Drug Groups

approved

Description

An antineoplastic agent that is a derivative of progesterone and used to treat advanced breast cancer. [PubChem]

Indication

For palliative treatment of advanced breast cancer in postmenopausal women.

Pharmacology

Testolactone is a synthetic anti-neoplastic agent that is structurally distinct from the androgen steroid nucleus in possessing a six-membered lactone ring in place of the usual five-membered carbocyclic D-ring. Despite some similarity to testosterone, testolactone has no in vivo androgenic effect. No other hormonal effects have been reported in clinical studies in patients receiving testolactone.

Toxicity

Oral LD₅₀s in mouse and dog are 1630 mg/kg and 593-926 mg/kg, respectively.

Affected Organisms

Biotransformation

Hepatic. Metabolized to several derivatives in the liver, all of which preserve the lactone D-ring.

Absorption

Testolactone is well absorbed from the gastrointestinal tract.

Protein Binding

~85%

Elimination

No clinical effects in humans of testolactone on adrenal function have been reported; however, one study noted an increase in urinary excretion of 17-ketosteroids in most of the patients treated with 150 mg/day orally. It is metabolized to several derivatives in the liver, all of which preserve the lactone D-ring. These metabolites, as well as some unmetabolized drug, are excreted in the urine.

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