PURPOSE: Treatment of impotence has advanced considerably by an orally active, effective and well-tolerated drug, sildenafil citrate. However, Sildenafil citrate is not so effective for the treatment of severe organic impotence patients. Intracavernosal injection of vasoactive substance is still the most effective therapy for those patients but side effects, e.g. pain, priapism, require a more comfortable therapy. We performed this study to assess the feasibility of sildenafil citrate as a new intracavernosal agent.
MATERIALS AND METHODS: In New Zealand white male rabbits (n=11), relaxations of precontracted cavernosal smooth muscle strips were studied after administration of sildenafil citrate, acetylcholine and sodium nitroprusside (SNP), respectively. In separate in vivo experiment, changes of intracavernosal pressure (ICP), duration of increased ICP and changes of systemic arterial blood pressure after retrograde selective internal pudendal arterial administration of four separate doses (0.1 mg, n=5; 0.3 mg, n=6; 0.5 mg, n=7; 1.0 mg, n=7) of sildenafil citrate were monitored in adult male cats (n=25).
RESULTS: Acetylcholine, SNP and sildenafil citrate effectively relaxed the precontracted strips in a dose-dependent manner (3x10 8-3x10 3 M), respectively. Maximal relaxation of strips to acetylcholine, SNP and sildenafil citrate were 50.11%, 98.65%, and 68.32%, respectively. The order of potency was acetylcholine