Interaction of weak base drug trimetazidine and carbopol as further retardation in the matrix tablet

Hydrophilic polymers using as matrix former in matrix tablets is a common approach and wellknown excipient Carbopol is widely used for this reason too. In common case polymer doesnit interact with drug but Carbopol is a weak polyacrylic acid and obviously can interact at physiological enteric conditions with weak base drugs like trimetazidine dihydrochloride. During matrix tablet dissolution at enteric conditions, the microenvironment pH inside tablet changes from surface to center. It was found that hydrated matrix has unusual structured in microenvironment pH diapason of possible trimetazidine-Carbopol interactions. This matrix structuration resulted in significant matrix behavior changing and increasing trimetazidine release retardation in comparison with release data at gastric conditions. Thus, the example of trimetazidine-Carbopol interactions demonstrate additional mechanism of drug retardation that could be used for another appropriate weak base drugs.