Comparative Pharmacology
Head-to-head clinical analysis: LEVONORGESTREL versus NORETHINDRONE ACETATE AND ETHINYL ESTRADIOL AND ETHINYL ESTRADIOL AND FERROUS FUMARATE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: LEVONORGESTREL versus NORETHINDRONE ACETATE AND ETHINYL ESTRADIOL AND ETHINYL ESTRADIOL AND FERROUS FUMARATE.
LEVONORGESTREL vs NORETHINDRONE ACETATE AND ETHINYL ESTRADIOL AND ETHINYL ESTRADIOL AND FERROUS FUMARATE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Synthetic progestin that suppresses gonadotropin release (GnRH, LH, FSH) via negative feedback on the hypothalamic-pituitary-ovarian axis; inhibits ovulation, thickens cervical mucus, and alters endometrial lining.
Combination of norethindrone acetate (progestin) and ethinyl estradiol (estrogen) suppresses gonadotropin (FSH and LH) release from the pituitary, inhibiting ovulation, thickening cervical mucus to impede sperm penetration, and altering endometrial lining to reduce implantation. Ethinyl estradiol (in 7-day extended regimen) maintains hormone levels. Ferrous fumarate provides iron supplementation.
For emergency contraception: 1.5 mg orally as a single dose or 0.75 mg orally 12 hours apart. For hormonal contraception: 0.03 mg to 0.05 mg orally once daily in combined oral contraceptives; for progestin-only oral contraceptive (mini-pill): 0.03 mg orally once daily. For intrauterine system (IUD): 52 mg intrauterine device inserted for up to 5 years.
One tablet (containing norethindrone acetate 1 mg, ethinyl estradiol 20 mcg, and ferrous fumarate 75 mg) orally once daily for 28-day cycle (21 active pills, 7 placebo with ferrous fumarate).
None Documented
Clinical Note
moderateLevonorgestrel + Sulfisoxazole
"The metabolism of Sulfisoxazole can be decreased when combined with Levonorgestrel."
Clinical Note
moderateLevonorgestrel + Erythromycin
"The metabolism of Erythromycin can be decreased when combined with Levonorgestrel."
Clinical Note
moderateLevonorgestrel + Cyclosporine
"The metabolism of Cyclosporine can be decreased when combined with Levonorgestrel."
Clinical Note
moderateLevonorgestrel + Fluconazole
None Documented
Terminal half-life: 24-30 hours (range 11-45 hours). This prolonged half-life supports once-daily or extended-cycle dosing in contraceptive formulations.
Norethindrone: Terminal half-life approximately 8–11 hours. Ethinyl estradiol: Terminal half-life approximately 13–27 hours (mean 17 hours). Clinical context: Steady state reached after 5–7 days.
Renal: 45-60% (metabolites), Fecal: 32-45% (unchanged and metabolites). Biliary excretion contributes to fecal elimination.
Norethindrone acetate: Urine (39% as metabolites, 1% unchanged); Feces (35% as metabolites). Ethinyl estradiol: Urine (40% as glucuronide conjugates, <1% unchanged); Feces (40% as metabolites). Ferrous fumarate: Iron absorbed and utilized; unabsorbed iron excreted in feces.
Category C
Category D/X
Progestin
Progestin
"The metabolism of Fluconazole can be decreased when combined with Levonorgestrel."