Comparative Pharmacology
Head-to-head clinical analysis: ETHINYL ESTRADIOL ETONOGESTREL versus MEGACE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ETHINYL ESTRADIOL ETONOGESTREL versus MEGACE.
ETHINYL ESTRADIOL; ETONOGESTREL vs MEGACE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
ETHINYL ESTRADIOL is an estrogen; ETONOGESTREL is a progestin. The combination suppresses gonadotropin (FSH and LH) release from the pituitary, inhibiting ovulation, thickening cervical mucus to impede sperm penetration, and altering endometrial receptivity.
Megestrol acetate is a synthetic progestin that inhibits pituitary gonadotropin secretion, leading to suppression of ovarian function and reduction of sex hormone levels. It also has antineoplastic effects through interference with estrogen receptor binding and may stimulate appetite via effects on neuropeptide Y and cytokines.
One vaginal ring (0.120 mg etonogestrel/0.015 mg ethinyl estradiol per day) inserted vaginally and left in place for 3 weeks, followed by a 1-week ring-free period.
Oral: 625 mg (suspension) or 400–800 mg (tablets) once daily.
None Documented
None Documented
Ethinyl estradiol: ~13 hours (range 7-20 h); etonogestrel: ~25 hours (range 15-36 h). At steady state, elimination half-life extends to 20-30 h for etonogestrel.
Terminal elimination half-life: 70-95 hours (mean 85 hours) in chronic dosing; shorter in initial doses; clinical context: requires 3-4 weeks to reach steady state.
Urine (60-70% as metabolites, <10% unchanged), feces (20-30% via biliary elimination).
Primarily renal: ~75% as glucuronide conjugates and unchanged drug; biliary/fecal: ~25% as metabolites.
Category D/X
Category C
Progestin
Progestin