High-performance liquid chromatographic analysis of indomethacin in serum

A rapid high-performance liquid chromatographic (HPLC) method for quantitative determination of indomethacin in serum is described. The assay was performed after single extraction of indomethacin and itraconazole (internal standard) from serum using diethyl ether and eluted from a 4 micron C-18 reversed-phase column at ambient temperature. The mobile phase consisted of ethanol:water:glacial acetic acid (65:34:1, v/v) pumped isocratically at a flow rate of 1.3 ml/min. The effluent was monitored at 254 nm. Quantification was achieved by the measurement of the peak area ratio, and the absolute recoveries ranged from 94 to 97%. Within-day coefficients of variation (CV) ranged from 2.72 to 5.70% and between-day CV varied from 3.61 to 6.1%. Stability testing indicated that indomethacin is stable for at least 30 days in serum at -20 degrees C. The method was used to study indomethacin pharmacokinetics in rabbits.