Effects of acute treatment with tamsulosin versus alfuzosin on ejaculatory function in normal volunteers

The frequency of ejaculatory dysfunction in men varies among the alpha-blockers used in the treatment of lower urinary tract symptoms associated with benign prostatic hyperplasia. We assessed the effect of acute administration of tamsulosin, alfuzosin and placebo on ejaculate volume and sperm concentration in post-ejaculate urine, and addressed the mechanism of action of tamsulosin and alfuzosin on ejaculation.

Using a randomized, 3-way crossover design, the effects of 5 days of treatment with 0.8 mg tamsulosin daily, 10 mg alfuzosin daily and placebo on ejaculation in healthy adult men were compared. The primary end points of the study were ejaculate volume and sperm concentration in post-ejaculate urine on each treatment. To aid in clinical interpretation of primary efficacy end points, each primary end point was transformed into a binary outcome, that is subjects with a greater than 20% decrease in ejaculate volume and subjects with a greater than 20% increase in sperm concentration in post-ejaculate urine.

In healthy volunteers who completed the study (48), tamsulosin resulted in significantly decreased ejaculate volume (-2.4 +/- 0.17 ml) compared to alfuzosin (+0.3 +/- 0.18 ml, p < 0.0001 vs tamsulosin) or placebo (+0.4 +/- 0.18 ml, p < 0.0001 vs tamsulosin, p = nonsignificant vs alfuzosin). Among completers the incidence of more than 20% decreased ejaculate volume was significantly greater with tamsulosin (89.6%) compared to alfuzosin (20.8%, p < 0.0001 vs tamsulosin) or placebo (12.5%, p < 0.0001 vs tamsulosin, p = nonsignificant vs alfuzosin). While on tamsulosin 35.4% of 48 completers had complete lack of ejaculation (anejaculation) and no subjects experienced anejaculation while on alfuzosin or placebo.

On 0.8 mg tamsulosin daily ejaculatory function in subjects was marked by decreased ejaculate volume in almost 90% of subjects and anejaculation in approximately 35% of participants. These ejaculatory disorders with tamsulosin were not attributed to retrograde ejaculation. In contrast, anejaculation was not observed in any subjects in the alfuzosin or placebo groups.