Determination of the anti-ischaemic drug bepridil in human plasma using gas chromatography with nitrogen-sensitive...

An assay has been developed to determine the anti-ischaemic drug bepridil (as its free base) in human plasma. The assay procedure comprises n-hexane extraction from basic plasma and gas chromatography using nitrogen-selective detection. An analogue of bepridil is used as internal standard. The accuracy and precision of the assay is determined by repeated analyses of drug-free plasma samples spiked with 5, 10, 20, 100, 400 and 1000 ng of bepridil per ml of plasma. The accuracy, defined as the relative difference between the mean bepridil concentration found and the true value, was 8% or better. The precision (relative standard deviation) was 13% at the 5 ng/ml level and 5% at the 1000 ng/ml level. The assay is suitable to monitor routinely bepridil plasma levels during clinical studies.