Effect of acute in vivo sildenafil citrate and in vitro 8-bromo-cGMP treatments on semen parameters and sperm function

Objective: To determine the effect of acute in vivo sildenafil citrate (VIAGRA) and in vitro 8-Bromo-cGMP treatments on semen parameters and sperm function. Design: Prospective double-blind, placebo-controlled, crossover, two-period clinical investigation. Setting: Healthy volunteers in an academic research environment. Patient(s): Twenty male volunteers with normal erectile function and normal electrocardiogram were recruited. Intervention(s): In vivo: 50 mg of sildenafil citrate (VIAGRA) or placebo was administered p.o., and semen samples were collected 1 hour after administration of the test drug. In vitro: 8-Bromo-cGMP (20 muM; 60 minutes) was added to semen samples. Main Outcome Measure(s): Macroscopic and microscopic seminal parameters were measured and motility studies performed. Various acrosome reaction studies and sperm-zona pellucida binding studies were also done. Result(s): Either sildenafil citrate (VIAGRA) or 8-Bromo-cGMP treatments had no effect on both macroscopic and microscopic seminal parameters as well as the acrosome reaction. Sperm-zona pellucida binding results were however increased to 148.75% and 134%, respectively, by these treatments. Various kinematical parameters increased after treatment with the most significant increase detected in the population of rapid cells. Conclusion(s): VIAGRA can be used successfully to enhance sperm motility and binding to the oocyte especially during fertility treatments. (C) 2004 by American Society for Reproductive Medicine.