Evaluation of esophageal transit of tablets and capsules in 30 cats

We have reported tablet-induced focal esophagitis and esophageal stricture formation in cats. The proposed mechanism is thought to be abnormal esophageal tablet retention resulting in focal esophagitis with subsequent stricture formation. The objective of this study was to evaluate the passage of tablets and capsules when given alone (dry swallow) and when followed by a water bolus (wet swallow) to determine if this could, in part, explain the esophageal stricture formation we have observed in cats. Fluoroscopy was used to evaluate tablet or capsule passage after administration. The percentage of dry tablet swallows that successfully passed into the stomach was 0.0% at 30 and 60 seconds, 6.7% at 90 seconds, 13.3% at 120 seconds, 26.7% at 180 and 240 seconds, and 36.7% at 300 seconds. Wet tablet swallows successfully passed 90.0% of the time at 30 seconds, 93.3% of the time at 60 seconds, and 100.0% of the time thereafter. The percentage of dry capsule swallows that successfully passed was 16.7% at each time interval. Wet capsule swallows successfully passed 96.7% of the time at 30 seconds and 100% of the time thereafter. For each time interval, wet swallows achieved significantly greater percentage passage into the stomach when compared to dry swallows (P < .05). This study shows that tablets or capsules given by dry swallow have prolonged retention in the esophagus compared to those given by wet swallow. On the basis of this study, we recommend the routine administration of a water bolus to cats receiving tablets or capsules PO to facilitate esophageal clearance. This practice may help prevent medication-associated esophagitis or stricture formation.