The subject invention provides pharmaceutical compositions Containing laquinimod or a pharmaceutically acceptable salt thereof, an isolated compound of N-ethyl-4-hydroxyl-1 -methyl-5- (methyl (2, 3,4,5, 6-pentahydroxyhexyl) amino) -2-oxo-N-phenyl-1, 2- dihydroquinoline- 3 -carboxamide or a salt thereof, compositions containing N-ethyl-4-hydroxyl-1-methyl-5- (methyl (2,3,4,5,6- pentahydroxyhexyl) amino) -2-oxo-N-phenyl-1, 2-dihydroquinoline-3-carboxamide and methods of preparing the same.