Comparative Pharmacology
Head-to-head clinical analysis: CYCLAFEM 1 35 versus NORLESTRIN FE 1 50.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLAFEM 1 35 versus NORLESTRIN FE 1 50.
CYCLAFEM 1/35 vs NORLESTRIN FE 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 of ethinyl estradiol and norethindrone acetate provides negative feedback on gonadotropin release, suppressing ovulation. Also causes cervical mucus thickening and endometrial thinning.
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 (norethindrone 1 mg and ethinyl estradiol 50 mcg plus ferrous fumarate 75 mg) orally once daily for 28 days, with 21 active tablets and 7 placebo tablets.
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: 5-12 hours (mean 8 hours). Ethinyl estradiol: 11-16 hours. Clinical context: Steady state reached in 5-7 days.
Renal 40-60% as glucuronide and sulfate conjugates, biliary/fecal 20-40%.
Norethindrone: 20% renal, 80% fecal. Ethinyl estradiol: 40% renal, 60% fecal.
Category C
Category C
Oral Contraceptive
Oral Contraceptive