Objectives: To determine whether the response to sildenafil citrate (Viagra) in patients with erectile dysfunction after radical prostatectomy was influenced by the presence or absence of neurovascular bundles, the interval from surgery to the initiation of drug therapy, and the dose of the drug.
Methods: Baseline and follow-up data from 91 patients presenting with erectile dysfunction after radical prostatectomy were obtained. The patients were stratified according to the type of nerve-sparing (NS) procedure: bilateral NS, unilateral NS, and non-NS. They were interviewed using the Cleveland Clinic Post Prostatectomy (CCPP) questionnaire and the International Index of Erectile Function (IIEF) questionnaire.
Results: The presence or absence of the neurovascular bundles influenced the ability to achieve vaginal intercourse. In the patients who had undergone bilateral NS, 71.7% (38 of 53) responded; in those with unilateral NS, 50% (6 of 12) responded; and in those with non-NS, 15.4% (4 of 26) responded. The IIEF questionnaire confirmed the quality of the positive responses, with significant improvements in response to question 3 (frequency of penetration), question 4 (frequency of maintenance of erection), and question 7 (satisfaction with intercourse). The magnitude of improvement in responses was higher in the bilateral NS group than in the unilateral NS and non-NS groups (P <0.05). When the data of the 48 positive responders were analyzed, no difference in the response rate was found when the interval from surgery to drug therapy was stratified by the following three intervals: 0 to 6 months (44%), 6 to 12 months (55%), and greater than 12 months (53%). Of the positive responders, 14 (29.1%) required the 50-mg dose, and 34 (70.9%) required the 100-mg dose. The most common side effects were transient headaches (28.6%), flushing (21.9%), dizziness (8.8%), dyspepsia (6.5%), and nasal congestion (5.4%), with an increase in the incidence of headaches seen at the higher dose (P = 0.04).
Conclusions: Successful treatment of erectile dysfunction with sildenafil citrate after radical prostatectomy depends on the presence of the neurovascular bundles. Our data suggest that the response to sildenafil is not related to the interval between the surgery and initiation of drug therapy but is related to the dose.