TRI-PREVIFEM
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TRI-PREVIFEM (TRI-PREVIFEM).
Combination oral contraceptive: ethinyl estradiol and norgestimate exert contraceptive effects primarily by suppression of gonadotropin secretion (FSH and LH), thereby inhibiting ovulation. Additionally, progestin induces changes in cervical mucus and endometrial receptivity.
| Metabolism | Ethinyl estradiol is primarily metabolized via CYP3A4; norgestimate is extensively metabolized by hepatic CYP3A4 and other enzymes, undergoing hydrolysis and reduction to active metabolites (norelgestromin, norgestrel). |
| Excretion | Ethinyl estradiol: 40% renal, 60% fecal; norgestimate and its metabolites: 80% renal, 20% fecal. |
| Half-life | Ethinyl estradiol: terminal half-life 13-27 hours; norgestimate: terminal half-life of norelgestromin (active metabolite) 12-30 hours; clinical context: once-daily dosing provides steady-state concentrations within 7-10 days. |
| Protein binding | Ethinyl estradiol: 97-98% bound to albumin; norgestimate/norelgestromin: >99% bound to albumin and sex hormone-binding globulin (SHBG). |
| Volume of Distribution | Ethinyl estradiol: 3.8-5 L/kg; norelgestromin: 2-3 L/kg; indicates extensive distribution into tissues. |
| Bioavailability | Oral: ethinyl estradiol 38-48%; norgestimate is a prodrug with nearly 100% conversion to active metabolite norelgestromin during first pass; overall oral bioavailability of active metabolites is about 60-70% due to first-pass metabolism. |
| Onset of Action | Oral: contraceptive efficacy begins within 24 hours if started on day 1 of menstrual cycle; therapeutic effects on menstrual cycle regulation occur within first cycle. |
| Duration of Action | Duration of contraceptive protection is 24 hours with daily dosing; requires consistent daily administration to maintain efficacy. |
| Molecular Weight | 376.9 |
One tablet (norgestimate 0.180 mg/ethinyl estradiol 0.025 mg) orally once daily for 21 days, followed by 7 days of placebo; repeat cycle.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Contraindicated in severe renal insufficiency or acute renal failure due to potential for fluid retention and electrolyte disturbances. |
| Liver impairment | Contraindicated in acute hepatic disease, hepatocellular carcinoma, or Child-Pugh class B or C cirrhosis. For mild hepatic impairment (Child-Pugh A), use with caution; no specific dose adjustment available but monitor liver function. |
| Pediatric use | Not indicated for postmenarcheal adolescents; safety and efficacy established for use after menarche. Dose same as adults: one tablet daily for 21 days, then 7 placebo. |
| Geriatric use | Not indicated for postmenopausal women. No specific dose adjustments for elderly; generally not used in this population due to increased risk of thromboembolic events and contraindication in women over 35 years who smoke. |
| 1st trimester | Combined hormonal contraceptives are contraindicated in pregnancy due to risk of fetal harm, including cardiovascular and limb defects from sex hormones. Should not be used in first trimester. |
| 2nd trimester | Avoid use in second trimester. Pregnancy is an absolute contraindication for combined hormonal contraceptives. |
| 3rd trimester | Avoid use in third trimester. No known benefit and potential risks to fetus. |
Clinical note
Comprehensive clinical and safety monograph for TRI-PREVIFEM (TRI-PREVIFEM).
| Placental transfer | Estrogen and progestin components cross the placenta; transfer documented in human studies. |
| Breastfeeding | Combined hormonal contraceptives are generally not recommended during breastfeeding due to potential reduction in milk production and passage of estrogen and progestin into breast milk. Use non-hormonal or progestin-only methods if contraception is needed. |
■ FDA Black Box Warning
Cigarette smoking increases the risk of serious cardiovascular events from combination oral contraceptives. This risk increases with age and with the number of cigarettes smoked, and is quite marked in women over 35 years of age. Women who use combination oral contraceptives should be strongly advised not to smoke.
| Serious Effects |
PregnancyHistory of or current venous thromboembolismCardiovascular disease (e.g., ischemic heart disease, stroke)Uncontrolled hypertensionDiabetes with vascular involvementSevere liver disease (e.g., hepatic adenoma, hepatocellular carcinoma)Known thrombogenic mutations (e.g., Factor V Leiden)Systemic lupus erythematosus with positive antiphospholipid antibodiesMigraine with aura (especially in women >35 years)Major surgery with prolonged immobilizationSmoking in women over 35Carcinoma of the breast or endometriumUnexplained vaginal bleeding
| Precautions | Thrombotic events (including venous thromboembolism, stroke, myocardial infarction), hepatic neoplasia, gallbladder disease, hypertension, carbohydrate/lipid effects, headache, irregular bleeding, depression, interaction with other drugs (e.g., anticonvulsants, antibiotics). |
| Food/Dietary |
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| Lactation Rating | L3 (Moderately Safe) - but alternatives preferred |
| Teratogenic Risk | FDA Pregnancy Category X. Contraindicated in pregnancy. First trimester exposure associated with cardiovascular defects and limb reduction defects. Second and third trimester exposure linked to female genital tract abnormalities (e.g., vaginal adenosis, clear cell adenocarcinoma) and urogenital anomalies in male fetuses (e.g., hypospadias). |
| Fetal Monitoring | Monitor blood pressure, liver function, glucose tolerance, and signs of thromboembolism. Perform pregnancy test before initiation. Ultrasound monitoring if exposure occurs. |
| Fertility Effects | Normal fertility returns after discontinuation. No permanent effects. Female fertility may be delayed temporarily. |
| Grapefruit juice may increase estrogen levels; avoid large amounts. No significant food restrictions, but maintain consistent diet to minimize nausea. Alcohol in moderation; excessive use may increase liver enzyme effects. |
| Clinical Pearls | TRI-PREVIFEM is a combination oral contraceptive containing ethinyl estradiol and norgestimate. Do not prescribe to women with BMI >35 or smokers over 35. Monitor for breakthrough bleeding; if persistent, rule out pregnancy. Check blood pressure at baseline and follow-up. CYP3A4 inducers (e.g., rifampin, St. John's wort) reduce efficacy; consider alternative contraception. |
| Patient Advice | Take one tablet daily at the same time; missed doses reduce effectiveness. · Watch for signs of thromboembolism: sudden chest pain, leg swelling, headache, vision changes. · Use backup contraception (e.g., condoms) if vomiting or diarrhea occurs within 4 hours of dosing. · This does not protect against HIV or other STIs; use condoms as needed. · Consult doctor before starting new medications, especially antibiotics or anticonvulsants. |