Comparative Pharmacology
Head-to-head clinical analysis: LO LARIN FE versus NORTREL 1 35 21.
Peer-Reviewed Evidence
Head-to-head clinical analysis: LO LARIN FE versus NORTREL 1 35 21.
LO LARIN FE vs NORTREL 1/35-21
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Combination of ethinyl estradiol (estrogen) and norethindrone (progestin) inhibits gonadotropin release, preventing ovulation; increases cervical mucus viscosity, impeding sperm penetration; alters endometrial lining, reducing implantation likelihood.
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 orally once daily for 28 consecutive days. Each tablet contains norethindrone acetate 1 mg and ethinyl estradiol 20 mcg. Active tablets (21 days) followed by ferrous fumarate 75 mg inert tablets (7 days).
One tablet orally once daily for 21 days, followed by 7 days off, then repeat.
None Documented
None Documented
Ethinyl estradiol: ~13-17 hours; norethindrone: ~8-12 hours; steady-state achieved within 5-7 days; clinical significance: missed doses may require backup contraception.
Norethindrone: 5-14 hours; Ethinyl estradiol: 17-24 hours. Steady-state achieved after 10 days.
Renal: 30-50% as ethinyl estradiol metabolites and norethindrone metabolites; fecal: 30-50% primarily as norethindrone metabolites; biliary excretion contributes to enterohepatic circulation.
Renal 50-60% as metabolites, fecal 40-50% as conjugates, <1% unchanged
Category C
Category C
Oral Contraceptive
Oral Contraceptive