Comparison of the renal effects of angiotensin converting enzyme inhibitor and calcium antagonist in hypertensive type 2 (non-insulin-dependent) diabetic patients with microalbuminuria: a randomised controlled trial

Abstract

Seven of eight hypertensive Type 2 (non-insulin-dependent) diabetic patients with microalbuminuria completed a randomised crossover trial to compare the renal effects of angiotensin converting enzyme inhibitor (enalapril) and calcium antagonist (nicardipine). Four-week fixed oral maintenance dosages of enalapril (10-20 mg/day) and nicardipine (60-120 mg/day) significantly (p less than 0.05) lowered the systolic and diastolic blood pressures without altering renal blood flow, glomerular filtration rate and filtration fraction. Both drugs significantly reduced (p less than 0.05) urinary albumin excretion rate and fractional clearance of albumin to similar extents. Total renal vascular resistance decreased significantly by nicardipine (p less than 0.05) and non-significantly by enalapril. Plasma osmotic pressure, plasma aldosterone concentration, total serum protein concentration, serum electrolytes and HbA1c remained unchanged by these drugs, whereas plasma renin activity was significantly higher (p less than 0.05) in the enalapril than in the control and nicardipine phases. These results suggest that both drugs have similar renal function preserving effects with a concomitant hypotensive action in hypertensive Type 2 diabetic patients with microalbuminuria, and that the angiotensin converting enzyme inhibitor may not have advantageous renal effects when compared to the calcium antagonist and vice versa. Both drugs might be useful for treatment of high blood pressure in hypertensive diabetic patients, if long-term studies of these drugs can be shown to benefit the patients over other conventional antihypertensive therapies.