Evaluation of a mouse monoclonal antibody for the determination of serum theophylline by fluorescence polarization immunoassay.

Theophylline concentrations in spiked human serum and serum specimens obtained from patients with normal and impaired renal function were measured by fluorescence polarization immunoassay (FPIA) using a mouse monoclonal antitheophylline antibody. The interday coefficients of variation of the assay after 14 days were 4.2, 3.3, and 2.4% at serum theophylline concentrations in pooled human serum of 7.1, 12.2 and 26.9 mg/L. Theophylline concentrations determined by FPIA and high performance liquid chromatography (HPLC) were used to generate the following linear regression equations relating the corresponding theophylline concentrations measured by each method in serum specimens from 50 patients with normal renal function (FPIA = 1.00 HPLC + 1.01, r = 0.98) and 50 patients with end-stage renal disease (FPIA = 1.04 HPLC + 0.08, r = 0.99). In contrast to previous studies performed with a polyclonal antitheophylline antibody, the precision, accuracy, and specificity of the FPIA were adequate for analysis of theophylline in serum specimens obtained from patients with end-stage renal disease.