Comparative Pharmacology
Head-to-head clinical analysis: LEVONORGESTREL versus PROMETRIUM.
Peer-Reviewed Evidence
Head-to-head clinical analysis: LEVONORGESTREL versus PROMETRIUM.
LEVONORGESTREL vs PROMETRIUM
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.
Progesterone binds to progesterone receptors in target tissues, promoting endometrial maturation, reducing uterine contractility, and suppressing ovulation.
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: 200 mg once daily at bedtime for 12 consecutive days per 28-day cycle in combination with conjugated estrogens 0.625 mg daily. For secondary amenorrhea: 400 mg once daily at bedtime for 10 days. Intravaginal: 4% gel (90 mg) or 8% gel (180 mg) applied every other day for 6 doses in postmenopausal women with intact uterus on estrogen therapy.
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 half-life: Approximately 16-18 hours for oral micronized progesterone (Prometrium); permits twice-daily dosing for luteal phase support.
Renal: 45-60% (metabolites), Fecal: 32-45% (unchanged and metabolites). Biliary excretion contributes to fecal elimination.
Urine (50-60% as metabolites, <1% unchanged); feces (20-30% as metabolites); minor biliary elimination.
Category C
Category C
Progestin
Progestin
"The metabolism of Fluconazole can be decreased when combined with Levonorgestrel."