ESTRADIOL AND NORGESTIMATE
Clinical safety rating: avoid
Inducers of CYP450 enzymes (eg carbamazepine) may decrease estrogen levels Increases risk of thromboembolic disorders and endometrial cancer.
Estradiol is an estrogen that binds to estrogen receptors, modulating gene expression and exerting effects on reproductive tissues, bone, and cardiovascular system. Norgestimate is a progestin that acts as a partial agonist at progesterone receptors, suppressing gonadotropin secretion and altering cervical mucus and endometrial lining to prevent pregnancy.
| Metabolism | Estradiol is metabolized primarily in the liver via CYP3A4 to estrone and estriol, followed by glucuronidation and sulfation. Norgestimate is rapidly metabolized to norelgestromin and levonorgestrel via first-pass metabolism, with further metabolism by CYP3A4 and CYP2C9. |
| Excretion | Estradiol: primarily renal (50-80% as glucuronide and sulfate conjugates), fecal (10-20%). Norgestimate: metabolites excreted renally (55-65%) and fecally (30-40%). |
| Half-life | Estradiol: terminal half-life ~12-14 hours; Norgestimate: norelgestromin terminal half-life ~28 hours, norgestrel ~25 hours. Clinical context: steady-state achieved within 5-7 days. |
| Protein binding | Estradiol: 96-98% bound to sex hormone-binding globulin (SHBG) and albumin. Norelgestromin: 99% bound to SHBG and albumin. |
| Volume of Distribution | Estradiol: Vd ~1.2 L/kg. Norelgestromin: Vd ~2.5 L/kg. Clinical meaning: extensive tissue distribution. |
| Bioavailability | Transdermal estradiol: ~5-10% (due to first-pass metabolism; absolute bioavailability not well defined). Oral estradiol: <5% (extensive first-pass metabolism). Norgestimate: oral bioavailability >90% (norelgestromin). |
| Onset of Action | Transdermal: estradiol absorption detectable within 4-8 hours, clinical effects (e.g., vasomotor symptom relief) within 2-4 weeks. Oral: peak levels in 1-2 hours, clinical effects in 2-4 weeks. |
| Duration of Action | Transdermal patch: 7 days (replaced weekly). Oral: 24 hours (daily dosing). Clinical notes: continuous estrogen and progestin exposure. |
| Molecular Weight | Estradiol: 272.38 Da; Norgestimate: 369.50 Da (as norgestimate); active metabolite norelgestromin: 327.46 Da. |
Estradiol 1 mg and norgestimate 0.18/0.215/0.25 mg orally once daily for the first 28-day cycle, with the norgimate dose titrated: 0.18 mg on days 1–7, 0.215 mg on days 8–14, and 0.25 mg on days 15–21, followed by placebo on days 22–28.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Not studied in severe impairment or dialysis; use with caution. |
| Liver impairment | Contraindicated in acute hepatic disease or Child-Pugh Class B or C cirrhosis. For mild hepatic impairment (Child-Pugh Class A), no specific dose adjustment available; use with caution. |
| Pediatric use | Not indicated for use in premenopausal pediatric patients. Safety and efficacy not established in children. |
| Geriatric use | No specific dose adjustment recommended for elderly patients >65 years, but use the lowest effective dose and consider increased risk of adverse effects such as cardiovascular events and dementia. |
| 1st trimester | Estradiol and norgestimate are contraindicated in pregnancy. Use during first trimester is associated with risk of congenital defects, including cardiovascular and limb defects, although data are limited. If exposure occurs, weigh risks. |
| 2nd trimester | Use during second trimester is contraindicated. High doses may cause virilization of female fetus. There is no therapeutic indication for use in pregnancy. |
| 3rd trimester | Use during third trimester is contraindicated. Estrogens can inhibit lactation and may cause withdrawal bleeding in neonate. Norgestimate may affect fetal development. |
Clinical note
Inducers of CYP450 enzymes (eg carbamazepine) may decrease estrogen levels Increases risk of thromboembolic disorders and endometrial cancer.
| FDA category | Positive |
| Placental transfer | Both estradiol and norgestimate cross the placenta. Estradiol transfer is moderate; norgestimate and its metabolites cross readily. Fetal exposure occurs. |
■ FDA Black Box Warning
Cigarette smoking increases the risk of serious cardiovascular events from combination hormonal contraceptive use. This risk increases with age, especially in women over 35 years of age, and with the number of cigarettes smoked. Women who use combination hormonal contraceptives should be strongly advised not to smoke.
| Common Effects | osteoporosis prevention |
| Serious Effects |
PregnancyCurrent or past breast cancer (estrogen-sensitive)Active thromboembolic disorders (e.g., DVT, PE)History of cerebrovascular or coronary artery diseaseUncontrolled hypertensionDiabetes with vascular involvementKnown or suspected estrogen-dependent neoplasiaUndiagnosed abnormal genital bleedingLiver tumors (benign or malignant) or active liver diseaseKnown hypersensitivity to any componentCigarette smoking in women over 35 years (due to increased cardiovascular risk)
| Precautions | Thromboembolic disorders: increased risk of venous thromboembolism and arterial thrombosis, Cardiovascular disease: increased risk of myocardial infarction and stroke, especially in smokers and women with hypertension, Carcinoma of the breast and reproductive organs: estrogens may increase risk, Hepatic effects: jaundice, cholestasis, liver tumors, Gallbladder disease: increased risk, Ocular changes: retinal thrombosis, vision loss, Elevated blood pressure, Hypertriglyceridemia, Glucose tolerance changes, Fluid retention, Depression, Unscheduled bleeding |
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| Breastfeeding | Estradiol and norgestimate are excreted in breast milk in small amounts. Estradiol may reduce milk production and quality. Norgestimate and its metabolites are present in milk. Use is generally not recommended during breastfeeding; consider alternative contraception or discontinue drug or nursing. |
| Lactation Rating | L3 (Moderately Safe) - Limited data; potential for adverse effects in infant. |
| Teratogenic Risk | First trimester: Combination estrogen-progestin oral contraceptives are not recommended during pregnancy due to a potential but low risk of congenital anomalies; some studies suggest a slight increase in cardiovascular defects and limb reduction defects. Second and third trimesters: Use is contraindicated as it may cause fetal harm; exposure has been associated with masculinization of female fetuses (due to progestin) and possible cardiovascular and genitourinary tract anomalies. Withdrawal of therapy is advised if pregnancy is detected. |
| Fetal Monitoring | Routine pregnancy testing if pregnancy is suspected. No specific fetal monitoring required beyond standard prenatal care. Monitor for signs of thrombotic events, hypertension, and hepatic dysfunction. Inadvertent use during pregnancy does not typically require invasive fetal monitoring. |
| Fertility Effects | This combination estrogen-progestin acts primarily by suppressing ovulation. Upon discontinuation, ovulation typically resumes within 1-3 months, but transient delay in return to fertility may occur. No permanent effects on fertility have been documented. Long-term use does not impair future fecundity. |
| Food/Dietary | Grapefruit or grapefruit juice may increase ethinyl estradiol levels and risk of adverse effects; avoid concurrent use. St. John's wort, a dietary supplement, can reduce contraceptive efficacy by inducing CYP3A4 metabolism of EE and progestin; advise against use. There are no significant food restrictions, but maintain a consistent diet if taking the pill with meals to minimize nausea. |
| Clinical Pearls | Estradiol/norgestimate is a combined hormonal contraceptive (CHC) used for oral contraception and treatment of moderate acne vulgaris in women aged ≥15 years who have reached menarche. It contains ethinyl estradiol (EE) and norgestimate, a third-generation progestin with low androgenic activity. Norgestimate is a prodrug rapidly converted to norelgestromin and levonorgestrel. This CHC has a higher risk of venous thromboembolism (VTE) compared with levonorgestrel-containing pills. Do not use in women with migraine with aura, hypertension (systolic ≥160 mm Hg or diastolic ≥100 mm Hg), or BMI >35 kg/m² (relative contraindication). Assess for VTE risk factors (smoking, obesity, thrombophilia). Prescribe continuous or extended regimens only if patient tolerates withdrawal bleeding. Monitor for breakthrough bleeding, which is common in first 3 cycles. If missed pills, use back-up contraception. Norgestimate may improve acne due to its low androgenicity. |
| Patient Advice | Take one pill at the same time every day. Do not skip pills even if you don't have sex. · If you miss a pill, follow the package instructions for missed pills. Use backup contraception (condoms) if directed. · This medication does not protect against HIV or other sexually transmitted infections (STIs). Use condoms for STI prevention. · Smoking increases your risk of serious cardiovascular side effects (stroke, blood clots). Do not smoke while taking this medication, especially if you are over 35 years old. · Tell your healthcare provider if you have unexplained leg swelling, sudden severe headache, chest pain, or vision changes — these may be signs of a blood clot. · You may experience spotting or breakthrough bleeding, especially during the first few months. This is usually not serious but contact your doctor if it persists. · If you are breastfeeding, this medication may reduce milk production. Discuss alternative contraception with your doctor. · Take a pregnancy test if you miss two consecutive periods. This medication should not be used during pregnancy. · This medication can help improve acne, but it may take several months to see full effect. · Store at room temperature, away from moisture and heat. |