. . . "The dissolution inhibitor may be represented by the following formula (I): wherein R1 and R2 each independently is a hydroxyl group, a C1-8 hydroxyalkyl group, or a C3-8 hydroxycycloalkyl group; R3, R4 and R5 each independently is a hydrogen, a C1-8 hydroxyalkyl group, a C1-6 carboxylic acid or a C3-8 carboxylic acid ester; k is an integer of 0, 1, 2, 3, 4, 5 or 6." . .