RESEARCH MONOGRAPH · KDC-MN-391

Boldenone

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

56/100

Veterinary AAS used in horses; pharmacology is essentially 1-dehydro-testosterone with slower kinetics

Boldenone is 1-dehydrotestosterone, the C1-C2 double bond is the structural difference from testosterone itself, and that single modification reduces aromatization to estradiol substantially (still some, just less than testosterone) and modestly increases AR binding affinity. The undecylenate ester (Equipoise, the veterinary product) is the form most commonly encountered, designed for slow IM release over weeks.

The clinical evidence in humans is thin to nonexistent. Boldenone was never developed for human use; it's a veterinary product approved for horses. Most of what's 'known' about its human pharmacology is reverse-engineered from athletic and bodybuilding use, which means it's not really known in the rigorous sense, just observed.

What we like as a research tool: it's a relatively clean DHT-like AR agonist for in vitro work where you want a 5AR-resistant androgen without the heavy aromatization of testosterone. The undecylenate ester PK is the longest of the common AAS esters, which is useful for chronic-exposure protocols.

What we don't like: the human data simply isn't there, so any translational claim is speculation. The cardiovascular and prostatic safety profile compared to testosterone is unknown in a controlled-trial sense. The cosmetic and athletic literature describes slower mass accrual and milder estrogenic side effects than testosterone, which tracks mechanistically, but those are observational and confounded.

The doping control history is consistent. Boldenone is detected as boldenone-glucuronide in urinary samples, and there have been some notable false positive concerns from natural boldenone production in livestock, which complicates testing in beef-heavy diets. The CAS and IUPAC nomenclature for the various positional isomers also gets confusingly used in the literature, so reading older papers requires attention.

Sourcing is regulated as Schedule III. Reference standards for analytical work are available, HPLC purity reliable. The veterinary product is widely diverted, which means a lot of black-market boldenone is unreliable in concentration and purity. For research applications use only analytical-grade material.

Staying power is moderate. The molecule is unlikely to find a clinical human indication at this point but it remains a useful AR agonist tool compound.

Evidence: 40
Mechanism: 75
Reliability: 65
Safety: 55
Sourcing: 50
Value: 55
Signal: 55
Staying power: 50

Plain-language summary Intrigue 42 / 100

Boldenone is essentially testosterone with an added double bond between carbons 1 and 2. Originally approved in 1949 as a human drug at Ciba (Parenabol, withdrawn) and later developed for veterinary use as Equipoise, the name still associated with it. The 1,2 double bond makes the molecule a poorer substrate for aromatase, so it converts to estrogen at roughly half the rate of testosterone at equivalent doses, the main practical feature distinguishing it. The undecylenate ester gives the injectable formulation a long half-life around 14 days. Schedule III in the US under the AAS Control Act despite never having current human medical approval. Reference low-aromatizing testosterone analog in steroid pharmacology research. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Testosterone analog (1-dehydro testosterone)

A 1-dehydro testosterone analog; an injectable AAS originally developed for veterinary use, widely diverted to human non-medical use.

Abstract

Boldenone (17-beta-hydroxyandrosta-1,4-dien-3-one; CAS 846-48-0; molecular formula C19H26O2; molecular weight 286.41) is a 1-dehydro testosterone analog originally developed at Ciba and approved by the FDA in 1949 (Parenabol, withdrawn) and subsequently developed for veterinary use as Equipoise (the brand most associated with the compound). The 1,2 double bond reduces aromatase substrate quality, producing approximately 50 percent the estrogen conversion of testosterone at equivalent doses; this is the principal pharmacological feature distinguishing boldenone from testosterone. The undecylenate ester (Equipoise) provides a long half-life (approximately 14 days) for veterinary or non-medical injectable use. Schedule III in the US (covered by the AAS Control Act despite no human medical approval). Plasma half-life of native boldenone is short; ester formulations release over weeks. Used as a reference low-aromatizing testosterone analog in research.

Mechanism of action

1-dehydro testosterone analog; AR agonism with reduced aromatase substrate quality (~50 percent estrogen conversion vs testosterone).

Reported research dose ranges

Reported research dose ranges vary across the published literature.

References

Kicman AT. Pharmacology of anabolic steroids. Br J Pharmacol 2008.
Ferenchick GS. Anabolic-androgenic steroid abuse in horses: epidemiology and pharmacology. J Vet Pharmacol Ther 1996.
Llewellyn W. Anabolics. Body of Science 2011.

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KDC-MN-391

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

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Boldenone

Abstract

Mechanism of action

Reported research dose ranges

References

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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