To the Editor.—Filippone and colleagues1 designed their study to examine the potential reversibility of the adsorption of aspirin to activated charcoal, and to quantify its extent. In vitro reversibility of adsorption of toxins to charcoal is well known, with its extent being dependent on several variables. More important is whether this process occurs significantly in clinical situations. Thus the question to be answered is whether their model is reasonably representative.
Cooney's2 book is an authoritative review of activated charcoal. Throughout he presents both in vitro and in vivo data demonstrating reversibility (pp 31-40 and 58-61), and characterizes it as a dynamic process. Influencing variables include the charcoal-to-drug ratio, the absolute amount of charcoal with a constant charcoal-to-drug ratio, the presence of food and other intestinal contents, and the temperature and pH of the milieu. Of importance, desorption is less likely with high charcoal-to-drug ratios, and with greater