Newer formulations of oral testosterone undecanoate: development and liver side effects.

Introduction: Testosterone deficiency is a clinical disorder due to either failure of the testes to produce testosterone or failure of the hypothalamus or pituitary to produce sufficient gonadotropins. Previous formulations of oral testosterone therapy, particularly methyltestosterone, have been associated with adverse liver effects. Many different routes of testosterone delivery have been developed, each with their own administrative benefits and challenges. Newer formulations of oral testosterone undecanoate (TU) provide a convenient administration option, although their use has been limited by hepatotoxicity concerns based on older methyltestosterone data, and prescribing physicians may still be concerned about adverse liver effects.

Objectives: In this review, we discuss the history of oral testosterone development, clarify the mechanism of action of oral TU, and describe the relevant liver safety findings.

Methods: Relevant literature was allocated to present a review on the history of oral TU development and the mechanism of action of oral TU. We pooled data from individual studies of oral TU products to present a safety summary.

Results: Overall, safety results from studies of the newer formulations of oral TU showed that increased liver function test values are not generally associated with oral TU formulations and that no clinically significant liver toxicities were noted in clinical trials of oral TU.

Conclusion: Continued research into the safety of oral TU will contribute to a better understanding of the potential risks in patients receiving this therapy, an outcome that highlights the importance of providing patient education and reassurance regarding oral TU safety.