Antimetabolites are used to treat organ transplant rejection, certain cancers, and autoimmune disorders. They also have other uses, such as treating blood disorders. One way this broad medication class is thought to work is by interfering with DNA or RNA production, which stops the growth of rapidly-dividing cells. These medications come in different forms, including oral pills and injections. Examples include mycophenolate (CellCept), azathioprine (Imuran, Azasan), and hydroxyurea (Hydrea, Droxia, Siklos).