Pill Shape Determines Esophageal Transit Times-A Pill-to-Pill Study

When manufacturing medications, several parameters are considered in pill design, particularly shape and size. We hypothesized that oval-shaped pills would transit more quickly through the esophagus than round pills.

Esophageal transit time (pill) (ETTp) of round and oval barium dummy-pills, derived from VFSS in 112 healthy individuals with no swallowing complaints and 50 individuals referred with swallowing complaints, was compared. ETTp was measured using quantitative software.

ETTp differed significantly by shape. In healthy adults, median round (13 mm, 1 g) ETTp was 26.4 s (SD 23.6) compared to oval ETTp (13 mm long axis, 1 g) of 5.4 s (SD 4) [p < 0.001]. In those with swallowing complaints, round ETTp was 45 s (SD 44) vs. oval ETTp 9 s (SD 14) [p < 0.001]. Gender and age differed across groups, with normal oval pill swallowers younger and more likely to be female than those with swallow complaints (39 vs. 69 years, p < 0.001; 70% female vs. 31% female, p = 0.018).

Medication shape affects ETTp, with oval-shaped pills traveling significantly faster through the esophagus than round pills. However, oval-shaped pills do not highlight abnormality in the esophagus to the same degree as a round pill. Therefore, consideration of the purpose of pill administration during VFSS should guide pill shape choice, with round pills most suited for diagnostic testing. In a clinical setting, oval-shaped medication should be favored, if possible, for those with compromised swallow ability.