A novel and simple LC-MS/MS quantitative method for dextromethorphan and dextrorphan in oral fluid

Area of Science:

• Analytical Chemistry
• Pharmacology

Background:

• Dextromethorphan (DXM) and its metabolite dextrorphan (DT) are commonly found in over-the-counter cough suppressants.
• Accurate quantification in biological matrices is crucial for clinical and toxicological assessments.

Purpose of the Study:

• To develop and validate a straightforward liquid chromatography-tandem mass spectrometry (LC-MS/MS) method.
• To determine DXM and DT concentrations in human oral fluid samples.

Main Methods:

• Samples were prepared using protein precipitation.
• Chromatographic separation was achieved on a phenyl column with isocratic elution.
• LC-MS/MS analysis was performed with a total run time of 7 minutes.

Main Results:

• The method demonstrated good accuracy for DT (1-100 ng/ml) and DXM (5-1000 ng/ml), with deviations ranging from -13.6% to 8.8%.
• Precision variations were within acceptable limits (≤7.5%), and matrix effects were minimal (≤11.8%).
• Short retention times of 2.6 min for DT and 5 min for DXM were observed.

Conclusions:

• The developed LC-MS/MS method is simple and effective for quantifying DXM and DT in human oral fluid.
• This validated method can be applied to both clinical and forensic toxicology settings.