Testosterone undecanoate: a new orally active androgen

Area of Science:

• Endocrinology
• Pharmacology

Background:

• Androgen replacement therapy is crucial for managing hypogonadism.
• Oral administration of testosterone undecanoate (TU) is explored as a convenient alternative to injections.

Purpose of the Study:

• To evaluate the efficacy and pharmacokinetic profile of oral testosterone undecanoate (TU) for androgen replacement therapy.
• To assess the impact of oral TU on plasma androgen levels and urinary steroid excretion.

Main Methods:

• Administration of single and daily doses of oral TU in normal and hypogonadal men.
• Measurement of plasma androgen levels using radioimmunoassay and gas chromatography.
• Analysis of urinary 17-ketosteroid excretion.

Main Results:

• A single 100 mg dose of oral TU increased plasma androgen levels and urinary 17-ketosteroid excretion in healthy men.
• Daily doses (90 mg and 60 mg) in a hypogonadal man led to sustained, seemingly physiological androgen levels.
• Chromatographic analysis revealed that dihydrotestosterone, not testosterone, was the primary androgen detected in plasma.
• Both testosterone undecanoate and dihydrotestosterone undecanoate were detected in plasma, suggesting absorption as esters.

Conclusions:

• Oral TU demonstrates potential as an effective androgen replacement therapy due to its convenience and prolonged action.
• The study suggests oral TU is absorbed as an ester and hydrolyzed to release the active steroid.
• Oral administration may offer a safer alternative with potentially fewer liver-related side effects compared to other oral androgens.