Comparative Pharmacology
Head-to-head clinical analysis: FEMCON FE versus NORTREL 1 35 21.
Peer-Reviewed Evidence
Head-to-head clinical analysis: FEMCON FE versus NORTREL 1 35 21.
FEMCON FE vs NORTREL 1/35-21
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive containing norethindrone and ethinyl estradiol. Inhibits ovulation via suppression of gonadotropins (FSH, LH); increases cervical mucus viscosity, impairing sperm penetration; alters endometrial receptivity.
Combination of ethinyl estradiol (estrogen) and norethindrone (progestin) suppresses gonadotropin (FSH and LH) release from the pituitary, inhibiting ovulation, altering cervical mucus to impede sperm penetration, and inducing endometrial changes that reduce implantation likelihood.
One tablet (norethindrone 0.5 mg + ethinyl estradiol 35 mcg) orally once daily for 28 days.
One tablet orally once daily for 21 days, followed by 7 days off, then repeat.
None Documented
None Documented
The terminal elimination half-life of ethinyl estradiol is 13-18 hours; for norethindrone, it is 7-12 hours. Both allow once-daily dosing for contraceptive efficacy.
Norethindrone: 5-14 hours; Ethinyl estradiol: 17-24 hours. Steady-state achieved after 10 days.
Renal excretion accounts for approximately 40-60% of the dose as metabolites; fecal excretion is about 20-30% via bile. Unchanged drug excretion is minimal.
Renal 50-60% as metabolites, fecal 40-50% as conjugates, <1% unchanged
Category C
Category C
Oral Contraceptive
Oral Contraceptive