Drug metabolism , generally metabolite quantitation

The use of deuterated pharmaceuticals to study intermediary drug metabolism with GC—MS analytical techniques has increased enormously in the last decade and has been discussed in a previous section. Quantitative isotope mass spectrometry may well come into its own in this field in the near future for general screening. Whilst individual metabolites cannot be monitored, the total deuterium excreted in the urine can be accurately measured and thus provide a good indication of the excretion time course of total deuterium label. 

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