The present invention relates to co-crystals of tramadol and co-crystal formers selected from NSAIDs/coxibs, processes for preparation of the same and their uses as medicaments or in pharmaceutical formulations, more particularly for the treatment of pain. In a preferred embodiment, the co-crystal is (rac) - tramadol. HcI - celecoxib (1:1).La presente invención se refiere a co-cristales de tramadol y formadores de co-cristal seleccionados de NSAIDs/coxibs, procesos para preparación de los mismos y sus usos como medicamentos o en formulaciones farmacéuticas, más particularmente para el tratamiento del dolor.
