Effects of Tablet Size and Head Posture on Drug Swallowing: A Preliminary Examination Using Endoscopy in Healthy Subjects

Tablet size and head posture have been reported to affect swallowing of medications, but no previous studies have evaluated their effects in detail. Our aim was to investigate for the first time the effect of tablet size and head posture on drug swallowing by endoscopic evaluation in healthy subjects. Round tablets (7,10, 12, and 14 mm in diameter) were swallowed by 15 healthy adults with an endoscope inserted in the neutral, head flexion, and head extension positions. Evaluation of swallowing difficulty using a numeric rating scale (NRS), presence or absence of pharyngeal residue and its location, and tablet oral transit time (TOTT) were recorded. In the neutral position, the NRS score was higher with the 14 mm tablets than with the 7 mm tablets. The TOTT with the 7 mm tablets was significantly shorter in the head extension than in the neutral position. Swallowing difficulty increased when the tablet diameter was more than 7 mm. Residues were found in the epiglottis, pyriform sinus, and tongue base. These findings suggest that head extension shortens the TOTT and assists oral-pharyngeal transport.