Animal pharmacology of nicardipine and its clinical relevance.

Nicardipine has high affinity for the dihydropyridine-binding site and has been shown to inhibit the influx of extracellular calcium through membrane slow channels. The calcium antagonist activity of nicardipine is greater in vascular smooth muscle than in cardiac muscle. Nicardipine has also been shown to possess greater activity in coronary than in peripheral vascular smooth muscle. This in vitro profile accounts for the decreased blood pressure and increased coronary blood flow in animal models in vivo. These pharmacologic properties are the basis for nicardipine's clinical utility in essential hypertension and acute myocardial ischemia. Nicardipine has been shown to be more vascular selective than other calcium antagonists and, therefore, possibly less inclined to produce negative inotropicity. This latter property has been confirmed in human hemodynamic studies. Nicardipine is effective in models of acute myocardial ischemia and hypertension. These results have been confirmed in antianginal and antihypertensive studies in humans. This new calcium antagonist has been shown to limit myocardial infarct size in both dogs and baboons subject to left anterior descending coronary artery ligation and to reduce the extent of ischemia-induced cerebral neuronal death in rats. Other protective effects of nicardipine have been demonstrated in paracetamol overdose in mice, chloroform-induced hepatotoxicity in rats and cerebral ischemia in gerbils and baboons. The mechanism of this cell protection of nicardipine may be related to physicochemical effects.