Effects of temperature on the therapeutic efficacy and pharmacokinetics of ifosfamide.

Abstract

The influence of tumor temperature (28, 32, 37, 39, 41, or 43 degrees C for 1 h) on the therapeutic efficacy of i.v. single bolus injections of ifosfamide (IFO) (32, 65, 125, or 250 mg/kg body weight) in human tumor xenografts (MX1 breast carcinoma) grown in nude mice (n = 240) was studied. Tumor temperature was controlled by water bath immersion. Sixty days after treatment the percentage of tumor-free survival was determined. For example, at 37 degrees C IFO in a dose of 65 mg/kg body weight led to 10% tumor-free survival in the treated animals. At 43 degrees C the same dose resulted in 60% tumor-free survival. A clear drug dose- and temperature-dependent increase of the therapeutic efficacy of an active oxazaphosphorine compound was also demonstrated in vitro. The concentrations of IFO and of 4-hydroxyifosfamide in blood and tumors at different body temperatures (controlled by water bath immersion) were determined over 120 min and WBC counts were obtained. The half-lives and the areas under the curve for IFO in blood were not significantly different at 37 degrees C and 41 degrees C. Since the half-life of IFO depends mainly on hepatic metabolism, the similarity of half-lives and of areas under the curve for IFO at 37 degrees C and 41 degrees C indicates a constant activation rate. However, significantly lower plasma concentrations of the activated drug at a liver (body) temperature of 41 degrees C, compared with 37 degrees C, were found, indicating a higher elimination rate. The concentration of the activated drug in the tumors within the initial 60 min at 41 degrees C, however, exceeded by > 2-fold that at 37 degrees C. The bone marrow toxicity of the same drug dose did not significantly increase with body temperature.

• Authors: G J Wiedemann, H J Siemens, M Mentzel, A Biersack, W Wössmann, D Knocks, C Weiss, T Wagner
• Journal: Cancer research (Cancer Res) Vol. 53 Issue 18 Pg. 4268-72 (Sep 15 1993) ISSN: 0008-5472 [Print] United States
• PMID: 8364922 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Ifosfamide

Topics

• Animals
• Body Temperature
• Breast Neoplasms
• Dose-Response Relationship, Drug
• Female
• Humans
• Ifosfamide (pharmacokinetics, therapeutic use, toxicity)
• Mice
• Neoplasm Transplantation
• Neoplasms, Experimental (drug therapy, metabolism)
• Transplantation, Heterologous
• Tumor Cells, Cultured