Springer Online Journal Archives 1860-2000
Summary Due to its paramount adsorption capacity, activated charcoal is supposed to be the remedy of choice for binding a variety of drugs in the gastrointestinal tract. Hence it is surprising — at least according to the advice of German textbooks — that activated charcoal is only recommended for administration after time-consuming treatments like induced emesis and gastric lavage. Particularly with infants at home, a ready-for-use suspension of activated charcoal would allow the early management of acute poisoning. In such cases, inactivation of the poison by adsorption could be particularly helpful, since the period after ingestion is usually short. The charcoal-sorbitol-suspension (30 g activated charcoal in 150 ml of 70% sorbitol) is a creamy preparation which is easy to drink, because density and viscosity prevent sedimentation. The prescription-free drugs can be dispensed by each pharmacist. The present study was undertaken to investigate the influence of sorbitol on the adsorption capacity of activated charcoal. To this end, adsorption isotherms were established in vitro and compared with results in volunteers to whom NAPAP, diphenhydramine or codeine was administered separately. These drugs are gaining increasing importance in medicinal toxicology since they are constituents of various analgesics and cold remedies. To determine absorption, the cumulative urinary excretion was estimated of the parent drugs and their main metabolites. Without charcoal the volunteers were dosed with 500 mg NAPAP, 50 mg diphenhydramine-HCl, and 50 mg codeine phosphate, respectively. When the charcoal-sorbitol-suspension was swallowed two min after ingestion of the tablett-slurry, the five-fold dose of each drug was administered. The charcoal-sorbitol-suspension significantly (p〈0.01) diminished systemic absorption of codeine to 12%, of diphenhydramine to 28% and of NAPAP to 44% (means, n=5). These results demonstrate the effectiveness of the charcoal-sorbitol-suspension to inhibit drug absorption. In vitro, sorbitol at neutral and acidic pH reduced the maximal adsorbance capacity of charcoal mainly for codeine (by 72%), less for diphenhydramine (19%) and least for NA-PAP (14%). Hence it is obvious that in-vitro experiments hardly predict the efficacy in vivo. This discrepancy suggests that part of the drugs had been already absorbed before binding to charcoal. This assumption is underlined by one experiment when diphenhydramine and charcoal-sorbitol were taken together. In this case less than 2% of the drug was absorbed. The charcoal-sorbitol-suspension was generally well tolerated besides marked flatulence. Black stools appeared within 1–3 h, the laxative action persisted for about 8 hours. It is recommended to administer activated charcoal to acutely poisoned patients as soon as possible (children 1 g/kg). The only exceptions are obtunded patients or ingestion of caustics. This first aid measure should start immediately at home or at work (e.g. after advice by telephone), in the ambulance car, and in busy (lack of staff !) intensive care units. When charcoal is rather ineffective (alcohol, iron or lithium salts) or in case of very large quantities of the ingested poison, emesis and gastric lavage can be performed even after charcoal administration.
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