Automatic injection device

An automatic injection device for delivering a dose from a medicine-containing syringe, the injection device comprising:

• an outer casing comprising a first opening at a proximal end and a second opening at a distal end;
• a housing configured to contain the syringe, the housing being disposed within the outer casing and being axially movable within the outer casing, a proximal end of the housing being configured to pass through the first opening of the outer casing;
• a firing mechanism configured to apply a force to eject medicine from the syringe;
• a trigger coupled to the firing mechanism and configured to release the firing mechanism to cause an injection, the trigger being attached to the housing and configured to release the firing mechanism when the trigger is moved axially in a proximal direction relative to the housing, the trigger being configured to pass through the second opening of the outer casing;
• a boot covering a needle attached to the syringe to protect and maintain sterility of the needle;
• a first mechanical interlock configured to prevent actuation of the trigger prior to removal of the boot and to allow actuation or commencement of an actuation sequence following removal of the boot;
• a second mechanical interlock configured to detect pressure applied to the device by a user's skin following removal of the boot, and configured to prevent actuation of the trigger in absence of pressure and to allow actuation when sufficient pressure is detected;
• and
• a boot remover configured to remove the boot,
• wherein the boot remover provides said first mechanical interlock, the boot remover being disposed at the proximal end of the outer casing, and being further disposed, prior to removal, to hold the housing in a first position,
• wherein, in the first position, the housing is disposed proximally relative to the outer casing such that the proximal end of the housing projects through the first opening of the outer casing and the trigger is held within the outer casing, thereby restricting access to the trigger.