The Place of Isradipine in the Treatment of Hypertension

Abstract

Isradipine is a new dihydropyridine calcium antagonist with a high degree of selectivity for the coronary, cerebral, and skeletal muscle vasculature. The drug has minimal depressant activity on sinoatrial node automaticity and negligible negative chronotropic, dromotropic, and inotropic actions. Isradipine reduces blood pressure and systemic vascular resistance without changes in cardiac output and stroke volume. Renal blood flow is maintained while renal vascular resistance is reduced; this is accompanied by both short- and long-term diuretic and natriuretic effects. Doses of 1.25 to 5 mg twice daily lowers blood pressure effectively over 24 h. In open as well as placebo-controlled trials, 2.5 to 10 mg isradipine twice daily was safe and well tolerated, and reduced systolic and diastolic values in up to 85% of patients with mild-to-moderate hypertension. Efficacy is similar to those of nifedipine and nitrendipine, and potentially superior to those of propranolol, atenolol, prazosin, hydrochlorothiazide, and diltiazem. The drug can be safely combined with beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, and diuretics. Adverse effects are dose-dependent and secondary to arterial vasodilatation, such as headache, flushing, ankle edema, dizziness, palpitations, and tachycardia. At the recommended dose of 2.5 mg twice daily, the total incidence of side effects does not differ from that with placebo. The antiatherosclerotic, antitrophic, and cerebroprotective effects seen in experimental animal models are promising for the drug in the treatment of human hypertension. Isradipine may not only reduce blood pressure, but may also reduce the risk for the consequences of this peril, namely, cerebral stroke and myocardial infarction.