Patent ID: 7863278

Claim:
An isethionate salt of 6-acetyl-8-cyclopentyl-5-methyl-2-(5-piperazin-1-yl-pyridin-2-ylamino)-8H-pyrido[2,3-d]pyrimidin-7-one comprising a mono-isethionate salt of Form A, characterized by one or more of the following: a powder X-ray diffraction pattern having peaks at 2Î¸ values of about 8.7, 13.5, and 17.6, or a Raman spectrum having peaks at Raman Shift values of about 1600 cm âˆ’1 , 1290 cm âˆ’1 , 675 cm âˆ’1 , 470 cm âˆ’1 , 450 cm âˆ’1 , and 425 cm âˆ’1 , or a DSC thermogram having a sharp endotherm at about 273Â° C.