Routes of
administration Oral Protein binding ~85% Molar mass 300.39 g/mol | ATC code none Metabolism | |
 | ||
AHFS/Drugs.com Consumer Drug Information Pregnancy
category US: C (Risk not ruled out) | ||
Testolactone (INN, USAN) (brand name Teslac) is a non-selective, irreversible, steroidal aromatase inhibitor used as an antineoplastic drug to treat advanced-stage breast cancer. The drug was discontinued in 2008 and is no longer available for medical use.
Contents
Testolactone meaning
Uses
This drug is mainly used for treating various types of breast cancer in women who have been through menopause or whose ovaries no longer function. It works by blocking the production of estrogen, which helps prevent the growth of breast cancers that are activated by estrogen. It may also prevent tumor cells from being activated by other hormones. It also has been used to postpone precocious puberty because of its ability to block estrogen production.
Side effects
The most common side effects include:
Pharmacology
The principal action of testolactone is reported to be inhibition of aromatase activity and the reduction in estrogen synthesis that follows. Androstenedione, a 19-carbon steroid hormone produced in the adrenal glands and the gonads, is where estrone synthesis originates and is the source of estrogen in postmenopausal women. In vitro studies report that the aromatase inhibition may be noncompetitive and irreversible, and could possibly account for the persistence of this drug's effect on estrogen synthesis after drug withdrawal.
In addition to its activity as an aromatase inhibitor, testolactone also reportedly possesses some anabolic activity and weak androgenic activity via binding to and activation of the androgen receptor. However, androgenic side effects such as hirsutism, acne, and voice changes have been reported in no women in clinical trials.
Chemistry
Testolactone is a synthetic 18-oxasteroid and a D-homo-18-oxo analogue of androstenedione (androst-4-en-3,17-dione), with a six-membered lactone ring in place of the five-membered carbocyclic D-ring.