Rapid adjustment of theophylline: a kinetic model.

This study was designed to test the validity and applicability of basic kinetic equations to describe theophylline disposition. The method involves early determination of clearance from a nonsteady-state level, dosage adjustment on the basis of the estimated clearance, and measurement of serum theophylline concentration at a point very near steady state. To test the method, a 32-patient study group was examined. The results were encouraging, with the actual mean level 19-28 hours after dosage adjustment being 13.4 micrograms/ml (SD, 3.1) as compared with a projected level of 13.2 micrograms/ml (SD, 2.9). Although further investigation is necessary, these findings indicate that within the limitations of the population studied this approach is a reliable and rapid method to achieve therapeutic serum theophylline levels while at the same time avoiding toxicity and subtherapeutic responses.