The efficacy and safety of sildenafil citrate for erectile dysfunction (ED) has been established in patients with end-stage renal disease on dialysis, but not in those who have undergone renal transplantation. ED persists in at least 25% of individuals after transplantation.OBJECTIVE
To determine whether sildenafil is an effective and well-tolerated treatment for ED in renal allograft recipients.DESIGN
Adult renal transplant recipients were eligible to enter this randomized, double-blind, placebo-controlled crossover trial if they had confirmed ED, stable allograft function for the preceding 6 months, and were in a stable relationship of ≥6 months' duration with a female partner. Patients with proliferative diabetic retinopathy or penile anatomic deformity, and patients who had recently experienced a stroke, were among those excluded.INTERVENTION
Participants were randomized to receive 50 mg sildenafil or placebo 1 h before sexual intercourse for 8 weeks; they then entered a 2-week washout period and subsequently switched to the other treatment for a further 8 weeks. The dose of sildenafil could be adjusted to between 25 mg and 100 mg as necessary, but only one dose was permitted per day. A self-administered 15-question instrument (the International Index of Erectile Function [IIEF]) and a global efficacy question ('Did the treatment improve your erection?') were used to assess therapeutic response at the end of each treatment phase. If the patient obtained a score of ≥26 for the erectile function domain of the IIEF, he was excluded from the analysis. Patients recorded adverse events in diaries.OUTCOME MEASURES
The endpoints were patient-assessed erectile function and adverse events.RESULTS
The analysis included 32 patients (mean age 40 years; mean time since transplantation and duration of erectile dysfunction 4.7 years and 17 months, respectively). The mean numbers of sildenafil and placebo tablets taken during the study were similar (24.3 and 23.8, respectively). IIEF scores increased significantly after sildenafil treatment for all the thirteen questions relating to erectile function, intercourse satisfaction, orgasmic function and overall satisfaction (P <0.001 for all), but not for the two questions relating to sexual desire. After placebo treatment, scores only increased significantly from baseline for question 13 (relationship satisfaction; P = 0.03). Significantly more sildenafil-treated patients than placebo-treated patients answered 'yes' to the question 'Did the treatment improve your erection?' (26 vs 6 [81.3% vs 18.7%]; P≤0.01). The area under the curve and maximum concentration of ciclosporin (assessed in 5 patients) were similar in the sildenafil and placebo phases. Serum creatinine level and blood urea nitrogen were also similar before and after sildenafil treatment. Adverse events included headache (5 patients in the sildenafil group; 2 patients in the placebo group), rhinorrhea and flushing (2 patients in the sildenafil group) and bluish visual hallucination (1 patient in the sildenafil group).CONCLUSION
Sildenafil improves ED in renal transplant recipients, with an acceptable safety profile.