High-performance size-exclusion chromatographic analysis of dextran-methylprednisolone hemisuccinate in rat plasma

A size exclusion chromatographic method is presented for the measurement of the concentrations of a macromolecular prodrug of methylprednisolone (MP), dextran-methylprednisolone succinate (DEX-MPS), in rat plasma. After preci pitation of the plasma (100 mu l) proteins with perchloric acid, the sample s are injected into a size exclusion column with a mobile phase of water:ac etonitrile:glacial acetic acid (75:25:0.2) and a flow-rate of 1 ml/min. The DEX-MPS conjugate, detected at 250 nm, elutes at a retention time of simil ar to 6.5 min, free of endogenous peaks. Excellent linear relationships (r( 2)=0.997) were found between the detector response and the concentrations o f DEX-MPS in the range of 2-100 mu g/ml (MP equivalent), with intra- and in ter-run C.V.s of <6% and error values of <5%. The application of the assay was also demonstrated by measurement of the plasma concentrations of DEX-MP S after single 5 or 10 mg/kg doses of the conjugate administered intravenou sly to rats. (C) 2000 Elsevier Science B.V. All rights reserved.