Stability studies of 14C-Cytostasan solutions and its extraction using dicarbolide of cobalt

In this study the stability of 14C-Cytostasan (1, bendamustine), in water solutions was investigated. In distilled water a rapid degradation of carrier-free 14C-1 occurred. The degradation products of 14C-1 are 14C-monohydroxy-1 and 14C-dihydroxy-1 (evidence with the TLC). The degradation rate of 14C-1 was reduced by addition of nonlabelled 1 to the 14C-1 stock solution. The possibility of using distribution coefficient as a stability indicator of 14C-1 solutions was investigated. A number of organic solvents ranging from polar to nonpolar were used for extraction of 14C-1 from water solution. Only ethyl acetate was slightly effective. The distribution coefficient of 14C-1 was dramatically enhanced in presence of dicarbolide of cobalt (DC-H+) in benzene at extraction from HClO4 (0.5 mol.l-1).