Comparative Pharmacology
Head-to-head clinical analysis: CYCLAFEM 1 35 versus TRI LEGEST FE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLAFEM 1 35 versus TRI LEGEST FE.
CYCLAFEM 1/35 vs TRI-LEGEST FE
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.
Tri-Legest FE is a combination oral contraceptive containing ethinyl estradiol and norethindrone acetate. It prevents ovulation by inhibiting gonadotropin release (FSH and LH) and alters cervical mucus and endometrial lining to impede sperm penetration and implantation.
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 28-day cycle: 21 days active tablets (norethindrone/ethinyl estradiol) followed by 7 days placebo. For contraception only.
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: 7-8 hours; Ethinyl estradiol: 18 hours (terminal). Steady-state reached after 7 days; clinical contraceptive efficacy requires consistent dosing.
Renal 40-60% as glucuronide and sulfate conjugates, biliary/fecal 20-40%.
Renal: ~60% (metabolites), Fecal: ~30% (metabolites), Biliary: minor (~5% as conjugates)
Category C
Category C
Oral Contraceptive
Oral Contraceptive