Differential effects of Ramipril on ambulatory blood pressure in African Americans and Caucasians

Background: On average, angiotensin-converting enzyme inhibitors produce less office blood-pressure lowering in African Americans compared with Caucasians. Past studies did not compare daytime and nighttime ambulatory blood-pressure responses to angiotensin-converting enzyme inhibitors in African Americans and Caucasians. Methods: We measured the office and ambulatory bloodpressure response to 8 weeks of a fixed dose of 10 mg daily of the angiotensin-converting enzyme inhibitor ramipril in a cohort of 72 African Americans and 89 Caucasians. Results: Ramipril lowered age-adjusted daytime ambulatory systolic blood pressure 6 mm Hg and diastolic blood pressure 3 mm Hg less in African Americans compared with Caucasians (both P =.02). This difference persisted after adjusting for baseline blood pressure, body mass index, urine sodium and potassium, plasma aldosterone, and other covariates. Despite the difference in mean response, there was a 72% overlap in daytime blood-pressure response to ramipril between African Americans and Caucasians. Among Caucasians, ramipril lowered systolic blood pressure 2 mm Hg less during nighttime compared with daytime, whereas among African Americans, blood pressure lowering was equivalent during day and night. Nighttime blood-pressure response to ramipril did not differ significantly between African Americans and Caucasians. Conclusions: Ramipril was more effective in lowering daytime blood pressure in Caucasians compared with African Americans, but appreciable differences in response did not persist at night. Despite the small difference in mean response between groups, the majority of African Americans and Caucasians had a similar blood-pressure response to a fixed dose of ramipril.