Comparative Pharmacology
Head-to-head clinical analysis: CYCLAFEM 0 5 35 versus ENOVID E.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLAFEM 0 5 35 versus ENOVID E.
CYCLAFEM 0.5/35 vs ENOVID-E
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive containing norethindrone (progestin) and ethinyl estradiol (estrogen). Inhibits gonadotropin release, suppressing ovulation. Increases cervical mucus viscosity and alters endometrium, reducing sperm penetration and implantation.
Combination estrogen-progestin contraceptive. Suppresses gonadotropin release, inhibits ovulation, increases cervical mucus viscosity, and alters endometrial morphology.
One tablet (0.5 mg norethindrone/35 mcg ethinyl estradiol) orally once daily for 21 days, followed by 7 placebo days (or no tablets) per cycle.
5 mg orally once daily for 20 days starting on day 5 of menstrual cycle
None Documented
None Documented
Terminal elimination half-life of norethindrone is 5-14 hours (mean 7.6 hours); ethinyl estradiol half-life is 7-20 hours (mean ~13 hours). Steady-state is achieved within 5-7 days.
Norethynodrel: 5-10 hours; mestranol: 2-5 hours (metabolized to ethinyl estradiol, half-life 10-20 hours). Steady-state reached in 5-7 days.
Renal excretion accounts for approximately 50-60% of the dose (as metabolites), with 30-40% excreted in feces via biliary elimination. Unchanged drug is minimal in urine.
Renal (50-60% as metabolites, <1% unchanged); fecal (40-50%)
Category C
Category C
Oral Contraceptive
Oral Contraceptive