Comparison of serum hydroquinidine determination by fluorescence polarization immunoassay and liquid chromatography

Hydroquinidine is a structural analogue of quinidine. It is used in the treatment and prevention of cardiac arrhythmias and necessitates serum monitoring. Fluorescence polarization immunoassay (FPIA) of quinidine has been proposed and we have tested the performance of this assay for hydroquinidine using its cross-reaction with quinidine. Tracer (quinidine labelled with fluorescein) and anti-serum were purchased from Abbott S.A. Standard curves were obtained using specifically prepared hydroquinidine calibrators and within-run and run-to-run precision values (expressed as relative standard deviation) (RSD) lower than 5.3% (n = 10). In order to evaluate specificity of this assay in the clinical situation, FPIA and liquid chromatography results were compared.