Comparative Pharmacology
Head-to-head clinical analysis: CYCLAFEM 1 35 versus LESSINA 28.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLAFEM 1 35 versus LESSINA 28.
CYCLAFEM 1/35 vs LESSINA-28
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 a progestin (levonorgestrel) and an estrogen (ethinyl estradiol). Inhibits ovulation by suppressing gonadotropin release; increases cervical mucus viscosity to impede sperm penetration, and induces endometrial changes that reduce 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 (0.1 mg levonorgestrel and 0.02 mg ethinyl estradiol) orally once daily for 28 days, starting on the first day of menstrual cycle.
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.
Terminal elimination half-life: 18-22 hours; clinically relevant for once-daily dosing.
Renal 40-60% as glucuronide and sulfate conjugates, biliary/fecal 20-40%.
Renal: 30% as unchanged drug and metabolites; biliary/fecal: 70% as metabolites.
Category C
Category C
Oral Contraceptive
Oral Contraceptive