Transient renal effects of sildenafil in male kidney transplant recipients

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 mi nor decrease in blood pressure. We evaluated the effect of one dose of sild enafil on graft function and hemodynamics in impotent male transplant recip ients. Methods. Two sets of combined lithium, inulin, and p-amino hippurate cleara nce 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 calcul ated renal vascular resistances decreased by 40+/-18 from the baseline valu e 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 t he function of the graft. In terms of renal physiology, the observed modifi cations did not warrant any specific precautions when offering sildenafil t o KTRs suffering from erectile dysfunction.