Fluorescence polarization immunoassay for the determination of therapeutic drug levels in human plasma.

Fluorescence polarization immunoassay (FPIA) is a technique which has been known for a number of years, but despite its many advantages, its has not seen clinical utility. The main reason for this is the lack of simple, rapid, high performance instrumentation suitable for use in a clinical laboratory. This problem has been addressed in this laboratory and an instrument has been developed which meets these needs. The solutions of the two other problems associated with the technique (i.e. non-specific binding of tracer to serum proteins and the intrinsic fluorescence of serum) have also been accomplished. Assays for a variety of therapeutic drugs including gentamicin, theophylline, phenytoin, and phenobarbital have been developed and shown to correlate well with a number of reference method. The assays have been totally automated with a concomitant increase in speed and ease of use and a significant improvement in performance over the manual system.