This study aimed to evaluate the bitterness of famotidine (FAM) combined with each of three non-steroidal anti-inflammatory drugs (NSAIDs): ibuprofen (IBU), flurbiprofen (FLU), and naproxen (NAP), which have potential as fixed-dose combination (FDC) drugs. We evaluated the bitterness of FAM and each NSAID by taste sensor AN0 and C00, respectively. FAM showed high sensor output representing sensitivity to bitterness, whereas three NSAIDs did not show large sensor output, suggesting that the

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... rness intensities of three NSAIDs were lower than that of FAM. The bitterness of FAM on sensor AN0 was suppressed in a concentration-dependent manner when mixed with IBU, FLU, or NAP. Among three NSAIDs, IBU most effectively inhibited bitterness on sensor output, and the gustatory sensation test confirmed that adding IBU to FAM reduced the bitterness of FAM in a concentration-dependent manner. MarvinSketch confirmed that the drugs were mostly present in an ionic solution when FAM was mixed with NSAIDs. The 1H-NMR spectroscopy analysis also revealed the presence of electrostatic interactions between FAM and NSAIDs, suggesting that the electrostatic interaction between FAM and NSAIDs might inhibit the adsorption of FAM on the bitter taste sensor membrane, thereby masking the bitter taste.