Telmisartan (Pharmascience) Product Monograph

SUMMARY PRODUCT INFORMATION

INDICATIONS AND CLINICAL USE

Treatment of Essential Hypertension

Telmisartan (telmisartan) is indicated for the treatment of mild to moderate essential hypertension.

Telmisartan may be used alone or in combination with thiazide diuretics.

The concurrent use with angiotensin converting enzyme inhibitors is not recommended.

Geriatrics (> 65 years of age):

No dosing adjustment is necessary. It should be recognized, however, that greater sensitivity in some older individuals cannot be ruled out.

Pediatrics (< 18 years of age):

Telmisartan is not recommended for use in children below 18 years. The safety and efficacy of telmisartan for use in children below 18 years have not been established.

CONTRAINDICATIONS

Telmisartan is contraindicated in:

• Concomitant use of angiotensin receptor antagonists (ARBs) –including Telmisartan - with aliskiren-containing drugs in patients with diabetes mellitus (type 1 or type 2) or moderate to severe renal impairment (GFR < 60 ml/min/1.73m2) is contraindicated (see WARNINGS and PRECAUTIONS, Cardiovascular, Dual Blockade of the Renin-Angiotensin System (RAS) and Renal, and DRUG INTERACTIONS, Dual Blockade of the Renin-Angiotensin System (RAS) with ARBs, ACEIs or aliskiren-containing drugs).
• Patients who are hypersensitive to this drug or any ingredient in the formulation or components of the container. For a complete listing, see the DOSAGE FORMS, COMPOSITION AND PACKAGING section of the product monograph.

• Pregnant women (see WARNINGS AND PRECAUTIONS, Special Populations –

  Pregnant Women)

• Nursing women (see WARNINGS AND PRECAUTIONS, Special Populations –

  Nursing Women)

• Patients who are lactose intolerant.

WARNINGS AND PRECAUTIONS

Serious Warnings and Precautions

When used in pregnancy, angiotensin receptor (AT₁) blockers (ARB) can cause injury or even death of the developing fetus. When pregnancy is detected Telmisartan should be discontinued as soon as possible (see WARNINGS AND PRECAUTIONS, Special Populations).

General

A case of rare but fatal angioedema occurred in a patient who had been medicated for about 6 months with telmisartan, the active component of Telmisartan. The Autopsy Report described evidence of edema of the laryngeal mucosa, with terminal respiratory and circulatory failure. This is in the context of approximately 5.2 million patient-years exposure to telmisartan annually.

If laryngeal stridor or angioedema of the face, extremities, lips, tongue, or glottis occurs, Telmisartan should be discontinued immediately, the patient treated appropriately in accordance with accepted medical care, and carefully observed until the swelling disappears. In instances where swelling is confined to the face and lips, the condition generally resolves without treatment, although antihistamines may be useful in relieving symptoms. Where there is involvement of tongue, glottis, or larynx, likely to cause airway obstruction, appropriate therapy (including, but not limited to 0.3 to 0.5 ml of subcutaneous epinephrine solution 1:1000) should be administered promptly (see ADVERSE REACTIONS - Post Marketing Adverse Drug Reactions).

Patients with a known hypersensitivity (anaphylaxis) or angioedema to ARBs should not be treated with Telmisartan (see ADVERSE REACTIONS, Clinical Trial Adverse Drug Reactions -All Clinical Trials, Immune System, Not known: angioedema and ADVERSE REACTIONS - Post Market Adverse Drug Reactions).

Cardiovascular

Aortic and Mitral Valve Stenosis, Obstructive Hypertrophic Cardiomyopathy As with other vasodilators, special caution is indicated in patients suffering from aortic or mitral stenosis, or obstructive hypertrophic cardiomyopathy. These patients are at risk of decreased coronary perfusion resulting from a cardiac output that is limited by a fixed cardiac vascular obstruction.

Hypotension

In patients who are volume-depleted by diuretic therapy, dietary salt restriction, dialysis, diarrhea or vomiting, symptomatic hypotension may occur after initiation of therapy with Telmisartan. Such conditions, especially volume and/or sodium depletion, should be corrected prior to administration of Telmisartan. In these patients, because of the potential fall in blood pressure, therapy should be started under close medical supervision. Similar considerations apply to patients with ischemic heart or cerebrovascular disease, in whom an excessive fall in blood pressure could result in myocardial infarction or cerebrovascular accident.

Dual blockade of the Renin-Angiotensin System (RAS)

There is evidence that co-administration of angiotensin receptor antagonists (ARBs), such as telmisartan, or of angiotensin-converting-enzyme inhibitors (ACEIs) with aliskiren increases the risk of hypotension, syncope, stroke, hyperkalemia and deterioration of renal function, including renal failure, in patients with diabetes mellitus (type 1 or type 2) and/or moderate to severe renal impairment (GFR < 60 ml/min/1.73m2). Therefore, the use of Telmisartan in combination with aliskiren-containing drugs is contraindicated in these patients (see CONTRAINDICATIONS).

Further, co-administration of ARBs, including Telmisartan, with other agents blocking the RAS, such as ACEIs or aliskiren-containing drugs, is generally not recommended in other patients, since such treatment has been associated with an increased incidence of severe hypotension, renal failure, and hyperkalemia.

Endocrine and Metabolism

Hyperkalemia

Drugs such as telmisartan that affect the renin-angiotensin-aldosterone system can cause hyperkalemia. Monitoring of serum potassium in patients at risk is recommended. Based on experience with the use of drugs that affect the renin-angiotensin system, concomitant use with potassium-sparing diuretics, potassium supplements, salt substitutes containing potassium or other medicinal products that may increase the potassium level (heparin, etc.) may lead to a greater risk of an increase in serum potassium.

The use of a dual renin-angiotensin-aldosterone system (RAAS) blockade may lead to increased occurrence of hyperkalemia when given as add-on therapy in patients with controlled blood pressure.

Fertility

No studies on fertility in humans have been performed. (see Part II: TOXICOLOGY, Reproduction).

Hepatic/Biliary/Pancreatic

Hepatic Impairment:

As the majority of telmisartan is eliminated by biliary excretion, patients with cholestasis, biliary obstructive disorders or hepatic insufficiency have reduced clearance of telmisartan. Three to four fold increases in C_max and AUC were observed in patients with liver impairment as compared to healthy subjects. Telmisartan should be used with caution in these patients (see DOSAGE AND ADMINISTRATION).

Neurologic

Effects on ability to drive and use machines:

No studies on the effect on the ability to drive and use machines have been performed. However, when driving vehicles or operating machinery it should be taken into account that dizziness or drowsiness may occasionally occur when taking antihypertensive therapy.

Renal

In patients whose renal function may depend on the activity of the renin-angiotensin-aldosterone system, such as patients with bilateral renal artery stenosis, unilateral renal artery stenosis to a solitary kidney, or severe congestive heart failure, dual blockade of the renin- angiotensin-aldosterone system (e.g. concomitant use of an ARB with an ACE-inhibitor or the direct renin-inhibitor aliskiren) and treatment with agents that inhibit this system have been associated with oliguria, progressive azotemia, and rarely acute renal failure and/or death. There is no experience with long term use of telmisartan in patients with unilateral or bilateral renal artery stenosis but an effect similar to that seen with ACE inhibitors should be anticipated. In susceptible patients, concomitant diuretic use may further increase the risk. Use of telmisartan should include appropriate assessment of renal function in these types of patients.

There is no experience regarding the administration of telmisartan in patients with a recent kidney transplant.

Renal Impairment:

The use of ARBs – including Telmisartan – or of ACEIs with aliskiren-containing drugs is contraindicated in patients with moderate to severe renal impairment (GFR < 60 ml/min/1.73m²). (See CONTRAINDICATIONS and DRUG INTERACTIONS, Dual Blockade of the Renin-Angiotensin System (RAS) with ARBs, ACEIs, or aliskiren-containing drugs).

Special Populations

Pregnant Women: Drugs that act directly on the renin-angiotensin-aldosterone-system (RAAS) can cause fetal and neonatal morbidity and death when administered to pregnant women. When pregnancy is detected, Telmisartan should be discontinued as soon as possible.

The use of angiotensin receptor (AT₁) blockers (ARBs) is not recommended during pregnancy and should not be initiated during pregnancy. Epidemiological evidence regarding the risk of teratogenicity following exposure to angotensin converting enzyme inhibitors (another class of therapeutic products interfering with the RAAS) during the first trimester of pregnancy has not been conclusive; however a small increase in risk cannot be excluded. Given the current evidence available on the risk with ARB, similar risks may exist for this class of drugs. Patients planning pregnancy should be changed to alternative anti-hypertensive treatments which have an established safety profile for use in pregnancy. When pregnancy is diagnosed, treatment with angiotensin II antagonists should be stopped immediately, and, if appropriate, alternative therapy should be started.

The use of ARBs during the second and third trimesters is known to induce human fetotoxicity (decreased renal function, oligohydramnios, skull ossification retardation) and neonatal toxicity (renal failure, hypotension, hyperkalemia).

Infants with a history of in utero exposure to ARBs should be closely observed for hypotension, oliguria, and hyperkalemia. If oliguria occurs, attention should be directed toward support of blood pressure and renal perfusion. Exchange transfusion may be required as a means of reversing hypotension and/or substituting for disordered renal function; however, limited experience with those procedures has not been associated with significant clinical benefit.

It is not known if telmisartan can be removed from the body by hemodialysis.

Preclinical studies with telmisartan do not indicate teratogenic effect, but have shown fetotoxicity. No teratogenic effects were observed when telmisartan was administered to pregnant rats at oral doses of up to 50 mg/kg/day and to pregnant rabbits at oral doses up to 45 mg/kg/day with saline supplementation. In rabbits, fetotoxicity (total resorptions) associated with maternal toxicity (reduced body weight gain, mortality) was observed at the highest dose level (45 mg/kg/day). In rats, maternally toxic (reduction in body weight gain and food consumption) telmisartan doses of 50 mg/kg/day in late gestation and during lactation were observed to produce adverse effects in rat fetuses and neonates, including reduced viability, low birth weight, delayed maturation, and decreased weight gain. Significant levels of telmisartan were present in rat milk and rat fetuses’ blood during late gestation.

Nursing Women: It is not known whether telmisartan is excreted in human milk but significant levels have been found in the milk of lactating rats. Because many drugs are excreted in human milk and because of their potential for affecting the nursing infant adversely, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

Diabetic Patients: In diabetic patients with undiagnosed coronary artery disease (CAD) on blood pressure lowering therapy, the risk of fatal myocardial infarction and unexpected cardiovascular death may be increased. In patients with diabetes mellitus, CAD may be asymptomatic and therefore undiagnosed. These patients should undergo appropriate diagnostic evaluation, e.g. exercise stress testing, to detect and to treat CAD accordingly before initiating blood pressure lowering treatment with Telmisartan.

Pediatrics (< 18 years of age): Telmisartan is not recommended for use in children below 18 years due to limited data on safety and efficacy.

Geriatrics (> 65 years of age): Of the total number of patients receiving telmisartan in clinical studies, 551 (18.6%) were 65 to 74 years of age and 130 (4.4%) were ≥ 75. No overall age related differences were seen in the adverse effect profile, but greater sensitivity in some older patients cannot be ruled out.

Monitoring and Laboratory Tests

For specific monitoring and laboratory tests, see WARNINGS AND PRECAUTIONS (Cardiovascular, Endocrine and Metabolism, Hepatic and Renal) and DRUG INTERACTIONS sections.

ADVERSE REACTIONS

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.

Side effects were reported in clinical trials with telmisartan in the indication hypertension.

Telmisartan has been evaluated for safety in 27 clinical trials involving 7968 patients treated for hypertension. Of these 7968 patients, 5788 patients were treated with telmisartan monotherapy including 1058 patients treated for ≥1 year and 1395 patients treated in placebo-controlled trials.

In 3400 patients, discontinuation of therapy due to adverse events was required in 2.8% of telmisartan patients and 6.1% of placebo patients. The following potentially serious adverse events have been reported rarely with telmisartan in controlled clinical trials: syncope and hypotension. In placebo-controlled trials, no serious adverse event was reported with a frequency of greater than 0.1% in telmisartan-treated patients.

The adverse drug reactions listed below have been accumulated from controlled clinical trials in patients treated for hypertension and from post-marketing reports.

All Clinical Trials

The adverse drug events listed below have been accumulated from 27 clinical trials including 5788 hypertensive patients treated with telmisartan. Adverse events have been ranked under headings of frequency using the following convention: very common (≥1/10); common (≥1/100, <1/10); uncommon (≥1/1000, <1/100); rare (≥1/10000, <1/1000); very rare (<1/10000).

Body as a Whole, General:

Common: Chest pain, influenza-like symptoms, fatigue, conjunctivitis. Uncommon: Hyperhidrosis, asthenia (weakness).

Blood and Lymphatic System:

Uncommon: Anemia.

Rare: Thrombocytopenia.

Not known: Eosinophilia.

Cardiovascular System:

Common: Edema, palpitation.

Uncommon: Bradycardia, orthostatic hypotension, hypotension.

Rare: Tachycardia.

Central and Peripheral Nervous System:

Very Common: Headache.

Common: Dizziness, insomnia.

Uncommon: Vertigo.

Eye Disorders:

Rare: Visual disturbance.

Gastro-Intestinal System:

Common: Abdominal pain, diarrhea, dyspepsia, nausea, constipation, gastritis. Uncommon: Dry mouth, flatulence, vomiting.

Rare: Stomach discomfort.

Hepato-biliary Disorders:

Rare: Hepatic function abnormal/liver disorder.*

*Most cases of hepatic function abnormal / liver disorder from post-marketing experience with telmisartan occurred in patients in Japan, who are more likely to experience these adverse reactions

Immune System:

Rare: Hypersensitivity.

Not known: Anaphylactic reaction, angioedema.

Infections and Infestations:

Uncommon: Upper respiratory tract infections (including pharyngitis, sinusitis, bronchitis, rhinitis and coughing) and urinary tract infections (including cystitis).

Not known: Sepsis including fatal outcome.

Investigations:

Uncommon: Blood creatinine increased.

Rare: Blood uric acid increased, hepatic enzymes increased, blood creatinine phosphokinase increased, haemoglobin decreased.

Metabolism and Nutrition Disorders:

Uncommon: Hyperkalemia.

Rare: Hypoglycemia (in diabetic patients).

Musculo-Skeletal System:

Common: Arthralgia, muscle spasms (cramps in legs) or pain in extremity (leg pain), myalgia, arthritis, arthrosis.

Uncommon: Tendon pain (tendonitis like symptoms), back pain.

Nervous System:

Uncommon: Syncope (faint).

Psychiatric System:

Common: Anxiety, nervousness.

Uncommon: Depression.

Renal and Urinary System:

Uncommon: Renal impairment including acute renal failure.

Respiratory System:

Common: Dyspnea.

Skin and Appendages System:

Common: Skin disorders like rash.

Uncommon: Pruritus.

Rare: Erythema, drug eruption, eczema, toxic skin eruption. Not known: Urticaria.

Hemoglobin:

Infrequently, a decrease in hemoglobin has been observed which occurs more often during treatment with telmisartan than with placebo.

Placebo-controlled Trials

The overall incidence of adverse events reported with telmisartan (41.4%) was usually comparable to placebo (43.9%) in controlled clinical trials. Adverse events occurring in ≥ 1% of 1395 hypertensive patients treated with telmisartan monotherapy in placebo-controlled clinical trials, regardless of drug relationship, include the following:

Table 1: Adverse Events Occurring in > 1% of Hypertensive Patients Treated with

Telmisartan Monotherapy

The incidence of adverse events was not dose-related and did not correlate with the gender, age, or race of patients.

Less Common Clinical Trial Adverse Events (<1%)

In addition, the following adverse events, with no established causality, were reported at an incidence <1% in placebo-controlled clinical trials.

Autonomic Nervous System Disorders: sweating increased.

Body as a Whole: abdomen enlarged, allergy, cyst nos, fall, fever, leg pain, rigors, syncope.

Cardiovascular Disorders, General: hypotension, hypotension-postural, leg edema.

Central & Peripheral Nervous System Disorder: hypertonia, migraine-aggravated, muscle contraction-involuntary.

Gastrointestinal System Disorders: anorexia, appetite increased, flatulence, gastrointestinal disorder nos, gastroenteritis, gastroesophageal reflux, melena, mouth dry, abdominal pain.

Heart Rate & Rhythm Disorders: arrhythmia, tachycardia.

Metabolic & Nutritional Disorders: diabetes mellitus, hypokalaemia.

Musculoskeletal System Disorders: arthritis, arthritis aggravated, arthrosis, bursitis, fascitis plantar, tendinitis.

Myo Endo Pericardial & Valve Disorders: myocardial infarction.

Psychiatric Disorders: nervousness.

Red Blood Cell Disorders: anemia.

Reproductive Disorders, Female: vaginitis.

Resistance Mechanism Disorders: abscess, infection, bacterial, moniliasis genital, otitis media.

Respiratory System Disorders: bronchospasm, epistaxis, pneumonia, bronchitis

Skin & Appendage Disorders: rash, skin dry.

Urinary System Disorders: dysuria, hematuria, micturition disorder, urinary tract infection.

Vascular (Extracardiac) Disorders: cerebrovascular disorder, purpura.

Vision Disorders: vision abnormal

Abnormal Hematologic and Clinical Chemistry Findings

In placebo-controlled clinical trials involving 1041 patients treated with telmisartan monotherapy, clinically relevant changes in standard laboratory test parameters were rarely associated with administration of telmisartan.

Creatinine, Blood Urea Nitrogen:

Increases in BUN (≥ 11.2 mg/dl) and creatinine (≥ 0.5 mg/dl) were observed in 1.5% and 0.6% of telmisartan-treated patients; the corresponding incidence was 0.3% each for placebo-treated patients. These increases occurred primarily with telmisartan in combination with hydrochlorothiazide. One telmisartan treated patient discontinued therapy due to increases in creatinine and blood urea nitrogen.

Hemoglobin, Hemotocrit:

Clinically significant changes in hemoglobin and hematocrit (<10 g/dl and <30%, respectively) were rarely observed with telmisartan treatment and did not differ from rates in placebo-treated patients. No patients discontinued therapy due to anemia.

Serum Uric Acid:

An increase in serum uric acid (≥ 2.7 mg/dl) was reported in 1.7% of patients treated with telmisartan and in 0.0% of patients treated with placebo. Clinically significant hyperuricemia (>10 mEq/L) was observed in 2.3% of patients with telmisartan, with 0.4% reported in patients at baseline. Increases in serum uric acid were primarily observed in patients who received telmisartan in combination with hydrochlorothiazide. No patient was discontinued from treatment due to hyperuricemia.

Liver Function Tests:

Clinically significant elevations in AST and ALT (>3 times the upper limit of normal) occurred

in 0.1% and 0.5% respectively of patients treated with telmisartan compared to 0.8% and 1.7% of patients receiving placebo. No telmisartan-treated patients discontinued therapy due to abnormal hepatic function.

Serum Potassium:

Marked laboratory changes in serum potassium (≥ ±1.4 mEq/L) occurred rarely and with a lower frequency in telmisartan-treated patients (0.3%, 0.1%, respectively) than in placebo patients (0.6%, 0.3%, respectively). Clinically significant changes in potassium (that exceeded 3 mEq/L) were found in 0.6% of telmisartan-treated patients, with 0.5% of these reported at baseline. The corresponding rates for placebo-treated patients were 0.6% and 0.8%.

Cholesterol:

In placebo-controlled trials, marked increases in serum cholesterol were reported in a total of 6 telmisartan-treated patients (0.4%) and no placebo patients. Two of these patients were followed over time, in both cases cholesterol values reverted to baseline levels.

Serum elevations in cholesterol were reported as adverse events in 11 of 3445 patients (0.3%) in all clinical trials. There were no reported cases of hypercholesterolemia in telmisartan-treated patients in placebo-controlled trials.

Post-Market Adverse Drug Reactions

Since the introduction of telmisartan in the market, cases of anxiety, dizziness, vision troubled, vertigo, abdominal distension, abdominal pain, retching, hyperhidrosis, arthralgia, myalgia, muscle spasm, back pain, asthenia, pain in extremity, fatigue, chest pain, blood creatinine increased, erythema, pruritus, syncope/faint, insomnia, depression, stomach discomfort, vomiting, hypotension (including orthostatic hypotension), bradycardia, tachycardia, abnormal hepatic function/liver disorder, renal impairment including acute renal failure, hyperkalemia, dyspnoea, anaemia, eosinophilia, thrombocytopenia, and weakness have been reported. The frequency of these effects is unknown. As with other angiotensin II antagonists, rare cases of angioedema (with fatal outcome), pruritus, rash and urticaria have been reported.

Cases of muscle pain, muscle weakness, myositis and rhabdomyolysis have been reported in patients receiving angiotensin II receptor blockers.

In addition, since the introduction of telmisartan in the market, cases with increased blood creatinine phosphokinase (CPK) have been reported.

DRUG INTERACTIONS

Drug-Drug Interactions

Table 2: Established or Potential Drug-Drug Interactions

Drug-Food Interactions

When telmisartan is taken with food, the reduction in the area under the plasma concentration-time curve (AUC) of telmisartan varies from approximately 6% (40 mg) to approximately 19% (160 mg), and the reduction in C_max varies from approximately 26% (40 mg) to 56% (160 mg). However, three hours after administration, plasma concentrations are similar whether telmisartan is taken with or without food.

Drug-Herb Interactions

Interactions with herbal products have not been established.

Drug-Laboratory Interactions

Interactions with laboratory tests have not been established.

Drug-Lifestyle Interactions

No studies on the effect on the ability to drive and use machines have been performed. However, when driving vehicles or operating machinery it should be taken into account that dizziness or drowsiness may occasionally occur when taking antihypertensive therapy.

DOSAGE AND ADMINISTRATION

Dosing Considerations

The antihypertensive effect is present within 2 weeks and maximal reduction is generally attained after four weeks. If additional blood pressure reduction is required, a thiazide diuretic may be added.

Telmisartan should be taken consistently with or without food.

Recommended Dose and Dosage Adjustment

Treatment of Essential Hypertension:

The recommended dose of Telmisartan is 80 mg once daily.

No initial dosing adjustment is necessary for elderly patients or for patients with renal impairment, but greater sensitivity in some older individuals cannot be ruled out. Markedly reduced telmisartan plasma levels were observed in patients on hemodialysis.

For patients with hepatic impairment a starting dose of 40 mg is recommended (see WARNINGS AND PRECAUTIONS, Hepatic/Biliary/Pancreatic).

Missed Dose

Telmisartan should be taken at the same time each day, preferably in the morning. However, if a dose is missed during the day, the next dose should be continued at the usual time. Do not double dose.

OVERDOSAGE

Limited data are available with regard to overdosage in humans. The most prominent manifestations of overdosage were hypotension and/or tachycardia; bradycardia also occurred. If symptomatic hypotension should occur, supportive treatment should be instituted. Telmisartan is not removed by hemodialysis.

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

ACTION AND CLINICAL PHARMACOLOGY

Mechanism of Action

Telmisartan is an orally active angiotensin II AT₁ receptor antagonist. By selectively blocking the binding of angiotensin II to the AT₁ receptors telmisartan blocks the vasoconstrictor and aldosterone secreting effects of angiotensin II. Telmisartan does not exhibit any partial agonist activity at the AT₁ receptors, and has essentially no affinity for the AT₂ receptors. AT₂ receptors have been found in many tissues, but to date they have not been associated with cardiovascular homeostasis. In vitro binding studies indicate that telmisartan has no relevant affinity for other receptors nor does it inhibit human plasma renin.

Telmisartan does not inhibit angiotensin converting enzyme, also known as kininase II, the enzyme that converts angiotensin I to angiotensin II and degrades bradykinin, nor does it affect renin or other hormone receptors or ion channels involved in cardiovascular regulation of blood pressure and sodium homeostatis.

In hypertensive patients blockade of angiotensin II AT₁ receptors results in two to three fold increase in plasma renin and angiotensin II plasma concentrations. Long term effects of increased AT₂ receptor stimulation by angiotensin II are unknown.

Pharmacodynamics

Treatment of Essential Hypertension

In normal volunteers, a dose of telmisartan 80 mg inhibited the pressor response to an intravenous infusion of angiotensin II by about 90% at peak with approximately 40% inhibition persisting for 24 hours.

In hypertensive patients with normal renal function, no clinically significant effects on renal plasma flow, filtration fraction, or glomerular filtration rate were observed. In multiple dose studies in hypertensive patients, telmisartan had no adverse effect on renal function as measured by serum creatinine or blood urea nitrogen.

The antihypertensive effects of telmisartan were demonstrated in six placebo-controlled clinical trials, in a total of 1773 patients, 1031 of whom were treated with telmisartan. Upon initiation of

antihypertensive treatment with telmisartan, blood pressure was reduced after the first dose and there was a gradual increase in the antihypertensive effect during continued treatment for ≤ 12 weeks, with most of the increase occurring during the first month. Onset of antihypertensive activity occurs within 3 hours after administration of a single oral dose. The antihypertensive effect of once daily administration of telmisartan is maintained for the full 24-hour dose interval. The magnitude of blood pressure reduction from baseline, after placebo subtraction, was on average (SBP/DBP) -11.3/-7.3 mmHg for telmisartan 40 mg once daily, and -13.7/-8.1 mmHg for telmisartan 80 mg once daily. Upon abrupt cessation of treatment with telmisartan, blood pressure gradually returned to baseline values over a period of several days. During long term studies (without placebo control) the effect of telmisartan appeared to be maintained for ≥ 1 year.

For those patients treated with telmisartan 80 mg once daily who required additional blood pressure reduction, addition of a low dose of hydrochlorothiazide (12.5 mg) resulted in incremental blood pressure reductions of -9.4/-7.0 mmHg.

The antihypertensive effect of once-daily telmisartan (40-80 mg) was similar to that of once-daily amlodipine (5-10 mg), atenolol (50-100 mg), enalapril (5-20 mg) and lisinopril (10-40 mg).

There was essentially no change in heart rate in telmisartan-treated patients in controlled trials.

In clinical trials with post-dose in-clinic monitoring no excessive blood pressure lowering peak effect was observed even after the first dose, and the incidence of symptomatic orthostasis was very low (0.04%). With automated ambulatory blood pressure monitoring, the 24-hour trough-to-peak ratio for telmisartan was determined to be at least 80% for both systolic and diastolic blood pressure.

The antihypertensive effect of telmisartan is not influenced by patient age, weight or body mass index. Blood pressure in hypertensive black patients (usually a low renin population) is significantly reduced by telmisartan (compared to placebo), but less so than in non-black patients.

Diabetic Patients: Multiple exploratory post hoc analyses were carried out on the two cardiovascular (CV) outcome trials (ONTARGET and PRoFESS). In PRoFESS, an increased risk of unexpected CV death was seen with telmisartan versus placebo in diabetics without previously diagnosed coronary artery disease (CAD) but not in those with a documented history of CAD. No such increased risk was demonstrated in ONTARGET for telmisartan versus ramipril in diabetes patients without previously diagnosed CAD.

These findings in diabetics with added cardiovascular risk, could be related to a pre-existing but asymptomatic or silent CAD. Diabetics with undiagnosed and therefore untreated CAD may be at increased risk when lowering blood pressure too far, e.g. when initiating antihypertensive therapy, due to a further reduction of perfusion in an already narrowed coronary artery.

Pharmacokinetics

Absorption: Following oral administration, telmisartan is well absorbed, with a mean absolute bioavailability of about 50%. Mean peak concentrations of telmisartan are reached in 0.5-1 hour after dosing.

The pharmacokinetic profile is characterized by greater than proportional increases of plasma concentrations (C_max and AUC) with increasing doses ≥ 40 mg. Telmisartan shows bi-exponential decay kinetics with a terminal elimination half life of approximately 24 hours, and does not accumulate in plasma upon repeated once-daily dosing.

Metabolism: Telmisartan is metabolized by conjugation with glucuronic acid to form an acylglucuronide of telmisartan. This glucuronide is the only metabolite which has been identified in human plasma and urine. Following both oral dosing and intravenous administration of radiolabeled telmisartan, the parent compound represented approximately 85% and the glucuronide approximately 11% of total radioactivity in plasma. No pharmacological activity has been shown for the glucuronide conjugate.

The CYP 450 isoenzymes are not responsible for telmisartan metabolism.

Excretion: Total plasma clearance of telmisartan is >800 mL/min. Half-life and total clearance appear to be independent of dose. Biliary excretion is the main route of elimination of telmisartan and its metabolite. Following intravenous and oral administration of C¹⁴ labelled telmisartan 0.91% and 0.49% of administered dose were found in the urine as glucuronide, respectively. Most of the oral and intravenous dose, >97%, was excreted in feces as the parent compound.

Women have a lower telmisartan clearance and have a greater systolic blood pressure response at trough than men.

Distribution: Telmisartan is >99.5% bound to plasma protein, mainly albumin and a1-acid glycoprotein. Plasma protein binding is constant over the concentration range achieved with therapeutic doses. The volume of distribution for telmisartan is approximately 500 liters, indicating additional tissue binding sites.

When telmisartan is taken with food, the reduction in the area under the plasma concentration-time curve (AUC) of telmisartan varies from approximately 6% (40 mg) to approximately 19% (160 mg), and the reduction in C_max varies from approximately 26% (40 mg) to 56% (160 mg). However, three hours after administration, plasma concentrations are similar whether telmisartan is taken with or without food.

Special Populations and Conditions

Pediatrics:

Telmisartan pharmacokinetics have not been investigated in patients <18 years of age.

Geriatrics:

The pharmacokinetics of telmisartan do not differ between the elderly and those younger than 65 years. (see DOSAGE AND ADMINISTRATION)

Gender:

Plasma concentrations of telmisartan are generally 2-3 fold higher in females than in males. No

dosage adjustment is necessary.

Hepatic Insufficiency:

In patients with hepatic insufficiency, plasma concentrations of telmisartan are increased, and absolute bioavailability approaches 100%. A lower starting dose should be considered. (see WARNINGS AND PRECAUTIONS, and DOSAGE AND ADMINISTRATION)

Renal Insufficiency:

Renal excretion of telmisartan is negligible. No dosage adjustment is necessary in patients with renal insufficiency. In patients on hemodialysis both C_max and AUC of telmisartan were markedly reduced as compared to healthy volunteers. Telmisartan is not removed by hemodialysis. (see WARNINGS AND PRECAUTIONS, and DOSAGE AND ADMINISTRATION)

Genetic Polymorphism:

No studies were conducted to evaluate the influence of genetic polymorphisms on the pharmacokinetics or pharmacodynamics of telmisartan.

STORAGE AND STABILITY

Telmisartan tablets are hygroscopic and require protection from moisture. Tablets are packaged in blisters and bottles and should be stored at room temperature, 15-30°C. Tablets should not be removed from blisters and bottles until immediately prior to administration.

DOSAGE FORMS, COMPOSITION AND PACKAGING

Telmisartan is available as white, oblong, plane tablets containing 40 mg or 80 mg of telmisartan. The tablets are debossed with “SZ” on one side and with “223” or “224” on the other side for the 40 mg and 80 mg strengths, respectively.

Each Telmisartan tablet contains telmisartan 40 mg or 80 mg, and the following non-medicinal ingredients: crospovidone, lactose anhydrous, lactose monohydrate, magnesium stearate, meglumine, povidone and sodium hydroxide.

Telmisartan tablets 40 mg are available in bottles of 100 tablets.

Telmisartan tablets 80 mg are available in bottles of 100 tablets.

PART II: SCIENTIFIC INFORMATION

PHARMACEUTICAL INFORMATION

Drug Substance

Proper name: Telmisartan

Chemical name: 4’-[[4-methyl-6-(1-methyl-1H-benzimidazol-2-yl)-2-propyl-1H-benzimidazol-1-yl] methyl] biphenyl-2-carboxylic acid

Molecular Formula: C₃₃H₃₀N₄O₂

Molecular Mass: 514.6 g/mol

Structural Formula:

Physicochemical Properties:

Description:

Telmisartan is a white or slightly yellowish, crystalline powder. It is practically insoluble in water and in the pH range of 3 to 9, sparingly soluble in strong acid (except HCl), and soluble in strong base.

Polymorphism: Drug substance shows polymorphism. Two polymorphic forms (A and B) and one pseudopolymorphic form (C) of telmisartan have been disclosed. Telmisartan pure form A is used for manufacture of tablets.

Melting point: 261 -263 °C

Partition coefficient: 3.2 (n-octanol/water at pH=7.4)

CLINICAL TRIALS

A blinded, randomized, single-dose, two-period, two-sequence, two-treatment, crossover oral bioequivalence study of Telmisartan 80 mg tablets and Micardis® 80 mg tablets was conducted in thirty-one (31) normal, healthy, non-smoking, male and post-menopausal and/or surgically sterile female subjects under fasting conditions.

* Telmisartan 80 mg tablets (manufactured for Pharmascience Inc.).

^† Micardis^® 80 mg tablets (manufactured by Boehringer Ingelheim (Canada) Ltd.and purchased in Canada). ¥ AUC_I and T_½ parameters were estimated for 23 subjects (test) and 26 subjects (reference) out of 31 subjects who completed the study. These parameters (AUC_I and T_½) could not be accurately estimated for all subjects due to the long half-life of the active ingredient and the design of the study.

^# Expressed as Median (Range)

^§ Expressed as the arithmetic mean (CV%) only.

Study demographics and trial design

Table 3: Summary of patient demographics for clinical trials in specific indication

* median age

Study results

Table 4: Results of studies

BP = blood pressure

DBP = diastolic blood pressure

SBP = systolic blood pressure

DETAILED PHARMACOLOGY

In in vitro studies, telmisartan displaced ¹²⁵I-angiotensin II from its binding site at the AT₁ receptor with an inhibitor constant (Ki) of 3.7 nM.

In isolated strips of rabbit aorta, telmisartan exerted potent angiotensin II antagonism: the calculated dissociation constant was K_B 3.3•10^-10M.

In vivo results showed that telmisartan was a potent and long acting antagonist of the functional response to exogenously administered angiotensin II in rats, rabbits and dogs after both intravenous and oral administration. Telmisartan showed dose dependent and long lasting (>24h) antihypertensive effects after single or repeated oral administration in various rodent models of experimental hypertension.

TOXICOLOGY

Acute Toxicity

In acute oral toxicity studies no deaths and no changes occurred in rats or dogs at 2000 mg/kg, the highest oral dose tested. The IV LD₅₀ in rats was 150-200 mg/kg in males and 200-250

mg/kg in females.

Chronic Toxicity

Chronic oral toxicity of telmisartan was evaluated in studies following administration of doses up to 500 mg/kg for up to 26 weeks in rats, and ≤ 1 year in dogs. Chronic intravenous toxicity was evaluated in studies of ≤ four weeks at doses ≤ 20 mg/kg in rats and ≤ 50 mg/kg in dogs.

Repeated dose administration of telmisartan resulted in marked and long lasting hypotension, hyperplasia of juxtaglomerular apparatus and lesions of the gastrointestinal tract. Further effects were reduced body weight gain, heart weight and red blood cell indices, increased potassium and AST and ALT, the latter in the absence of morphological evidence of toxicity. No effect doses were not identified for decreased erythroid indices, increased BUN and juxtaglomerular hypertrophy/hyperplasia in rats and dogs.

Reproduction

In studies on fertility and reproductive performance in male and female rats no effect on mating performance, reproductive organs, or fertility in either sex, or on litter parameters was observed with telmisartan doses of 5-100 mg/kg. No teratogenic or embryotoxic potential in rats was observed at doses ≤ 50 mg/kg administered from day 7 through day 16 of pregnancy. However, at toxic dose levels, non-clinical studies indicated some hazardous potential of telmisartan to fetal development (increased number of late resorptions in rabbits) and to the postnatal development of the offspring: lower body weight, delayed eye opening, and higher mortality.

Telmisartan was detectable in the placenta, fetus and amniotic fluid of rats after single oral doses of 1 mg/kg.

Mutagenicity

Telmisartan was not mutagenic at a concentration range of 10 to 2500 mcg/plate in the bacterial reverse mutation assay, with or without metabolic activation. No potential for chromosomal damage was found in the mouse micronucleus test at a dose range of 250 to 1000 mg/kg. No forward mutations at the HPRT locus in V79 cells were induced at a concentration range of 10 to 100 mcg/ml, with or without metabolic activation. No chromosomal aberrations were induced in human peripheral lymphocytes in vitro at concentrations ≤ 100 mcg/ml without metabolic activation and concentrations ≤ 200 mcg/ml with metabolic activation.

Carcinogenicity

The carcinogenic potential of telmisartan was assessed in 2-year feeding studies in mice at doses of 10, 100 and 1000 mg/kg and in rats at 3, 15 and 100 mg/kg. Drug administration did not affect survival time in either study and also tumor mortality was not increased. Incidence and time to appearance of palpable masses showed no treatment influence in mice and rats. No increases were observed in overall tumor incidence, incidence of benign and malignant tumors or tumor multiplicity.

Gastrointestinal Tract

Gastric and/or duodenal mucosal erosions and ulcers were seen in rats given ≥ 4 mg/kg orally or ≥ 2 mg/kg IV and in dogs given ≥ 40 mg/kg orally. Most lesions were small, focal or multifocal in distribution and limited to the mucosa and submucosa. Ulcers and erosions healed rapidly after drug withdrawal.

Urinary Tract and Electrolytes

Hypertrophy of the juxtaglomerular apparatus and increased granularity of renin-producing cells of the juxtaglomerular apparatus, afferent arterioles and interlobular arteries of the kidney were observed in rats at doses of ≥ 1 mg/kg and in dogs at ≥ 5 mg/kg. In rats and dogs subjected to long term treatment with telmisartan, plasma renin activity returned to normal levels after 26 to 52 weeks of treatment. Reversible slight to mild increases in serum potassium levels occurred in rats at oral doses of ≥ 4 mg/kg. In dogs, non-progressive increases in serum potassium levels were noted at 50 and 500 mg/kg in the 52 week oral study. Minimal to mild, reversible increases in blood urea nitrogen and creatinine were evident at oral doses of ≥ 4 mg/kg in rats and ≥ 5 mg/kg in dogs.

Hematology

Slight to mild reversible reductions of red blood cell count, hematocrit, and/or hemoglobin were observed after repeated oral dosing with telmisartan ≥50 mg/kg in the rat and ≥5 mg/kg in the dog.

REFERENCES

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