Evaluation of a rapid high-performance liquid chromatographic method for plasma theophylline analysis and its use in therapeutic drug monitoring.

A high-performance liquid chromatographic (HPLC) assay for theophylline has been developed and evaluated, and interferences eliminated. The method has been compared to an enzyme multiplied immunoassay technique (EMIT) with respect to cost and speed of analysis, recovery of added analyte, precision, accuracy, and performance in an external quality assessment scheme. The HPLC method, although less rapid than EMIT, was superior with respect to precision and less expensive to perform.