Effect of captopril on congestive heart failure.

1) Captopril was orally administered in a dose of 12.5 mg to 12 patients with congestive heart failure to follow changes in its blood concentration and determine changes in clinical test values. 2) The blood concentration of captopril reached its peak in 2 h after medication, the mean value being 274 ng/ml and the half-life 3.16 h. The Tmax and T1/2 were found to be extended as compared with those of normal humans and hypertensive patients that had been reported. No significant differences were noted between Group I of mild cases and Group II of serious cases. 3) Following administration of captopril, a rise in angiotensin I and renin activity and a reduction in aldosterone were noted. These were found to be correlated or inversely correlated with the changes in the blood concentration of captopril. Greater changes were noted in Group II than in Group I. All clinical test values in each group tended to return to the control value 6h after the administration.