Pharmacobezoar: an evolving new entity.

Pharmacobezoars, bezoars comprised of medications, are unusual entities. Medications reported to cause bezoars include aluminum hydroxide gel, enteric-coated aspirin, sucralfate, guar gum, cholestyramine, enteral feeding formulas, psyllium preparations, nifedipine XL, and meprobamate. They most often occur, as do bezoars of any type, in a background of altered motility or anatomy of the gastrointestinal tract. Bowel hypoactivity, dehydration, and concomitant use of anticholinergics and narcotis appear to contribute to the propensity for bezoar formation by aluminum hydroxide gel and Isocal. The hygroscopic properties of psyllium and guar gum appear to contribute to their propensity to form bezoars. Insolubility of the carrying vehicle of enteric-coated aspirin and nifedipine is the setting in which these medications form bezoars. In contrast to nonmedication bezoars, pharmacobezoars may produce additional symptoms, those related to the release of their active ingredients. In patients with suspected gastrointestinal tract emptying problems, whether esophageal, gastric, small bowel, or colonic, the astute clinician should consider pharmacobezoar in the differential diagnosis.