High-performance liquid chromatographic quantification of rifampicin in human plasma: Method for therapeutic drug monitoring

A high performance liquid chromatography (hplc) method has been developed that allows quantification of rifampicin in human plasma. the method is based on the precipitation of proteins in human plasma with methanol. optimal assay conditions were found with a c18 column and a simple mobile phase consisting of 0.05 m dipotassic hydrogen phosphate buffer and acetonitrile (53/47,v/v) with 0.086 % diethylamin,ph = 4.46. the flow-rate was 0.6 ml/min and the drug was monitored at 340 nm. results from the hplc analyses showed that the assay method is linear in the concentration range of 1-40 μg/ml (r2 >0.99). the limit of quantification and limit of detection of rifampicin were 0.632 μ;g/ml and 0.208 μg/ml,respectively. intraday and interday coefficient of variation and bias were below 10% for all samples,suggesting good precision and accuracy of the method. recoveries were greater than 90% in a plasma sample volume of 100 μl. the method is being successfully applied to therapeutic drug monitoring of rifampicin in plasma samples of tuberculosis and staphylococcal infections patients.