Oral testosterone therapy: past, present, and future

Introduction Testosterone replacement therapy (TRT) remains a commonly utilized treatment for men with testosterone deficiency (TD). Despite the recent FDA approval of new oral TRT medications, concerns remain regarding their efficacy and safety, and prescription rates for these medications have decreased compared to those for TD medications with other routes of administration. Objective In this study we sought to investigate the efficacy and safety of oral testosterone undecanoate (oTU), a new oral TRT medication. Methods A comprehensive review of the literature was performed using the Medline, EMBASE, and Cochrane Library databases; 1269 articles were identified, with 44 articles included in the final review and 12 used to perform meta-analyses to investigate the change in serum total testosterone (TT) and risk of adverse effects following oral testosterone undecanoate (oTU) use. Articles were also reviewed to investigate the reported effects of oTU on body composition, liver function, hematologic assays, lipid profiles, hormone assays, prostate growth, hypertension, and symptoms of TD. Results Across placebo-controlled randomized trials, there was no significant increase in TT for those receiving oTU vs placebo (mean difference, -0.26 [95% CI, -1.26 to 0.73]). On subanalysis, when eugonadal participants received oTU, a significant decrease in TT was demonstrated (mean difference -0.86 [95% CI, -1.28 to 0.43]). When participants who were hypogonadal at baseline received oTU, a significant increase in TT compared to placebo was seen (mean difference 1.25 [95% CI, 0.22-2.29]). There was no significant risk of adverse effects (RR, -0.03 [95% CI, -0.08 to 0.03]) or serious adverse effects (RR, 0.15 [95% CI, -0.66 to 0.96]) in the oTU groups compared to placebo. Conclusion oTU was found to be well tolerated in hypogonadal patients, resulting in improved testosterone levels, height velocity, and sexual symptoms, without significant hepatotoxicity, prostatic enlargement, or worsening hypertension. There was no consensus regarding the effect of oTU on lean and fat mass percentages, hematologic assays, lipid profiles, mood, and general well-being.