Comparative Pharmacology
Head-to-head clinical analysis: CYCLAFEM 7 7 7 versus LEVONEST.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLAFEM 7 7 7 versus LEVONEST.
CYCLAFEM 7/7/7 vs LEVONEST
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination estrogen-progestin contraceptive. Ethinyl estradiol suppresses gonadotropin release (FSH, LH) via negative feedback on hypothalamic-pituitary axis; norethindrone induces endometrial changes that inhibit implantation and thickens cervical mucus.
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.
One tablet (norethindrone 0.5 mg/ethinyl estradiol 35 mcg) orally once daily for 7 days, then one tablet (norethindrone 0.75 mg/ethinyl estradiol 35 mcg) orally once daily for 7 days, then one tablet (norethindrone 1 mg/ethinyl estradiol 35 mcg) orally once daily for 7 days. Dispensed in a 21-tablet pack with 7 placebo tablets. For contraception, take one tablet daily at same time each day for 28 days; begin next pack after 28-day cycle.
One tablet (levonorgestrel 1.5 mg) orally as a single dose within 72 hours of unprotected intercourse.
None Documented
None Documented
Terminal half-life: 5-13 hours (mean 8 hrs); clinical context: supports every-28-day dosing interval for intramuscular depot.
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.
Renal: ~50-60% as conjugated metabolites; Fecal: ~30-40% via bile; <1% unchanged.
Renal excretion of conjugated metabolites accounts for approximately 60-80% of an administered dose; fecal elimination via bile accounts for 20-40%.
Category C
Category C
Oral Contraceptive
Oral Contraceptive