24-HOUR BLOOD-PRESSURE AND RENAL-FUNCTION IN PATIENTS WITH HEART-FAILURE DURING THE TITRATION PERIOD WITH CAPTOPRIL OR ENALAPRIL

In 33 patients with heart failure (NYHA II-III) 24-h blood pressure was examined during the titration of two ACE-inhibitors. Blood pressure was measured by the oscillometric method using the blood pressure monitor 90202 from SpaceLabs, Inc. The measurements were taken from 06.00 to 22.00 hours every 20 min, and from 22.00 to 06.00 hours every 1 h. All patients received an additional therapy, either with captopril (group 1, n = 17) or enalapril (group 2, n = 16) in random order. Serum-electrolytes, serum-creatinine, and plasma-renin activity were measured before and during therapy with both ACE-inhibitors. 24-h blood pressure measurements were taken before and on the first and fifth day of the treatment with ACE-inhibitors. The groups did not different in respect to the degree of heart failure, the concomitant medication, or the 24-h profiles of blood pressure and heart rate. The mean initial dose of captopril was 9.2 +/- 1.2 mg. Each patient of group 2 received an initial dose of 2.5 mg enalapril. The maximal decrease of diastolic blood pressure occurred after 1 h in group 1 and after 4 h in group 2 and was similar in both groups (8 vs, 7 mm Hg). The 24-h blood pressure values on day 5 were consistently below the pretreatment values (p < 0.005). Heart rate was not affected by either ACE-inhibitor. The groups did not differ significantly during ACE-inhibition in their 24-h blood pressure and heart rate profiles. Before treatment, serum-sodium, -potassium and -creatine were within the normal range. The increase of potassium (0.5 +/- 0.1 mmol/l) reached statistical significance (p < 0.01) only in the captopril group, whereas it was not significant in the enalapril group (0.1 +/- 0.1 mmol/l). Serum-creatinine was not significantly altered by either ACE-inhibitor. No relation could be found between the changes of serum-potassium or -creatinine and the decreases of the mean of the 24-h blood-pressure values. Captopril and enalapril showed comparable blood pressure profiles and similar effects on renal function at the end of the titration on day 5. It can therefore be concluded that the effects on blood pressure and renal function are similar with a single daily dose of enalapril compared to captopril given three times daily.