Characterization of colonic transit of nondisintegrating tablets in healthy subjects

The transit of pharmaceutical dosage forms through the colon has been shown to be highly variable. The amount of fiber in the diet is known to alter gastrointestinal transit; however, the dietary intake of the subjects in previous studies was not adequately controlled. Using the technique of gamma scintigraphy, we have therefore characterized the variability in the colonic transit of nondisintegrating tablets, by strictly controlling the dietary fiber intake of the subjects. Eight healthy male subjects followed a diet containing 25 g dietary fiber per day, for six days prior to dosing. Each subject received five 6-mm nondisintegrating tablets on three consecutive days. Mouth-to-anus transit times exhibited a high degree of variability. Regional differences in colonic transit were evident. Tablet stasis appeared to occur mainly in the ascending colon and hepatic flexure. Despite the diets of the volunteers being identical, colonic transit was still observed to be highly variable, which suggests that this variability is intrinsic.