Hollow needle applicator for cartridged drugs

A hollow needle applicator for cartridged drugs etc which affords automatic needle retraction after cartridge contents expression, the applicator comprising a hollow elongate body having a top portion and a bottom portion and that, at least in operation, houses

• a hollow drugs etc cartridge biased toward the bottom portion of the body and having side walling slidable in the body and a discharge piston with a piston rod extending out of the cartridge as such longitudinally of the body, and
• a hollow piston actuator biased toward the top portion of the body and slidable in the body and capable of at least partially bodily accommodating the cartridge as well as the piston rod;
• the piston rod having deflectable arms that extend sideways further than the side walling of the cartridge, the piston actuator having receiving formations with which the deflectable arms make temporary driving engagement until the deflectable arms are engaged and released during bias driven movement of the piston actuator toward the bottom portion of the body before bias driven movement of the cartridge toward the bottom portion of the body, and a triggering ring about the cartridge to serve in first engaging the deflectable arms to initiate retraction of the cartridge and piston rod after cartridge contents expression.