Objective: To compare the abilities of low-surface-area (LSA) vs 2 types of high-surface-area (HSA) activated charcoal given orally to adsorb acetaminophen in the gastrointestinal (GI) tract, as demonstrated by the impact of these agents on the serum levels and area under the curve (AUC) in a simulated human overdose model.
Methods: The main arm of the study was a prospective double-blind crossover trial in which 6 volunteers, serving as their own controls, ingested acetaminophen (50 mg/kg), followed randomly in 10 minutes by either powdered LSA charcoal (950 m2/g) or powdered HSA charcoal (2,000 m2/g) in a charcoal:drug ratio of 8:1. In a second arm of the study, 3 subjects additionally ingested an equal dose of a granular preparation of the HSA charcoal. Serial serum acetaminophen levels were analyzed at various intervals (30, 60, 90, 120, 180, 240, and 300 minutes postingestion), and a 5-hour AUC was calculated. The subjects also rated the charcoal preparations for palatability.
Results: Serum acetaminophen levels were lower at all measured times in the groups receiving both forms of the HSA charcoal vs the LSA product. With the powdered HSA charcoal, comparison serum levels were significantly lower at 120 minutes postingestion and all times thereafter (p < 0.05), reaching high significance at 4 and 5 hours (p < 0.001). The subjects receiving the granular HSA charcoal also had consistently lower serum acetaminophen levels than did those receiving the LSA product, and the difference in mean serum levels was significant at the 4- and 5-hour sample (p = 0.012). Compared with the LSA charcoal, at the 4-hour postingestion sample, serum acetaminophen levels were reduced by 44% to 85% by the powdered HSA charcoal. The total AUC for the 5-hour study period was also significantly reduced by the powdered HSA product (p = 0.005) and the granular HSA product (p = 0.043). All the subjects rated the powdered HSA charcoal to be more palatable and easier to drink than the powdered LSA charcoal.
Conclusion: The surface area of oral activated charcoal is a major determining factor in its ability to limit acetaminophen absorption and to fulfill its adsorptive role in GI decontamination. In a human acetaminophen overdose model, 2 types of HSA charcoal, when compared with equal doses of LSA charcoal, significantly reduced serum levels and total acetaminophen absorption as measured by the AUC.