Norgestimate is a synthetic progestin developed in the 1970s and introduced in the 1980s as part of the third-generation oral contraceptives. It was designed to provide effective pregnancy prevention with improved tolerability compared to earlier progestins, particularly by reducing androgenic side effects such as acne, weight gain, and unfavorable changes in lipid profiles. Since its introduction, it has been widely used in combination oral contraceptive formulations due to its strong contraceptive efficacy and relatively favorable side-effect profile.
BRAND NAMES
Norgestimate is a progestin used in combination oral contraceptives along with ethinyl estradiol for pregnancy prevention and also in the treatment of acne. It is marketed under several brand names, including Ortho-Cyclen, Ortho Tri-Cyclen, Sprintec, Estarylla, Mili, Tri-Lo-Marzia, Mono-Linyah, and VyLibra.
MECHANISM OF ACTION
Norgestimate is a third-generation progestin that prevents pregnancy mainly by suppressing ovulation through inhibition of FSH and LH release. It also mimics the action of progesterone by thickening cervical mucus and inducing changes in the endometrium that make implantation less likely. After administration, it is rapidly converted into active metabolites, including 17-desacetylnorgestimate and norgestrel, which exert their effects by binding to progesterone and estrogen receptors.
PHARMACOKINETICS
Absorption: After oral administration, norgestimate is rapidly and extensively metabolized in the intestine and/or liver.
Metabolism:
Converted mainly to norelgestromin (NGMN), the primary active metabolite formed by deacetylation.
Distribution:
Norelgestromin binds predominantly to albumin (~99%).
Elimination:
Metabolites are eliminated via both renal (urine) and fecal routes.
PHARMACODYNAMICS
Norgestimate is a third-generation synthetic progestin used in combined oral contraceptives. It has strong progestogenic activity with very low androgenic effects. As a prodrug, it is quickly converted into active metabolites, mainly norelgestromin and levonorgestrel. These metabolites prevent pregnancy by suppressing FSH and LH secretion, thereby inhibiting ovulation, while also thickening cervical mucus and modifying the endometrium to reduce the likelihood of fertilization and implantation.
ADMINISTRATION
Norgestimate/ethinyl estradiol is an oral contraceptive taken daily to prevent pregnancy and help manage acne. It must be taken consistently, with one tablet at the same time each day to ensure effectiveness. Most blister packs include 21 active pills followed by 7 inactive (placebo) pills, usually white or green in color.
DOSAGE AND STRENGTH
Norgestimate is available only in combination oral contraceptive formulations with ethinyl estradiol. The dosage varies depending on whether it is monophasic or triphasic:
Monophasic tablets (constant dose):
Norgestimate 0.25 mg + Ethinyl estradiol 35 µg (e.g., Sprintec, Mono-Linyah)
Norgestimate 0.18–0.25 mg + Ethinyl estradiol 25–35 µg (varies by brand)
Triphasic tablets (variable dose across cycle):
Phase 1: Norgestimate 0.18 mg + Ethinyl estradiol 25 µg
Phase 2: Norgestimate 0.215 mg + Ethinyl estradiol 25 µg
Phase 3: Norgestimate 0.25 mg + Ethinyl estradiol 25 µg
Typical regimen:
One tablet taken daily for 21 active days, followed by 7 placebo tablets in a 28-day cycle.
FOOD INTERACTIONS
Norgestimate/ethinyl estradiol, a commonly used combined oral contraceptive, may interact with certain foods, especially grapefruit, which can increase drug levels and the risk of side effects. Although taking it with food can help reduce nausea, it is generally advised to avoid grapefruit, limit excessive caffeine intake, and avoid smoking to reduce potential adverse effects.
DRUG INTERACTIONS
Norgestimate (in combination with ethinyl estradiol) can interact with several drugs that affect its effectiveness. Enzyme inducers such as rifampin, carbamazepine, phenytoin, and St. John’s wort may reduce contraceptive efficacy by increasing hormone metabolism. Conversely, enzyme inhibitors like certain antifungals and antibiotics may increase hormone levels and side effects. It may also interact with drugs like lamotrigine, reducing its effectiveness, and can alter the levels of anticoagulants and cyclosporine, requiring dose adjustments or monitoring.
CONTRAINDICATIONS
Norgestimate and ethinyl estradiol is contraindicated in women over 35 who smoke, as well as in patients with a high risk of arterial or venous thromboembolic disorders. It should not be used in individuals with liver disease or liver tumors, breast cancer, unexplained abnormal uterine bleeding, or in those receiving hepatitis C treatment regimens containing ombitasvir/paritaprevir/ritonavir. It is also contraindicated in cases of confirmed or suspected pregnancy.
SIDE EFFECTS
Common side effects of norgestimate (in combination with ethinyl estradiol) include nausea, headache, breast tenderness, mood changes, and irregular menstrual bleeding. Some users may also experience weight changes, bloating, and mild acne improvement. Less commonly, it may increase the risk of serious effects such as blood clots (deep vein thrombosis or pulmonary embolism), hypertension, and liver-related issues.
TOXICITY
Norgestimate toxicity is uncommon but may occur mainly due to excessive hormonal exposure from combined oral contraceptives. It can lead to symptoms such as severe nausea, vomiting, headache, breast tenderness, and abnormal uterine bleeding. In more serious cases, there is an increased risk of thromboembolic events like deep vein thrombosis, pulmonary embolism, stroke, or myocardial infarction, especially in high-risk individuals. Management is mainly supportive, and discontinuation of the drug is required if significant toxicity or complications develop.
