High-Surface-Area Activated Charcoal for Gastrointestinal Decontamination
High-Surface-Area Activated Charcoal for Gastrointestinal Decontamination
Abstract & Commentary
Source: Roberts JR, et al. Advantage of high-surface-area charcoal for gastrointestinal decontamination in a human acetaminophen ingestion model. Acad Emerg Med 1997;4:167-174.
Roberts et al performed a human volunteer study in which six subjects ingested 50 mg/kg of acetaminophen followed in 12 minutes by either standard-surface-area activated charcoal (AC) (950 m2/g) or high-surface-area AC (2,000 m2/g) in a randomized cross-over design. Each subject was given AC in an 8:1 charcoal-to-drug ratio, and serial acetaminophen levels were recorded. For the six subjects, the four-hour acetaminophen levels showed a reduction of between 44% and 85% when the high-surface-area AC was compared to the standard-surface-area AC. In addition, the area under the concentration-versus-time curve was significantly less for the high-surface-area AC, demonstrating clear superiority. The study suffered from several minor flaws that are well-addressed in the manuscript and have little impact on the results.
COMMENT BY ROBERT HOFFMAN, MD
In the never-ending debate over the optimal method of gastrointestinal decontamination for poisoned patients, it has become evident over the last 10 years that when all else is equal, AC alone is probably sufficient. Several well-designed studies fail to demonstrate significant benefit from aggressive gastrointestinal decontamination in all but the most severely intoxicated patients while achieving quite satisfactory outcomes with AC.1-3 Despite the fact that both syrup of ipecac-induced emesis and orogastric lavage are of limited use because of long lists of contraindications and complications, many clinicians still perceive limited utility in routine overdose patients. If the efficacy of AC were enhanced, the role of aggressive decontamination techniques might be further reduced.
The obvious questions that remain are whether most of us are currently using an inferior product and whether we should lobby our hospitals’ pharmacies to purchase high-surface-area AC. There is no doubt that high-surface-area AC will adsorb more drug than an equal gram amount of standard-surface-area AC. This in and of itself is insufficient to warrant purchasing the agent. Most patients are adequately treated with a standard dose (1 g/kg) of standard-surface-area AC. If the high-surface-area AC is significantly more expensive, its administration would raise the cost of treatment without changing the outcome in routine cases. The major issue to consider is how we treat patients who have ingested massive gram amounts of toxin. Under most circumstances, a 10:1 AC-to-drug ratio is desirable. For the patient with a 30 g theophylline overdose, the desired 300 g of standard-surface-area AC is not easily obtained. In this circumstance, being able to provide high-surface-area AC might be preferable regardless of cost issues. In intermediate cases, administering a second dose of standard-surface-area AC might be equally acceptable depending on cost issues.
Reduced drug levels in simulated overdose models do not necessarily imply improved outcomes. I urge clinicians to consider both clinical outcome and pharmacoeconomics before they insist on the routine use of high-surface-area charcoals.
References
1. Kulig KW, et al. Management of acutely poisoned patients without gastric emptying. Ann Emerg Med 1985;14:562-567.
2. Merigan KS, et al. Prospective evaluation of gastric emptying in the self-poisoned patient. Am J Emerg Med 1990;8:479-483.
3. Pond SM, et al. Gastric emptying in acute overdose: A prospective study. Med J Aust 1995;163:345-349.
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