Auto-injector device

An auto-injector for hypodermic delivery of medication comprising:

• a housing;
• a medication cartridge positioned within the housing, the cartridge including a pierceable septum;
• a cartridge holder positioned within the housing and configured to receive the medication cartridge, the cartridge holder being moveable between a first position and a second position proximal from the first position, wherein, in the first position, the cartridge holder is prevented from moving in a proximal direction;
• a hollow injection needle having a longitudinal cavity therethrough and positioned within the housing, the needle being moveable between a first position and a second position, wherein, in the first position, the needle cavity is not in fluid communication with an interior of the cartridge, and in the second position, the needle cavity is in fluid communication with the interior of the cartridge;
• a cap, releasably attached to the housing, such that during removal of the cap from the housing, the needle moves from the first position to the second position so as to cause a distal end of the needle to pierce the septum of the cartridge;
• a moveable plunger rod positioned within the housing and biased to move in the proximal direction;
• a plunger release latch positioned within the housing to releasably retain the plunger rod in a locked position;
• and
• a moveable needle shield that moves from an extended position in which the needle shield is extended proximally beyond the needle to a retracted position where at least an end of the needle is exposed during injection;
• and
• wherein retraction of the needle shield to the retracted position causes propulsion of medication through the needle and
• wherein distal movement of the needle shield to the retracted position releases the cartridge holder from the first position and releases the latch to allow the plunger rod to move in the proximal direction and urge the cartridge holder from the first position to the second position.

An auto-injector for hypodermic delivery of medication, comprising:

• a housing;
• a cartridge holder positioned within the housing and configured to receive a medication cartridge, the cartridge holder being moveable between a first position and a second position proximal from the first position, wherein, in the first position, the cartridge holder is prevented from moving in a proximal direction;
• a moveable plunger rod positioned within the housing and biased to move in the proximal direction;
• a plunger release latch positioned within the housing to releasably retain the plunger rod in a locked position;
• a hollow injection needle having a longitudinal cavity through which medication can pass from the medication cartridge;
• and
• a needle shield movable relative to the cartridge holder between an extended position enclosing the needle and a retracted position in which at least an end of the needle is not enclosed by the needle shield;
• a. wherein distal movement of the needle shield both releases the cartridge holder from the first position and releases the latch to cause the plunger rod to move in the proximal direction and urge the cartridge holder from the first position to the second position.

A subassembly for an auto-injector, comprising:

• a cartridge holder, configured to receive a medication cartridge;
• a hollow injection needle having a longitudinal cavity therethrough through which medication can pass from the medication cartridge;
• a needle shield movable relative to the cartridge holder between an extended position enclosing the needle and a retracted position in which at least an end of the needle is not enclosed by the needle shield;
• a shell, at least partially encompassing the cartridge holder and the needle shield;
• and
• a removable cap which releasably locks the shell and needle shield such that, when in place, the cap prevents the needle shield and shell from moving relative to each other and, when removed, allows relative movement between the shell and needle shield;
• wherein the shell is configured to releasably connect to a second subassembly so as to form the auto-injector.