ACUTE EFFECTS OF NIFEDIPINE IN RENAL-TRANSPLANT RECIPIENTS TREATED WITH CYCLOSPORINE OR AZATHIOPRINE

Cyclosporine (CsA) impairs renal function, probably by preglomerular v asoconstriction. Vasodilating substances may therefore be of benefit t o ameliorate CsA-induced renal dysfunction. We studied the acute effec ts on blood pressure and renal function of the dihydropyridine calcium antagonist nifedipine (10 mg orally) in 20 CsA-treated renal transpla nt patients. In addition, we compared the effects of nifedipine when g iven immediately before and 4 weeks after elective conversion from CsA to azathioprine. Compared with placebo (n = 14), administration of ni fedipine led to a significant decrease in blood pressure and a strong natriuretic and diuretic response. Despite the reduction in blood pres sure, glomerular filtration rate improved from 60 +/- 20 (mean +/- SD) to 69 +/- 24 mL/ min/1.73 m(2) (P < 0.001) and renal plasma flow (RPF ) increased from 260 +/- 87 to 338 +/- 120 mL/min/1.73 m(2) (P < 0.001 ). The combination of a decreased blood pressure with an increased RPF was reflected in a sharp decrease in renal vascular resistance (0.34 +/- 0.18 units v 0.23 +/- 0.10 units; P < 0.001). The conversion from CsA to azathioprine by itself led to significant increases in glomerul ar filtration rate (62 +/- 15 mL/min/1.73 m(2) v 76 +/- 18 mL/min/1.73 m(2); P < 0.05) and RPF (280 +/- 86 mL/min/1.73 m(2) v 334 +/- 66 mL/ min/1.73 m(2); P < 0.05). During treatment with azathioprine an effect of nifedipine on glomerular filtration rate and RPF was no longer obs erved, although the natriuretic effect was similar on both occasions. The decrease in renal vascular resistance was larger during treatment with CsA than during treatment with azathioprine (P < 0.05). We conclu de that nifedipine was able to improve renal hemodynamics in CsA-treat ed renal transplant patients, while these effects were not observed in the same patients off CsA. By this property, nifedipine may be well s uited to prevent the renal injury that can occur during chronic treatm ent with CsA. (C) 1994 by the National Kidney Foundation, Inc.