-
Levonorgestrel
- indication:For the treatment of menopausal and postmenopausal disorders and alone or in combination with other hormones as an oral contraceptive.
- pharmacologypharmacology:
- mechanism: Binds to the progesterone and estrogen receptors. Target cells include the female reproductive tract, the mammary gland, the hypothalamus, and the pituitary. Once bound to the receptor, progestins like levonorgestrel will slow the frequency of release of gonadotropin releasing hormone (GnRH) from the hypothalamus and blunt the pre-ovulatory LH (luteinizing hormone) surge.
- toxicity: LD<sub>50</sub>>5000 mg/kg (orally in rats)
- absorprion: Levonorgestrel is not subjected to a "first-pass" effect and is virtually 100% bioavailable.
- halflife:
- roouteelimination: About 45% of levonorgestrel and its metabolites are excreted in the urine and about 32% are excreted in feces, mostly as glucuronide conjugates.
- volumedistribution: * 260 L [Healthy Female Volunteers under Fasting Conditions] * 1.8 L/kg
- clearance: * 7.7 +/- 2.7 L/h [Healthy Female Volunteers under Fasting Conditions]