Return of nocturnal erections and erectile function after bilateral nerve-sparing radical prostatectomy in men treated nightly with sildenafil citrate: subanalysis of a longitudinal randomized double-blind placebo-controlled trial

Abstract

Introduction: After bilateral nerve-sparing radical retropubic prostatectomy (BNSRRP), nocturnal and sexually mediated erections may help to preserve normal erectile function (EF).

Aim: To investigate nocturnal penile tumescence and rigidity (NPTR) in a subset (N = 54 men) from a randomized, double-blind trial (N = 76) of nightly sildenafil after BNSRRP.

Methods: Inclusion required preoperative "normal" EF (defined as a combined score of >/=8 for International Index of Erectile Function questions 3 (penetration) and 4 (maintained erection after penetration) and NPTR testing (>/=10 continuous minutes of >/=55% rigidity [R >/= 55%] at the base). Postoperative assessments were at weeks 4 (pretreatment), 16, 28, 40 (during 36 weeks of nightly prophylaxis: sildenafil 50 mg [N = 17], 100 mg [N = 18] or placebo [N = 19]), and 48 (after 8 weeks of no erectile dysfunction therapy, when "responders" were delineated by the defined normal EF and a "yes" response to "Over the past 4 weeks, have your erections been good enough for satisfactory sexual activity?"). Base and tip rigidity and tumescence were measured using penile plethysmography.

Main outcome measures: Duration of R >/= 55% and area under the curves for rigidity and tumescence.

Results: Postoperatively, rapid profound reduction in nocturnal EF was noted in all groups. There was a gradual dose-dependent improvement in base and tip rigidity in the sildenafil groups but little improvement in the placebo group. Eight weeks after treatment termination (48 weeks postoperatively), 24% (4/17) of 50-mg sildenafil recipients, 33% (6/18) of 100-mg sildenafil recipients, and 5% (1/19) of placebo recipients were responders. Tip R >/= 55% was the most discriminating NPTR measure between nonresponders and responders to sildenafil, in whom it regained baseline (preoperative) levels (whereas base R >/= 55% did not). It was most prolonged in responders to sildenafil 100 mg.

Conclusions: In our subset analysis, nightly sildenafil for 9 months post-BNSRRP objectively improved nocturnal erections and pharmaceutically unassisted EF.