Comparative Pharmacology
Head-to-head clinical analysis: CYCLAFEM 1 35 versus NORLESTRIN 28 1 50.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLAFEM 1 35 versus NORLESTRIN 28 1 50.
CYCLAFEM 1/35 vs NORLESTRIN 28 1/50
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 estrogen-progestin oral contraceptive; suppresses gonadotropin release via negative feedback on pituitary, inhibits ovulation, thickens cervical mucus, alters endometrial receptivity.
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, each containing norethindrone 1 mg and ethinyl estradiol 50 mcg.
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.
Norethindrone: 8 hours; ethinyl estradiol: 12-15 hours; steady state achieved within 5-10 days.
Renal 40-60% as glucuronide and sulfate conjugates, biliary/fecal 20-40%.
Norethindrone: 40% renal, 60% fecal; ethinyl estradiol: 40% renal, 60% fecal.
Category C
Category C
Oral Contraceptive
Oral Contraceptive