NEW YORK (Reuters Health) Nov 12 - Sildenafil(Viagra) acutely increases sperm motility in young infertile men, Italian researchers report in the October issue of Fertility and Sterility. The opposite is true for tadalafil(Cialis).

Dr. Giorgio Pomara and colleagues at the University of Pisa in Rome, administered a single 50 mg dose of sildenafil or 20 mg of tadalafil to 18 young infertile men in a randomized, double-blind crossover study with a two-week washout period between treatment arms.

Semen samples collected one to two hours after each treatment. The investigators report that sperm progressive motility significantly increased with sildenafil from 28.5% at baseline to 37.0% after treatment. Tadalafil significantly decreased sperm progressive motility from 28.5% at baseline to 21.5% after treatment.

“These preliminary results indicate that sperm motility appears to be acutely affected in young, infertile patients by a single dose of sildenafil and tadalafil, with opposite effects: stimulatory by the former and inhibitory by the latter,” Dr. Pomara and associates conclude.

“The use of phosphodiesterase-type 5 inhibitors is becoming a routine procedure in in vitro fertilization centers, because the percentage of patients having temporary erectile dysfunction during semen collection is relatively high,” they observe. “In this context, the actual effect of these drugs on semen parameters could be relevant.”