A LC-MS/MS METHOD FOR THE QUANTIFICATION OF DEFLAZACORT METABOLITE IN HUMAN PLASMA: DEVELOPMENT, VALIDATION AND APPLICATION TO A PHARMACOKINETIC STUDY

Abstract

Deflazacort is a methyl-oxazoline derivative of prednisolone used for its anti-inflammatory and immunosuppressive effects. It is an inactive prodrug which is converted rapidly to its active metabolite 21- desacetyl deflazacort. A simple, rapid, sensitive and specific liquid chromatography-tandem mass spectrometry method was developed for the estimation of 21-desacetyl deflazacort in human plasma. Sample preparation involved simple solid phase extraction of 21-desacetyl deflazacort and internal standard. The samples were analyzed using a reversed phase column and detected using positive mode ESI tandem mass spectrometry. The LLOQ was 0.5 ng/mL and the assay was linear over the range of 0.5-100 ng/mL using a sample volume of 250µL. The method was validated for specificity, linearity, precision, accuracy and stability parameters. The method was applied to the analysis of plasma samples after oral administration of 6 mg DFZ tablets of marketed product in healthy adult subjects in a fasting bioavailability study.