Comparative Pharmacology
Head-to-head clinical analysis: CYCLAFEM 7 7 7 versus LEVORA 0 15 30 28.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLAFEM 7 7 7 versus LEVORA 0 15 30 28.
CYCLAFEM 7/7/7 vs LEVORA 0.15/30-28
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.
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.
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 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 half-life: 5-13 hours (mean 8 hrs); clinical context: supports every-28-day dosing interval for intramuscular depot.
Ethinyl estradiol: 13-27 hours (terminal); Levonorgestrel: 11-45 hours (terminal, dose-dependent due to SHBG binding).
Renal: ~50-60% as conjugated metabolites; Fecal: ~30-40% via bile; <1% unchanged.
Renal: ~50% (as glucuronide and sulfate conjugates of ethinyl estradiol and levonorgestrel); Fecal: ~50% (enterohepatic recirculation).
Category C
Category C
Oral Contraceptive
Oral Contraceptive