High-performance liquid chromatographic analysis of piroxicam and tenoxicam in plasma, blood and buffer solution. Application to pharmacokinetic studies in small laboratory animals.

A rapid and sensitive high-performance liquid chromatographic procedure is described for the simultaneous determination of piroxicam (CAS 36322-90-4) and tenoxicam (CAS 59804-37-4) in blood, plasma and buffer solutions used in the equilibrium dialysis studies. The method can be used to measure either piroxicam and tenoxicam in these three fluids using the other as internal standard. A Nucleosil C18 and a mobile phase consisting of an acetonitrile-distilled water-acetic acid (58 : 38 : 4) mixture were used. The flow rate was 1 ml/min and the effluent was monitored at 365 nm with 0.02 AUFS (absorbance units full scale). The sensitivities of this method were 0.2 microgram/ml levels of piroxicam and tenoxicam in the plasma, blood and buffer solutions samples.