The determinants of response to diltiazem in hypertension

We examined factors (blood pressure, plasma renin activity, and age) influencing the antihypertensive response in essential hypertensive patients given 240 mg/day of slow-release diltiazem in an unblinded study after a placebo run-in period. Subjects provided a range of diastolic blood pressures (90 to 115 mm Hg), of age (31 to 70 years), and of plasma renin activity (0.1 to 2.7 ng angiotensin I/ml/hr) on a 70 to 150 mEq sodium diet. Blood pressure, plasma renin activity, and plasma diltiazem concentrations were measured after the first (n = 21) and final dose (n = 19) of 120 mg diltiazem, twice daily for 4 weeks. Multiple linear stepwise regression of change in blood pressure versus age, plasma renin activity, and baseline blood pressure showed baseline blood pressure was the only predictor of response (p = 0.0002). For each increase of 10 mm Hg in baseline pressure there was a 7 mm Hg greater decrease in diastolic blood pressure. We conclude that patient age and plasma renin activity are not clinically significant predictors of antihypertensive response to diltiazem in hypertension.