Comparative Pharmacology
Head-to-head clinical analysis: CYCLAFEM 1 35 versus TRI LO ESTARYLLA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLAFEM 1 35 versus TRI LO ESTARYLLA.
CYCLAFEM 1/35 vs TRI-LO-ESTARYLLA
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 containing ethinyl estradiol and norgestimate. Suppresses gonadotropin secretion, primarily FSH and LH, inhibiting ovulation; increases cervical mucus viscosity, impeding sperm penetration; alters endometrial lining, reducing implantation likelihood.
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 (20 mcg ethinyl estradiol/0.1 mg levonorgestrel) orally once daily for 21 days, followed by 7 days of placebo.
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.
Ethinyl estradiol: 19-24 hours (terminal); Norgestimate: active metabolite norelgestromin 28-38 hours; allows once-daily dosing.
Renal 40-60% as glucuronide and sulfate conjugates, biliary/fecal 20-40%.
Renal: ~40% as metabolites; Fecal: ~30% as metabolites (including ethinyl estradiol conjugates); Biliary: ~20% (enterohepatic recirculation).
Category C
Category C
Oral Contraceptive
Oral Contraceptive