Comparative Pharmacology
Head-to-head clinical analysis: KELNOR versus LEVORA 0 15 30 28.
Peer-Reviewed Evidence
Head-to-head clinical analysis: KELNOR versus LEVORA 0 15 30 28.
KELNOR vs LEVORA 0.15/30-28
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 levonorgestrel. Suppresses gonadotropin (FSH and LH) release from the pituitary, inhibiting ovulation. Also induces changes in cervical mucus (increasing viscosity) and endometrium (reducing receptivity) to impair sperm penetration and implantation.
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 at the same time each day for 28 days (21 active tablets containing 0.15 mg levonorgestrel and 0.03 mg ethinyl estradiol, followed by 7 placebo tablets).
None Documented
None Documented
Terminal elimination half-life 12-15 hours; clinically relevant for once-daily dosing.
Ethinyl estradiol: 13-27 hours (terminal); Levonorgestrel: 11-45 hours (terminal, dose-dependent due to SHBG binding).
Primarily renal excretion of unchanged drug (70-80%) and glucuronide conjugate (10-15%); biliary/fecal elimination accounts for <5%.
Renal: ~50% (as glucuronide and sulfate conjugates of ethinyl estradiol and levonorgestrel); Fecal: ~50% (enterohepatic recirculation).
Category C
Category C
Oral Contraceptive
Oral Contraceptive