Dosing and uses of Megace (megestrol)
Adult dosage forms and strengths
tablet
- 20mg
- 40mg
oral suspension
- 200mg/5mL
- 625mg/5mL
AIDS-Related Cachexia
Megace: 800 mg/day PO
Megace ES: 312.5-625 mg/day PO
Breast Cancer
40 mg PO q6hr
Endometrial Cancer
40-320 mg/day PO in divided doses; evaluate efficacy after 2 months of treatment; up to 800 mg/day may be used
Cancer-Related Cachexia (Off-label)
480-600 mg/day PO
Dosing Modifications
Renal impairment: Use with caution; in normal renal function, 57-78% is excreted in urine within 10 days
Pediatric dosage forms and strengths
Safety and efficacy not established
Megace (megestrol) adverse (side) effects
Frequency not defined
Common
- Hypertension
- Insomnia, mood swings
- Rash, sweating
- Amenorrhea, breakthrough bleeding, change in menstrual flow, hot sweats, impotence, spotting
- Diarrhea, flatulence, indigestion, nausea, vomiting, weight gain
Serious
- Deep vein thrombosis (DVT)
- Pulmonary embolism
- Thrombophlebitis
- Anemia
- Adrenal insufficiency
Postmarketing report
Asthenia, rash, impotence
Overdose may cause shortness of breath, cough, unsteady gait, listlessness, chest pain
Warnings
Contraindications
Known or suspected pregnancy
Acute thrombophlebitis, thromboembolic disorder, breast cancer
Undiagnosed abnormal genital bleeding
Prophylaxis of weight loss
Documented hypersensitivity
May induce vaginal bleeding in women
Cautions
Diabetes mellitus
History of thromboembolic disease
Not to be used as prophylaxis against weight loss or as diagnostic test for pregnancy
Adrenal insufficiency may occur in patients receiving or being withdrawn from long-term megestrol treatment
Megestrol is a progesterone derivative which may induce vaginal bleeding in women
Cushing syndrome reported with thearpy
Pregnancy and lactation
Pregnancy category: d
Lactation: Not safe; do not nurse
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Megace (megestrol)
Mechanism of action
Progestin derivative with antiestrogenic properties; interferes with estrogen cycle, resulting in lower luteinizing hormone (LH) titer; antineoplastic properties may come from direct effect on endometrium through anti-LH effect mediated via pituitary
Absorption
Bioavailability: Well absorbed PO
Peak plasma time: 1-3 hr (tablet); 3-5 hr (suspension)
Metabolism
Metabolized by liver
Metabolites: Sulfate and glucuronide metabolites (inactive)
Elimination
Half-life: 13-105 hr (mean, 34 hr)
Excretion: Urine (57-78%), feces (8-30%)
