This is generally directed to a drug delivery Device for the selection and distribution of several variables by a user, a dose of a drug.The device comprises a housing (10) having a tubular portion (12) with an inner thread, a plunger piston (30) that has a threaded portion (31) and a distal End, and a support (140) that has a proximal and a distal Face. (140) the support Rod comprises a retention (142) protruding from the proximal Face.(30) The piston rod includes a distal portion that has an outer diameter that is smaller than the inner diameter of the Inner thread of the tubular part (12) and which includes, in its distal End, at least one Fastener Retention (32, 33) which is coupled to the Shaft of R We therefore re (142).The axial length of the tubular part (12) is smaller or equal to the axial distance between the proximal Face of the support Disk (141) and the distal end of the threaded Rod part (31) of the piston (30).During the manufacture of the device, the Fastener Retention (32, 33) engages the retention rod (142) before the internal thread of the tubular part (12) coupling with the threaded Rod part (31) of the piston (30).La presente está dirigida generalmente a un dispositivo de administración de fármacos para la selección y la dispensación de varias dosis, variables por un usuario, de un medicamento. El dispositivo comprende un alojamiento (10) que tiene una parte tubular (12) con una rosca interior, un vástago (30) de pistón que tiene una parte roscada (31) y un extremo distal, y un apoyo (140) que tiene una cara distal y una cara proximal. El apoyo (140) comprende una varilla de retención (142) que sobresale desde la cara proximal. El vástago (30) de pistón comprende una parte distal que tiene un diámetro exterior que es más pequeño que el diámetro interior de la rosca interior de la parte tubular (12) y que comprende, en su extremo distal, por lo menos un sujetador de retención (33, 33) que se acopla a la varilla de retención (142). La longitud ax
