PREVEN EMERGENCY CONTRACEPTIVE KIT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PREVEN EMERGENCY CONTRACEPTIVE KIT (PREVEN EMERGENCY CONTRACEPTIVE KIT).
The levonorgestrel component is a progestin that inhibits ovulation and fertilization by altering the cervical mucus and endometrial lining, preventing implantation. The ethinyl estradiol component suppresses gonadotropin release, inhibits ovulation, and alters the endometrium.
| Metabolism | Metabolized primarily in the liver via CYP3A4; ethinyl estradiol is also metabolized by CYP2C9 and conjugation. |
| Excretion | Primarily renal (50-60% as metabolites, <1% unchanged) and fecal (30-40% as metabolites). |
| Half-life | 26 hours (range 17-35 hours; clinical: no significant accumulation with single dose). |
| Protein binding | 95-100% bound to serum proteins (including SHBG and albumin). |
| Volume of Distribution | 1.5 L/kg (extensive tissue distribution, including breast milk). |
| Bioavailability | Oral: ~65% (due to first-pass metabolism; absolute bioavailability not determined for levonorgestrel alone in this product). |
| Onset of Action | Within 24-36 hours post-ovulation if taken within 72 hours; effect is maximal within 120 hours. |
| Duration of Action | Single dose provides contraceptive effect for one menstrual cycle; no extended duration. |
The kit contains levonorgestrel 0.75 mg tablets. The regimen is two tablets: one tablet taken orally as soon as possible within 72 hours of unprotected intercourse, followed by a second tablet taken orally 12 hours later.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment is required for patients with renal impairment, as levonorgestrel is primarily metabolized in the liver. |
| Liver impairment | Contraindicated in severe hepatic insufficiency (Child-Pugh class C). In mild to moderate impairment (Child-Pugh A or B), no dose adjustment is necessary, but caution is advised. |
| Pediatric use | In postmenarchal adolescents, use same dosing as adults: one 0.75 mg tablet orally as soon as possible within 72 hours, followed by a second tablet 12 hours later. |
| Geriatric use | Not indicated for use in elderly women, as emergency contraception is intended for women of childbearing potential. No specific geriatric studies available. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PREVEN EMERGENCY CONTRACEPTIVE KIT (PREVEN EMERGENCY CONTRACEPTIVE KIT).
| Breastfeeding | Excreted in breast milk; M/P ratio not established. Use caution; avoid high doses. AAP recommends alternative methods. |
| Teratogenic Risk | Pregnancy Category X. High risk of fetal harm if pregnancy occurs after use. First trimester: potential for ectopic pregnancy and fetal anomalies. Second and third trimesters: not indicated for use; no data due to contraindication. |
| Fetal Monitoring |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events. Women over 35 who smoke should not use this product. Smoking cessation is advised.
| Serious Effects |
["Known or suspected pregnancy","Hypersensitivity to any component","History of thrombophlebitis or thromboembolic disorders","Undiagnosed abnormal genital bleeding","Hepatic adenoma or carcinoma","Use with ritonavir-boosted HIV protease inhibitors"]
| Precautions | ["Thrombotic disorders (venous thromboembolism, stroke, MI) with ethinyl estradiol","Liver disease (hepatocellular carcinoma, hepatic adenoma)","Ectopic pregnancy risk if pregnancy occurs after use","Increased risk in smokers >35 years"] |
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| Monitor for pregnancy test 3 weeks post-dose; rule out ectopic pregnancy if lower abdominal pain. No fetal monitoring required. |
| Fertility Effects | No long-term effects on fertility. Reversible suppression of ovulation; normal cycles resume within one cycle. |