Comparative Pharmacology
Head-to-head clinical analysis: MEGACE ES versus PROGESTERONE VAGINAL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: MEGACE ES versus PROGESTERONE VAGINAL.
MEGACE ES vs Progesterone (Vaginal)
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 the reproductive tract, converting proliferative endometrium to secretory endometrium, and reduces gonadotropin secretion, inhibiting ovulation.
625 mg orally once daily (MEGACE ES suspension contains 625 mg/5 mL; shake well before use). For appetite stimulation in cachexia.
For progesterone deficiency (e.g., assisted reproductive technology, luteal phase support): 90 mg intravaginally once daily. For secondary amenorrhea: 45 mg intravaginally every other day for up to 12 doses, then 90 mg if needed. For threatened abortion: 200-400 mg intravaginally once or twice daily.
None Documented
None Documented
Approximately 34 hours in plasma; steady-state achieved after 2-3 weeks of daily dosing.
The terminal elimination half-life of progesterone administered vaginally is approximately 5.5 to 6 hours (range: 4.5–8.0 hours) in women with normal renal and hepatic function. This short half-life necessitates twice-daily dosing for sustained effects.
Primarily renal (≤1% unchanged) and biliary; extensive metabolism to inactive glucuronide conjugates excreted in feces.
Primarily hepatic metabolism; about 50-60% of metabolites are excreted renally as glucuronide conjugates, with approximately 30-40% eliminated via feces. Less than 1% of unchanged progesterone is excreted in urine.
Category C
Category A/B
Progestin
Progestin