Worldwide study of the taste of bitter medicines and their modifiers

The bitter taste of medicines hinders patient compliance, but not everyone experiences these difficulties because people worldwide differ in their bitterness perception. To better understand how people from diverse ancestries perceive medicines and taste modifiers, 338 adults, European and recent US and Canadian immigrants from Asia, South Asia, and Africa, rated the bitterness intensity of taste solutions on a 100-point generalized visual analog scale and provided a saliva sample for genotyping. The taste solutions were 5 medicines, tenofovir alafenamide (TAF), moxifloxacin, praziquantel, amodiaquine, and propylthiouracil (PROP), and 4 other solutions, TAF mixed with sucralose (sweet, reduces bitterness) or 6-methylflavone (tasteless, reduces bitterness), sucralose alone, and sodium chloride alone. Bitterness ratings differed by ancestry for 2 of the 5 drugs (amodiaquine and PROP) and for TAF mixed with sucralose. Genetic analysis showed that people with variants in 1 bitter receptor variant gene (TAS2R38) reported PROP was more bitter than did those with a different variant (P = 7.6e-19) and that people with either an RIMS2 or a THSD4 genotype found sucralose more bitter than did others (P = 2.6e-8, P = 7.9e-11, respectively). Our findings may help guide the formulation of bad-tasting medicines to meet the needs of those most sensitive to them.