Differences in the Acute and Chronic Antihypertensive Effects of Lisinopril and Enalapril Assessed by Ambulatory Blood Pressure Monitoring

Although lisinopril and enalapril are equipotent angiotensin converting enzyme (ACE) inhibitors lisinopril has been reported to produce greater inhibition of plasma ACE 24 hours after single doses. This study compared the antihypertensive effects of once daily 10mg doses of the drugs using a randomised, double-blind, two period cross-over design with ambulatory blood pressure monitoring. Lisinopril lowered mean 24 hour systolic blood pressure significantly more than enalapril after 4 weeks of treatment (14/7 +/- 2/1mmHg & 9/6 +/- 2/1mmHg, respectively, adjusted SBP difference 4.8mmHg, P < 0.01). This difference was confined to the second 12 hours of the daily dosage interval (adjusted SBP difference 13-24 hours after dosing 9.9mmHg, P < 0.001). The diastolic pressure showed a similar trend but this was not statistically significant. The side effects of each agent were minor. We conclude that chronic, once daily therapy with 10mg of lisinopril reduces systolic blood pressure more effectively than an equal dose of enalapril due to its greater effect in the latter half of the 24 hour dosage interval.