ANTIHYPERTENSIVE EFFECTS OF INTRAVENOUS COMPARED WITH ORAL CAPTOPRIL

Twenty mild to moderate hypertensive subjects (11 men, 9 women, mean a ge 54.3 years, range 39-65 years) were studied to determine whether an intravenous form of captopril could be as safe and efficacious as an oral form and to estimate the time course of anti-hypertensive action over a wide dose range (100-fold) of i.v. doses versus oral captopril and placebo. Each subject demonstrated supine diastolic blood pressure (DBP) less than or equal to 90 mm Hg following prospective ACE inhibi tor monotherapy, with return of supine DBP to within 95-110 mm Hg 4 we eks after ACE inhibitor discontinuation. These subjects were then admi tted to an inpatient unit for six 24 h periods; an initial acclimation period followed by five single doses of i.v. captopril (1.25, 12.5 an d 125 mg) or placebo given as a 20 min infusion and oral captopril (25 mg) or placebo in a double-blind, double-dummy crossover study. Each dose was separated by 48 h. All 20 patients completed the study with n o clinically significant adverse events. Captopril at doses of 125 mg i.v., 12.5 mg i.v. and 25 mg orally produced similar BP reductions ove r the 12 h postdose interval, and were more effective in lowering BP t han intravenous captopril 1.25 mg or placebo. The 125 mg intravenous c aptopril dose was no more effective overall in BP reduction than the 1 2.5 mg i.v. and 25 mg oral doses and was associated with a greater inc idence of adverse events. Treatment with 12.5 mg i.v. captopril is saf e and comparable to 25 mg oral therapy.