A topical foam pharmaceutical composition for rectal administration comprising rifaximin in the form of nanosized particles is described. Also described is a method of making the composition and the use of the composition to as a medicament.L'invention concerne une composition pharmaceutique de mousse topique pour administration rectale, contenant de la rifaximine sous la forme de nanoparticules. L'invention concerne également un procédé de fabrication de la composition ainsi que l'utilisation de la composition comme médicament.