Selected ion monitoring assay for bromhexine in biological fluids.

This research discusses a new method that was developed for determining levels of bromhexine in plasma using gas chromatography mass spectrometry, proving its superiority over an earlier measurement method, particularly for lower levels. Additionally, it was utilized in studying bromhexine’s pharmacokinetic properties in horses and identifying its metabolites.

Methodology

• The research revolves around the development of a method for quantifying the concentration of bromhexine, a medication used for treating chest congestion, in the plasma. The tool utilized for this is gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring.
• A deuterium-labeled analogue was synthesized and used as the internal standard for this assay. Internal standards are substances that have a similar behavior to the analyte but can be differentiated from it, they help to increase the accuracy of the analyses.

Comparison to Previous Methods

• To test the efficiency of this new method, it was compared to a previously established gas chromatographic electron capture detection method. For this, 23 plasma samples were analyzed using both methods.
• The analysis exhibited a good correlation between both methods, however, the newly developed method was found to be superior at detecting bromhexine levels below 3ng ml-1, highlighting its elevated sensitivity.

Application in Pharmacokinetic Study

• The newly developed GC-MS method was also employed for conducting a pharmacokinetic study of how bromhexine behaves in horses, helping in understanding the drug’s absorption, distribution, metabolism, and excretion.
• Urine extracts from horses were subjected to GC-MS analysis to identify the different metabolites of bromhexine, which refers to the substances left after the drug has been processed (metabolized) in the body.
• This analysis led to the detection and identification of three groups of metabolites of bromhexine, improving our understanding of how this drug is metabolized in horses.