AN IMPROVED HPLC PROCEDURE FOR THE QUANTITATION OF DICLOFENAC IN PLASMA

A rapid, simple and sensitive high performance liquid chromatographic (HPLC) assay for the quantitation of diclofenac (DF) in dog plasma has been developed. Mefenamic acid (MA) was used as the internal standard . After acidification, DF and MA were extracted from plasma into chlor oform. Separation was achieved using a C18 reversed phase column. The retention times of DF and MA were 3.8 and 6.3 min., respectively at th e flow rate of 1.5 ml/min. The DF interday standard plots (n=4) were h ighly linear (r>0.99) over the concentration range of 0.01 to 10 mu g/ ml. DF mean recovery was 98% +/- 5.5, and the % CV of intra- and inter -day sample analyses ranged from 2.6 to 10.8% for the entire calibrati on range. The limit of quantification of DF in plasma was 0.01 mu g/ml with the CV of 9.4%. The method was applied for the determination of the pharmacokinetic parameters of DF given by oral and iv bolus admini stration to dogs.