Androstenetrione (6-OXO)

key facts

Legal Status (US): Not listed as a controlled substance

Average Dose:

Average Cycle Length: 4-8 weeks

6-OXO is a steroidal aromatase inhibitor, known as a suicidal inhibitor because it permanently binds to the aromatase enzyme. It is used for its anti-estrogen and testosterone boosting effects.

There is debate about whether or not 6-oxo actually lowers estrogen or increases testosterone. Several human studies have shown an increase in estrone levels following 6-oxo supplementation. However, one of the primary metabolites of 6-oxo is 6-oxoestrone which may have given a false positive for elevated estrone levels. The human study also concluded that 6-oxo raised testosterone levels, however it is possible that 6-oxotestosterone (which is another metabolite of 6-oxo) gave a false positive for the testosterone level as well.

Another interesting element to these articles is that despite the supposed increase in testosterone (enough to cause significant improvements in body composition if given via injection) no improvements where found for fat free mass (FFM) or strength. Therefore, 6-oxo is either a weak AI that doesn’t really inhibit estrogen at the recommended dose and simply converts to metabolites which give false readings, or it actually does increase testosterone, while the 6-oxo metabolites antagonize the androgen receptor enough to block any anabolic effect from testosterone.

Either way, no ergonomic or real world benefit could be found after 6-oxo supplementation.
Its also worth mentioning that 6-oxo should never be used post cycle, as its steroidial effects would likely interfere with recovery of natural testosterone production.

the science

Chemical Name(s):

Chemical Formula: C19H24O3
Molecular Weight: 300
Q Qatio: NA
Anabolic #: NA
Androgenic #: NA
Oral Bioavailability: Estimated at 40%
AR Binding Affinity: NA
SHBG Binding Affinity: NA
Half Life: 3-6 hours

related products


Immunological interference of the synthetic aromatase inhibitor 1,4,6-androstatriene-3,17-dione (ATD) and its metabolite(s) in the radioimmunoassay for testosterone.
MD Donaldson and MG Forest
Steroids, Dec 1980; 36(6): 717-21
Testosterone dose-response relationships in healthy young men
Shalender Bhasin, et al.
Am J Physiol Endocrinol Metab, Dec 2001; 281: E1172 – E1181.