✍ Scribed by Daisuke Kozutsumi; Akihiro Kawashima; Takako Sugimoto; Yumi Kotohda; Shiho Fujimori; Masao Takami; Tetsuya Kohno; Tsutomu Oikawa; Eiichi Sugino; Tominari Choshi; Satoshi Hibino
No coin nor oath required. For personal study only.
Medroxyprogesterone acetate (MPA) is widely used in endocrine therapy for breast cancer and other diseases. Recently, it has been demonstrated that 9alpha-fluoromedroxyprogesterone acetate (FMPA) also has anti-tumour activity in chemical-induced rat mammary tumour and its activity is greater than that of MPA. In the present study, the physico-chemical properties of FMPA and MPA and their pharmacokinetics in female rats were investigated. Partition coefficients (log P) of FMPA and MPA were 3.1 and 3.8, respectively, while the solubilities of FMPA and MPA in phosphate buffer saline were 3.8 and 1.1 microg/mL, respectively. When the two agents were intravenously or orally administered into female rats, there was no significant difference between their plasma concentrations. However, unmetabolized drug excreted into urine accounted for 4.7 and 0.7% of the intravenous dose of FMPA and MPA, respectively. The free fraction of FMPA in rat plasma was approximately four times that of MPA. Assuming the well-stirred model, hepatic intrinsic clearances of FMPA and MPA were estimated to be 64 and 293 L/h per kg, respectively. In addition, the free fraction of FMPA in blood is estimated to be higher than that of MPA, which may explain the higher anti-tumour activity.
📜 SIMILAR VOLUMES
Medroxyprogesterone acetate (MPA) has been administered to rats and dogs. Dogs received single oral doses of 2.5, 5, and lOmg MPA and a single intravenous dose of 1 mg MPA. Rats received single oral doses of 0.2, 1, 5, and 20 mg kg-1 MPA and multiple oral doses (14 daily doses) of 0.2, 5, and 20 mg