Effects of intracavernous calcium channel blockers in dogs

Intracavernous injection of smooth muscle relaxing agents can induce penile erection. In this experimental study, we compared the effects of intracavernously injected calcium channel blockers (CCBs) and papaverine in dogs, and investigated their clinical applicabilities. We administered 30 mg papaverine, 10 mg nifedipine, 10 mg nitrendipine and 2.5 mg verapamil to 10 adult male dogs intracavernously, each at different times. Intracavernous pressure values, systemic arterial pressure values and heart rate values were recorded for 45 minutes after the intracavernous injections. We used the paired Student t-test for statistical analysis. Papaverine induced full erection in all of the 10 dogs. Nifedipine induced full erection in 4, nitrendipine in 5, and verapamil in 6 of the 10 dogs. Nifedipine and nitrendipine caused significant decreases in blood pressure and increases in heart rate. In conclusion, the effects of intracavernous CCBs are not superior to those of papaverine. We cannot recommend nifedipine and nitrendipine for intracavernous injection, but verapamil may be included in intracavernous pharmacotherapeutic combinations.