Norgestrel was patented in 1961 and synthesized in the early 1960s by American scientist Herschel Smith at Wyeth Pharmaceuticals. It was first introduced for medical use in 1966, beginning in Germany as part of combined oral contraceptive pills under the brand name Eugynon, and later launched in the United States in 1968 as Ovral. Chemically, it is a racemic mixture of two stereoisomers, dextronorgestrel and levonorgestrel, with only levonorgestrel being biologically active, making norgestrel roughly half as potent as pure levonorgestrel. It functions as a progestin that prevents pregnancy by inhibiting ovulation, thickening cervical mucus, and altering the uterine lining to prevent implantation. In a recent milestone, the U.S. FDA approved norgestrel in July 2023 (marketed as Opill) for over-the-counter use, making it the first daily oral contraceptive available without a prescription in the United States. It is also used in menopausal hormone therapy and in managing conditions such as endometriosis.
BRAND NAMES
Norgestrel is a progestin primarily used for contraception and is best known in its progestin-only over-the-counter form as Opill. When combined with ethinyl estradiol, it is marketed under several brand names, including Cryselle, Elinest, Lo/Ovral, Low-Ogestrel, Ogestrel, and Turqoz. Its main function is to prevent pregnancy, primarily by suppressing ovulation.
MECHANISM OF ACTION
Norgestrel is a synthetic progestin that works as an agonist of the progesterone receptor to prevent pregnancy. It mainly acts by suppressing ovulation, increasing the thickness of cervical mucus to hinder sperm passage, and changing the uterine lining to reduce the likelihood of implantation. As a second-generation progestin, it also inhibits the pre-ovulatory luteinizing hormone (LH) surge and decreases the release of gonadotropin-releasing hormone (GnRH).
PHARMACOKINETICS
Absorption: Norgestrel is rapidly absorbed after oral administration, with peak plasma levels reached in about 1.6–2 hours.
Distribution: It is widely distributed in body tissues and is highly protein-bound (about 97.5–99%), mainly to sex hormone-binding globulin (SHBG).
Metabolism: It is metabolized in the liver through reduction, hydroxylation, and conjugation (sulfate and glucuronide formation), primarily involving the CYP3A4 enzyme.
Excretion: It is eliminated through urine (~45%) and feces (~32%), mostly as conjugated metabolites.
PHARMACODYNAMICS
Norgestrel is a synthetic progestin composed of a racemic mixture of levonorgestrel and dextronorgestrel that functions as a progesterone receptor agonist for contraception. It primarily works by suppressing the pre-ovulatory luteinizing hormone (LH) surge to inhibit ovulation, thickening cervical mucus to hinder sperm passage, and modifying the endometrial lining to reduce the likelihood of implantation.
DOSAGE AND ADMINISTRATION
Dosage form: Norgestrel is available as an oral tablet, either as a progestin-only pill or in combination with ethinyl estradiol.
Progestin-only use: Typically taken as one tablet daily at the same time each day without interruption.
Combination oral contraceptives: Usually taken in a 21-day active tablet cycle followed by a 7-day pill-free or placebo interval (depending on the product).
Administration: Should be taken orally with or without food, but consistency in timing is important for effectiveness.
Missed dose management: If a dose is missed, it should be taken as soon as remembered; backup contraception may be required depending on timing.
Initiation: Can be started on the first day of the menstrual cycle or as directed by a healthcare provider, sometimes requiring additional contraceptive protection for the first few days.
Adherence: Daily and consistent use is essential to maintain contraceptive effectiveness.
FOOD INTERACTIONS
Norgestrel, a progestin used for contraception, can interact with grapefruit products, which may raise its blood levels, and with St. John’s Wort, which can decrease its effectiveness. It is recommended to take it at the same time every day for best results, as irregular timing or certain food-related factors may increase side effects such as nausea or potentially reduce contraceptive effectiveness.
DRUG INTERACTIONS
Norgestrel may interact with certain substances that affect its effectiveness. Grapefruit products can increase its blood levels, potentially raising the risk of side effects, while St. John’s Wort can reduce its contraceptive efficacy by enhancing hormone metabolism. Other enzyme-inducing drugs may also decrease its effectiveness, so consistent daily use and informing a healthcare provider about all medications and supplements is important.
CONTRAINDICATIONS
Norgestrel is contraindicated in individuals with known hypersensitivity to the drug or its components. It should not be used in patients with current or past thromboembolic disorders, severe liver disease or liver tumors, undiagnosed abnormal genital bleeding, or known or suspected breast cancer. It is also not recommended during pregnancy.
SIDE EFFECTS
Menstrual changes: Irregular periods, spotting between cycles, or missed periods
Gastrointestinal effects: Nausea, vomiting, abdominal pain, or cramps
Neurological effects: Headache and dizziness
Breast effects: Tenderness or discomfort
Skin changes: Acne or other blemishes
Metabolic/fluid effects: Changes in appetite and fluid retention
Serious side effects (seek medical attention):
Severe abdominal pain, which may indicate rare complications such as ectopic pregnancy
Unusual or heavy vaginal bleeding that continues
New or worsening migraine headaches
Allergic reactions such as hives, itching, or swelling of the face or throat (including sensitivity to additives like yellow dye tartrazine)
TOXICITY
Norgestrel toxicity is rare but may occur in cases of overdose or excessive hormone exposure. It is generally not life-threatening, but it can lead to symptoms such as severe nausea, vomiting, dizziness, abdominal pain, and significant menstrual disturbances. In some cases, hormonal imbalance may cause mood changes or breakthrough bleeding. Management is mainly supportive, and medical attention is advised if large doses are taken or if severe symptoms develop.
