Lidocaine and its active metabolites

Area of Science:

• Pharmacology
• Analytical Chemistry

Background:

• Lidocaine's antiarrhythmic and toxic effects are influenced by its metabolites, MEGX and GX.
• Existing analytical methods for these compounds are time-consuming or require specialized equipment.

Purpose of the Study:

• To develop a rapid, accurate, and precise high-performance liquid chromatography (HPLC) assay for quantifying lidocaine, MEGX, and GX in biological fluids.
• To investigate the pharmacokinetic profiles and relative contributions of lidocaine metabolites in patients.

Main Methods:

• Development and application of a novel HPLC assay for simultaneous determination of lidocaine, MEGX, and GX.
• Analysis of biological fluid samples from three patients receiving lidocaine therapy.

Main Results:

• The HPLC method demonstrated accuracy and precision in measuring lidocaine, MEGX, and GX.
• One patient exhibited MEGX concentrations nearly double that of lidocaine, with MEGX contributing significantly to the overall effect.
• Observed inverse relationship between lidocaine and MEGX concentrations in another patient.
• Lidocaine half-life determined in a third patient was consistent with literature values.

Conclusions:

• The developed HPLC assay provides a valuable tool for studying lidocaine and its active metabolites.
• The findings highlight the substantial role of MEGX in lidocaine's pharmacological activity and potential toxicity.
• Further research is warranted to fully elucidate the roles of lidocaine and its metabolites.