Comparative Pharmacology
Head-to-head clinical analysis: KELNOR versus ORTHO NOVUM 7 14 28.
Peer-Reviewed Evidence
Head-to-head clinical analysis: KELNOR versus ORTHO NOVUM 7 14 28.
KELNOR vs ORTHO-NOVUM 7/14-28
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 oral contraceptive containing ethinyl estradiol and norethindrone. Suppresses gonadotropin release (FSH, LH) via negative feedback, inhibiting ovulation. Also increases cervical mucus viscosity and alters endometrial receptivity.
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 daily for 28 days; each tablet contains norethindrone 0.5 mg and ethinyl estradiol 0.035 mg (days 1-7), norethindrone 0.75 mg and ethinyl estradiol 0.035 mg (days 8-14), norethindrone 1 mg and ethinyl estradiol 0.035 mg (days 15-21), and placebo (days 22-28). Take at same time each day.
None Documented
None Documented
Terminal elimination half-life 12-15 hours; clinically relevant for once-daily dosing.
Ethinyl estradiol: ~13-27 h (mean 17 h); Norethindrone: ~5-14 h (mean 8 h). Clinical context: steady-state achieved after ~5 days; half-life supports daily dosing.
Primarily renal excretion of unchanged drug (70-80%) and glucuronide conjugate (10-15%); biliary/fecal elimination accounts for <5%.
Renal: ~50-60% (metabolites); biliary/fecal: ~30-40% (metabolites); unchanged drug <1% in urine.
Category C
Category C
Oral Contraceptive
Oral Contraceptive