetes) should be referred to a dentist for examination and appropriate preventative dentistry should be performed prior to treatment with APO-RISEDRONATE. Patients should receive routine dental check-ups while taking APO-RISEDRONATE.

Musculoskeletal

Osteonecrosis of the Jaw: Osteonecrosis of the jaw (ONJ) has been reported post-market in patients treated with bisphosphonates as well as with other oral and intravenous bisphosphonates, including in, but not limited to, patients with cancer receiving treatment or patients that underwent invasive dental procedures such as root canal or dental extraction (see 8.5 Post-Market Adverse Reactions).

Prior to treatment with APO-RISEDRONATE, a routine oral examination should be performed. Patients with possible risk factors (e.g., cancer, immunosuppression, chemotherapy, angiogenesis inhibitors, head and neck radiotherapy, corticosteroids, poor oral hygiene, and diabetes) should be referred to a dentist for examination and appropriate preventative dentistry should be performed prior to treatment with APO-RISEDRONATE.

During treatment with risedronate sodium, patients should maintain good oral hygiene, undergo routine dental check-ups and immediately report any oral symptoms. While on treatment, these patients should avoid invasive dental procedures if possible but should continue with regular dental cleaning and oral hygiene. For patients requiring dental procedures, there are no data available to suggest whether discontinuation of bisphosphonate treatment prior to the procedure reduces the risk of ONJ. In patients who develop ONJ while on bisphosphonate therapy, surgery at the affected area may exacerbate the condition. Clinical judgment of the treating physician should guide the management of patients undergoing dental procedures, based on individual benefit/risk assessment.

The following should be considered when evaluating a patient's risk of developing ONJ:

• Potency of the medicinal product that inhibits bone resorption (higher risk for highly potent compounds),
• Route of administration (higher risk for parenteral administration),
• Cumulative dose of bone resorption therapy.
• Co-morbid conditions (e.g. anaemia, coagulopathies) and smoking,
• Periodontal disease, poorly fitting dentures, history of dental disease.

Atypical Subtrochanteric and Diaphyseal Femoral Fractures: Atypical, low-energy, or low trauma fractures of the femoral shaft have been reported in bisphosphonate-treated patients. These fractures can occur anywhere in the femoral shaft from just below the lesser trochanter to above the supracondylar flare and are transverse or short oblique in orientation without evidence of comminution.

Atypical femur fractures most commonly occur with minimal or no impact trauma to the affected area. They may be bilateral and many patients report prodromal pain in the affected area, usually presenting as dull, aching thigh pain, weeks to months before a complete fracture occurs. Poor healing of these fractures was also reported.

Any patient with a history of bisphosphonate exposure who presents with thigh or groin pain should be suspected of having an atypical fracture and should be evaluated to rule out an incomplete femur fracture. Patients presenting with an atypical fracture should also be assessed for symptoms and signs of fracture in the contra-lateral limb. Interruption of bisphosphonate therapy should be considered, pending a risk/benefit assessment. Although causality has not been established, the role of bisphosphonates cannot be ruled out.

Musculoskeletal Pain: In post-marketing experience, severe and occasionally incapacitating bone, joint, and/or muscle pain has been reported in patients taking bisphosphonates (see 8.1 Adverse Reaction Overview). The time-to-onset of symptoms varied from one day to several months after starting the drug. Most patients had relief of symptoms after stopping the medication. A subset of patients had recurrence of symptoms when rechallenged with the same drug or another bisphosphonate. Consider discontinuing use if severe symptoms develop.

Ophthalmologic

Ocular disturbances including conjunctivitis, uveitis, episcleritis, iritis, and scleritis have been reported with risedronate sodium therapy. Patients with ocular events other than uncomplicated conjunctivitis should be referred to an ophthalmologist for evaluation. If ocular inflammatory symptoms are observed, treatment may have to be discontinued.

Renal

Risedronate sodium is not recommended for use in patients with severe renal impairment (creatinine clearance < 30 mL/min).

7.1 Special Populations

7.1.1 Pregnant Women

Risedronate sodium is not intended for use during pregnancy. There are no studies of risedronate sodium in pregnant women.

7.1.2 Breast-feeding

Risedronate sodium is not intended for use with nursing mothers. It is not known whether risedronate is excreted in human milk. Risedronate was detected in feeding pups exposed to lactating rats for a 24-hour period post-dosing, indicating a small degree of lacteal transfer. Since many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from bisphosphonates, 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.

7.1.3 Pediatrics

Pediatrics (<18 years of age): No data are available to Health Canada; therefore, Health Canada has not authorized an indication for pediatric use.

7.1.4 Geriatrics

In risedronate sodium osteoporosis studies, 26 to 46% of patients were between 65 and 75 years of age and 10 to 23% were over 75 years of age. No overall differences in efficacy or safety were observed between these patients and younger patients (< 65 years of age) in the above osteoporosis studies. See 14 CLINICAL TRIALS.

8 ADVERSE REACTIONS

8.1 Adverse Reaction Overview

Bisphosphonates may cause upper gastrointestinal disorders such as dysphagia, esophagitis, esophageal ulcer and gastric ulcer. It is therefore important to follow the recommended dosing instructions. See 4.4 Administration.

Musculoskeletal pain, rarely severe, has been reported as a common adverse event in patients who received risedronate sodium.

In risedronate sodium osteoporosis studies, the most commonly reported adverse reactions were abdominal pain, dyspepsia and nausea. In addition, diarrhea was the most commonly reported adverse reaction for the highest risedronate sodium monthly dose.

8.2 Clinical Trial Adverse Reactions

Clinical trials are conducted under very specific conditions. The adverse reaction rates observed in the clinical trials; therefore, may not reflect the rates observed in practice and should not be compared to the rates in the clinical trials of another drug. Adverse reaction information from clinical trials may be useful in identifying and approximating rates of adverse drug reactions in real-world use.

Treatment and Prevention of Postmenopausal Osteoporosis: Risedronate sodium 5 mg daily has been studied for up to 3 years in over 5000 women enrolled in Phase III clinical trials for treatment or prevention of postmenopausal osteoporosis. Most adverse events reported in these trials were either mild or moderate in severity, and did not lead to discontinuation from the study. The distribution of severe adverse events was similar across treatment groups. In addition, the overall incidence of adverse events (AEs) was found to be comparable amongst risedronate sodium and placebo-treated patients.

Table 2 lists adverse events considered possibly or probably drug-related, reported in ≥ 1% of risedronate sodium 5 mg daily-treated patients, in Phase III postmenopausal osteoporosis trials. Discontinuation of therapy due to serious clinical adverse events occurred in 5.5 % of risedronate sodium 5 mg daily-treated patients and 6.0% of patients treated with placebo.

Table 2 Drug-Related* Adverse Events Reported in ≥ 1% of Risedronate Sodium 5 mg Daily-Treated Patients in Combined Phase III Postmenopausal Osteoporosis Trials

Weekly Dosing: In the 1-year, double-blind, multicentre study comparing risedronate sodium 35 mg Once-a-Week to risedronate sodium 5 mg daily for the treatment of osteoporosis in postmenopausal women, the overall safety and tolerability profiles of the 2 oral dosing regimens were similar.

The proportion of patients who experienced an upper gastrointestinal adverse event and the pattern of those events were found to be similar between the risedronate sodium 35 mg Once-a-Week and risedronate sodium 5 mg daily-treated groups. In addition to the previously described adverse reactions reported in risedronate sodium osteoporosis clinical trials, arthralgia (risedronate sodium 35 mg, 2.1%; risedronate sodium 5 mg, 1.3%) was reported in ≥ 1% of patients and in more risedronate sodium 35 mg weekly treated patients than risedronate sodium 5 mg daily treated patients.

In the 1-year, double-blind, multicentre study comparing risedronate sodium 35 mg Once-a-Week to placebo for the prevention of osteoporosis in postmenopausal women, the overall safety and tolerability profiles of the two groups were comparable with the exception of arthralgia. Specifically, 1.5% of patients taking risedronate sodium 35 mg Once-a-Week experienced arthralgia compared to 0.7% of placebo patients. The overall safety profile observed in this study showed no substantive difference from that observed in the risedronate sodium 5 mg daily versus risedronate sodium 35 mg Once-a-Week treatment study.

Monthly Dosing: (Once-a-Month) - In a 1-year, double-blind, multicentre study for the treatment of osteoporosis in postmenopausal women comparing risedronate sodium 150 mg Once-a-Month to risedronate sodium 5 mg daily, the overall safety profiles of the dosing regimens were similar. The proportion of patients who experienced an upper gastrointestinal adverse event and the pattern of those events were found to be similar between the risedronate sodium 150 mg Once-a-Month and the risedronate sodium 5 mg daily treated groups. In addition to the previously described adverse reactions diarrhea (risedronate sodium 150 mg, 3.1%; risedronate sodium 5 mg, 0.5%), vomiting (risedronate sodium 150 mg, 1.5%; risedronate sodium 5 mg, 0.6%), arthralgia (risedronate sodium 150 mg, 1.5%; risedronate sodium 5 mg, 0.9%) and myalgia (risedronate sodium 150 mg, 1.1%; risedronate sodium 5 mg, 0.3%) were reported in ≥1% of patients and in more risedronate sodium 150 mg treated patients than in risedronate sodium 5 mg daily treated patients.

Symptoms consistent with acute phase reactions have been reported. Based on reporting of any 33 acute phase reaction-like symptoms (without regard to causality) within the first 3 days of first dose and lasting less than 7 days, the overall incidence of acute phase reaction was 5.2 % of patients in the risedronate sodium 150 mg once-a-month group and 1.1% in the risedronate sodium 5 mg daily group. Fever or influenza-like illness (without regard to causality) occurring within the first 3 days of first dose and lasting less than 7 days was reported by 1.4% of patients in the risedronate sodium 150 mg Once-a-Month group and 0.2% of patients in the risedronate sodium 5 mg daily group.

Endoscopic Findings: Risedronate sodium 5 mg daily clinical studies enrolled over 5700 patients for the treatment and prevention of postmenopausal and glucocorticoid-induced osteoporosis, many with pre-existing gastrointestinal disease and concomitant use of NSAIDs or ASA. Investigators were encouraged to perform endoscopies in any patients with moderate-to-severe gastrointestinal complaints while maintaining the blind. These endoscopies were ultimately performed on equal numbers of patients between the treated and placebo groups (75 risedronate sodium; 75 placebo).

Across treatment groups, the percentage of patients with normal esophageal, gastric and duodenal mucosa on endoscopy was similar (21% risedronate sodium; 20% placebo). Positive findings on endoscopy were also generally comparable across treatment groups. There were a higher number of reports of mild duodenitis in the risedronate sodium group; however, there were more duodenal ulcers in the placebo group. Clinically important findings (perforations, ulcers or bleeding) among this symptomatic population were similar between groups (39% risedronate sodium; 51% placebo).

At the 1-year time point in the studies, comparing risedronate sodium 35 mg Once-a-Week to risedronate sodium 5 mg daily in the treatment of postmenopausal osteoporosis, endoscopies performed during the studies revealed no dose dependent pattern in the number of patients with positive endoscopic findings or in the anatomical location of abnormalities detected. Endoscopies were conducted only on consenting patients experiencing moderate to severe gastrointestinal complaints.

In a 1-year study for the treatment of osteoporosis in postmenopausal women comparing risedronate sodium 150 mg Once-a-Month to risedronate sodium 5 mg daily, a similar percentage of patients for each of the intermittent regimens had at least one abnormal endoscopic finding when compared to the daily regimen (risedronate sodium 150 mg, 3.4%; risedronate sodium 5 mg, 4.2%).

8.3 Less Common Clinical Trial Adverse Reactions

The following adverse drug reactions were reported in ≤ 1% of patients who received risedronate sodium for all indications:

• Eye Disorders: iritis (0.1 to 1.0%)
• Gastrointestinal Disorders: duodenitis (0.1 to 1.0%), glossitis (<0.1%)
• Investigations: abnormal liver function tests (<0.1%)

8.4 Abnormal Laboratory Findings: Hematologic, Clinical Chemistry and Other Quantitative Data

Clinical Trial Findings

Asymptomatic mild decreases in serum calcium and phosphorus levels have been observed in some patients. See 10.2 Pharmacodynamics.

Rare cases of leukemia have been reported following therapy with bisphosphonates. Any causal relationship to either the treatment or to the patients' underlying disease has not been established.

8.5 Post-Market Adverse Reactions

Hypersensitivity and Skin Reactions: angioedema, generalized rash and bullous skin reactions, some severe.

Musculoskeletal and Connective tissue: low-energy femoral shaft fractures, osteonecrosis of the jaw. See Musculoskeletal.

Ophthalmologic: conjunctivitis, episcleritis, iritis, scleritis and uveitis. See Ophthalmologic.

9 DRUG INTERACTIONS

9.2 Drug Interactions Overview

No specific drug-drug interaction studies were performed with risedronate sodium film-coated tablets. Animal studies have demonstrated that risedronate is highly concentrated in bone and is retained only minimally in soft tissue. No metabolites have been detected systemically or in bone. The binding of risedronate to plasma proteins in humans is low (24%), resulting in minimal potential for interference with the binding of other drugs. In an additional animal study, there was also no evidence of hepatic microsomal enzyme induction. In summary, risedronate sodium is not systemically metabolized, does not induce cytochrome P₄₅₀ enzymes and has low protein binding.

Risedronate sodium is therefore not expected to interact with other drugs based on the effects of protein binding displacement, enzyme induction or metabolism of other drugs.

9.3 Drug-Behavioural Interactions

No drug-behavioural interactions have been identified.

9.4 Drug-Drug Interactions

Patients in the clinical trials were exposed to a wide variety of commonly used concomitant medications (including NSAIDs, H₂-blockers, proton pump inhibitors, antacids, calcium channel blockers, beta-blockers, thiazides, glucocorticoids, anticoagulants, anticonvulsants, cardiac glycosides). While there was no apparent evidence of clinically relevant interactions in the clinical trials, such interactions cannot be ruled out on the basis on these data.

The drugs listed in Table 3 are based on either drug interaction case reports or predicted interactions due to the expected magnitude and seriousness of the interaction (i.e., those identified as contraindicated).

Table 3 - Established or Potential Drug-Drug Interactions

Of over 5700 patients enrolled in the risedronate sodium 5 mg daily Phase III osteoporosis studies, ASA use was reported by 31% of patients and NSAID use by 48%. Among these ASA or NSAID users, the incidence of upper gastrointestinal adverse events was similar between the risedronate sodium -treated patients and placebo-treated patients.

In the 1-year study comparing risedronate sodium 35 mg Once-a-Week to risedronate sodium 5 mg daily, ASA use was reported by 56% and NSAID use by 41%. The incidence of upper gastrointestinal adverse events was similar between the risedronate sodium weekly- and daily-treated groups.

In a 1-year study comparing risedronate sodium 150 mg once-a-month to risedronate sodium 5 mg daily in postmenopausal women, 46% (150 mg) of patients reported the use of ASA and/or NSAIDs. Among these ASA or NSAID users, the incidence of upper gastrointestinal adverse events was similar in the risedronate sodium monthly-treated groups when compared to the daily-treated groups respectively.

9.5 Drug-Food Interactions

Clinical benefits may be compromised by failure to take risedronate sodium on an empty stomach. For dosing information see 4.4 Administration.

9.6 Drug-Herb Interactions

Interactions with herbs have not been studied.

9.7 Drug-Laboratory Test Interactions

Bisphosphonates are known to interfere with the use of bone-imaging agents. Specific studies with risedronate sodium have not been performed.

10 CLINICAL PHARMACOLOGY

10.1 Mechanism of Action

Risedronate sodium, a pyridinyl-bisphosphonate in the form of hemi-pentahydrate with small amounts of monohydrate, inhibits osteoclast bone resorption and modulates bone metabolism. Risedronate has a high affinity for hydroxyapatite crystals in bone and is a potent antiresorptive agent. At the cellular level, risedronate inhibits osteoclasts. The osteoclasts adhere normally to the bone surface, but show evidence of reduced active resorption (e.g., lack of ruffled border). Histomorphometry in rats, dogs, minipigs and humans showed that risedronate treatment reduces bone turnover (i.e., activation frequency, the rate at which bone remodelling sites are activated) and bone resorption at remodelling site.

10.2 Pharmacodynamics

Treatment and Prevention of Osteoporosis in Postmenopausal Women: Osteoporosis is a degenerative and debilitating bone disease characterized by decreased bone mass and increased fracture risk at the spine, hip, and wrist. The diagnosis can be confirmed by the finding of low bone mass, evidence of fracture on x-ray, a history of osteoporotic fracture, or height loss or kyphosis indicative of vertebral fracture. Osteoporosis occurs in both men and women but is more common among women following menopause.

In healthy humans, bone formation and resorption are closely linked; old bone is resorbed and replaced by newly-formed bone. In postmenopausal osteoporosis, bone resorption exceeds bone formation, leading to bone loss and increased risk of bone fracture. After menopause, the risk of fractures of the spine and hip increases dramatically; approximately 40% of 50-year-old women will experience an osteoporosis-related fracture of the spine, hip, or wrist during their remaining lifetimes. After experiencing one osteoporosis-related fracture, the risk of future fracture increases 5-fold compared to the risk among a non-fractured population. One in five men older than 50 years will have an osteoporotic fracture, most commonly at the spine, hip and wrist.

Risedronate sodium treatment decreases the elevated rate of bone turnover and corrects the imbalance of bone resorption relative to bone formation that is typically seen in postmenopausal osteoporosis. In clinical trials, administration of risedronate sodium to postmenopausal women resulted in dose-dependent decreases in biochemical markers of bone turnover, including urinary markers of bone resorption and serum markers of bone formation, at doses as low as 2.5 mg daily. At the 5 mg daily dose, decreases in resorption markers were evident within 14 days of treatment. Changes in bone formation markers were observed later than changes in resorption markers, as expected, due to the coupled nature of bone formation and bone resorption; decreases in bone formation of about 20% were evident within 3 months of treatment. Bone turnover markers (BTMs) reached a nadir of about 40% below baseline values by the sixth month of treatment and remained stable with continued treatment for up to 3 years.

These data demonstrate that risedronate sodium 5 mg administered daily to postmenopausal women produces a rapid reduction in bone resorption without over-suppression of bone formation. Bone turnover is decreased as early as 2 weeks and maximally within about 6 months of treatment, with achievement of a new steady-state which more nearly approximates the rate of bone turnover seen in premenopausal women.

In weekly and monthly risedronate sodium postmenopausal osteoporosis dosing studies, consistent decreases in bone resorption (50 to 60%) and bone formation (30 to 40%) markers were observed at Month 12.

As a result of the inhibition of bone resorption, asymptomatic and usually transient decreases from baseline in serum calcium (about 2%) and serum phosphate levels (about 5%) and compensatory increases in serum parathyroid hormone (PTH) levels were observed within 6 months in risedronate sodium 5 mg daily-treated patients in postmenopausal osteoporosis trials. No further decreases in serum calcium or phosphate, or increases in PTH were observed in postmenopausal women treated for up to 3 years.

In two 1-year studies for the treatment of osteoporosis in postmenopausal women comparing risedronate sodium 35 mg Once-a-Week to risedronate sodium 150 mg Once-a-Month respectively to risedronate sodium 5 mg daily, similar mean changes from baseline in serum calcium, phosphate and PTH were found for each of the intermittent regimens when compared to the daily dosage regimen.

Consistent with the effects of risedronate sodium on biochemical markers of bone turnover, daily oral doses as low as 2.5 mg produced dose dependent, significant increases in lumbar spine bone mineral density (BMD) (risedronate sodium 2.5 mg, 3% to 3.7%; risedronate sodium 5 mg, 4% to 4.5%) after 12 months of treatment in large-scale postmenopausal osteoporosis trials. A dose-dependent response to treatment was also observed in the BMD of the femoral neck over the same time (risedronate sodium 2.5 mg, 0.7% to 0.9%; risedronate sodium 5 mg, 1.5% to 2%). In two 1-year weekly and monthly dosing studies for the treatment of osteoporosis in postmenopausal women, comparing risedronate sodium 35 mg Once-a-Week and risedronate sodium 150 mg Once-a-Month respectively to risedronate sodium 5 mg daily, similar mean changes from baseline in BMD of the lumbar spine, total proximal femur, femoral neck and femoral trochanter were found for each of the intermittent regimens when compared to the daily regimen. See Treatment of Osteoporosis in Postmenopausal Women.

APO-RISEDRONATE tablets are film-coated.

10.3 Pharmacokinetics

Table 4 - Summary of Pharmacokinetic Parameters of Risedronate

Absorption

Absorption after an oral dose is relatively rapid (t_max ~1 hour) for the film-coated tablet and occurs throughout the upper gastrointestinal tract. Absorption is independent of dose up to 75 mg two consecutive days per month; systemic exposure increases disproportionally at 150 mg (about 2-fold greater than expected based on dose). Steady-state conditions in the serum are observed within 57 days of daily dosing. The mean oral bioavailability of the 30 mg film-coated tablet is 0.63% and is bioequivalent to a solution. Extent of absorption when administered 30 minutes before breakfast is reduced by 55% compared to dosing in the fasting state (i.e., no food or drink for 10 hours prior to or 4 hours after dosing). Dosing 1 hour prior to breakfast reduces extent of absorption by 30% compared to dosing in the fasting state. Dosing either 30 minutes prior to breakfast or 2 hours after a meal results in a similar extent of absorption.

Distribution

The mean steady-state volume of distribution is 6.3 L/kg in humans. Human plasma protein binding of drug is about 24%. Preclinical studies in rats and dogs dosed intravenously with single doses of [¹⁴C] risedronate indicate that approximately 60% of the dose is distributed to bone. The remainder of the dose is excreted in the urine. After multiple oral dosing in rats, the uptake of risedronate in soft tissues was found to be minimal (in the range of 0.001% to 0.01%), with drug levels quickly decreasing after the final dose.

Metabolism

There is no evidence that risedronate is systemically metabolized.

Elimination

Approximately half of the absorbed dose is excreted in urine within 24 hours, and 85% of an intravenous dose is recovered in the urine over 28 days. The mean renal clearance is 105 mL/min (CV = 34%) and mean total clearance is 122 mL/min (CV = 19%), with the difference primarily reflecting non-renal clearance or clearance due to adsorption to bone. The renal clearance is not concentration dependent, and there is a linear relationship between renal clearance and creatinine clearance. Unabsorbed drug is eliminated unchanged in feces. Once risedronate is absorbed, the serum concentration-time profile is multi-phasic with an initial half-life of about 1.5 hours and a terminal exponential half-life of 480 hours. Although the elimination rate of bisphosphonates from human bone is unknown, the 480 hour half-life is hypothesized to represent the dissociation of risedronate from the surface of bone.

Special Populations and Conditions

• Pediatrics: Risedronate pharmacokinetics have not been studied in patients < 18 years of age.
• Geriatrics: Bioavailability and disposition are similar in elderly (> 65 years of age) and younger subjects. No dosage adjustment is necessary.
• Sex: Bioavailability and disposition following oral administration are similar in men and women.
• Genetic Polymorphism: No data are available.
• Ethnic Origin: Pharmacokinetic differences due to race have not been studied.
• Hepatic Insufficiency: No studies have been performed to assess risedronate's safety or efficacy in patients with hepatic impairment. Risedronate is not metabolized in rat, dog, and human liver preparations. Insignificant amounts (< 0.1% of intravenous dose) of drug are excreted in the bile in rats. Therefore, dosage adjustment is unlikely to be needed in patients with hepatic impairment.
• Renal Insufficiency: Risedronate is excreted intact primarily via the kidney. Patients with mild-to-moderate renal impairment (creatinine clearance > 30 mL/min) do not require a dosage adjustment. Exposure to risedronate was estimated to increase by 44% in patients with creatinine clearance of 20 mL/min. Risedronate sodium is not recommended for use in patients with severe renal impairment (creatinine clearance < 30 mL/min) because of a lack of clinical experience.

11 STORAGE, STABILITY AND DISPOSAL

Store at room temperature 15°C - 30°C. Keep out of reach and sight of children.

12 SPECIAL HANDLING INSTRUCTIONS

There are no special handling instructions.

PART II: SCIENTIFIC INFORMATION

13 PHARMACEUTICAL INFORMATION

Drug Substance

Proper name: risedronate sodium hemi-pentahydrate

Chemical name: Risedronate sodium tablets contain risedronate sodium in the form of hemi - pentahydrate with small amounts of monohydrate. The chemical name of risedronate sodium is [1-hydroxy-2-(3-pyridinyl)ethylidene]bis[phosphonic acid] monosodium salt hemipentahydrate.

Molecular Formula and molecular mass: C₇H₁₀NO₇P₂Na·2.5 H₂O.

Anhydrous: 305.09 g/mol

Hemi-pentahydrate: 350.03 g/mol

Structural formula:

Physicochemical properties: Risedronate sodium is a white powder.

• Solubility: Risedronate Sodium is soluble in water and essentially insoluble in common organic solvents. Risedronate Sodium, in terms of Biopharmaceutical Pharmaceutics Classification System (BCS), is considered a low soluble drug (BCS Class 4 established based on the 75 mg dose).
• Solution pH: 4.2
• Dissociation Constants: pKa: pKa1= 13.81, pKa2= 11.03, pKa3= 5.99, pKa4= 5.02, pKa5= 2.52, pKa6= 1.24 (Risedronic Acid, calculated values)
• Partition Coefficient: 0.55 + 0.44 (Risedronic Acid, calculated value)

14 CLINICAL TRIALS

14.1 Clinical Trials by Indication

Treatment of Osteoporosis in Postmenopausal Women

Table 5 - Summary of patient demographics for clinical trials of Risedronate Sodium in the Treatment of Osteoporosis in Postmenopausal Women

Results of Study 1:

Table 6 - Comparison of Risedronate Sodium Once-a-Month vs. Daily Dosing in the Treatment of Osteoporosis in Postmenopausal Women – Primary Efficacy Analysis

In the first year of a 2-year, double-blind, multicentre study of postmenopausal women with osteoporosis, risedronate sodium 150 mg Once-a-Month was shown to be non-inferior to risedronate sodium 5 mg daily. Risedronate sodium 150 mg Once-a-Month was statistically shown to be non-inferior to the risedronate sodium 5 mg daily regimen for the primary efficacy variable of percent change from baseline to 1 year in increasing lumbar spine BMD. The two treatment groups were similar with regard to BMD increases at the lumbar spine, total proximal femur, femoral neck and femoral trochanter. The incidence of vertebral and non-vertebral fractures, reported as adverse events, was similar in the two treatment groups. Risedronate sodium 150 mg Once-a-Month is similar in safety and efficacy to risedronate sodium 5 mg daily for the treatment of postmenopausal osteoporosis. The safety and efficacy of risedronate sodium 150 mg Once-a-Month is currently being assessed beyond one year of treatment.

Histology/Histomorphometry: Histomorphometric evaluation of 278 bone biopsy samples from 204 postmenopausal women who received risedronate sodium 5 mg or placebo once daily for 2 to 3 years (including 74 pairs of biopsies, 43 from risedronate sodium-treated patients) showed a moderate and expected decrease in bone turnover in risedronate sodium-treated women.

Histologic assessment showed no osteomalacia, impaired bone mineralization, or other adverse effects on bone in risedronate sodium-treated women. These findings demonstrate that the bone formed during risedronate sodium administration is of normal quality.

14.2 Comparative Bioavailability Studies

A randomized, single-dose, double-blinded, 2-way, crossover comparative bioavailability study of ^PrAPO-RISEDRONATE 150 mg tablets (Apotex Inc.) and ^PrACTONEL® 150 mg tablets (Procter & Gamble Pharmaceuticals Canada Inc.) was conducted in healthy adult male and female subjects under fasting conditions. Comparative bioavailability data from the 36 subjects that were included in the statistical analysis are presented in the following table:

SUMMARY TABLE OF THE COMPARATIVE BIOAVAILABILITY DATA

^{1 Pr}APO-RISEDRONATE (risedronate as risedronate sodium hemi-pentahydrate) tablets, 150 mg (Apotex Inc.)

^{2 Pr}ACTONEL® (risedronate as risedronate sodium hemi-pentahydrate) tablets, 150 mg (Procter & Gamble Pharmaceuticals Canada, Inc.)

³ Expressed as the median (range) only

⁴ Expressed as the arithmetic mean (CV %) only

15 MICROBIOLOGY

No microbial information is required for this drug product.

16 NON-CLINICAL TOXICOLOGY

General Toxicology:

Acute Toxicity: Lethality after single oral doses was seen in female rats at 903 mg/kg (5826 mg/m²) and male rats at 1703 mg/kg (10967 mg/m²). The minimum lethal dose in mice, rabbits, and dogs was 4000 mg/kg (10909 mg/m²), 1000 mg/kg (10870 mg/m²), and 128 mg/kg (2560 mg/m²), respectively. These values represent 140 to 620 times the human 30 mg dose based on surface area, mg/m².

Chronic Toxicity: In a 1-year daily repeat dose toxicity study in dogs, the limiting toxicity of risedronate was observed at 8 mg/kg/day (160 mg/m²) and consisted of liver, testicular, renal, and gastrointestinal changes. Gastrointestinal effects at 16 mg/kg (111 mg/m²) were the first limiting toxicity in rats in a 26-week study. These doses are equivalent to approximately 6.25 to 9 times the human 30 mg dose based on surface area, mg/m². In 6 month and 1-year monthly repeat dose toxicity studies in dogs, the limiting systemic toxicity of risedronate was observed at 32 mg/kg (640 mg/m²) and consisted of liver, testicular, and renal toxicities. Gastric lesions were observed at 16 mg/kg (320 mg/m²). These doses are equivalent to approximately 3.5 and 7 times the human 150 mg dose based on surface area, mg/m².

A 13-week oral dog study was performed to evaluate the gastric and lower gastrointestinal toxicity and toxicokinetics of risedronate (8 and 16 mg/kg) when dosed with or without EDTA (2.5 and 12.5 mg/kg) following 14 once-weekly oral doses. No additional GI toxicity was observed with the addition of either dose of EDTA to either dose of risedronate. No new organs of toxicity were identified when dogs were treated with risedronate in combination with EDTA

(vs risedronate alone). Treatment with EDTA alone was not associated with any treatment-related changes.

Co-administration of EDTA with 8 and/or 16 mg/kg risedronate was associated with potentiation of risedronate-mediated histologic alterations in the liver, kidneys, and testes (incidence and/or severity). Potentiation of toxicity was more evident at 12.5 mg/kg EDTA when compared with 2.5 mg/kg EDTA. With respect to expected pharmacological effects (e.g. increased bone), 12.5 mg/kg EDTA potentiated the severity of rib hypertrophy and the incidence of increased bone in nasal turbinates when administered in combination with 8 and 16 mg/kg risedronate (vs risedronate alone). These findings may be related to the observed increase in exposure noted when risedronate was administered in combination with EDTA.

Carcinogenicity: Three carcinogenicity studies in two species (mouse and rat) have been completed. All studies clearly showed dose-dependent bone pharmacologic effects. Risedronate was not carcinogenic in male or female rats dosed daily by gavage for 104 weeks at doses up to 24 mg/kg/day (12 times the human 30 mg dose based on surface area, mg/m²). Similarly, there was no evidence of a carcinogenic potential in male or female mice dosed daily by gavage for 80 weeks at doses up to 32 mg/kg/day (5 times the human 30 mg dose based on surface area, mg/m²).

Genotoxicity: In a series of seven in vitro and in vivo mutagenicity assays, risedronate was not genotoxic. An in vitro chromosomal aberration assay in Chinese hamster ovary cells was weakly positive at highly cytotoxic doses (> 675 mcg/mL). However, when the assay was repeated at doses exhibiting increased cell survival (300 mcg/mL), risedronate was negative.

Reproductive and Developmental Toxicology: In female rats, ovulation was inhibited at an oral dose of 16 mg/kg/day (approximately 5.2 times the 30 mg/day human dose based on surface area, mg/m²). Decreased implantation was noted in female rats treated with doses ≥ 7 mg/kg/day (approximately 2.3 times the 30 mg/day human dose based on surface area, mg/m²). In male rats, testicular and epididymal atrophy and inflammation were noted at 40 mg/kg/day (approximately 13 times the 30 mg/day human dose based on surface area, mg/m²). Testicular atrophy was also noted in male rats after 13 weeks of treatment at oral doses of 16 mg/kg/day (approximately 5.2 times the 30 mg/day human dose based on surface area, mg/m²). There was moderate-to-severe spermatid maturation block after 13 weeks in male dogs at an oral dose of 8 mg/kg/day (approximately 8 times the 30 mg/day human dose based on surface area, mg/m²). These findings tended to increase in severity with increased dose and exposure time.

Survival of neonates was decreased in rats treated during gestation with oral doses ≥ 16 mg/kg/day (approximately 5.2 times the 30 mg/day human dose based on surface area, mg/m²). Body weight was decreased in neonates from dams treated with 80 mg/kg (approximately 26 times the 30 mg/day human dose based on surface area, mg/m²). In rats treated during gestation, the number of fetuses exhibiting incomplete ossification of sternebrae or skull was statistically significantly increased at 7.1 mg/kg/day (approximately

2.3 times the 30 mg/day human dose based on surface area, mg/m²). Both incomplete ossification and unossified sternebrae were increased in rats treated with oral doses ≥ 16 mg/kg/day (approximately 5.2 times the 30 mg/day human dose based on surface area, mg/m²). A low incidence of cleft palate was observed in fetuses from female rats treated with oral doses ≥ 3.2 mg/kg/day (approximately 1 time the 30 mg/day human dose based on surface area, mg/m²). The relevance of this finding to human use of risedronate sodium is unclear. No significant fetal ossification effects were seen in rabbits treated with oral doses up to 10 mg/kg/day during gestation (approximately 6.7 times the 30 mg/day human dose based on surface area, mg/m²). However, in rabbits treated with 10 mg/kg/day, 1 of 14 litters were aborted and 1 of 14 litters were delivered prematurely.

Similar to other bisphosphonates, treatment during mating and gestation with doses as low as 3.2 mg/kg/day (approximately 1 time the 30 mg/day human dose based on surface area, mg/m²) has resulted in periparturient hypocalcemia and mortality in pregnant rats allowed to deliver.

Bisphosphonates are incorporated into the bone matrix, from which they are gradually released over periods of weeks to years. The amount of bisphosphonate incorporation into adult bone, and hence, the amount available for release back into the systemic circulation, is directly related to the dose and duration of bisphosphonate use. There are no data on fetal risk in humans. However, there is a theoretical risk of fetal harm, predominantly skeletal, if a woman becomes pregnant after completing a course of bisphosphonate therapy. The impact of variables such as time between cessation of bisphosphonate therapy to conception, the particular bisphosphonate used, and the route of administration (intravenous versus oral) on this risk has not been studied.

17 SUPPORTING PRODUCT MONOGRAPHS

1. 1. ACTONEL, tablets 35 mg and 150 mg, submission control 267898, Product Monograph, AbbVie Corporation. (NOV 3, 2022)