In vitro effects of sildenafil and phentolamine, drugs used for erectile dysfunction, on human sperm motility.

Abstract

The aim of this study was to determine the effects of sildenafil and phentolamine on sperm motility in vitro. Semen or washed sperm was mixed with various doses of sildenafil or phentolamine and analyzed for motility during a 30-minute period. The pH was measured for each of the samples tested. Statistical analyses were performed with analysis of variance. A 200-microg/mL dose of sildenafil had no effect on sperm motility. However, the highest dose (2000 microg/mL) significantly reduced motility by about 50%. The pH was reduced in this high-dose sample. The lowest dose of phentolamine (20 microg/mL) had no effect, whereas a dose of 200 microg/mL resulted in a significant reduction in sperm motility. The highest dose (2000 microg/mL) stopped virtually all sperm from moving. This study demonstrated a direct dose-related effect of phentolamine on reducing sperm motility. Only the highest dose of sildenafil had an effect, which may have been caused by a decline in pH.