Reversible adsorption (desorption) of aspirin from activated charcoal.

The potential desorption of aspirin from activated charcoal was investigated in eight patients in a randomized cross-over study. Despite prebinding of aspirin, systemic absorption did occur. Desorption from activated charcoal was characterized by a peak salicylate concentration that was 16% of control and a time to peak salicylate concentration that was delayed in the study group. Bioavailability of aspirin from activated charcoal described by area under the curve was 19% of control. Elimination half-lives were similar in both groups until 12 hours after ingestion, but after 12 hours the half-life of the study group was prolonged while salicylate concentrations were undetectable in the control group. Fifteen percent to 20% of aspirin prebound to charcoal may desorb leading to systemic absorption. Furthermore, release from activated charcoal is initially delayed then sustained through 30 hours.