Fluoroimmunoassays for procainamide and N-acetylprocainamide compared with a liquid-chromatographic method

Area of Science:

• Clinical Chemistry
• Pharmacokinetics
• Analytical Chemistry

Background:

• Accurate therapeutic drug monitoring is crucial for optimizing patient outcomes.
• Procainamide and its active metabolite, N-acetylprocainamide (NAPA), require precise quantification in serum.
• Existing analytical methods may have limitations in terms of speed, cost, or complexity.

Purpose of the Study:

• To develop and validate a novel fluorimmunoassay for measuring procainamide and NAPA.
• To compare the performance of the new fluorimmunoassay against a high-performance liquid chromatographic method.
• To assess the clinical applicability of the fluorimmunoassay in pharmacokinetic studies.

Main Methods:

• Sera from 37 patients (80 samples) were analyzed using both a new fluorimmunoassay and an established high-performance liquid chromatography (HPLC) method.
• Assessed method agreement using additive and proportional differences.
• Evaluated between-day coefficients of variation (CVs) for both procainamide and NAPA at specified concentrations.

Main Results:

• The fluorimmunoassay demonstrated excellent agreement with the HPLC method for both procainamide and NAPA.
• Additive differences were 0.07 mg/L for procainamide and 0.62 mg/L for NAPA.
• Proportional differences were 9% for procainamide and 16% for NAPA, with low between-day CVs (2.2% for procainamide, 1.2% for NAPA).

Conclusions:

• The developed fluorimmunoassay is a reliable and accurate method for quantifying procainamide and NAPA in human serum.
• This assay offers a viable alternative to HPLC for routine therapeutic drug monitoring and pharmacokinetic analysis.
• The method's precision and accuracy support its use in clinical settings for patient management.