Objectives: To assay the efficacy and safety of sildenafil 50 mg and placebo.

Setting: Clinic- and home-based assessments in the United Kingdom.

Methods: A total of 27 subjects who were able to achieve at least a grade 2 erection (hard, but not hard enough for penetration) in response to penile vibratory stimulation (PVS) were recruited. In Part I, the reflexogenic response of the penis to PVS was evaluated in the clinic while in Part II, the response to treatment was assessed in the home (global efficacy, questionniare, diary).

Results: In Part I, 17/26 (65%) subjects had erections of >60% rigidity at the penile base (median duration 3.5 min) after sildenafil compared with 2/26 (8%) (median duration 0 min) after placebo (P = 0.0003). In Part II, 9/12 (75%) subjects on sildenafil and 1/14 (7%) subjects on placebo reported that the treatment had improved their erections (P < 0.005), and 8/12 (67%) and 2/13 (15%) men, respectively, indicated that they wished to continue treatment (P < 0.02). An analysis of diary data showed no difference between the groups with respect to the mean number of erections hard enough for penetration (P = 0.08). The mean proportion of attempts at sexual intercourse that were successful was 30 and 15%, respectively (r = 0.21). Similarly, responses to the end-of-treatment questionnaire indicated that there were no significant differences between the groups with respect to the frequency of erections hard enough for sexual intercourse (P = 0.47) or that lasted as long as the subject would have liked (P = 0.11). No subject discontinued sildenafil due to adverse events.

Conclusion: Sildenafil is an effective, well-tolerated oral treatment for ED in SCI subjects.

Sponsorship: This study was funded by Pfizer Inc.