Increased serum theophylline clearance with orally administered activated charcoal

The purpose of this study was to determine whether the oral administration of activated charcoal would increase the clearance of theophylline. Seven normal subjects received aminophylline intravenously (8 mg/kg) on 2 separate days. On Day 1 at 2-h intervals starting immediately after the completion of the aminophylline infusion, subjects ingested 4 doses of a slurry of activated charcoal (30 g each). On Day 2 they received no charcoal. The order of the days the subjects received charcoal or no charcoal was randomized. Plasma theophylline levels were determined by an enzyme immunoassay (Syva) every 2 h after the completion of the intravenous infusion. The theophylline half-life was reduced with charcoal from 10.2 to 4.6 h (p less than 0.001), and clearance increased from 35.6 to 72.6 ml/kg/h (p less than 0.001). In a patient with an initial serum theophylline concentration of 31.0 micrograms/ml and signs of toxicity (arrhythmias and seizures), the administration of charcoal (4 doses of 30 g every 2 h) reduced the half-life from 34.4 to 5.7 h concomitant with rapid resolution of signs of toxicity. We conclude that orally administered activated charcoal significantly enhances the clearance of theophylline and offers a new therapeutic modality in the treatment of theophylline toxicity.