Testosterone Undecanoate is a long-acting ester of testosterone, primarily used to treat male hypogonadism (low testosterone levels). Available in both oral and injectable forms, it helps restore normal testosterone levels, supporting muscle growth, bone density, libido, and overall well-being.

Medical Uses

• Male Hypogonadism: Used in testosterone replacement therapy (TRT) to treat conditions such as primary and secondary hypogonadism.

• Delayed Puberty: In some cases, it is prescribed to stimulate puberty in adolescent males.

• Gender-Affirming Therapy: Used as part of hormone therapy for transgender men.

• Cachexia & Muscle Wasting: Sometimes used off-label to counteract muscle loss due to chronic illnesses like HIV/AIDS.

Mechanism of Action

Testosterone Undecanoate acts as a prodrug of testosterone. Upon administration, the ester is cleaved, releasing free testosterone into circulation. This binds to androgen receptors in various tissues, leading to:

• Increased protein synthesis and muscle mass.

• Stimulation of red blood cell production.

• Enhanced libido and sexual function.

• Regulation of fat distribution and bone density.

Side Effects

While effective, Testosterone Undecanoate may cause side effects, including:

• Common: Acne, oily skin, increased red blood cell count (polycythemia), mood changes, and increased appetite.

• Serious: Cardiovascular risks (hypertension, increased risk of heart disease), liver toxicity (oral form), and prostate enlargement.

• Endocrine Effects: Suppression of natural testosterone production and potential testicular shrinkage.

Interactions

• Anticoagulants: May increase the risk of bleeding.

• Corticosteroids: Combined use may enhance fluid retention and cardiovascular risks.

• Insulin & Diabetes Medications: Testosterone may affect glucose metabolism, requiring dosage adjustments.