Comparative Pharmacology
Head-to-head clinical analysis: NORINYL 1 35 21 DAY versus NORINYL 1 50 21 DAY.
Peer-Reviewed Evidence
Head-to-head clinical analysis: NORINYL 1 35 21 DAY versus NORINYL 1 50 21 DAY.
NORINYL 1+35 21-DAY vs NORINYL 1+50 21-DAY
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive containing norethindrone (progestin) and ethinyl estradiol (estrogen). Suppresses gonadotropin release (FSH, LH) via negative feedback on hypothalamic-pituitary-ovarian axis, inhibiting ovulation. Increases cervical mucus viscosity and alters endometrial structure to impair sperm penetration and implantation.
Norinyl 1+50 21-Day contains norethindrone (a progestin) and mestranol (an estrogen). Mestranol is converted to ethinyl estradiol, which provides negative feedback on gonadotropin release, inhibiting ovulation. Norethindrone suppresses gonadotropins and alters cervical mucus and endometrial lining to prevent implantation.
One tablet orally once daily for 21 consecutive days, followed by 7 days off therapy.
One tablet (1 mg norethindrone + 0.05 mg mestranol) orally once daily for 21 days, followed by 7 placebo tablets. Start on day 1 of menstrual cycle or first Sunday after onset.
None Documented
None Documented
Norethindrone: 7-8 hours; Ethinyl estradiol: 13-27 hours (mean ~17 hours). Steady state achieved by day 10-14.
Norethindrone: 5-8 hours; Ethinyl estradiol: 7-15 hours; steady-state reached within 5-7 days
Renal (50-60% as metabolites, primarily glucuronide and sulfate conjugates) and fecal (30-40% as metabolites). Less than 1% excreted unchanged.
Renal (40% as metabolites), fecal (50% as metabolites), <1% unchanged
Category C
Category C
Combined Oral Contraceptive
Combined Oral Contraceptive