indication

For the prevention of pregnancy

pharmacology

Norgestimate is used as a female contraceptive. Norgestimate is a progestin or a synthetic form of the naturally occurring female sex hormone, progesterone. In a woman's normal menstrual cycle, an egg matures and is released from the ovaries (ovulation). The ovary then produces progesterone, preventing the release of further eggs and priming the lining of the womb for a possible pregnancy. If pregnancy occurs, progesterone levels in the body remain high, maintaining the womb lining. If pregnancy does not occur, progesterone levels in the body fall, resulting in a menstrual period. Norgestimate tricks the body processes into thinking that ovulation has already occurred, by maintaining high levels of the synthetic progesterone. This prevents the release of eggs from the ovaries.

mechanism of action

Norgestimate binds to androgen and progestogen receptors. Target cells include the female reproductive tract, the mammary gland, the hypothalamus, and the pituitary. Once bound to the receptor, progestins like Norgestimate will slow the frequency of release of gonadotropin releasing hormone (GnRH) from the hypothalamus and blunt the pre-ovulatory LH (luteinizing hormone) surge.

biotransformation

GI tract/Hepatic

half life

12-30 hours

drug interactions

Artemether: Artemether may decrease the effectiveness of norgestimate by increasing its metabolism via CYP3A4. Consider an alternate non-hormonal means of contraception during artemether therapy.

Bexarotene: Bexarotene may decrease the serum concentration of Contraceptives (Progestins). Since bexarotene is teratogenic and can lower serum concentrations of norgestimate, it is advised that women of childbearing potential use two forms of contraception (including at least one non-hormonal form).

Colesevelam: Bile Acid Sequestrants may decrease the serum concentration of Contraceptives (Progestins). Administer oral progestin-containing contraceptives at least 1-4 hours prior to or 4-6 hours after administration of a bile acid sequestrant. Consider alternatives in order to avoid this combination when possible, due to the risk for impaired contraceptive effectiveness.

Thiopental: Thiopental may decrease the effect of Norgestimate. Contraceptive failure may occur. Alternative nonhomomonal contraception should be used during concomitant therapy.

Tretinoin: Oral Tretinoin may decrease the effect of oral contraceptive, Norgestimate. An alternate form of contraception should be used during concomitant therapy.

Warfarin: Norgestimate may alter the anticoagulant effect of warfarin. Concomitant therapy should be avoided. Monitor for changes in coagulation status if norgestimate is initiated, discontinued or dose changed.