Comparative Pharmacology
Head-to-head clinical analysis: NORCEPT E 1 35 28 versus NORINYL 1 50 21 DAY.
Peer-Reviewed Evidence
Head-to-head clinical analysis: NORCEPT E 1 35 28 versus NORINYL 1 50 21 DAY.
NORCEPT-E 1/35 28 vs NORINYL 1+50 21-DAY
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination estrogen (ethinyl estradiol) and progestin (norethindrone) contraceptive: suppresses gonadotropin release, inhibits ovulation, thickens cervical mucus, and alters endometrial lining.
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.
1 tablet orally once daily for 21 days, followed by 7 days of placebo tablets.
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: 5-14 hours; ethinyl estradiol: 13-27 hours. The terminal half-life of norethindrone is about 10 hours, allowing once-daily dosing; ethinyl estradiol's longer half-life contributes to steady-state concentrations within 3-5 days.
Norethindrone: 5-8 hours; Ethinyl estradiol: 7-15 hours; steady-state reached within 5-7 days
Renal (primarily as metabolites) and fecal; approximately 50-60% excreted in urine, 30-40% in feces. Ethinyl estradiol and norethindrone are extensively metabolized via hydroxylation and conjugation; glucuronide and sulfate conjugates are eliminated in urine and bile.
Renal (40% as metabolites), fecal (50% as metabolites), <1% unchanged
Category C
Category C
Combined Oral Contraceptive
Combined Oral Contraceptive