Determinants of antihypertensive response to calcium antagonists in systemic hypertension

Calcium antagonists are an important group of drugs in the treatment of systemic hypertension. Examination of the factors that determine the magnitude of antihypertensive response to calcium antagonists is of interest for clinical and basic pathophysiologic reasons. Possible factors influencing response include drug dose, plasma drug concentration, plasma renin activity, baseline blood pressure, nonionized calcium in blood and inside vascular smooth muscle cells, patient age and patient race. Published studies have examined the determinants of antihypertensive response. The striking fact about many of these studies is that they fail to control for other possible factors that might influence response. This article reviews the methods used and the results of 23 different studies that examined the determinants of response to calcium antagonists. Possible relationships between plasma renin activity, intra- and extracellular calcium levels, and the antihypertensive response, are of interest from a pathophysiologic point of view. From a clinician's standpoint, the only determinants that matter are the dose of the drug and the degree of elevation of the blood pressure. In this regard, calcium channel blocking drugs are no different from other drugs that act by peripheral vasodilation.