Comparative Pharmacology
Head-to-head clinical analysis: LEVONORGESTREL versus NORETHINDRONE ACETATE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: LEVONORGESTREL versus NORETHINDRONE ACETATE.
LEVONORGESTREL vs NORETHINDRONE ACETATE
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.
Progestin that suppresses gonadotropin secretion, inhibits ovulation, and induces endometrial thinning. Also binds to progesterone receptors, exerting antiestrogenic effects.
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.
Oral, 5 mg once daily for 14 days per cycle, beginning on day 1 of menstrual cycle; for endometriosis, 5 mg daily for 14 days then 10 mg daily for 14 days, then 15 mg daily, or as tolerated up to 15 mg daily continuous.
None Documented
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
Terminal half-life: 24-30 hours (range 11-45 hours). This prolonged half-life supports once-daily or extended-cycle dosing in contraceptive formulations.
Terminal elimination half-life is approximately 5-8 hours (mean 7.5 hours). Clinically, steady-state is achieved within 2-3 days of daily dosing.
Renal: 45-60% (metabolites), Fecal: 32-45% (unchanged and metabolites). Biliary excretion contributes to fecal elimination.
Renal (39-61% as metabolites), biliary/fecal (35-49% as metabolites). Less than 1% excreted unchanged.
Category C
Category D/X
Progestin
Progestin
"The metabolism of Fluconazole can be decreased when combined with Levonorgestrel."