Testosterone Undecanoate

hormone · endocrine · digestive · immune-hematologic · Intramuscular · Oral

Testosterone Undecanoate, a hormone. C11 fatty-acid ester of testosterone — long-acting depot androgen. IM dosing every 10–14 weeks (vs… Intramuscular half-life 30 d.

C11 fatty-acid ester of testosterone — long-acting depot androgen. IM dosing every 10–14 weeks (vs cypionate every 1–2 weeks). Lymphatic absorption when oral, minimizing first-pass. PK (Behre 1999 PMID:9876028 + Aveed FDA label 2014): IM oily depot ester; tissue-esterase cleavage releases free testosterone slowly from intramuscular depot. Peak serum T (~eugonadal range) reaches by ~2 weeks post-injection, slowly decays over 10-14 weeks. Aveed approved regimen: 750 mg IM at 0, 4, 10 weeks loading then q10 weeks maintenance — much less frequent than cypionate/enanthate (weekly-biweekly). Apparent V/F large but ester-hydrolysis-rate-limited (ka ≈ 0.002/hr drives the slow release; true testosterone PK kinetics after release are short-t½ as usual).

Pharmacokinetics

• Intramuscular — t½ 30.0 d · F 100% · ka 0.002 h⁻¹ · Vd 50 L

Sources: PMID:9876028