Comparative Pharmacology
Head-to-head clinical analysis: MICROGESTIN FE 1 20 versus NORLESTRIN 21 2 5 50.
Peer-Reviewed Evidence
Head-to-head clinical analysis: MICROGESTIN FE 1 20 versus NORLESTRIN 21 2 5 50.
MICROGESTIN FE 1/20 vs NORLESTRIN 21 2.5/50
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive containing ethinyl estradiol (estrogen) and norethindrone acetate (progestin). Suppresses gonadotropins via negative feedback on hypothalamic-pituitary axis, inhibiting ovulation; increases cervical mucus viscosity and alters endometrial lining.
Combination oral contraceptive containing an estrogen (ethinyl estradiol) and a progestin (norethindrone acetate). Inhibits ovulation by suppressing gonadotropin release. Increases viscosity of cervical mucus, impeding sperm penetration, and alters endometrial receptivity.
One tablet orally once daily, containing norethindrone acetate 1 mg and ethinyl estradiol 20 mcg, taken at the same time each day for 21 days followed by 7 days of placebo (iron tablets) or continuous cycling per prescribing information.
One tablet orally once daily for 21 days, followed by 7 days off, then repeat.
None Documented
None Documented
Norethindrone: 5-14 hours (mean 8 hours); Ethinyl estradiol: 12-24 hours (mean 18 hours); Steady-state in 5-7 days
Norethindrone: 8 hours (terminal); Ethinyl estradiol: 13 hours (terminal). Clinical context: Steady-state achieved after 3-5 days; dosing interval based on once-daily administration.
Renal: ~50-60% as metabolites; Fecal: ~30-40% as metabolites; Biliary: minor; <1% unchanged
Renal: 50-60% as metabolites (glucuronide and sulfate conjugates of norethindrone and ethinyl estradiol); fecal: 30-40% via biliary elimination; <1% unchanged.
Category C
Category C
Oral Contraceptive
Oral Contraceptive