Transient renal effects of sildenafil in male kidney transplant recipients

Abstract

Background. Sildenafil (Viagra) improves erection by sustaining Guanosine 3′, 5′-cyclic monophosphate (cGMP)-mediated smooth muscle relaxation in the corpus cavernosum. It also induces systemic vasodilation, resulting in a minor decrease in blood pressure. We evaluated the effect of one dose of sildenafil on graft function and hemodynamics in impotent male transplant recipients. Methods. Two sets of combined lithium, inulin, and p-amino hippurate clearance studies were conducted, with and without sildenafil (100 mg orally) in 11 male kidney transplant recipients (KTRs). Results. Sildenafil increased glomerular filtration rate by 14±4 from the baseline value of 55±7 ml·min-1.1.73 m2-1 (P<0.01), whereas calculated renal vascular resistances decreased by 40±18 from the baseline value of 247±29 mmHg/L·min-1.1.73 m2-1 (P<0.05). Conclusions. The oral administration of sildenafil in KTRs did not impair the function of the graft. In terms of renal physiology, the observed modifications did not warrant any specific precautions when offering sildenafil to KTRs suffering from erectile dysfunction.