Comparative Pharmacology
Head-to-head clinical analysis: LEVONEST versus LEVORA 0 15 30 21.
Peer-Reviewed Evidence
Head-to-head clinical analysis: LEVONEST versus LEVORA 0 15 30 21.
LEVONEST vs LEVORA 0.15/30-21
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.
Combination oral contraceptive: ethinyl estradiol suppresses gonadotropin release via negative feedback on hypothalamic-pituitary axis; levonorgestrel inhibits ovulation and thickens cervical mucus, impairing sperm penetration. Also induces endometrial atrophy.
One tablet (levonorgestrel 1.5 mg) orally as a single dose within 72 hours of unprotected intercourse.
One tablet orally once daily for 21 days, followed by 7 tablet-free days.
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.
20-30 hours for ethinyl estradiol; 2-4 hours for levonorgestrel. Steady-state reached in 5-7 days
Renal excretion of conjugated metabolites accounts for approximately 60-80% of an administered dose; fecal elimination via bile accounts for 20-40%.
Urine (50-60% as metabolites), feces (30-40% as glucuronides); <10% unchanged
Category C
Category C
Oral Contraceptive
Oral Contraceptive