The transit of dosage forms through the small intestine is considered to be constant at around 3 h, and unaffected by the presence of food. Here we address this assumption and examine how the timing of tablet and food administration can influence small intestine transit time.
A non-disintegrating, radiolabelled tablet was given to ten healthy volunteers in a three-way crossover study using three different feeding regimens (1) fasted (tablet administered on an empty stomach and food withheld for four hours) (2) fed (tablet administered after food) and (3) pre-feed (tablet administered 45 min before food). Tablet transit through the gastrointestinal tract was followed using gamma scintigraphy.
The small intestinal transit times of tablets after fasted and fed dosing regimens were similar, median 204 and 210 min respectively. With the pre-feed dose, small intestinal transit time was significantly shorter than in the fasted or fed state at 141 min. With this dosing regimen, in six of the volunteers tablets were in the upper small intestine when food arrived and these had a median small intestinal transit time of 100 min.
The timing of food ingestion has a clear effect on small intestinal transit of single-unit formulations and this has implications for drug bioavailability.