Sildenafil (Viagra): is there an influence on psychological performance?

Sildenafil (Viagra) is a well-introduced medicine for erectile dysfunction; many studies about effects and side effects are published. Beside these aspects of treatment the influence of sildenafil on psychophysical performance is of interest. cGMP is one of the most important second messengers in the central nervous system (CNS), so even very small changes of the intracellular cGMP-level caused by phosphodiesterases inhibition may be relevant for CNS-function. We wanted to verify the hypothesis whether sildenfail influences human psychomotor performance, especially under the aspect of traffic safety, or not.

Designed as a pilot study we tested 6 male healthy volunteers using a test battery of 7 different psychophysical performances tests. Each individual did the test battery twice, once without drug and once after a single oral dose of 100-mg sildenafil. 3 persons did the first and 3 others did the second experiment under the influence of drug (UID). All results (37 parameters) were analysed by t-test for paired samples using a confidence interval of 95%.

Only two parameters of 2 different tests showed significant differences. In the simple choice reaction test (DR2) the mean reaction time got better in the group with sildenafil; in the multiple choice reaction test with stress induction (RST3) the amount of wrong answers indicated a weak influence of performance without statistical significance, six parameters (dominantly in the speed anticipation test (DEST)) represented an increase and one other (RST3 second part) showed a decrease UID. The uppermost parameters (76% of all items) stayed on equal levels for both groups.

Sildenafil showed no important impairment of psychophysical performance, no strong improvement was found as well. With a look at the therapeutically indication of sildenafil the improvement in sexual activity may indicate no incapacity in traffic and other psychomotoric/psychophysical functions.