Tea Beverage-Dependent Reduction in Risperidone Concentration Following Mixing with Risperidone Oral Solution

Risperidone (RIS) oral solution has a bitter taste and is sometimes mixed with beverages to improve palatability and medication adherence. Although the package insert advises against mixing with tea beverages, the effects of beverage type and tea leaf variety on RIS concentration remain unclear. RIS oral solution was mixed with commercially available black tea, green tea, and hojicha beverages, and black tea leaf extracts. RIS concentration in the supernatant was quantified by high-performance liquid chromatography, and its recovery from precipitates was evaluated in selected samples. RIS concentration decreased in all black tea and green tea beverages and black tea extracts, whereas some hojicha beverages showed no significant decrease. The extent of reduction differed among beverage types and black tea leaf varieties. RIS was substantially recovered from precipitates redissolved in methanol or dissolution test fluid 1 (pH 1.2), whereas recovery from dissolution test fluid 2 (pH 6.8) was lower. Chromatographic and UV spectral analyses supported the presence of RIS in redissolved precipitates. The reduction in RIS concentration is associated, at least in part, with transfer into precipitates and depends on beverage type and tea leaf variety. These findings support the recommendation to avoid diluting RIS oral solution with tea beverages.