The present invention discloses a pharmaceutical composition including solid dispersion of cyclin inhibitor and preparation method thereof. In particular, the present invention relates to a compound of formula I 6- acetyl-8-cyclopentyl- 5-methyl-2- (5-piperazin-1-yl -pyridin-2-yl-amino) - 8H- pyrido [2,3-d] pyrimidin-7-one as an active ingredient of pharmaceutical composition, its preparation method and the use thereof. The said pharmaceutical composition comprises solid dispersion prepared by formula I, disintegrant, diluent, blinder, glidant or lubricant. Preparation solid disperision or using inclusion technology improves the dissolution and bioavailability of poorly soluble drugs.本發明公開了含有細胞週期蛋白抑制劑固體分散體的醫藥組成物及其製備方法。具體地，本發明涉及一種以式I所示的6-乙醯基-8-環戊基-5-甲基-2-(5-哌嗪-1-基-吡啶-2-基胺基)-8H-吡啶並[2,3-d]嘧啶-7-酮為活性成分的醫藥組成物及其製備方法和用途，該醫藥組成物包括式I化合物所製備的固體分散體、崩解劑、稀釋劑、黏合劑、助流劑或潤滑劑。藉由採用固體分散體或包合物技術，提高了難溶藥物的溶出度，改善了其體內生物利用度。
