Comparative Pharmacology
Head-to-head clinical analysis: LOESTRIN FE 1 20 versus NORINYL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: LOESTRIN FE 1 20 versus NORINYL.
LOESTRIN FE 1/20 vs NORINYL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive consisting of ethinyl estradiol and norethindrone acetate. Inhibits gonadotropin secretion (FSH, LH) via negative feedback on the hypothalamic-pituitary-ovarian axis, suppressing ovulation. Increases cervical mucus viscosity and alters endometrial structure, impeding sperm penetration and implantation.
Combination of norethindrone (progestin) and ethinyl estradiol (estrogen) provides contraception by inhibiting gonadotropin secretion via negative feedback on the hypothalamic-pituitary-ovarian axis, suppressing ovulation, increasing cervical mucus viscosity, and altering endometrial receptivity.
One tablet (norethindrone acetate 1 mg and ethinyl estradiol 20 mcg) orally once daily for 21 consecutive days, followed by one ferrous fumarate tablet (75 mg) orally once daily for 7 days.
One tablet (norethindrone 1 mg/ethinyl estradiol 0.035 mg) orally once daily for 21 days, followed by 7 placebo tablets. For first cycle, start on first Sunday after menstruation begins or on day 1 of menstrual cycle.
None Documented
None Documented
Norethindrone: 6-9 hours (terminal). Ethinyl estradiol: 13-27 hours (terminal, mean 16 hours). Steady-state reached within 5-7 days.
Terminal half-life: norethindrone 7-8 hours, ethinyl estradiol 13-27 hours; clinical context: steady-state achieved in 3-5 half-lives
Norethindrone: 50-60% renal (as metabolites), 20-30% fecal. Ethinyl estradiol: 40-50% renal (as glucuronide conjugates), 30-40% fecal (as sulfate conjugates).
Renal: ~60% as metabolites, biliary/fecal: ~40% as glucuronide conjugates
Category C
Category C
Combined Oral Contraceptive
Combined Oral Contraceptive