Validation of a rat behavioral avoidance model from a drug delivery perspective

Conventional taste-masking strategies are used to overcome the bitter taste perception of pharmaceuticals by coating the drug particles and/or adding flavoring agents. However, for certain product categories such as rapid dissolve sublingual tablets, taste-masking is challenging. Programs exploring such formulation strategies in the LO-CS phase or post CS phase possess very little toxicological information available in order to conduct human taste panel studies. The potential of a bitter taste perception can present a significant business risk. The objective of the study was to validate a rat behavioral avoidance model that identifies bitter-tasting compounds. Most classic bitter substances elicit a response in the micromolar concentration range while most drugs elicit a response in the millimolar range, hence a validation exercise was conducted to examine if the existing biological model was sensitive enough to identify known bitter tasting drugs as such. Five compounds: ergotamine tartrate, fluoxetine, sucrose, sumatriptan and povidone were chosen to represent a spectrum of compounds. The bitter tasting compounds were identified as such in the model. Based on these results, the assay may serve as a useful surrogate test to identify compounds that may have bitter taste issues.