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megestrol and estrogen

G03FB04

Forms & Strengths

Combined oral formulations containing megestrol acetate and an estrogen (varies by regional availability/historical combination products)

Adult Dosing

Endometriosis: Dosing determined by specific product labeling and clinical guideline recommendations
Menopausal hormone therapy: Regimens tailored to symptom severity and patient risk profile

Pediatric Dosing

Not indicated for pediatric use

Indications

Management of vasomotor symptoms associated with menopause
Treatment of endometriosis and related symptoms

Mechanism of Action

Estrogen component replaces declining endogenous estrogen, alleviating vasomotor symptoms and maintaining bone density
Megestrol acetate provides progestogenic activity, inducing endometrial secretory transformation and suppressing gonadotropin secretion

Contraindications

Known or suspected pregnancy
History of or active venous thromboembolism (DVT, PE)
Active or recent arterial thromboembolic disease (stroke, myocardial infarction)
Known or suspected estrogen- or progestin-dependent neoplasms
Undiagnosed abnormal genital bleeding
Active liver disease or hepatic impairment

Adverse Reactions

Thromboembolic events (deep vein thrombosis, pulmonary embolism)
Weight gain and fluid retention
Breast tenderness and enlargement
Nausea, abdominal cramps, and bloating
Headache and mood changes
Breakthrough bleeding or spotting

Drug Interactions

CYP3A4 inducers (e.g., rifampin, carbamazepine, St. John's wort) may increase clearance and reduce efficacy
CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) may increase plasma concentrations
Antidiabetic agents: Hormone therapy may diminish glucose-lowering efficacy
Anticoagulants: May alter therapeutic response to warfarin or oral anticoagulants

Curated Content: Needs Vetting Before Put to Clinical Use