NORGESTIMATE AND ETHINYL ESTRADIOL
Clinical safety rating: avoid
Inducers of CYP450 enzymes (eg carbamazepine) may decrease estrogen levels Increases risk of thromboembolic disorders and endometrial cancer.
Combination oral contraceptive: ethinyl estradiol suppresses gonadotropin release via estrogen receptor; norgestimate is a progestin that inhibits ovulation and thickens cervical mucus.
| Metabolism | Ethinyl estradiol: primarily metabolized by CYP3A4 via hydroxylation; undergoes conjugation. Norgestimate: rapidly hydrolyzed to norelgestromin (active) and levonorgestrel; further metabolized by CYP3A4 and CYP2C9. |
| Excretion | Urine (primarily as glucuronide and sulfate conjugates; ~50-60% of dose), feces (~30-40% of dose as metabolites), minimal unchanged drug in urine |
| Half-life | Norgestimate: ~21.3 hours (range 16-36 hours); active metabolite 17-deacetyl norgestimate: ~33.2 hours (range 22-45 hours). Ethinyl estradiol: ~17.1 hours (range 14-22 hours). Terminal half-life supports once-daily dosing; steady-state achieved within 10-14 days. |
| Protein binding | Norgestimate and 17-deacetyl norgestimate: ~99% bound to albumin and sex hormone-binding globulin (SHBG). Ethinyl estradiol: ~97-98% bound to albumin and to a lesser extent SHBG. |
| Volume of Distribution | Norgestimate: ~2.5 L/kg (indicating extensive tissue distribution). Ethinyl estradiol: ~3.5 L/kg (moderately large Vd, consistent with distribution into body tissues). |
| Bioavailability | Norgestimate: ~60% (undergoes first-pass metabolism to active metabolite 17-deacetyl norgestimate). Ethinyl estradiol: ~45-55% (first-pass metabolism with interindividual variability). |
| Onset of Action | Oral administration: Contraceptive effect begins after 7 days of continuous therapy if started within first 5 days of menstrual cycle; otherwise, additional contraceptive measures needed for first 7 days. |
| Duration of Action | Contraceptive protection lasts for the duration of daily administration; misses dose increases risk of ovulation. Withdrawal bleed typically occurs 2-3 days after last active tablet in 28-day regimen. |
One tablet (norgestimate 0.250 mg/ethinyl estradiol 0.035 mg) orally once daily for 21 consecutive days followed by 7 placebo tablets.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Use is contraindicated in severe renal impairment or acute renal failure due to potential for fluid retention and electrolyte disturbances. |
| Liver impairment | Contraindicated in Child-Pugh class B and C cirrhosis. For Child-Pugh class A, no dose adjustment is recommended but use with caution; monitor for signs of hepatic impairment. |
| Pediatric use | Not indicated for use before menarche. Postmenarcheal adolescents: same adult dosing regimen. Weight-based dosing not established. |
| Geriatric use | Not indicated for use in postmenopausal women due to lack of efficacy and safety concerns; increased risk of thromboembolic events and myocardial infarction in women over 35 who smoke or have cardiovascular risk factors. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Inducers of CYP450 enzymes (eg carbamazepine) may decrease estrogen levels Increases risk of thromboembolic disorders and endometrial cancer.
| FDA category | Positive |
| Breastfeeding | Excreted in breast milk; may reduce milk production and composition. Use is not recommended during breastfeeding. M/P ratio not well established. |
| Teratogenic Risk | Pregnancy category X. No increased risk of birth defects from inadvertent first-trimester use; however, use is contraindicated due to potential fetal harm from progestin and estrogen exposure. Estrogens may cause feminization of male fetuses and other developmental effects in animal studies. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptives. Risk increases with age and heavy smoking (≥15 cigarettes/day). Women over 35 who smoke should not use this product.
| Common Effects | osteoporosis prevention |
| Serious Effects |
Venous or arterial thromboembolic disease; cerebrovascular/coronary artery disease; known/suspected pregnancy; breast cancer; liver disease/tumors; undiagnosed abnormal uterine bleeding; hypersensitivity; smoking >35 years of age; migraine with focal aura; uncontrolled hypertension; diabetes with vascular involvement.
| Precautions | Cardiovascular risk (thrombosis, stroke, MI); hypertension; gallbladder disease; liver tumors; carbohydrate/lipid effects; headache; depression; irregular bleeding; reduced efficacy with enzyme-inducing drugs. |
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| Fetal Monitoring | Monitor for signs of thromboembolism, hypertension, glucose intolerance, and hepatic dysfunction. In case of inadvertent use during early pregnancy, no specific fetal monitoring beyond routine prenatal care is indicated. |
| Fertility Effects | This combination hormonal contraceptive is used for contraception. Return to baseline fertility after discontinuation may be delayed but is not permanently impaired. |