Comparative Pharmacology
Head-to-head clinical analysis: NORTREL 7 7 7 versus TRI NORINYL 28 DAY.
Peer-Reviewed Evidence
Head-to-head clinical analysis: NORTREL 7 7 7 versus TRI NORINYL 28 DAY.
NORTREL 7/7/7 vs TRI-NORINYL 28-DAY
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination estrogen-progestin oral contraceptive. Suppresses gonadotropin release, inhibiting ovulation. Increases cervical mucus viscosity and alters endometrial receptivity.
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 orally once daily, taken at the same time each day. Each tablet contains norethindrone 0.5 mg/ethinyl estradiol 35 mcg for days 1-7, norethindrone 0.75 mg/ethinyl estradiol 35 mcg for days 8-14, and norethindrone 1 mg/ethinyl estradiol 35 mcg for days 15-21, followed by 7 placebo tablets.
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
Norelgestromin terminal half-life is approximately 28 hours; ethinyl estradiol terminal half-life is approximately 17 hours. The extended half-life supports once-weekly dosing.
Ethinyl estradiol: 17 ± 6 hours (terminal); Norethindrone: 10 ± 3 hours (terminal). Steady-state achieved after 7-14 days.
Renal excretion of metabolites (primarily ethinyl estradiol and norelgestromin conjugates) accounts for approximately 50% of elimination; fecal/biliary excretion accounts for the remainder (about 35-40% fecal, 10-15% biliary).
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