palatability (medicinal product)

Palatability describes overall acceptability of an oral medicine in terms of smell, taste, aftertaste, and mouthfeel, as defined by the EMA guideline EMA/CHMP/QWP/805880/2012 Rev. 2. WHO Technical Report Series 970, Annex 5, uses the same idea and also includes dose volume or dosage-form size in assessment. Bitterness is one taste factor affecting acceptability, and research measuring or moderating pharmaceutical bitterness is often ultimately assessed within this palatability framework.

The EU guideline for developing pediatric medicines says information on an active ingredient's palatability should be obtained early, from a dedicated adult panel or existing literature, for example. Unless there is a particular reason otherwise, the pediatric formulation itself should have satisfactory taste and mouthfeel without mixing it with food or drink. The same guideline warns against making pediatric formulations too attractive, like candy, because this is known to raise the incidence of accidental poisoning.

WHO and EMA both state that palatability strongly affects patient acceptability and, through it, adherence to medication. The WHO annex says palatability can be decisive for adherence and that the active ingredient's taste can influence dosage-form choice and design, including taste-masking components. In interviews with 172 children aged 3–10 and 130 mothers in Philadelphia, 89 responding children (58.2%) described having refused medication; among 86 who gave a reason, 73 (84.9%) cited taste or flavor, whereas only 7 (8.1%) cited swallowing or choking.

The interview study's authors themselves say it is unknown how many actual medication failures are due solely to unpleasant taste and that prospective research is needed to understand individual differences. Regulatory documents repeatedly frame palatability as an important link between bitterness and adherence, but the strength of that link has not been supported by measurement in the materials checked here.

Methodological guidance on sensory evaluation of pharmaceutical formulations identifies confusion between actual bitterness and similar sensations such as sourness and astringency as the most common misuse of terms. It says vocabulary understood by panelists matters for characterizing product flavor accurately. The same guidance says taste is one of the major factors in formulation acceptability when the active ingredient contacts oral taste buds, and cites earlier research indicating that children are more sensitive than adults to bitterness, which is naturally aversive unlike sweetness.

A study of the same orally disintegrating tablet measured overall acceptability (palatability) as well as bitterness. During disintegration, overall palatability VAS scores were 38–46 for formulations comparable to no citric acid, but fell to 26 and 20 with 5% and 10% citric acid, respectively. Despite suppressing bitterness, higher citric-acid concentrations thus worsened overall palatability. After spitting out the tablet, however, formulations with 0.1% and 2.5% citric acid scored 54 and 55 for overall palatability, above the no-additive score of 44.