Determination of meloxicam in human plasma using a HPLC method with UV detection and its application to a pharmacokinetic study

A simple and sensitive high performance liquid chromatography method using UV detection (HPLC-UV) for the determination of meloxicam in human plasma was developed and validated. After extraction with diethyl ether, the chromatographic separation of meloxicam was carried out using a reverse phase Sunfire C₁₈ column (150 mm × 4.6 mm, 5 μm) with a mobile phase of acetonitrile-20 mM potassium hydrogen phosphate (40:60, v/v, pH 3.5) and UV detection at a wavelength of 355 nm. The flow rate of mobile phase was 1.2 ml/min and the retention time of meloxicam and internal standard, piroxicam, was found to be 11.6 and 6.3 min, respectively. The calibration curve was linear within the concentration range, 10-2400 ng/ml (r² > 0.9999). The lower limit of quantification was 10 ng/ml. This method improved the sensitivity for the quantification of meloxicam in plasma using a HPLC-UV. The mean accuracy was 98-114%. The coefficient of variation (precision) in the intra- and inter-day validation was 1.6-4.3 and 2.4-7.3%, respectively. The pharmacokinetics of meloxicam was evaluated after administering an oral dose of 15 mg to 11 healthy Korean subjects. The AUC_inf, C_max, t_max and t_1/2 were 42.4 ± 13.2 μg h/ml, 1445.7 ± 305.5 ng/ml, 4.1 ± 0.3 h and 22.0 ± 4.9 h, respectively.