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Telmisartan

Pronunciation: (tell-mih-SAHR-tan)
Class: Angiotensin ΙΙ receptor antagonist

Trade Names:
Micardis
- Tablets 20 mg
- Tablets 40 mg
- Tablets 80 mg

Pharmacology

Antagonizes the effect of angiotensin ΙΙ (vasoconstriction and aldosterone secretion) by blocking the angiotensin ΙΙ (AT ₁ receptor) in vascular smooth muscle and the adrenal gland, producing decreased BP.

Pharmacokinetics

Absorption

Telmisartan T _max is 0.5 to 1 h after dosing. Food slightly reduces bioavailability of telmisartan, with an AUC reduction of about 6% with a 40 mg tablet and 20% with a 160 mg dose. At 40 and 160 mg, the bioavailability was 42% and 58%. Trough plasma concentrations with every day dosing are about 10% to 25% of peak plasma concentrations.

Distribution

Telmisartan is more than 99.5% protein bound. Vd is about 500 L.

Metabolism

Telmisartan is metabolized by conjugation to form a pharmacologically-inactive acylglucuronide. The glucuronide of the parent compound is the only metabolite that has been identified in human plasma and urine.

Elimination

Telmisartan t _½ is approximately 24 h and total plasma Cl is greater than 800 mL/min. After IV or oral administration, more than 97% is eliminated unchanged in feces via biliary excretion.

Special Populations

Hepatic Function Impairment

Plasma concentrations are increased and absolute bioavailability approaches 100%.

Gender

Plasma concentrations are generally 2 to 3 times higher in women than in men.

Indications and Usage

Treatment of hypertension.

Contraindications

Standard considerations.

Dosage and Administration

Adults

PO 20 to 80 mg/day; usual starting dose, 40 mg/day.

Storage/Stability

Store at room temperature (59° to 86°F).

Drug Interactions

Digoxin

May increase plasma levels of digoxin, that may increase toxicity.

Lithium

Plasma concentrations may be increased by telmisartan, resulting in an increase in the pharmacologic effects and adverse reactions of lithium.

Laboratory Test Interactions

None well documented.

Adverse Reactions

EENT

Sinusitis (3%); pharyngitis (1%).

GI

Diarrhea (3%).

Respiratory

Upper respiratory tract infection (7%).

Miscellaneous

Back pain (3%).

Precautions

Warnings

Pregnancy

When used in pregnancy during the second and third trimesters, drugs that act directly on the renin-angiotensin system can cause injury and even death to the developing fetus. When pregnancy is detected, discontinue therapy as soon as possible.

Pregnancy

Category C (first trimester); Category D (second and third trimester).

Lactation

Undetermined.

Children

Safety and efficacy not established.

Renal Function

Use with caution in patients whose renal function may depend on the activity of the renin-angiotensin-aldosterone system (eg, patients with severe CHF); use may be associated with oliguria, progressive azotemia, acute renal failure, and death.

Hepatic Function

Use with caution.

Black patients

Telmisartan may not be as effective in black patients.

Dialysis

Patients on dialysis may develop orthostatic hypotension.

Hypotension/Volume-depleted patients

Symptomatic hypotension may occur after telmisartan initiation in intravascularly volume-depleted patients (eg, those treated with diuretics). Correct these conditions prior to administration or use lower starting dose.

Overdosage

Symptoms

Hypotension, dizziness, tachycardia, bradycardia.

Patient Information

Instruct patient to take the medication as prescribed at the same time each day.
Inform patient that telmisartan controls but does not cure hypertension.
Caution patient to take the dose exactly as prescribed and not to stop taking the medication even if feeling better. Instruct patient not to increase or decrease the dosage.
Instruct family and patient in BP and pulse measurement skills. Caution patient to call primary health care provider should abnormal measurements occur.
Instruct patient in methods of fall prevention including rising slowly and sitting on the side of the bed before standing, especially early in therapy.
Inform patient of the importance of adjunct therapies such as dietary planning, regular exercise program, weight reduction, low sodium diet, alcohol reduction, smoking cessation, and stress management.
Instruct patient to report symptoms of weakness, fatigue, dizziness, or lightheadedness to health care provider.
Caution patient to notify health care provider or dentist of use of this product prior to surgery or treatment.
Advise women to contact health care provider if pregnant, planning to become pregnant, or breast-feeding. Inform the patient of potential harm to the fetus.