1,4,6-Androstatrien-3,17-dione (ATD) is a potent irreversible aromatase inhibitor

Aromatase inhibitor

Aromatase inhibitors are a class of drugs used in the treatment of breast cancer and ovarian cancer in postmenopausal women. AIs may also be used off-label to treat or prevent gynaecomastia in men....

 that inhibits estrogen biosynthesis by permanently binding and inactivating aromatase

Aromatase

Aromatase is an enzyme responsible for a key step in the biosynthesis of estrogens. It is a member of the cytochrome P450 superfamily , which are monooxygenases that catalyze many reactions involved in steroidogenesis. In particular, aromatase is responsible for the aromatization of androgens into...

 in adipose

Adipose tissue

In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...

 and peripheral tissue. It is used to control estrogen

Estrogen

Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...

 synthesis

Chemical synthesis

In chemistry, chemical synthesis is purposeful execution of chemical reactions to get a product, or several products. This happens by physical and chemical manipulations usually involving one or more reactions...

.

ATD is present in some over-the-counter

Over-the-counter drug

Over-the-counter drugs are medicines that may be sold directly to a consumer without a prescription from a healthcare professional, as compared to prescription drugs, which may be sold only to consumers possessing a valid prescription...

 bodybuilding

Bodybuilding

Bodybuilding is a form of body modification involving intensive muscle hypertrophy. An individual who engages in this activity is referred to as a bodybuilder. In competitive and professional bodybuilding, bodybuilders display their physiques to a panel of judges, who assign points based on their...

 supplements as well as Topical ATD solutions that work transdermally. While not banned, ATD may cause positive urinalysis

Urinalysis

A urinalysis , also known as Routine and Microscopy , is an array of tests performed on urine, and one of the most common methods of medical diagnosis...

 results leading to disqualification from competitive sports. ATD has many names in sports supplements including: 1,4,6 etiollochan-dione, 3, 17-keto-etiochol-triene, androst-1,4,6-triene-3,17-dione and many others. These all refer to CAS# 633-35-2.

ATD may cause a positive test for the anabolic steroid boldenone, of which it is a metabolite and is also prohibited in amateur and professional sports which forbids aromatase inhibitors.

A related agent is exemestane

Exemestane

Exemestane is a drug used to treat breast cancer. It is a member of the class of drugs known as aromatase inhibitors. Some breast cancers require estrogen to grow. Those cancers have estrogen receptors , and are called ER-positive. They may also be called estrogen-responsive,...

(Aromasin).