In vivo evaluation of the adsorptive capacity of activated charcoal for camphor.

Camphor, a cyclic terpene, is the toxic ingredient in many over-the-counter (OTC) products. Early seizure activity due to camphor ingestion often contraindicates the use of traditional decontamination therapies in favor of oral activated charcoal use. No research data supports the affinity of activated charcoal for camphor. This study was conducted to evaluate the effectiveness of activated charcoal in preventing camphor absorption in a rat model. Camphor 40% in cottonseed oil (1 g/kg) was administered to 100 male Sprague-Dawley rats via oral gavage. Aqueous activated charcoal suspension (2 g/kg) was administered to the study group of 50 rats. Serum camphor concentrations were determined by gas chromatography at defined intervals over 10 h. No mortality occurred in either the control or activated charcoal-treated group. Area-under-the-curve bioavailability comparisons of each group revealed no significant differences (activated charcoal 421 micrograms x h/ml vs camphor 409 micrograms x h/ml). The absorption rate constants (Ka) and T 1/2 and elimination rate constants (Ke) and T 1/2 of each group were nearly identical and similar to those reported for humans. These preliminary data indicate the need for careful evaluation of the efficacy of oral activated charcoal administration as the sole means of preventing the absorption of camphor.