Measurement of Rifampicin and Clarithromycin in Serum by High-performance Liquid Chromatography with Electrochemical Detection

Rifampicin (RFP) induces hepatic drug-metabolizing enzymes, making drug interactions a very important clinical problem. Clarithromycin (CAM) metabolism is reportedly enhanced by induction of hepatic drug-metabolizing enzymes (CYP3A4) by RFP, so that the blood lend of CAM decreases when RFP is administered concurrently. We connected an electrochemical detector to a high-performance liquid chromatograph (HPLC) for simple, rapid, easy measurement of blood concentrations of RFP and CAM. Using samples of patient serum, normal serum, and reference standards, we compared HPLC by an external laboratory and the results of LC/MS/MS analysis with those of this new assay. A strong correlation was seen between our HPLC results and those of the external laboratory in RFP levels (r=0.975, p