Deuterated testosterone
Pharmaceutical compound
From Wikipedia, the free encyclopedia
Deuterated testosterone (developmental code name AVA-291), also known as d3-testosterone (d3-T), is an androgen or androgen receptor agonist which is under development for the treatment of breast cancer, female sexual dysfunction, hypogonadism, decreased libido, fatigue, and muscular atrophy.[1][2][3][4][5][6][7][8] It is taken orally, transdermally, or parenterally.[1]
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| Other names | AVA-291; AVA291; d-Testosterone; d3-Testosterone; d3-T; Deutestosterone; Testosterone-19-d3; 17β-Hydroxyandrost-4-en-3-one-19,19,19-D3 |
| Routes of administration | Oral, transdermal, parenteral[1] |
| Drug class | Androgen; Anabolic steroid |
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| Formula | C19H28O2 |
| Molar mass | 288.431 g·molâ1 |
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The drug is an isotopologue of testosterone.[1][2][8] More specifically, the three hydrogen atoms on the C19 methyl group have been replaced with the deuterium isotopes.[1][8] Unlike testosterone, deuterated testosterone is highly resistant to metabolism into estradiol by aromatase, showing a half-life that is 4 to 7 times longer than that of testosterone in an aromatase-containing system in vitro (55.9â79.9 minutes vs. 7.7â18.5 minutes, respectively).[7][8] On the other hand, they were metabolized at similar rates in rat and human hepatocytes.[7][8][4] In addition, deuterated testosterone had similar potency and efficacy as testosterone as an androgen receptor agonist in vitro.[7][8] As such, deuterated testosterone is expected to retain activity as an androgen similarly to testosterone but to lack or have greatly reduced estrogenic activity.[4][7][8] Accordingly, deuterated testosterone showed 1,000-fold lower potential in stimulating breast cancer cell proliferation compared to testosterone.[4][9]
The chemical synthesis of deuterated testosterone has been described.[10][11][8]
Deuterated testosterone was first described in the scientific literature by 1978.[11] It is under development by Lennham Pharmaceuticals and Aviva Biopharm.[1][2][3][12] As of December 2025, the drug is in the preclinical research stage of development.[1][2][3] A phase 1 trial is being planned for early 2026.[2][4] Deuterated testosterone was patented in 2021.[6][8] It is expected to have improved tolerability and safety relative to testosterone in certain contexts, for instance avoiding gynecomastia (male breast development) or treating estrogen-sensitive breast cancer.[4][9][7][8]