A solid dispersion comprising an amorphous thienotriazolodiazepine compound of the Formula (I), wherein X is a halogen, R1 is C1-C4 alkyl, R2 is C1-C4 alkyl, a is an integer of 1-4, R3 is C1-C4 alkyl, C1-C4 hydroxyalkyl, C1-C4 alkoxy, phenyl optionally having substituent(s), or heteroaryl optionally having substituent(s), a pharmaceutically acceptable salt thereof or a hydrate thereof； and a pharmaceutically acceptable polymer. In one embodiment, the pharmaceutically acceptable polymer is HPMCAS. The solid dispersion may be made by spray drying.
