Comparative Pharmacology
Head-to-head clinical analysis: KELNOR versus NORINYL 1 80 21 DAY.
Peer-Reviewed Evidence
Head-to-head clinical analysis: KELNOR versus NORINYL 1 80 21 DAY.
KELNOR vs NORINYL 1+80 21-DAY
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 norethindrone (a progestin) and ethinyl estradiol (an estrogen). Inhibits ovulation by suppressing gonadotropin release (FSH and LH). Also increases cervical mucus viscosity and alters endometrial morphology.
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 orally once daily for 21 days, followed by 7 days of no active treatment.
None Documented
None Documented
Terminal elimination half-life 12-15 hours; clinically relevant for once-daily dosing.
Norethindrone: 8-11 hours; Mestranol: 12-24 hours (metabolized to ethinyl estradiol with half-life 20-27 hours). Steady-state after 5-7 days.
Primarily renal excretion of unchanged drug (70-80%) and glucuronide conjugate (10-15%); biliary/fecal elimination accounts for <5%.
Renal (40-60% as metabolites), fecal (20-30%)
Category C
Category C
Oral Contraceptive
Oral Contraceptive