Clinical experience with theophylline. Relarionships between dosage, serum concentration, and toxicity
M. H. Jacobs, R. M. Senior and G. Kessler
Relationships between theophylline dosage, serum theophylline
concentration, and theophylline toxicity were evaluated retrospectively in
47 hospitalized adults. The amount of theophylline administered daily
varied more than sixfold, from 6 to 38 mg/kg. The serum theophylline
concentrations, however, varied 24-fold from 2 to 49 mug/ml. The
relationship between daily dosage and serum concentration was unpredictable
in an individual patient. Fourteen patients (30%) had a toxic reaction to
theophylline. Toxic symptoms, which were not always gastrointestinal,
occurred commonly with serum concentrations over 25 mug/ml but were not
noted with concentrations below 15 mug/ml. High serum theophylline
concentrations and a toxic reaction developed just as often with the oral
route as when the drug was given intravenously. In six patients,
measurement of serum theophylline concentration disclosed subtherapeutic
concentrations. Serum theophylline determination appears to be important
clinically in guiding effective and safe usage of theophylline.
