Determination of indomethacin in serum by an extractive alkylation technique and gas-liquid chromatography

A method for determining indomethacin in serum has been developed, involving extractive alkylation, in which indomethacin is converted into its ethyl ester, and subsequent gas chromatographic determination of the ester. The method is specific and permits the determination of amounts down to 50 ng/ml in serum. The indomethacin concentration in serum was followed for 24 h after oral and rectal application and the results are compared with those reported in the literature.