The Effects of Sildenafil Citrate as an Intracavernosal Agent / 대한남성과학회지

ABSTRACT

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<sildenafil citrateadministration of 0.1 mg, 0.3 mg, 0.5 mg, and 1.0 mg of sildenafil citrate were 2.85 mmHg, 4.63 mmHg, 11.1 mmHg, and 26.7 mmHg, respectively. Mean duration of increased ICP were 2.14, 10.25, 11.9, and 36.0 minutes, respectively. There was no significant drop of systemic systolic arterial blood pressure after administration of four separate dose of sildenafil citrate, respectively.

CONCLUSIONS:

Sildenafil citrate was an effective in relaxing the precontracted cavernosal strips in vitro and in erecting feline penis after local administration in vivo. These results suggest that phosphodiesterase inhibitor has a potential to be developed as a new safe and effective intracavernosal agent for the treatment of impotence patients.