Comparative Pharmacology
Head-to-head clinical analysis: TRI NORINYL 21 DAY versus TRI NORINYL 28 DAY.
Peer-Reviewed Evidence
Head-to-head clinical analysis: TRI NORINYL 21 DAY versus TRI NORINYL 28 DAY.
TRI-NORINYL 21-DAY vs TRI-NORINYL 28-DAY
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive containing ethinyl estradiol and norethindrone. Ethinyl estradiol suppresses gonadotropin release via negative feedback on hypothalamic-pituitary axis; norethindrone induces progestational effects, increases viscosity of cervical mucus, alters endometrial morphology, and inhibits ovulation.
Combination oral contraceptive containing ethinyl estradiol and norethindrone. Suppresses gonadotropin (FSH and LH) release via negative feedback, inhibiting ovulation. Also increases viscosity of cervical mucus and alters endometrial lining to reduce implantation likelihood.
One tablet (35 mcg ethinyl estradiol, 0.5 mg norethindrone for 7 days, 1 mg norethindrone for 9 days, 0.5 mg norethindrone for 5 days) orally once daily for 21 days, then 7 days off. Start on first day of menstrual period or first Sunday after onset.
One tablet orally once daily for 21 days, followed by one placebo tablet orally once daily for 7 days. Each active tablet contains 0.035 mg ethinyl estradiol and 0.5 mg norethindrone (7 days), 0.035 mg ethinyl estradiol and 1.0 mg norethindrone (9 days), and 0.035 mg ethinyl estradiol and 0.5 mg norethindrone (5 days).
None Documented
None Documented
Norethindrone: 5-14 hours; Ethinyl estradiol: 17-23 hours. Steady-state reached within 5-7 days; clinical relevance for missed dose timing and resumption of ovulation.
Ethinyl estradiol: 17 ± 6 hours (terminal); Norethindrone: 10 ± 3 hours (terminal). Steady-state achieved after 7-14 days.
Renal: ~50-60% (as metabolites); Fecal: ~30-40% (via bile); unchanged drug <1%.
Renal: 40% as metabolites; Fecal: 50% as metabolites; Biliary: minor; unchanged ethinyl estradiol excreted in urine <5%, norethindrone <1%.
Category C
Category C
Oral Contraceptive
Oral Contraceptive