Activated charcoal in theophylline intoxication

To test the hypothesis that orally administered activated charcoal alters the elimination kinetics of intravenously administered theophylline, six dogs were twice infused with theophylline, 28 mg/kg, over 20 minutes 1 week apart. In a random sequence separated by 1 week, they received either activated charcoal, 30 gm in a water suspension or water only through a nasogastric tube every 2 hours after theophylline infusion, for a total of four doses. The time needed for plasma levels to fall below 20 mg/L was approximately 5 hours regardless of charcoal treatment. However, activated charcoal decreased theophylline halflife from 4.02 to 2.76 hours and volume of distribution from 0.72 to 0.61 L/kg. We conclude that although activated charcoal hastened the elimination of theophylline in dogs, the usefulness of orally administered activated charcoal in the treatment of theophylline overdose may be limited by the inability to shorten the time during which plasma levels are toxic.