Comparative Pharmacology
Head-to-head clinical analysis: KELNOR versus OGESTREL 0 5 50 28.
Peer-Reviewed Evidence
Head-to-head clinical analysis: KELNOR versus OGESTREL 0 5 50 28.
KELNOR vs OGESTREL 0.5/50-28
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combined oral contraceptive; inhibits ovulation by suppressing gonadotropin release (FSH and LH) primarily via progestational activity; increases viscosity of cervical mucus to inhibit sperm penetration; alters endometrium.
Combination estrogen-progestin contraceptive; suppresses gonadotropins (FSH, LH) via negative feedback on hypothalamic-pituitary axis, inhibiting ovulation; increases cervical mucus viscosity and alters endometrial development.
KELNOR (norethindrone acetate and ethinyl estradiol) is a combined oral contraceptive. Typical adult dose: 1 tablet (norethindrone acetate 1 mg/ethinyl estradiol 20 mcg) orally once daily for 21 days, followed by 7 placebo tablets, starting on day 1 of menstrual cycle.
One tablet (norgestrel 0.5 mg/ethinyl estradiol 50 mcg) orally once daily for 28-day cycle.
None Documented
None Documented
Terminal elimination half-life 12-15 hours; clinically relevant for once-daily dosing.
Norgestrel: ~45 hours (range 24-56 h) enabling once-daily dosing; Ethinyl estradiol: ~17 hours (range 10-27 h).
Primarily renal excretion of unchanged drug (70-80%) and glucuronide conjugate (10-15%); biliary/fecal elimination accounts for <5%.
Renal: 50-60% as metabolites (glucuronide and sulfate conjugates of norgestrel and ethinyl estradiol); Fecal: 30-40% via biliary elimination; Unchanged drug: <1%.
Category C
Category C
Oral Contraceptive
Oral Contraceptive