AMEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for AMEN (AMEN).
Progesterone receptor agonist; induces secretory endometrium, inhibits gonadotropin release, and alters cervical mucus.
| Metabolism | Hepatic via CYP3A4, CYP2C9, CYP2C19; primary metabolite is 20α-dihydroprogesterone. |
| Excretion | Primarily hepatic metabolism to inactive metabolites, with <1% excreted unchanged in urine. Fecal elimination of metabolites accounts for ~30%. |
| Half-life | Terminal elimination half-life is approximately 4-6 hours. In severe hepatic impairment, half-life may be prolonged up to 12 hours. |
| Protein binding | 98% bound primarily to albumin and sex hormone-binding globulin. |
| Volume of Distribution | 4.4 L/kg, indicating extensive tissue distribution, particularly to adipose tissue. |
| Bioavailability | Oral: 20-25% (with high first-pass metabolism); Sublingual: 60-70%; Transdermal: 10-15% (depending on formulation). |
| Onset of Action | Oral: 30-60 minutes; Sublingual: 5-10 minutes; Transdermal: 2-6 hours. |
| Duration of Action | Oral: 4-6 hours; Sublingual: 2-4 hours; Transdermal: 7 days (with patch). |
Medroxyprogesterone acetate (AMEN): 5-10 mg orally once daily for 5-10 days, starting on day 16 or 21 of menstrual cycle; also 150 mg IM every 3 months for contraception.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for renal impairment; caution in severe renal failure due to potential fluid retention. |
| Liver impairment | Contraindicated in severe hepatic disease (Child-Pugh class C). For mild to moderate impairment (Child-Pugh A/B): use with caution, consider dose reduction, monitor liver function. |
| Pediatric use | Not indicated for use in pediatric patients; safety and efficacy not established. |
| Geriatric use | No specific dose adjustment; use lowest effective dose due to increased risk of thromboembolic events and cognitive decline. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for AMEN (AMEN).
| Breastfeeding | Contraindicated during breastfeeding. Methotrexate (active ingredient) is excreted in human milk at low levels (M/P ratio approximately 0.08). However, drug accumulation in the nursing infant due to long half-life and potential for severe toxicity (e.g., immunosuppression, mucositis) preclude use. Discontinue breastfeeding or therapy. |
| Teratogenic Risk | FDA Category X. Contraindicated in pregnancy. First trimester: High risk of major congenital anomalies including cleft palate, cardiac malformations, and neural tube defects due to anti-folate activity. Second/third trimesters: Associated with fetal growth restriction, preterm birth, and neonatal myelosuppression. Effective contraception required before, during, and after therapy. |
■ FDA Black Box Warning
Not to be used during pregnancy; increased risk of congenital anomalies including cardiovascular and neural tube defects.
| Serious Effects |
Known or suspected pregnancy; active thrombophlebitis or thromboembolic disorders; undiagnosed vaginal bleeding; liver dysfunction; known sensitivity to progesterone.
| Precautions | Thromboembolic disorders; impaired liver function; depression; fluid retention; glucose tolerance decrease; ophthalmic changes. |
| Food/Dietary | No significant food interactions. However, maintain adequate calcium and vitamin D intake to mitigate potential bone density loss with prolonged use. |
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| Fetal Monitoring | Pregnancy test before initiation and monthly throughout therapy. Ultrasound for fetal anomalies if exposure occurs. Monitor maternal CBC, liver function, renal function, and methotrexate trough levels. Assess for fetal growth restriction and oligohydramnios in second/third trimester if inadvertently used. |
| Fertility Effects | Reversible oligospermia and menstrual irregularities with short-term use. High-dose or prolonged therapy may cause irreversible gonadal damage (ovarian failure, azoospermia). Pre-treatment fertility counseling and consideration of gamete preservation recommended. |
| Clinical Pearls |
| AMEN (medroxyprogesterone acetate) is a progestin used for contraception and endometrial conditions. For contraceptive use, administer 150 mg IM within 5 days of menses onset to ensure non-pregnant status. Monitor for bone mineral density loss with long-term use; avoid in patients with osteoporosis risk factors. May cause irregular bleeding initially; counsel on potential amenorrhea after 1 year. Contraindicated in pregnancy, breast cancer, and active thromboembolic disease. |
| Patient Advice | This injection prevents pregnancy for 3 months; you must receive a repeat injection every 3 months. · Irregular bleeding or spotting is common in the first months; some women stop having periods after a year. · It does not protect against sexually transmitted infections; use condoms for protection. · May cause weight gain, mood changes, or headache; report severe symptoms to your doctor. · Long-term use may reduce bone density; ensure adequate calcium and vitamin D intake. |