Rifampicin concentrations in cerebrospinal fluid and plasma of the rabbit by high performance liquid chromatography

A high performance liquid chromatographic (HPLC) assay has been developed for the measurement of rifampicin in cerebrospinal fluid and plasma samples in the rabbit. The method involved a preliminary organic solvent extraction of the drug and p-dimethylaminobenzoic acid (internal standard) from biological samples and subsequent concentration and analysis by HPLC. An aliquot (25 microliters) of the concentrate was injected into the liquid chromatograph and eluted with acetonitrile-10 mM phosphate buffer of pH 3.5 (48: 52, v/v) on a 30 microns C8 reversed phase column linked to a 5 microns C8 analytical column at ambient temperature (25 +/- 1 degrees C). The eluate was detected at 215 nm. The method has been used to investigate the disposition of rifampicin in plasma and CSF in rabbits.