Bitterness evaluation of intact and crushed Vesicare orally disintegrating tablets using taste sensors

Objective Vesicare tablets, whose main component is solifenacin succinate, are known to be extremely bitter. The purpose of this study was to evaluate the effect of crushing on the bitterness of the Vesicare orally disintegrating tablets (ODTs). Method Vesicare ODTs and conventional Vesicare tablets (CTs) were crushed either heavily or lightly. The bitterness scores and release rates of sample solutions obtained 5, 10, 30, 60, 90 or 120 s after placing a crushed CT or ODT containing 5mg solifenacin in 40ml of water were predicted using two taste sensors (SA402B and a-ASTREE) and HPLC, respectively. The particle size and the surfaces of the crushed tablets were observed microscopically. Key findings The predicted bitterness scores and the drug release rates of CTs were high, irrespective of the degree of crushing. The lightly crushed ODT was predicted to be less bitter than the heavily crushed ODT. In lightly crushed ODTs, spherical particles were observed, about 200mm in diameter. Conclusions The degree of crushing was a critical factor in determining the expression of bitterness by crushed ODTs. When intact tablets of Vesicare must be crushed to adjust the dosage, it is strongly recommended that ODTs be crushed gently.