Endocrine and vascular responses in hypertensive patients to long-term treatment with diltiazem

Forty patients (aged 28-66 years) with essential hypertension were randomized to 14 weeks of treatment with diltiazem or hydrochlorothiazide (HCTZ) in a double-blind, parallel study design. A significant reduction in supine body weight (-6.0 +/- 1.5 lb; p less than 0.001) and increase in pulse (+6 +/- 2 beats/min; p less than 0.001) occurred in HCTZ-treated patients. Patients receiving diltiazem had no change in weight, but did have a significant fall in pulse (-5 +/- 2 beats/min; p less than 0.05). The average reduction in supine systolic and diastolic blood pressures was comparable in both patient groups (-16 +/- 4/-11 +/- 2 mm Hg for HCTZ; -17 +/- 3/-12 +/- 1 for diltiazem). The reduction in blood pressure in HCTZ- and diltiazem-treated patients was not dependent on baseline plasma renin activity (PRA), but did not correlate significantly with changes in PRA and prostaglandin E2-metabolite (PGE2-M) (r = 0.51, p = 0.016). PRA increased +2.8 +/- 0.6 ng/ml/h (p less than 0.001) with HCTZ and +0.8 +/- 0.3 ng/ml/h (p less than 0.05) with diltiazem. PGE2-M also rose with both drugs (52 +/- 22 pg/ml for HCTZ; 63 +/- 36 pg/ml for diltiazem). Thus, diltiazem and HCTZ were similar in that the depressor response to each drug activated the renin-angiotensin system, which in turn was accompanied by increased production of PGE2-M.