Investigators from Oxford, England, determined the efficacy of sildenafil (Viagra) for erectile dysfunction after rectal excision for cancer and inflammatory bowel disease.
Controlled trials have so far not demonstrated the efficacy of sildenafil for erectile dysfunction with underlying pelvic parasympathetic nerve damage.
A total of 32 patients with erectile dysfunction after rectal excision were randomly assigned in a double-blind manner to sildenafil (n = 14) or placebo (n = 18) groups.
After unblinding, placebo patients crossed over to open sildenafil.
The researchers measured improvement in erectile function on a global efficacy question and erectile function questionnaire scores.
Frequency and severity of side effects were also assessed.
It was found that 79% of patients responded to sildenafil, on global efficacy assessment, compared with 17% of those who took placebo.
Sildenafil improved both erectile function domain scores (mean difference, 13.3) and total International Index of Erectile Function scores (mean difference, 30.6) from pretreatment baseline scores.
|Improvement in erectile dysfunction :|
| Diseases of the Colon & Rectum |
Placebo did not produce improvement in either erectile function (mean difference, 1.7) or total International Index of Erectile Function scores (mean difference, 5).
Furthermore, all of the 10 crossover patients not responding to placebo did respond to sildenafil.
Again, sildenafil improved both erectile function domain scores (mean difference, 16.8) and total International Index of Erectile Function scores (mean difference, 29.5) from precrossover baseline scores.
Half of the patients on sildenafil, compared with 22% of those on placebo, experienced side effects. However, 91% of these were mild and well tolerated.
Ian Lindsey, of the John Radcliffe Hospital, Oxford, said on behalf of his colleagues, "Sildenafil completely reverses or satisfactorily improves post-proctectomy erectile dysfunction in 79% of patients.
"Side-effects are usually mild and well tolerated."
"The damage incurred by the pelvic nerves after proctectomy, less profound than after prostatectomy, is likely to result in a partial parasympathetic nerve lesion," he concluded.