An injector device for automatic reconstitution of a substance comprising: a mechanism (12) adjusting the dose having a surface (57) engaging with the cartridge seextiende therefrom, said adjustment mechanism of the adjustable dose to define a dose for eldispositivo injector a housing (14) which engages cooperatively with said adjustment mechanism dela dose and means (94) thrust for selectively moving said adjusting mechanism of desdeuna dose first position to a second position relative to said housing, moving said surface (57) engaging with the cartridge a predetermined distance from said housing when dichomecanismo of titration is moved from said first position to said second position, further comprising a cartridge (216) of drug that has a distal end with an opening selladapor a wall (22) pierceable and one end (24) open proximal, a first plug (26) allowed eldeslizamiento and sealingly in said drug cartridge between said distal ends proximaly being located where the movement of said mechanism (12) adjusting the dose from said said posiciónhasta the said second position causes movement of said first stop (26) towards said end distalde said drug cartridge under the force of movement of said engaging surface with the cartridge, further comprising a button (140) release the cartridge engaged so operativacon said housing (14) to be movable selectively between release positions and deenclavamiento, wherein said drug cartridge includes a protuberance (144), wherein, when said cartuchode drug has said protuberance (144) located in said housing, and when said button (140) deliberation cartridge is in said locking position, said button (140) delcartucho release meshes with interference with said protrusion (144) after distal movement of said cartuchode drug with respect to said housing, thereby preventing removal of said cartridge (216) defármaco said housing, and wherein when said cartridge drug having said protuberance (144) estásituado in said housing (14), and when the
