'Second generation' dihydropyridine calcium antagonists. Greater vascular selectivity and some unique applications

The newer dihydropyridine calcium antagonists are structurally related to nifedipine, but may provide greater vascular selectivity and wider clinical utility. Five new dihydropyridines-nisoldipine, nicardipine, nimodipine, felodipine and nitrendipine-are reviewed with regard to their preclinical pharmacology, haemodynamic effects and clinical indications. Nisoldipine is a potent arterial vasodilator with minimal electrophysiological and negative inotropic effects. Although data are still preliminary, the drug has shown some efficacy in both exertional angina and essential hypertension. The dosing interval is not yet clearly established, but may be twice daily. Utility in congestive heart failure awaits confirmation, but preliminary studies are promising. Nicardipine is an especially potent peripheral, cerebral and coronary arterial vasodilator that causes 10-fold less myocardial depression in animals than nifedipine, and may provide important cardioprotective effects during ischaemia. Human haemodynamic studies have confirmed nicardipine's lack of negative inotropism, its ability to reduce coronary and peripheral vascular resistance, and its lack of effect on cardiac conduction. Several controlled trials have documented its efficacy in exertional angina, vasospastic angina, and essential hypertension. Nicardipine's potential as an antiatherosclerotic agent is currently under investigation. Nimodipine is undergoing a unique clinical development programme aimed at cerebrovascular disorders. In almost all species, nimodipine selectively increases cerebral blood flow and reverses cerebral artery spasm without altering cerebral oxidative metabolism or systemic blood pressure. In humans, a large, double-blind, placebo-controlled trial in subarachnoid haemorrhage showed that nimodipine significantly reduced the severity of neurological deficits associated with delayed cerebral vasospasm. Several uncontrolled trials with larger numbers of patients support these results. Nimodipine has also proved useful in reducing cerebral artery spasm during intracranial surgery, and in the prophylactic treatment of migraine headaches. A preliminary study of nimodipine in acute stroke showed promising results in limiting neurological disability. Felodipine is a very potent systemic arterial vasodilator with negligible myocardial depressant activity. It is also a renal artery vasodilator. Unlike the other new dihydropyridines, felodipine prolongs the A-H interval on electrophysiological testing, but only to about 50% of that observed with verapamil. Felodipine is undergoing clinical trials in essential hypertension.(ABSTRACT TRUNCATED AT 400 WORDS)