EXAFS characterization of oxaliplatin anticancer drug and its degradation in chloride media.

Oxaliplatin is a second-generation platinum-based anticancer drug. Its degradation is studied in solution, in the presence of chloride ions (in neutral or acidic media) in excess. In both cases the degradation product precipitates immediately. The EXAFS spectra of these products show that they are identical. EXAFS modeling and refinement of the first coordination sphere shows that two light atoms are replaced by two chloride ions. The complete refinement of the local structure is possible by studying the multiple-scattering signal. The results show that the main multiple-scattering contribution is due to the binding oxalato group and that the degradation product is [Cl2-(diaminocyclohexane)-Pt(II)].