In dogs and mice, a single dose of tadalafil 20 mg was observed to increase the rate at which blood vessels were opened when an individual entered penile tissue.


Tadalafil is a selective phosphodiesterase-5 inhibitor used for erectile dysfunction. It inhibits the PDE5 enzyme, and increased levels of nitric oxide are released by vascular smooth muscle cells. The vasodilatory mechanism of tadalafil was investigated.


The results of an 8-week, randomized, double-blind, placebo-controlled study were analyzed. Thirty-six male dogs and 6 male mice were randomized into control, pro-bono, high-dose placebo-controlled studies. Dose size was measured after administration using duplex ultrasound. At 8 weeks, whooping girth measurements were done. The blood pressure and postoperative erections were measured.


Full response was found in the pro-bono treatment group versus no improvement on all 7 measures. In the placebo-controlled group, sedation was achieved in 8 of the 9 female mice, whereas no improvement was observed on blood pressure measurements. Blood flow in the pro-bono group was increased with treatment during the course of 16, 48, and 67 hours, respectively. No improvements were noted on blood flow measurements other than increase in clitoral pain.


Tadalafil was safely and effectively used in the distribution of erectile dysfunction and exercise maintenance program to improve sexual activity and male reproduction.