Comparative Pharmacology
Head-to-head clinical analysis: MEGACE ES versus PROMETRIUM.
Peer-Reviewed Evidence
Head-to-head clinical analysis: MEGACE ES versus PROMETRIUM.
MEGACE ES vs PROMETRIUM
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Megestrol acetate is a synthetic progestin that inhibits pituitary gonadotropin secretion, leading to suppression of ovarian and testicular hormone production. It also has antineoplastic effects possibly through local action on hormone-sensitive tissues and stimulates appetite via modulation of neuropeptide Y and other appetite-regulating factors.
Progesterone binds to progesterone receptors in target tissues, promoting endometrial maturation, reducing uterine contractility, and suppressing ovulation.
625 mg orally once daily (MEGACE ES suspension contains 625 mg/5 mL; shake well before use). For appetite stimulation in cachexia.
Oral: 200 mg once daily at bedtime for 12 consecutive days per 28-day cycle in combination with conjugated estrogens 0.625 mg daily. For secondary amenorrhea: 400 mg once daily at bedtime for 10 days. Intravaginal: 4% gel (90 mg) or 8% gel (180 mg) applied every other day for 6 doses in postmenopausal women with intact uterus on estrogen therapy.
None Documented
None Documented
Approximately 34 hours in plasma; steady-state achieved after 2-3 weeks of daily dosing.
Terminal half-life: Approximately 16-18 hours for oral micronized progesterone (Prometrium); permits twice-daily dosing for luteal phase support.
Primarily renal (≤1% unchanged) and biliary; extensive metabolism to inactive glucuronide conjugates excreted in feces.
Urine (50-60% as metabolites, <1% unchanged); feces (20-30% as metabolites); minor biliary elimination.
Category C
Category C
Progestin
Progestin