Isradipine

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

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.

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.

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).

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

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

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

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

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.

Calcium-channel blockers

Store below 30° C.