Armistane is sold by SARMs Store strictly as a research compound. Nothing on this page is medical advice or an instruction for human use.
Armistane, more often written arimistane, is sold as an aromatase inhibitor and sits in our prohormones range. Its mechanism is well grounded in enzymology, its status in sport is unambiguous, and its own research base is very thin. This page separates what is known about the enzyme from what is known about the compound, because the two are frequently conflated.
What Armistane is
Armistane is androsta-3,5-diene-7,17-dione, a steroidal compound with ketones at the 7 and 17 positions. It is closely related to 7-keto-DHEA, itself a metabolite of dehydroepiandrosterone. Arimistane turns up in urine after 7-keto-DHEA, but laboratory work from the Rome anti-doping laboratory suggests it forms from 7-keto-DHEA by chemical breakdown rather than by metabolism (Martinez Brito and colleagues, 2021).
Its proposed mechanism is suicide inhibition of aromatase. Aromatase, the product of the CYP19A1 gene, converts androgens to oestrogens: testosterone to oestradiol, androstenedione to oestrone. A suicide inhibitor, more precisely a mechanism-based irreversible inhibitor, is a substrate analogue that the enzyme begins to process and which then bonds covalently to the active site, permanently disabling that enzyme molecule. New enzyme must be synthesised for activity to return. This contrasts with competitive inhibitors such as anastrozole and letrozole, which occupy the active site reversibly.
The steroidal suicide inhibitors are a real and well-studied class. Exemestane, a licensed medicine used in breast cancer, works exactly this way, as does formestane. The chemistry that makes a 7-substituted or diene-containing androstane a candidate aromatase inhibitor has been explored in the medicinal chemistry literature, notably by Numazawa and colleagues on androstenedione derivatives across the 1990s and 2000s. Armistane belongs, structurally, to a family whose mechanism is genuinely established.
What the research found
What is not established is armistane itself in humans.
No clinical trials. There is no published randomised controlled trial of androsta-3,5-diene-7,17-dione in humans, no published pharmacokinetic study of it, and no trial measuring its effect on oestradiol, testosterone, luteinising hormone or any body composition endpoint. The only human data are anti-doping excretion work: Martinez Brito and colleagues, in 2019, mapped its urinary metabolites in three volunteers after a single administration and saw no relevant change in the urinary steroid profile. Any percentage quoted for oestrogen suppression by armistane does not come from a published human study.
In vitro and medicinal chemistry. Evidence for aromatase inhibition by compounds of this structural type comes largely from enzyme assays in cell-free and cellular systems, and from structure-activity work on steroidal aromatase inhibitors. This establishes that the class can inhibit the enzyme. It does not establish the potency, bioavailability or duration of effect of this particular molecule taken orally by a person.
The closest human analogue. The most useful published human study here is not of armistane but of 6-OXO, androst-4-ene-3,6,17-trione, another steroidal compound sold in the same era on the same mechanism. Rohle and colleagues, in the Journal of the International Society of Sports Nutrition in 2007, studied 6-OXO in resistance-trained men. Free testosterone, dihydrotestosterone and the testosterone to oestrogen ratio rose, but aromatase was not completely inhibited and body composition did not change. That result is the most instructive piece of human data in this category and is routinely omitted from marketing.
7-keto-DHEA. The related compound 7-keto-DHEA has its own small literature, mostly on body composition and safety in short trials, with modest and contested findings. It does not tell you what arimistane does.
Side effects reported
There is no controlled safety dataset for armistane. What can be said is what aromatase inhibition does when it is achieved, because that is well documented from the licensed medicines in the class.
Suppressing oestradiol in men reduces bone mineral density over time, because oestrogen rather than testosterone is the principal regulator of male bone maintenance. It adversely affects the lipid profile in many reports. It is associated with joint pain and stiffness, one of the most common complaints with exemestane and anastrozole in clinical use. Low oestradiol in men is also associated with reduced libido and mood disturbance, the opposite of what is usually expected from a compound marketed in this category. These are consequences of effective aromatase inhibition rather than of armistane specifically, and given the 6-OXO result it is unclear how much oestrogen suppression an oral steroidal supplement of this type achieves.
Comparison with related compounds
Exemestane and formestane are steroidal suicide inhibitors with established potency and full clinical datasets. Anastrozole and letrozole are non-steroidal competitive inhibitors with full datasets. All four are prescription medicines. Armistane shares the proposed mechanism of the first pair and has none of the data. Within the supplement category its closest relatives are 6-OXO and androstatrienedione, both of which entered the market on the same rationale and neither of which produced convincing human oestrogen suppression data. Tamoxifen and clomifene, often discussed alongside these compounds, are selective oestrogen receptor modulators and work differently again.
How to check a supplier
For a compound with no human pharmacokinetic data, knowing exactly what is in the capsule is the minimum requirement. Ask for the batch-specific certificate of analysis from an independent laboratory, with identity confirmed by HPLC or LC-MS, a stated purity figure and a batch number matching the bottle. Check the label declares the chemical name as well as the market name, states amount per capsule and capsule count, and carries a research-only notice. Because this compound is explicitly named on the WADA list, its presence as an undeclared ingredient is a documented anti-doping risk, which makes batch testing more important here than almost anywhere else. Alpha Labs Armistane is made in the UK at 50 mg per capsule, 90 capsules per bottle, and batch certificates of analysis are being published on the product page as testing is completed.
Frequently asked questions
What is armistane chemically? Androsta-3,5-diene-7,17-dione, a compound closely related to 7-keto-DHEA, itself a metabolite of DHEA.
How is it supposed to work? As a mechanism-based, irreversible inhibitor of aromatase, the enzyme converting androgens to oestrogens. This is the mechanism of the licensed medicine exemestane.
Are there human trials of armistane? No. There is no published human efficacy, safety or pharmacokinetic study.
What is the 6-OXO study and why does it matter? Rohle and colleagues, in 2007, studied a closely related steroidal supplement in resistance-trained men and found raised free testosterone and dihydrotestosterone, but aromatase was not completely inhibited.
Is armistane banned in sport? Yes. Aromatase inhibitors are prohibited at all times under WADA section S4.1 and this compound is named on the list.
Related reading
- Do the studies support a PCT after SARMs?
- Epistane (methylepitiostanol): the research
- SARMs versus steroids and prohormones
- Third-party testing: how to read a certificate of analysis
- Browse the range: prohormones range
Research product: Alpha Labs Armistane 50 mg, 90 capsules
Sources
Primary papers and official guidance cited in this guide, linked so each one can be checked directly.
- Rohle D et al., J Int Soc Sports Nutr 2007;4:13 (6-OXO and serum hormones in resistance-trained men). PubMed 17949492
- Martinez Brito D et al., Rapid Commun Mass Spectrom 2019;33:1894-1905 (urinary metabolites of arimistane in humans for anti-doping analysis). PubMed 31295379
- Martinez Brito D et al., Drug Test Anal 2021;13:1430-1439 (arimistane forms from 7-oxo-DHEA by degradation). PubMed 33783974
- Lorenz LM et al., Drug Test Anal 2019;11:1109-1115 (androsta-3,5-diene-7,17-dione identified in a dietary supplement). PubMed 30892803
- Numazawa M et al., Steroids 2000;65:871-882 (structure-activity work on steroidal aromatase inhibitors). PubMed 11077085
- Higa GM, Am J Health Syst Pharm 2002;59:2194-2201 (exemestane and irreversible inactivation of aromatase). PubMed 12455303
- WADA Prohibited List 2026.