Stability of diclofenac sodium in the inclusion complex with beta-cyclodextrin in the solid state.

The aim of this study was to characterize the thermal stability of diclofenac sodium both alone and in the inclusion complex with beta-cyclodextrin in the solid state, by determination of the number of the products of its decomposition, which were identified by GC-MS. The molar ratio of diclofenac sodium in the inclusion complex with beta-cyclodextrin was 1:1. The decomposition of diclofenac sodium both alone and in inclusion complex with beta-cyclodextrin occurred according to the first-order reaction. The HPLC of the samples thermostated at 80 degrees C gave five products of decomposition, which were identified by GC-MS. Diclofenac sodium in the inclusion complex with beta-cyclodextrin was more thermally stable. Thermal decomposition of diclofenac sodium leads to formation of five products, of which 4-chloro-10H-9-acridinone had not been reported previously in the literature.