ABSTRACT
This chapter reviews the liquid chromatographic procedures in the English literature for the determination of theophylline and related xanthines. The association between theophylline concentrations and efficacy or toxicity has been established by numerous studies. Some patient/risk factors are the result of changes in theophylline clearance caused primarily by differences in rate of hepatic biotransformation. The chapter describes recognition, resolution, and a calculation technique for a reliable and clinically useful estimation of theophylline concentration when resolution was not achieved. It emphasizes that long-term use of high-pressure liquid chromatography (HPLC) columns requires closer attention to possible interferences and the value of participating in external proficiency surveys. A potential for interference exists in all of the liquid chromatographic procedures. It is necessary to minimize the incidence and to recognize potential problems quickly. For the management of asthma and neonatal apnea, there is a well- documented need to monitor serum theophylline concentrations to maximize efficacy and minimize toxicity.
