Disclosed is a pharmaceutical preparation having 6-acetyl-8-cyclopentyl-5-methyl-2-(5-piperazine-1-yl-pyridine-2-yl amino group)-8H-pyrido[2,3-d]pyrimidine-7-one or salt thereof as an active ingredient, the salt comprising hydrochloride or isethionate, and the dosage form thereof comprising tablets and capsules both having good stability and excellent dissolution performance.
