Comparative Pharmacology
Head-to-head clinical analysis: NORCEPT E 1 35 21 versus NORDETTE 21.
Peer-Reviewed Evidence
Head-to-head clinical analysis: NORCEPT E 1 35 21 versus NORDETTE 21.
NORCEPT-E 1/35 21 vs NORDETTE-21
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive: estrogen (ethinyl estradiol) suppresses gonadotropin secretion, preventing ovulation; progestin (norethindrone) alters cervical mucus, endometrial lining, and inhibits sperm penetration.
Combination oral contraceptive containing ethinyl estradiol and levonorgestrel. Inhibits ovulation by suppressing gonadotropin release, increases viscosity of cervical mucus to prevent sperm penetration, and alters endometrial lining to reduce implantation likelihood.
One tablet (norethindrone 1 mg + ethinyl estradiol 35 mcg) orally once daily for 21 days, followed by 7 days of placebo or no tablets. Repeat cycle continuously.
One tablet (0.15 mg levonorgestrel, 0.03 mg ethinyl estradiol) orally once daily for 21 days, followed by 7 days off.
None Documented
None Documented
Ethinyl estradiol: terminal half-life approximately 17 hours (range 13-27 hours), consistent with once-daily dosing; norethindrone: terminal half-life approximately 7.6 hours (range 5-12 hours), permitting steady-state within 5 days.
Ethinylestradiol: 13 ± 7 hours (terminal), clinically relevant for once-daily dosing; Levonorgestrel: 24 ± 6 hours (terminal), supporting steady-state after ~5 days
Renal: 50-60% as metabolites (primarily ethinyl estradiol glucuronide and norethindrone metabolites); fecal: 20-30% via biliary elimination; unchanged drug: <5%.
Renal: ~50% (as glucuronide and sulfate conjugates); Fecal: ~40% (enterohepatic recirculation); Biliary: <10%
Category C
Category C
Combined Oral Contraceptive
Combined Oral Contraceptive