Prefilled disposable injection device

Abstract

The present invention relates to drug delivery systems that cannot be reloaded or reused and further include a passive safety shield system. The drug delivery devices described herein comprise a drug container comprising at least one bellow, wherein the at least one bellow comprises a first surface and an opposing second surface, wherein the first surface is comprised of a first Belleville spring and the opposing second surface is comprised of a second Belleville spring, wherein the second Belleville spring has a higher spring rate than the first Belleville spring; or a drug container extending between distal and proximal ends, and comprises a continuous change in cross section from proximal end to distal end; a needle, wherein the needle is in liquid communication with the drug container; a plunger extending between a proximal end and a distal end, wherein the plunger is in communication with the drug container and where upon axial movement of the punger, the drug container is compressed; a main body extending between a proximal end and a distal end and comprising an inner body and an outer body, wherein the inner body houses the plunger and the drug container and the outer body is capable of sliding over the inner body and extending past the needle; and a spring located between the inner body and the outer body for urging the outer body to slide over the inner body and extend past the needle.