Does ethanol modify antidotal efficacy of oral activated charcoal studies in vitro and in experimental animals.

The effect of ethanol on the adsorption of strychnine to activated charcoal was studied in vitro at pH 1.2 and 7.0. At high charcoal-drug ratios the adsorption of strychnine was significantly (p less than 0.001) more complete at neutral pH than at pH 1.2. At these ratios ethanol 10% increased (p less than 0.001) the unadsorbed fractions at both pHs. The acute toxicity of oral strychnine in mice was not influenced by ethanol. Activated charcoal (1000 mg/kg) mixed with strychnine prior to the administration increased its LD50 by 410 fold. When ethanol was administered with charcoal and strychnine, the increase in the LD50 was only 220 fold which is significantly (p less than 0.05) less than without ethanol. Accordingly, the concomitant ingestion of ethanol in drug intoxications may slightly impair the antidotal efficacy of oral activated charcoal. Despite this potential reduction of the antidotal efficacy of charcoal in some extreme situations, there should be no hesitation in administering activated charcoal in acute intoxications since it in any case very effectively inhibits the absorption of most drugs.