Comparative Pharmacology
Head-to-head clinical analysis: CYCLAFEM 7 7 7 versus NORTREL 1 35 28.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYCLAFEM 7 7 7 versus NORTREL 1 35 28.
CYCLAFEM 7/7/7 vs NORTREL 1/35-28
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination estrogen-progestin contraceptive. Ethinyl estradiol suppresses gonadotropin release (FSH, LH) via negative feedback on hypothalamic-pituitary axis; norethindrone induces endometrial changes that inhibit implantation and thickens cervical mucus.
Combination of ethinyl estradiol and norethindrone inhibits gonadotropin secretion via negative feedback on the hypothalamic-pituitary-ovarian axis, suppressing ovulation. Additionally, increases cervical mucus viscosity and alters endometrial receptivity.
One tablet (norethindrone 0.5 mg/ethinyl estradiol 35 mcg) orally once daily for 7 days, then one tablet (norethindrone 0.75 mg/ethinyl estradiol 35 mcg) orally once daily for 7 days, then one tablet (norethindrone 1 mg/ethinyl estradiol 35 mcg) orally once daily for 7 days. Dispensed in a 21-tablet pack with 7 placebo tablets. For contraception, take one tablet daily at same time each day for 28 days; begin next pack after 28-day cycle.
One tablet (norethindrone 1 mg + ethinyl estradiol 35 mcg) orally once daily for 28 days, followed by a 7-day placebo period (if using 28-day pack) or continuous if using 21-day pack with 7-day off. Start on first day of menstrual period.
None Documented
None Documented
Terminal half-life: 5-13 hours (mean 8 hrs); clinical context: supports every-28-day dosing interval for intramuscular depot.
Norethindrone: 5-14 hours (terminal); ethinyl estradiol: 13-27 hours (terminal). Context: steady-state after 5-7 days; dose adjustment in hepatic impairment.
Renal: ~50-60% as conjugated metabolites; Fecal: ~30-40% via bile; <1% unchanged.
Renal 60-70% (as glucuronide and sulfate conjugates), fecal 20-30% (via biliary excretion).
Category C
Category C
Oral Contraceptive
Oral Contraceptive