In vitro study of the effect of dog food on the adsorptive capacity of activated charcoal.

OBJECTIVE: To evaluate the effect of dog food on the adsorptive capacity of activated charcoal. DESIGN: In vitro laboratory study. SETTING: University veterinary teaching hospital. ANIMALS: None. INTERVENTIONS: None. MATERIALS AND METHODS: A fixed quantity of acetaminophen (50 mg) was added to a fixed quantity of activated charcoal (1 g), mixed with varying amounts of dog food (2-14 g). The admixture was agitated for 5 minutes, incubated at 38.5°C for 1 hour and then centrifuged for 30 minutes. The concentration of residual, nonadsorbed acetaminophen in the supernatant was quantitatively assayed by reverse phase high-pressure liquid chromatography with ultraviolet detection. Data were tested by linear regression analysis and statistical significance was set at P < 0.05. MEASUREMENTS AND MAIN RESULTS: A statistically significant reduction in the adsorptive capacity of activated charcoal was demonstrated with increasing amounts of dog food (R(2) = 0.54; P = 0.0018). However, all measurements of residual acetaminophen were less than 100 mg/L, representing a reduction in acetaminophen concentration of more than 98.6%. CONCLUSIONS: The addition of dog food to activated charcoal reduces its total adsorptive capacity for acetaminophen. However, this reduction in adsorptive capacity is unlikely to be clinically significant in the presence of both the formulation of dog food and the ratio of dog food to charcoal used in this study.