| Antiprogestogen | |
|---|---|
| Drug class | |
 Mifepristone, an antiprogestogen that is used to inducemedical abortions. | |
| Class identifiers | |
| Synonyms | Antiprogestins; Progesterone antagonists; Progesterone blockers |
| Use | Medical abortion,emergency contraception,uterine fibroids |
| ATC code | G03XB |
| Biological target | Progesterone receptor |
| Chemical class | Steroidal |
| Legal status | |
| In Wikidata | |
Antiprogestogens orantiprogestins, also known asprogesterone antagonists orprogesterone blockers, are a class ofdrugs which preventprogestogens likeprogesterone from mediating theirbiological effects in the body. These drugs competitively inhibit progestin at progesterone receptors, acting byblocking theprogesterone receptor (PR) and/orinhibiting orsuppressing progestogenproduction. Antiprogestogens are one of three types ofsex hormone antagonists, alongsideantiestrogens andantiandrogens.[1]
Antiprogestogens are used asabortifacients,emergency contraceptives, and in the treatment ofuterine fibroids. They are also being studied in the treatment ofbreast cancer. Examples include theprogesterone receptor weakpartial agonistmifepristone, theselective progesterone receptor modulator (SPRM)ulipristal acetate, and thesilent antagonistaglepristone.[2][3] Inmedical abortion, mifepristone is combined with aprostaglandin (e.g.,gemeprost), while ulipristal is used for emergency contraception.[4]
Several hundred antiprogestogens have been developed, but only three—mifepristone,lilopristone, andonapristone—have been administered to humans. Of these, only mifepristone has been approved and introduced for clinical use.[5]
Progestins, including progesterone, are vital for preparing the uterus for the implantation of a fertilized egg during the luteal phase of the menstrual cycle. If fertilization, implantation, and other events necessary for pregnancy occur, increased progestin (i.e., progesterone) levels are essential in maintaining the pregnancy. Blocking the effects of progestins like progesterone is associated with anti-gestational effects, resulting in the interruption of pregnancy maintenance.[4]
Media related toAntiprogestogens at Wikimedia Commons
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