Simultaneous HPLC Analysis of Acemetacin and Indometacin in Plasma and Its Application to Bioavailability Study

Acemetacin is a new potent non-steroidal anti-inflammatory compound which is used for the treatment of arthritis and rheumatic diseases. To establish an assay condition for bioavailability study of acemetacin, high-performance liquid chromatographic (HPLC) method using UV detection for the determination of acemetacin and its metabolite indometacin in blood has been developed. Samples were analysed with Luna C18 column (250×4.6 mm, 5 μm, Phenomenex) which maintained at 40oC. The mobile phase was composed of 0.02M phosphate buffer (pH 4.5):methanol=45:55. The flow rate was 1.4 mL/min. UV absorbance was monitored at 254 nm. Typical retention times were 23, 31 and 34 min for flubiprofen (internal standard), acemetacin and indometacin, respectively. Calibration curves for the determination of acemetacin and indometacin in plasma showed a good linearity at a concentration range from 100 to 3000 ng/mL(r2=0.999). Blood samples of eight human volunteers who had received 3 tablets of 60 mg of acemetacin orally were analysed with HPLC and pharmacokinetic parameters were evaluated. The developed analytical method afforded a simple, rapid and sensitive assay for the measurements of acemetacin and its metabolite, indometacin in plasma and can be employed for bioavailability study for acemetacin formulations.