Developing methodology to evaluate the oral sensory features of pharmaceutical tablet coatings

Acceptability of medicines is critical for effective pharmacotherapy. The aim of this study was to investigate the oral sensory properties of tablet coatings to determine how mouthfeel can improve acceptability. A randomised double-blind study was performed in 84 adult volunteers (51% ≥55 years). Each participant received 4 placebo tablets (3 coated and 1 uncoated) to evaluate (i) ease of swallowing and (ii) palatability. Visual analogue scales (VAS) were used to capture sensory parameters. Acceptability was assessed using the following parameters: ease of swallowing; amount of water taken with the tablet; rank order of preference; roughness; adhesiveness and slipperiness. Ease of swallowing was determined to be the most sensitive measure of acceptance. The best coating was the one that was reported to be the most slippery and smooth. The presence of a coating improved ease of swallowing, mouthfeel and overall palatability. This study demonstrates that slippery coatings improve acceptability of tablets. The study also demonstrates the value of VAS to measure the sensory attributes of coated tablets.