Testosterone Cypionate
Also sold as Test Cyp, Depo-Testosterone.
- Half-life
- 190 h
- Steady state
- ~40 d
- Class
- Androgen
- Category
- TRT
Published population averages. Steady state is the usual five half-life rule of thumb, not a measurement. See peptide half-life, explained.
Overview
Testosterone Cypionate is the most commonly prescribed testosterone ester in the United States for testosterone replacement therapy (TRT). It is a long-acting intramuscular injectable that provides stable testosterone levels with weekly or biweekly dosing. It is essentially identical to Testosterone Enanthate with a marginally longer half-life.
How it works
After intramuscular injection, the cyclopentylpropionic acid ester is cleaved by tissue esterases, releasing free testosterone. Testosterone then binds androgen receptors (AR) in target tissues, and is also converted to dihydrotestosterone (5α-reductase) and estradiol (aromatase) for additional effects. Suppresses gonadotropins (LH, FSH) via hypothalamic feedback.
Half-life and peak
Terminal half-life approximately 8 days (~190 hours). Peak serum levels reached 24–48 hours post-IM injection. Nadir occurs around day 7, supporting weekly dosing. Subcutaneous injection shows similar PK with slightly lower Cmax.
What it is studied for
Male hypogonadism, TRT optimization, cardiovascular safety (TRAVERSE trial), bone mineral density, body composition, sexual function, mood and cognition.
Research status
FDA-approved (Depo-Testosterone). TRAVERSE cardiovascular safety trial (2023, NEJM) established non-inferiority to placebo for MACE in men with hypogonadism. Decades of clinical experience.
Sources
- Testosterone — MedlinePlus · medlineplus.gov
- TRAVERSE cardiovascular safety trial — NEJM · doi.org
- Endocrine Society TRT guidelines · doi.org
- Testosterone cypionate PK comparison · doi.org
Educational reference only. This page describes what is published about a compound; it is not medical advice, not a recommendation to take anything, and not a dosing guide. Several compounds in this catalog are investigational and are not approved medicines. Talk to a doctor.
Guides that cover it
Peptide half-life, explained
Half-life is the number that decides how often something is injected, how long it takes to settle, and how long it lingers after you stop. Here is what it does tell you, and the three things people assume it tells them that it does not.
Tracking TRT: esters, timing and bloodwork
Testosterone replacement is the protocol where record-keeping pays off fastest, because the thing that decides your next dose is a blood test whose result depends on when in the week it was taken.