Site of bismuth absorption from bismuth subsalicylate: Implications for treatment of colonic conditions

Poorly absorbed bismuth preparations may benefit a variety of chronic colonic conditions including ulcerative colitis. Bismuth-induced neurotoxicity is a potential complication of the chronic use of these preparations, and a less-absorbable form of bismuth is needed. If bismuth absorption occurs primarily in the upper gut, a delayed-release bismuth preparation could reduce absorption. We studied the site of bismuth absorption from bismuth subsalicylate (BSS) in rats. For 15 days, BSS (50 mg/day) was ingested or infused directly into the cecum via a chronically implanted cannula. Oral BSS resulted in serum and urine bismuth levels many times higher (3.5 ± 0.3 μg/liter and 1570 ± 286 ±g/g creatinine, respectively) than with cecal administration (undetectable (<1.5 μg/liter) and 75 ± 25 μg/g creatinine). Thus, bismuth absorption from BSS occurred almost entirely in the upper gut. These findings provide a rationale for a similar study of delayed-release bismuth preparations in humans.