Safety and efficacy of enclomiphene and clomiphene for hypogonadal men

Background: Both clomiphene citrate and its isomer, enclomiphene, have become widespread within urologic practice; thus, understanding these medications' comparative benefits and risks is crucial for optimizing treatment and providing improved therapeutic options. We sought to investigate the longitudinal benefits and risks associated with enclomiphene, compared to clomiphene, and to provide valuable insights for clinicians when making treatment decisions in the management of hypogonadism.

Methods: We retrospectively studied patients at our academic center who had been prescribed clomiphene and, later, enclomiphene for hypogonadism. Baseline laboratory values were documented for each patient before being prescribed clomiphene, followed by subsequent values for each variable in the most recent visit before stopping clomiphene and any noted adverse effects experienced during this time. The same process was repeated for enclomiphene, using the clomiphene levels as an updated baseline. Two-tailed t-tests were employed using R to analyze the longitudinal impacts of clomiphene and enclomiphene on serum hormone values as well as a regression analysis to estimate the odds ratio (OR) for adverse events between the two therapies.

Results: Among 66 patients, enclomiphene exhibited a median testosterone increase of 166 (vs. 98 ng/dL, P=0.20) with lower estradiol change than clomiphene (-5.92 vs. 17.50 pg/mL, P=0.001). Adverse effects were statistically significantly less frequent with enclomiphene, including decreased libido (P=0.001), reduced energy (P=0.044), and mood changes (P=0.03). Regression analysis confirmed lower odds of adverse events with enclomiphene [OR: 0.18; 95% confidence interval (CI): 0.07-0.44, P=0.02].

Conclusions: Our findings demonstrate that enclomiphene provides improvement in testosterone levels with a lower rate of documented adverse events. These findings support enclomiphene as a comparable treatment option for hypogonadal men while minimizing the risk of adverse effects. Further research and more extensive studies are warranted to validate these conclusions and explore the additional long-term effects of enclomiphene to guide future patient counseling regarding these medications.