Comparative Pharmacology
Head-to-head clinical analysis: CYCLAFEM 1 35 versus LEVORA 0 15 30 21.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLAFEM 1 35 versus LEVORA 0 15 30 21.
CYCLAFEM 1/35 vs LEVORA 0.15/30-21
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive containing ethinyl estradiol and norethindrone. Suppresses gonadotropin (FSH, LH) secretion via estrogen and progestin negative feedback, inhibiting ovulation. Progestin alters cervical mucus (sperm penetration) and endometrial receptivity.
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 orally once daily. Each tablet contains 1 mg norethindrone and 0.035 mg ethinyl estradiol. Administer daily for 21 days followed by 7 days of placebo or no tablet.
One tablet orally once daily for 21 days, followed by 7 tablet-free days.
None Documented
None Documented
Half-life of norethindrone is 5-14 hours; ethinyl estradiol is 10-20 hours. Steady state reached after 5-7 days.
20-30 hours for ethinyl estradiol; 2-4 hours for levonorgestrel. Steady-state reached in 5-7 days
Renal 40-60% as glucuronide and sulfate conjugates, biliary/fecal 20-40%.
Urine (50-60% as metabolites), feces (30-40% as glucuronides); <10% unchanged
Category C
Category C
Oral Contraceptive
Oral Contraceptive