Comparative Pharmacology
Head-to-head clinical analysis: MEGACE ES versus NORETHINDRONE AND ETHINYL ESTRADIOL 10 11.
Peer-Reviewed Evidence
Head-to-head clinical analysis: MEGACE ES versus NORETHINDRONE AND ETHINYL ESTRADIOL 10 11.
MEGACE ES vs NORETHINDRONE AND ETHINYL ESTRADIOL (10/11)
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.
Combination oral contraceptive; ethinyl estradiol suppresses follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion, inhibiting ovulation; norethindrone alters cervical mucus, endometrial lining, and sperm penetration.
625 mg orally once daily (MEGACE ES suspension contains 625 mg/5 mL; shake well before use). For appetite stimulation in cachexia.
One tablet (norethindrone 0.5 mg/ethinyl estradiol 35 mcg for days 1-10; norethindrone 1 mg/ethinyl estradiol 35 mcg for days 11-21) orally once daily for 21 days, followed by 7 days of placebo or no tablets.
None Documented
None Documented
Approximately 34 hours in plasma; steady-state achieved after 2-3 weeks of daily dosing.
Norethindrone: terminal half-life ~7-8 hours. Ethinyl estradiol: terminal half-life ~13-27 hours (mean ~17 hours). Clinical context: Steady-state achieved within ~5-10 days; dosing interval based on maintaining contraceptive efficacy.
Primarily renal (≤1% unchanged) and biliary; extensive metabolism to inactive glucuronide conjugates excreted in feces.
Norethindrone and ethinyl estradiol are primarily eliminated via renal excretion. Norethindrone is excreted as glucuronide and sulfate conjugates, with ~50% renal and ~20-30% fecal. Ethinyl estradiol is extensively metabolized; ~40% renal and ~60% fecal as conjugates.
Category C
Category D/X
Progestin
Progestin