Drug-Tea Polyphenol Interaction (III) Incompatibility between Aripiprazole Oral Solution and Green Tea

The details of incompatibility between aripiprazole (ARIP) oral solution and green tea were examined. When the ARIP oral solution was mixed with a commercial PET bottled green tea beverage, the residual rate of ARIP in the mixed solution decreased to 15.7–17.6%. Mixing with ARIP reduced the content of gallate-type green tea polyphenols (GTPs) in the mixed solution but not the content of non-gallate-type GTPs. Furthermore, using pH 3.0 lactic acid buffer, 2.23 mM ARIP solution and 2.23 mM GTP solution were prepared, and the same volumes of ARIP solution and GTP solution were mixed. When the gallate-type GTP solution was mixed, the residual rate of ARIP in the mixed solution decreased. On the other hand, when the non-gallate-type GTP solution was mixed, the residual rate of ARIP in the mixed solution did not decrease. From the above results, it was found that the main reason for the incompatibility between ARIP oral solution and green tea was the formation of an insoluble substance composed of ARIP and gallate-type GTPs in green tea. Furthermore, experimental results using the continuous variation method revealed that ARIP and (−)-epigallocatechin gallate, which is the most representative gallate-type GTP, interact at a molar ratio of 3 : 2.