Lisinopril versus enalapril: evaluation of trough:peak ratio by ambulatory blood pressure monitoring

Abstract

In 34 out-patients with essential hypertension, the antihypertensive effect and the trough-to-peak ratios of once-daily enalapril or lisinopril were compared by ambulatory blood pressure monitoring (ABPM) according to a crossover design. The drug dose was titrated and a thiazide diuretic was added if necessary to attain a target office BP of less than 140/90 mm Hg. Both drugs significantly lowered BP but the effect of lisinopril was greater (P < 0.009): day- and night-time mean bp fell from 152/98 and 135/84 mm hg, respectively to 133/85 and 118/74 mm hg with enalapril and to 129/83 and 116/70 mm hg with lisinopril. bp goal was reached with an average dose of 18 mg enalapril with 8 mg hydrochlorothiazide and with 17 mg lisinopril combined with 6 mg diuretic. trough:peak ratio values, which were calculated after fourier analysis of abpm data in individual patients, were independent of drug dose. the combination with the diuretic resulted in slightly higher trough:peak ratios than with ace inhibitor monotherapy, but the difference was not significant. the median trough:peak ratio in patients when using enalapril-based therapy was 0.48 and, when taking lisinopril-based treatment, it was 0.65 (n = 28, P < 0.005). a significant correlation was found between trough:peak ratio and changes in daytime mean arterial pressure (map; spearman r = 0.43) and night-time MAP (r = 0.66). When 24-h ABPM was performed starting 24 h after last drug intake, both ACE inhibitors still had a significant antihypertensive effect (P < 0.001), which was similar for both drugs. eleven patients reported minor side effects. four patients stopped ace-inhibitor treatment because of cough. the data show that lisinopril has a longer duration of action than enalapril.