Increasing circulating androgens with oral testosterone undecanoate in eugonadal men

Area of Science:

• Endocrinology
• Pharmacokinetics

Background:

• Low sexual interest can be linked to diminished testosterone levels.
• Oral testosterone undecanoate (TU) presents an alternative administration route for testosterone replacement therapy.

Purpose of the Study:

• To assess the effects of oral testosterone undecanoate (TU) on plasma testosterone levels.
• To evaluate the absorption characteristics of oral TU in men with diminished sexual interest.

Main Methods:

• Nine men (average age 55) with loss of sexual interest received oral TU (80 mg).
• Absorption tests were conducted after the initial dose and after 3-4 weeks of chronic administration.
• Plasma testosterone and sex hormone-binding globulin (SHBG) levels were monitored.

Main Results:

• Plasma testosterone increased by at least 50% from baseline in 14 of 18 tests.
• Absorption timing was variable, with peaks occurring between 30 minutes and 5.5 hours post-dose.
• A faster metabolic clearance and reduced SHBG were observed on the second absorption test, but no other significant differences were noted.

Conclusions:

• Oral TU can effectively increase plasma testosterone levels.
• Absorption variability, potentially influenced by diet, is a key characteristic of oral TU.
• Oral TU may offer advantages for short-term testosterone administration in eugonadal men if absorption variability can be mitigated through dietary control.