Comparative Pharmacology
Head-to-head clinical analysis: NORINYL 1 80 28 DAY versus NORTREL 1 35 21.
Peer-Reviewed Evidence
Head-to-head clinical analysis: NORINYL 1 80 28 DAY versus NORTREL 1 35 21.
NORINYL 1+80 28-DAY vs NORTREL 1/35-21
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination oral contraceptive containing a progestin (norethindrone) and an estrogen (mestranol). Suppresses gonadotropin (FSH and LH) release via negative feedback, inhibiting ovulation. Also induces changes in cervical mucus and endometrium to impede sperm penetration and implantation.
Combination of ethinyl estradiol (estrogen) and norethindrone (progestin) suppresses gonadotropin (FSH and LH) release from the pituitary, inhibiting ovulation, altering cervical mucus to impede sperm penetration, and inducing endometrial changes that reduce implantation likelihood.
One tablet (1 mg norethindrone / 80 mcg ethinyl estradiol) orally once daily for 28-day cycle without placebo.
One tablet orally once daily for 21 days, followed by 7 days off, then repeat.
None Documented
None Documented
Norethindrone: terminal elimination half-life of 5.3-10.5 hours; Mestranol (as ethinyl estradiol): terminal half-life of 7-20 hours. Clinically, steady state is achieved after 5-7 days of daily dosing; the half-life supports once-daily dosing for consistent hormonal levels.
Norethindrone: 5-14 hours; Ethinyl estradiol: 17-24 hours. Steady-state achieved after 10 days.
Norethindrone is primarily excreted in urine (approximately 60%) and feces (approximately 40%) as glucuronide and sulfate conjugates. Mestranol is metabolized to ethinyl estradiol; ethinyl estradiol and its metabolites are excreted in urine (40%) and feces (60%).
Renal 50-60% as metabolites, fecal 40-50% as conjugates, <1% unchanged
Category C
Category C
Oral Contraceptive
Oral Contraceptive