Simultaneous analysis of dextran-methylprednisolone succinate, methylprednisolone succinate, and methylprednisolone by size-exclusion chromatography

An analytical HPLC method is reported for simultaneous measurement of low ( 1.0-100 mu g ml-') concentrations of dextran-methylprednisolone succinate ( DEX-MPS) and its degradation products methylprednisolone hemisuccinate (MPS ) and methylprednisolone (MP). The analytes were detected at 250 nm after r esolution using a size exclusion column with a mobile phase of KH2PO4 (10 m M): acetonitrile (3:1) and a flow rate of 1 mi min(-1). The resolution of M P and MPS peaks was substantially affected by the pH of the mobile phase; w hile MP and MPS co-eluted at pH 3.4, they were baseline-resolved at pH grea ter than or equal to 5. Linear relationships (r greater than or equal to 0. 997) were found between the detector response and the concentrations of the analytes (1.0-100 mu g ml(-1) for MP and MPS and 2.5-100 mu g ml(-1) for D EX-MPS). Intra- and inter-run error (< 13%) and precision (CV of less than or equal to 6%) data indicated that the assay could accurately and precisel y quantitate all three components in the examined concentration range. The application of the assay to determination of degree of substitution, purity , and stability of DEX-MPS was also demonstrated. (C) 1999 Elsevier Science B.V. All rights reserved.