Comparative Pharmacology
Head-to-head clinical analysis: LEVONEST versus NORQUEST FE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: LEVONEST versus NORQUEST FE.
LEVONEST vs NORQUEST FE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Levonorgestrel is a synthetic progestin that inhibits ovulation by suppressing luteinizing hormone (LH) surge, alters cervical mucus to impede sperm penetration, and induces endometrial changes that inhibit implantation.
NORQUEST FE is a combination oral contraceptive containing ethinyl estradiol and norethindrone. Ethinyl estradiol suppresses gonadotropin release, inhibiting ovulation. Norethindrone induces progestational changes in the endometrium, increasing cervical mucus viscosity, and also inhibits ovulation.
One tablet (levonorgestrel 1.5 mg) orally as a single dose within 72 hours of unprotected intercourse.
One tablet orally once daily, each tablet containing 1 mg norethindrone acetate and 20 mcg ethinyl estradiol (21 active tablets) followed by 7 ferrous fumarate tablets.
None Documented
None Documented
The terminal elimination half-life is approximately 24-30 hours. This relatively long half-life supports once-daily dosing and allows for stable plasma concentrations within 5-7 days of continuous use.
Terminal half-life: 6-8 hours. Clinical context: Supports once-daily dosing with sustained therapeutic effect.
Renal excretion of conjugated metabolites accounts for approximately 60-80% of an administered dose; fecal elimination via bile accounts for 20-40%.
Renal: 80% (50% unchanged, 30% as metabolites); Fecal: 19%; Biliary: <1%
Category C
Category C
Oral Contraceptive
Oral Contraceptive