The influence of density on the gastrointestinal transit of pellets

The gastric emptying, intestinal transit and caecum arrival times of 1 mm pellets of density 1.5 and 2.8 g cm-3 have been assessed in fed and fasted volunteers by means of gamma-scintigraphy. The pellets were prepared by extrusion/spheronisation, coated with ethylcellulose and labelled with technetium-99m. The position of the pellets in the gastro-intestinal tract was followed by a double-headed gamma camera to allow detailed information over a period of up to 10 h. Analysis of variance established that there was a highly significant difference in the time for 50% of the pellets to empty from the stomach both in fed and fasted states. The 2.8 g cm-3 pellets had an extended resident time in both the fed and fasted states. The gastric emptying time was prolonged in the fed state. There was no significant difference in intestinal transit time between the two formulations nor whether the volunteers were fed or fasted. The caecum arrival time was therefore modified only by the gastric emptying time.