Isradipine

Indications

Isradipine is indicated in the management of hypertension. It may be used alone or concurrently with thiazide-type diuretics.

Pharmacology

Isradipine is a dihydropyridine Calcium channel blocker. It prevents Ca++ ions from entering the slow channels or select voltage-sensitive areas of vascular smooth muscle and myocardium during depolarisation, producing a relaxation of coronary vascular smooth muscle and coronary vasodilation.

Dosage And Administration

Adult: Initially, 2.5 mg bid, increase if necessary after 3-4 wk to 5 mg bid, or 10 mg bid as required.
Elderly: Initially, 1.25 mg bid. Maintenance: 2.5 or 5 mg once daily.
Hepatic Impairment: Initially 1.25 mg bid. Maintenance: 2.5 or 5 mg once daily.

May be taken with or without food.

Interaction

Concurrent admin with enzyme-inducing drugs (e.g. rifampicin, phenobarbital, carbamazepine) reduced plasma concentrations of isradipine. Increased bioavailability with cimetidine. May increase serum levels with CYP3A4 inhibitors (e.g. macrolides, HIV protease inhibitors, azole antifungals, delavirdine).

Contraindications

Cardiogenic shock, within 1 mth of MI, unstable angina, treatment of hypertensive crisis.

 

Side Effects

Headache, dizziness, palpitations, tachycardia, peripheral oedema, flushing, dyspnoea, abdominal discomfort, rash, pruritus, polyuria, fatigue, malaise.

Pregnancy And Lactation

Pregnancy Category C. Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus

Precautions And Warnings

Patients with CHF, severe aortic stenosis, hypertrophic cardiomyopathy with outflow tract obstruction. Hepatic impairment. Pregnancy and lactation.

Overdose Effects

Symptoms: Excessive peripheral vasodilation with subsequent marked and prolonged systemic hypotension and tachycardia.

Management: Symptomatic and supportive treatment. Emesis, gastric lavage, admin of activated charcoal followed in 30 min by a saline cathartic. A vasoconstrictor (e.g. epinephrine) may be useful in restoring normotensive state. Refractory hypotension or AV conduction disturbances may be treated with IV Ca salts or glucagon.

Therapeutic Class

Calcium-channel blockers.

Storage Conditions

Store below 30° C.

Available Brand Names