Updated September 2026. 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 is one of the most requested compounds in the post-cycle category. 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, occurring as a metabolite of 7-keto-DHEA, itself a metabolite of dehydroepiandrosterone.
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. 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. 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, gave resistance-trained men 300 or 600 mg of 6-OXO daily for eight weeks. They found significant increases in free testosterone and dihydrotestosterone, and increases in luteinising hormone and follicle stimulating hormone, but no significant reduction in oestradiol at either dose. That result is the most instructive piece of human data in this category and is routinely omitted from marketing.
7-keto-DHEA. The parent compound 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 its metabolite does.
Doses used in the research
There are no human research doses for armistane to report. For the closest studied analogue, and for reference only, the Rohle study used 300 mg and 600 mg of 6-OXO daily for eight weeks. Products containing armistane historically declared 25 to 75 mg daily, figures drawn from the market rather than any trial. SARMs Store does not supply Armistane for human consumption and gives no dosing guidance.
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.
Legal status in the UK, 2026
Armistane is not a controlled substance under the Misuse of Drugs Act 1971. It is a steroidal compound but not an anabolic androgenic steroid in the sense captured by the Class C provisions, since its proposed activity is enzyme inhibition rather than androgen receptor agonism. That said, it is a steroid metabolite and classification questions can turn on detailed analysis, so anyone supplying or importing it should check the current Home Office and MHRA positions rather than relying on a summary.
If sold or advertised for human use it would be an unlicensed medicine, and the MHRA has taken enforcement action against UK sellers of aromatase inhibitor products presented that way. It is supplied here strictly for laboratory research.
For athletes the position is not ambiguous. Aromatase inhibitors are prohibited at all times under section S4.1 of the WADA Prohibited List, and androsta-3,5-diene-7,17-dione is named there explicitly. It has been the subject of anti-doping cases, including cases arising from supplement products, and UK Anti-Doping applies the same list.
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. Dexterz 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 metabolite of 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, gave resistance-trained men a closely related steroidal supplement for eight weeks and found increased free testosterone and gonadotrophins but no significant fall in oestradiol.
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.
Is armistane legal in the UK? It is not controlled under the Misuse of Drugs Act 1971, but it is an unlicensed medicine if sold for human use, so it is supplied as a research compound only.
Related reading
- Do the studies support a PCT after SARMs?
- Epistane (methylepitiostanol): the research and the UK position
- SARMs versus steroids and prohormones
- Third-party testing: how to read a certificate of analysis
Research product: Dexterz Labs Armistane 50 mg, 90 capsules
Sources: Rohle D et al., J Int Soc Sports Nutr 2007;4:13. Numazawa M and colleagues, structure-activity studies on steroidal aromatase inhibitors, J Med Chem and Steroids, 1990s. Clinical literature on exemestane and formestane as steroidal suicide aromatase inhibitors. WADA Prohibited List 2026, section S4.1.