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 step wise 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. Clinical Pharmacology and Therapeutics (1991) 50, 338–349; doi:10.1038/clpt.1991.145