OBJECTIVE: To determine the effect of avanafil, a novel phosphodiesterase-5 
inhibitor, on the treatment of erectile dysfunction associated with type 2 
diabetes mellitus (T2DM).
METHODS: In 2-day-old rats, T2DM was induced by single intraperitoneal injection 
of 90 mg/kg of streptozotocin (STZ; i.p.). Erectile responses were evaluated 
after 10 weeks on intracavernosal injection of avanafil (1 μM) to anesthetized 
rats and data expressed as intracavernosal pressure (ICP)/mean arterial pressure 
and total ICP. The relaxant and contractile responses of corpus cavernosum (CC) 
strips were obtained in vitro studies.
RESULTS: ICP/mean arterial pressure and total ICP responses were significantly 
reduced in T2DM rats compared with controls. Avanafil partially restored 
diminished ICP responses in diabetic rats. In CC strips from the diabetic group, 
electrical field stimulation (1-20 Hz)-induced relaxation responses were 
markedly enhanced by 45%, whereas acetylcholine (ACh; 10(-8)-10(-3))-induced 
relaxation responses were diminished by 73%. In addition, phenylephrine (PE; 
10(-8)-10(-3)) and electrical field stimulation (1-40 Hz)-induced contractile 
responses were significantly reduced in the diabetic group compared with 
controls. CC relaxant responses to sodium nitroprusside (SNP, 10(-8)-10(-3)) and 
avanafil (10(-8)-10(-3)) were unaltered in both groups.
CONCLUSION: The cavernous injection of avanafil in T2DM rats resulted in partial 
improvement in erectile responses. These findings suggest that intracavernosal 
administration of avanafil might be beneficial for the treatment of erectile 
dysfunction in patients with T2DM.