[Effect of lidocaine gargling on taste perception]

Because stomatitis is a painful condition, gargling with lidocaine is often prescribed before meals. However, because lidocaine inhibits nerve conduction, lidocaine gargling may affect taste perception. Therefore, we studied the effects of lidocaine gargle on taste. We prepared samples of the 5 basic tastes at equivalent concentration levels in terms of the taste quotient. We conducted sensory tests to judge whether the samples could be tasted, and the threshold concentrations (50% taste rate) were estimated from the taste rates. The sensory test was repeated after the subjects gargled with lidocaine, and the efficacy ratio was calculated by comparing the threshold concentrations. Although no interaction was observed between the lidocaine gargle and the threshold concentration levels in the logistic regression analysis, significant differences were observed in the primary effects of each standard, such as the concentration levels, flavor, and bitterness. When the efficacy ratios based on the threshold values were calculated, increases in the thresholds for flavor and bitterness were observed. The results of this study suggested that gargling with lidocaine before a meal increases the thresholds for the appreciation of flavor and bitterness. This increase in the threshold values due to lidocaine was associated not with the pharmacological effect of the drug but with its strong bitterness.