The validation of a fluoroimmunoassay for the determination of theophylline concentration in dried blood spots suitable for domiciliary therapeutic drug monitoring.

A commercially available substrate-labelled fluorescent immunoassay procedure has been modified to create a simple rapid method for the determination of capillary theophylline concentration in the dried filter paper blood spots of patients on theophylline therapy. The specimens are collected and dispatched to the laboratory by the patient; thus domiciliary monitoring of theophylline therapy can take place. The technique offers a convenient method for overcoming many of the practical problems that arise during theophylline therapy in asthmatic patients.