The present invention provides a pharmaceutical composition comprising a pyrrolo-fused six-membered heterocyclic compound or a pharmaceutically acceptable salt of the compound. Specifically, the invention provides a pharmaceutical composition comprising 5-(2-diethylamino-ethyl)-2-(5-fluoro-2-oxo-1, 2-dihydro-indol-3-ylidene-methyl)-3-met hyl-1, 5, 6, 7-tetrahydro-pyrrolo[3, 2-c]pyridin-4-one or a pharmaceutically acceptable salt thereof, and at least one water soluble filler. The pharmaceutical composition of the invention features rapid dissolution and good stability.