Responses to intravenous and oral diltiazem in elderly and younger patients with systemic hypertension.

Diltiazem concentrations and blood pressure, heart rate, PR interval and forearm vascular resistance responses to intravenous (25 and 50 mg) and oral (120 mg) diltiazem were compared in 13 elderly persons (mean age 68 +/- 4 years) and 10 young persons (mean 30 +/- 5 years) with essential hypertension. Diltiazem elimination was slower in the elderly. After a dose of 25 mg, clearance was 13 +/- 4 ml/min/kg in the elderly and 23 +/- 7 in the young (p less than 0.05); after 50 mg, 16 +/- 6 and 21 +/- 12 ml/min/kg (p less than 0.05); and after oral administration, 22 +/- 9 and 35 +/- 14 ml/kg/min (p less than 0.02). No age-related differences in volume of distribution (by model or area methods) were seen. Elimination half-lives were 4.5 +/- 2.2 hours in the elderly and 3.8 +/- 0.7 hour in the young persons (p less than 0.01); 4.5 +/- 1.6 and 3.3 +/- 0.7 hours (p = 0.10); and 4.7 +/- 1.5 and 3.3 +/- 1.8 hours (p = 0.08) after 50, 25 and 120 mg. Maximal decreases in mean blood pressure were from 113 +/- 14 to 91 +/- 12 mm Hg (19%) in the elderly patients and from 108 +/- 8 to 99 +/- 9 mm Hg in the younger patients (8%) after 50 mg; from 106 +/- 13 to 93 +/- 14 mm Hg and from 109 +/- 11 to 99 +/- 13 mm Hg, respectively, after 25 mg; and from 113 +/- 10 to 97 +/- 10 mm Hg and from 109 +/- 11 to 97 +/- 8 after 120 mg orally.(ABSTRACT TRUNCATED AT 250 WORDS)