Short-Term Effects of Calcium Antagonists on Renal Haemodynamics in Patients with Chronic Renal Failure

Abstract

Experimental evidence suggests that pharmacological manipulations of glomerular haemodynamics may affect the progression of chronic renal insufficiency and scarring. In this study, we have investigated the short-term (4 weeks) renal haemodynamic effects of nifedipine and nitrendipine (10 mg/thrice daily) in two separate groups of 6 patients with stable chronic renal failure (CRF) (glomerular filtration rate, GFR: 9.7–47.8 ml/min/ 1.73 m²). Patients were studied on three occasions: (1) before the administration of the calcium antagonist, (2) after 4 weeks of treatment and (3) 4 weeks after the discontinuation of the drug. Mean arterial pressure fell significantly on nifedipine: from 116.33 ± 12.25 to 107.22 ± 18.67 mm Hg, p < 0.05, and on nitrendipine: from 112.22 ± 10.04 to 102.22 ± 13.77 mm Hg, p < 0.05. There was no significant effect of either calcium antagonist on GFR, effective renal plasma flow (ERPF), proteinuria or natriuresis. Consequently, renal vascular resistance (RVR) fell in both experimental groups, nifedipine: from 51.40 ± 28.77 to 44.97 ± 30 dyn s cm^-5 × 10³ (mean ± SD), and nitrendipine: from 37.04 + 18.46 to 30.47 ± 15.56 dyn s cm^-5 × 10³, p < 0.05. These results show that calcium antagonists reduce systemic blood pressure whilst GFR and ERPF are maintained. The fall in the RVR of patients with CRF treated with calcium antagonists may confer on these agents a therapeutic advantage in the management of progressive renal insufficiency.