Anticonvulsants in serum, determined with a fully mechanized enzyme analyzer

Area of Science:

• Clinical Chemistry
• Biochemistry
• Analytical Chemistry

Background:

• Therapeutic drug monitoring (TDM) is crucial for optimizing patient outcomes with antiepileptic drugs.
• Existing analytical methods for antiepileptic drugs can be time-consuming or require specialized equipment.
• Enzyme immunoassays offer potential for rapid and automated drug level determination.

Purpose of the Study:

• To adapt the EMIT enzyme immunoassay system for automated analysis of phenobarbital, phenytoin, and primidone.
• To evaluate the performance of the automated EMIT system against a reference gas-chromatographic method.
• To assess the precision and accuracy of the automated immunoassay for these anticonvulsant drugs.

Main Methods:

• Adaptation of the EMIT (Enzyme Multiplied Immunoassay Technique) system using glucose-6-phosphate dehydrogenase as the enzyme label.
• Utilized a fully mechanized kinetic enzyme analyzer for high-throughput analysis.
• Compared results with the established gas-chromatographic method by Kupferberg.

Main Results:

• Weighted regression analysis showed strong correlation: y=(1.01+/-0.04)x for phenobarbital and y=(0.95+/-0.04)x for primidone.
• Within-run coefficients of variation (CV) were 9% (primidone), 11% (phenobarbital), and 22% (phenytoin).
• Run-to-run CVs were 6% (primidone, phenobarbital) and 13% (phenytoin), indicating good assay reproducibility.

Conclusions:

• The automated EMIT system provides a reliable and efficient method for analyzing phenobarbital, phenytoin, and primidone levels.
• This adaptation facilitates accurate therapeutic drug monitoring in clinical settings.
• The assay demonstrates acceptable precision and accuracy, comparable to gas chromatography.