A fixing element for fixing a source of fluid material (12) in relation to a pen injector (14) so as to allow the introduction of fluid material (12) into the pen injector (14), the element comprising ( 22): a body (46) having a proximal end and a distal end and having a band (48) with opposite proximal and distal faces, a distal wall (52) extending distally from said distal face (50) of said band (48), said distal wall (52) comprising at least partially a distal chamber (54), elements formed on said body (46) for detachable mounting on a pen injector (14), and elements formed on said body (46) for mounting on a source of fluid material (12)； and a cannula (20) extending through said band (48), said cannula (20) having proximal and distal ends with a lumen (44) extending between them, said distal end (42) of said cannula being located (20) in said distal chamber (54) and being positioned such that, with the element (22) mounted on a pen injector (14), said distal end (42) is positioned to be in the pen injector ( 14), said proximal end of said cannula (20) being proximally beyond said proximal face of said band (48) and said proximal end of said body, such that, with the element (22) mounted to a source of fluid material (12), said proximal end of said cannula (20) is positioned to be in communication with the fluid material (12).Un elemento de fijación para fijar una fuente de material fluido (12) con relación a un inyector de bolígrafo (14) de modo que se permita la introducción del material fluido (12) en el inyector de bolígrafo (14), comprendiendo el elemento (22): un cuerpo (46) que tiene un extremo proximal y un extremo distal y que tiene una banda (48) con caras proximal y distal opuestas, extendiéndose una pared distal (52) distalmente desde dicha cara distal (50) de dicha banda (48), abarcando dicha pared distal (52) al menos parcialmente una cámara distal (54), unos elementos formados sobre dicho cuerpo (46) para el montaje desmontable sobre un inyector d
