NEXPLANON
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NEXPLANON (NEXPLANON).
Progestin-only contraceptive that suppresses ovulation primarily by inhibiting the mid-cycle LH surge. It also thickens cervical mucus, impeding sperm penetration, and alters endometrial lining.
| Metabolism | Primarily metabolized by CYP3A4 via hydroxylation, with subsequent conjugation; also involves CYP2C9 and CYP2C19 to a lesser extent. |
| Excretion | Renal (40-50% as metabolites), fecal (30-40% as metabolites), with <1% unchanged in urine; enterohepatic circulation contributes to prolonged elimination. |
| Half-life | Terminal elimination half-life approximately 25 hours (range 20-30 hours) after removal; steady-state achieved within 3-4 days; clinical effect persists for 3-4 weeks post-removal due to residual subcutaneous depot. |
| Protein binding | ~95% bound to albumin and sex hormone-binding globulin (SHBG); free fraction ~5%. |
| Volume of Distribution | ~27 L/kg (mean 26-27 L/kg) indicating extensive tissue distribution; high volume due to lipophilicity and tissue binding. |
| Bioavailability | ~100% after subcutaneous insertion; dose proportionality for etonogestrel concentrations. |
| Onset of Action | Subcutaneous: Effective contraception within 24 hours (estradiol levels <50 pmol/L within 8 hours, ovulation suppressed within 24 hours). |
| Duration of Action | 3 years (approved) with continued contraception maintained throughout; after removal, ovulatory cycles resume within 3-4 weeks; prolonged use beyond 3 years is not recommended due to reduced efficacy. |
68 mg subdermal implant inserted in the inner upper arm; provides contraception for up to 3 years.
| Dosage form | IMPLANT |
| Renal impairment | No dose adjustment required for renal impairment. |
| Liver impairment | Contraindicated in women with severe hepatic disease (Child-Pugh class C). For mild to moderate impairment, use with caution and monitor for adverse effects. |
| Pediatric use | Approved for post-menarchal adolescents; dosing same as adults (68 mg subdermal implant). No weight-based adjustment necessary. |
| Geriatric use | Not indicated in postmenopausal women; no data available for geriatric use. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for NEXPLANON (NEXPLANON).
| Breastfeeding | Small amounts of etonogestrel (ENG) are excreted in breast milk (M/P ratio approximately 0.4-0.5). No adverse effects on infant growth or development have been reported; however, monitor infant for jaundice and weight gain. Use during breastfeeding is generally considered compatible. |
| Teratogenic Risk | No increased risk of birth defects observed in epidemiological studies; does not pose teratogenic risk in any trimester. However, pregnancy should be ruled out prior to insertion and removal due to potential risks of progestin exposure during early pregnancy. |
■ FDA Black Box Warning
None
| Serious Effects |
["Known or suspected pregnancy","Current or history of breast cancer","Active liver disease or severe decompensated cirrhosis","Undiagnosed abnormal genital bleeding","Known or suspected progestin-sensitive tumors","Hypersensitivity to any component"]
| Precautions | ["Thrombotic disorders: Discontinue if thrombotic events occur or are suspected.","Ectopic pregnancy: Increased risk, especially in those with history of ectopic pregnancy or PID.","Ovarian cysts: May occur but are usually benign and resolve spontaneously.","Breast cancer: Caution in current or history of breast cancer.","Liver disease: Contraindicated in acute liver disease or severe decompensated cirrhosis.","Depression: Monitor for worsening depression.","Menstrual bleeding changes: Common, including amenorrhea."] |
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| Fetal Monitoring |
| No specific fetal monitoring required. In pregnant patients with Nexplanon in situ, ultrasound to confirm intrauterine pregnancy and rule out ectopic pregnancy. Monitor for signs of infection at implant site if retained during pregnancy. |
| Fertility Effects | Reversible: rapid return to ovulation and fertility within 3-4 weeks after removal. No long-term impairment of fertility. |