Inhibition of peptic activity by sucralfate

It is known that antacids containing aluminum hydroxide inhibit peptic activity by raising intragastric pH and by adsorbing pepsin. Since sucralfate contains aluminum hydroxide moieties, the possibility that this drug might inhibit peptic activity by these same mechanisms was examined. Sucralfate was incubated at a concentration of 10 mg/ml with samples of human gastric juice having pH values between 1.5 and 4 for 30 minutes at 37 degrees C. The proteolytic activity of the supernatant was then determined at a pH of 2.2 against a bovine hemoglobin substrate. When the initial pH of the gastric juice sample was 1.5, sucralfate was converted to a viscous gel and the pH of the incubation mixture rose to 2.9. However, there was no decrease in the peptic activity of the supernatant. In contrast, when the pH of the gastric juice sample was more than 2, the drug remained in suspension, but there was a graded rise in pH to a maximum of 4.1 and a progressive decrease in peptic activity (determined at a pH of 2.2) to a nadir of 65 percent of the control value. However, because peptic activity declines rapidly at a pH of more than 3, peptic activity at the ambient pH of the samples was reduced to only 25 percent of the control value. The results indicate that at pH values of more than 2, sucralfate inhibits peptic activity by both adsorbing pepsin and buffering hydrogen ions.