Determination of isoniazid,rifampicin and pyrazinamide in human plasma by HPLC

Objective To develop an HPLC method for the simultaneous determination of isoniazid,rifampicin and pyrazinamide in human plasma.Methods The compounds and internal standard were extracted from the plasma by aprotein precipitation procedure with methanol.The separation of the analytes was performed on a C18column(150mm×4.6mm,5.0μm)at 40℃,using agradient elution program with solvents consisting of methanol,acetonitrile and 0.05mol·L-1 KH2PO3-H2O.The injection volume was 20μL.The compounds were detected by PDA.Results Calibration curves in spiked plasma were linear at 0.20-25.6,0.20-25.6and 0.40-25.6μg·mL-1 for isoniazid,rifampicin and pyrazinamide,respectively.The recoveries were 85%~115%,and the intra-day and inter-day RSDs were9.4%.Conclusion The method is specific,sensitive and accurate,and it can be used for the simultaneous determination of isoniazid,rifampicin and pyrazinamide in human plasma.