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Pharmacokinetics of 9α‐fluoromedroxyprogesterone acetate in rats: comparison with medroxyprogesterone acetate
Author(s) -
Kozutsumi Daisuke,
Kawashima Akihiro,
Sugimoto Takako,
Kotohda Yumi,
Fujimori Shiho,
Takami Masao,
Kohno Tetsuya,
Oikawa Tsutomu,
Sugino Eiichi,
Choshi Tominari,
Hibino Satoshi
Publication year - 1999
Publication title -
biopharmaceutics and drug disposition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.419
H-Index - 58
eISSN - 1099-081X
pISSN - 0142-2782
DOI - 10.1002/(sici)1099-081x(199909)20:6<277::aid-bdd186>3.0.co;2-t
Subject(s) - medroxyprogesterone acetate , pharmacokinetics , chemistry , medroxyprogesterone , saline , urine , chromatography , free fraction , pharmacology , phosphate buffered saline , endocrinology , medicine , biochemistry , hormone
Medroxyprogesterone acetate (MPA) is widely used in endocrine therapy for breast cancer and other diseases. Recently, it has been demonstrated that 9α‐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 μg/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. Copyright © 1999 John Wiley & Sons, Ltd.