Comparative Pharmacology
Head-to-head clinical analysis: NORTREL 1 35 21 versus TRI LO ESTARYLLA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: NORTREL 1 35 21 versus TRI LO ESTARYLLA.
NORTREL 1/35-21 vs TRI-LO-ESTARYLLA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
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.
Combination oral contraceptive containing ethinyl estradiol and norgestimate. Suppresses gonadotropin secretion, primarily FSH and LH, inhibiting ovulation; increases cervical mucus viscosity, impeding sperm penetration; alters endometrial lining, reducing implantation likelihood.
One tablet orally once daily for 21 days, followed by 7 days off, then repeat.
One tablet (20 mcg ethinyl estradiol/0.1 mg levonorgestrel) orally once daily for 21 days, followed by 7 days of placebo.
None Documented
None Documented
Norethindrone: 5-14 hours; Ethinyl estradiol: 17-24 hours. Steady-state achieved after 10 days.
Ethinyl estradiol: 19-24 hours (terminal); Norgestimate: active metabolite norelgestromin 28-38 hours; allows once-daily dosing.
Renal 50-60% as metabolites, fecal 40-50% as conjugates, <1% unchanged
Renal: ~40% as metabolites; Fecal: ~30% as metabolites (including ethinyl estradiol conjugates); Biliary: ~20% (enterohepatic recirculation).
Category C
Category C
Oral Contraceptive
Oral Contraceptive