Selected ion monitoring assay for bromhexine in biological fluids

A method has been developed for quantification of bromhexine in plasma using gas chromatography mass spectrometry with selected ion monitoring. A deuterium labelled analogue was synthesized and used as the internal standard. To evaluate the gas chromatographic electron capture detection method described earlier, 23 plasma samples have been analysed by both techniques. Although a good correlation was shown, selected ion monitoring was superior to the electron capture detection method for levels below 3 ng ml-1. The mass spectrometric method has also been used to set up a pharmacokinetic study of bromhexine in horses. Urine extracts were subjected to gas chromatographic mass spectrometric analysis to identify the different metabolites of bromhexine. Three groups of metabolites were detected and identified.