Plasma predictors of calcium channel blocker efficacy in hypertension

It has been reported previously that the blood pressure response to calcium channel blockers is inversely related to serum ionized calcium. We studied the relationship of serum total and ionized calcium, upright plasma renin activity, calcitonin, PTH, and 24 h urine sodium to the level of diastolic blood pressure and response to a dihydropyridine Ca channel blocker (nitrendipine) in patients with uncomplicated essential hypertension. Blood pressure response to nitrendipine tended to be greater in patients with lower plasma renin at baseline (r = - 0.55; p < 0.07). None of the other individual parameters measured correlated with the level of diastolic blood pressure. Similar analysis of data in a comparable group of patients treated with propranolol showed no correlation between plasma renin activity and the changes in diastolic blood pressures. Therefore, we concluded that the antihypertensive efficacy of nitrendipine could not be predicted on the basis of the concentrations of these biochemical elements in a small sample of patients. However, additional investigations with a larger patient population may show a relationship with renin.