Quantitative determination of 21-hydroxy-deflazacort in human plasma using gradient semi-microbore liquid chromatography.
A sensitive and selective liquid chromatographic procedure to quantitate the deflazacort metabolite 21-hydroxy-deflazacort (DF-21OH) in human plasma was developed and validated. DF-21OH and fludrocortisone acetate (internal standard, IS) were isolated from human plasma (2 mL) by solid-phase extraction onto C-18 cartridges. Potential interferences were selectively removed and analytes were eluted with ethyl acetate. Following evaporation, the residue was reconstituted for HPLC analysis. Separation was achieved by gradient elution using a 5 microns YMC Basic column (2.0 x 100 mm) with mobile phases consisting of 20% methanol and 50% acetonitrile in 50 mM phosphate buffer (pH 3) at a temperature of 50 degrees C. Flow rate was maintained at 0.3 mL/min., and analytes were quantified spectrophotometrically at 246 nm. The assay was validated over the range 1.0 to 500 ng/mL DF-21OH. Calibration curves were prepared using a weighted (1/concentration) nonlinear quadratic regression algorithm. Peak-height ratios were proportional to the amount of DF-21OH added to plasma. Assay precision (%RSD) ranged from 4.2 to 11%, with a corresponding assay accuracy (% relative error) of +/- 2.8%. Absolute recovery of DF-21OH from plasma was 78-86% over the concentration range. The minimum quantitation limit was 1.0 ng/mL.
A LC-MS/MS METHOD FOR THE QUANTIFICATION OF DEFLAZACORT METABOLITE IN HUMAN PLASMA: DEVELOPMENT, VALIDATION AND APPLICATION TO A PHARMACOKINETIC STUDY
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.
A simple access to N-(un)substituted isoquinolin-1(2H)-ones: unusual formation of regioisomeric isoquinolin-1(4H)-ones.
A ligand/additive/Pd-free Cu-mediated coupling/cyclization strategy afforded the first practical, one-pot and general approach towards synthesis of N-(un)substituted isoquinolin-1(2H)-ones. Both the catalyst and the solvent used are recyclable. The use of the Cu reagent in excess led to the unusual formation of regioisomeric and uncommon isoquinolin-1(4H)-ones.