The invention is directed to a drug delivery device comprising a preloaded syringe including a sterile hollow needle, a barrel in fluid communication with said sterile hollow needle, a plunger slidingly sealing a proximal end of said barrel and discharging a contents of said barrel out of said hollow needle, a flange and a needle cover preserving sterility of said sterile hollow needle； a proximal housing portion including a motor assembly； and a transmission converting a rotation motion of said motor assembly to a linear motion； and a distal housing portion including a channel fitting said preloaded syringe, said channel including a distal opening large enough for inserting said preloaded syringe into said channel, a proximal opening large enough to allow said sterile hollow needle to protrude from a proximal end of said proximal housing portion, wherein when said syringe is inserted into said channel, joining a distal end of said proximal housing to a proximal end of said distal housing operationally connects said transmission to said plunger such that activating said motor brings about discharging of said contents of said barrel, characterized in that, the distal housing includes an adhesive base (2442) for fastening said distal housing portion to a skin of a patient, the adhesive base (2442) including a needle aperture, in that an activation device is provided including: a handle (2394) accessible from outside of said channel (2488), an attachment mechanism exposed to said channel (2488), such that when said preloading syringe is fully inserted into said channel (2488), said attachment mechanism attaches to said needle cover, a coupler (1871, 1971) passing through the needle aperture in said adhesive base (2442), said coupler (1871, 1971) connecting said handle (2394) to said attachment mechanism, and an adhesive cover (2389) for said adhesive base (2442) connected to said handle (2394) by an extender for peeling said adhesive cover (2389) from said adhesive bas
