The present invention relates to purified 3-methanesulfonylpropionitrile or a pharmaceutically acceptable salt thereof, and a method for preparing such compound. The compound has at least 90% (w/w) purity. The present invention is also directed to a pharmaceutical composition comprises the purified compound and a pharmaceutically acceptable carrier. The present invention is further directed to a method for treating inflammation, inflammatory-related disorders, or pain, by administering 3-methanesulfonylpropionitrile or a pharmaceutically acceptable salt or solvate thereof to a subject in need thereof.