Disclosed are novel pharmaceutical formulations containing N-{3-[3-cyclopropyl-5- (2-fluoro-4-iodo-phenylamino)-6,8-dimethyl-2,4,7-trioxo-3,4,6,7 -tetrahydro-2H- pyrido[4,3-d]pyrimidin-1 -yl]phenyl}acetamide dimethyl sulfoxide solvate, methods of using the compositions in therapy and processes for preparing the same.Se divulgan composiciones farmacéuticas novedosas que contienen solvato de dimetilsulfóxido de N-{3-[3-ciclopropil-5-(2-fluoro-4-y odo-fenilamino)-6,8-dimetil-2,4,7-trioxo-3,4,6,7-tetrahidro-2H-pi rido-[4,3-d]pirimidin-1-il]fenil}acetamida, métodos para usar las composiciones en terapia y procesos para la preparación de las mismas.