Methods. BAY 41-2272 was administered to conscious rabbits intravenously (IV) and orally (130). Erection was assessed in a time-dependent manner by measuring the length of the uncovered penile mucosa. Erections were evaluated in the absence and presence of NO (with intravenous sodium nitroprusside [SNP] as the NO donor).

Results. BAY 41-2272 only induced weak penile erections in conscious rabbits after IV (1 mg/kg) and PO (10 mg/kg) administration in the absence of an NO donor. However, the efficacy of BAY 41-2272 was potentiated by the simultaneous administration of SNP. Through simultaneous SNP administration, the effective doses of BAY 41-2272 were reduced significantly (minimal effective dose 0.1 mg/kg IV and 1 mg/kg PO).

Conclusions. The results of this study clearly demonstrated the effect of BAY 41-2272 on penile erection in the conscious rabbit model after PO and IV administration. The time-course and onset of erection was concurrent with the stimulation by exogenous NO (SNP), suggesting that this new pharmacologic mechanism of soluble guanylyl cyclase stimulation could be used in the treatment of erectile dysfunction. Because the effect is increased by SNP, it can be expected that BAY 41-2272 would have enhanced activity during sexual arousal, when NO is produced endogenously.