The effect of activated charcoal on drug exposure following intravenous administration: A meta-analysis

Activated charcoal both reduces primary drug absorption and enhances drug elimination. However, the two mechanisms of action overlap and are indistinguishable from each other. In order to estimate the extend of enhanced elimination, we summarized the effect of activated charcoal on intravenously administered drugs, where reduced drug exposure can be attributed to enhanced elimination. We performed a meta-analysis of randomized controlled studies evaluating the effect of orally administered activated charcoal on the systemic exposure of intravenously administered drugs. We searched the bibliographic databases PubMed, Embase and Cochrane. Meta-regression analyses of selected physiochemical drug properties on the effect sizes of activated charcoal were performed. All but one of 21 included studies used multiple-dose activated charcoal (MDAC). MDAC reduced the median half-life of the intravenously administered study drugs by 45.7% (interquartile range: 15.3%-51.3%) and area under the concentration time curve by 47.0% (interquartile range: 36.4%-50.2%). MDAC significantly improved drug elimination across nine different intravenously administered drugs, but we were unable to identify factors allowing extrapolation to other drugs. The results offer a possible and plausible rationale for the previously observed effects of single-dose activated charcoal beyond the timeframe where ingested drug is present in the gastro-intestinal tract.