DOUBLE-BLIND CROSSOVER STUDY OF THE INTERACTION BETWEEN PERINDOPRIL AND AMLODIPINE ON BLOOD-PRESSURE AND HORMONES RELATED TO FLUID AND ELECTROLYTE BALANCE IN PATIENTS WITH ESSENTIAL-HYPERTENSION

This study was to investigate the interaction between low doses of per indopril (2 mg daily) and amlodipine (2.5 mg daily) on ambulatory bloo d pressure (BP), clinic BP, serum angiotensin-converting enzyme (ACE), plasma levels of renin (PRA), angiotensin II (Ang II), aldosterone, a nd atrial natriuretic peptide (alpha-h ANP) in subjects with essential hypertension. The study design was a parallel, two-period, placebo-co ntrolled, double-blind crossover design, with 11 subjects receiving pe rindopril and 10 receiving amlodipine during the run-in phase. The add ition of amlodipine to perindopril had no effect on ambulatory BP, whe reas the addition of perindopril to amlodipine reduced both systolic ( P = 0.027) and diastolic (P = 0.049) ambulatory BP. By contrast, the o pposite result was obtained for clinic BP at trough, whereby the addit ion of amlodipine to perindopril reduced erect systolic BP (P = 0.036) and both supine and erect diastolic BP (P = 0.038) whereas the additi on of perindopril to amlodipine was without effect. The addition of pe rindopril to amlodipine decreased serum ACE by 72% and increased PRA t wo-fold, without change in plasma levels of Ang II, aldosterone or alp ha-h ANP. The addition of amlodipine to perindopril increased plasma a ldosterone 1.7-fold but did not affect serum ACE, PRA, Ang II, or alph a-h ANP. These interactions between perindopril and amlodipine may hav e been conditioned by the specific effects of the therapy first given, as well as by the different circumstances of BP measurement (ambulato ry vs clinic).