Abstract: The present invention relates to syringes for apportioning set doses from an ampoule has a dose setting and injection mechanism comprising a dose setting member which may be moved in one direction to set a dose and in the opposite direction to inject the set dose. A piston advancing mechanism comprises a piston rod and a piston rod drive, and the dose setting and injection mechanism is coupled to the piston advancing mechanism through a unidirectional coupling transmitting only movement of the dose setting member in the dose injecting direction to the piston rod drive. Operation of an air shot button enables influence on the piston advancing mechanism to advance the piston to expel an adjustable fixed volume. The air shot button is either coupled to the piston rod drive through a unidirectional coupling through which the piston rod is advanced when the air shot button is pressed, or it moves the end stop for an injection button so that this button may be pressed beyond its normal depressed end position.

Abstract: A kit for mixing comprises a housing accommodating an ampoule containing a solid and a container containing a solvent which is either pre-pressurized or which may be pressurized when it is desired to mix to the liquid and solid components. A needle unit comprises a first needle, the opposite ends of which pierce rubber membranes closing the ampoule and the container, to establish a transport channel through which pressurized solvent flows from the container to the ampoule. The ampoule is vented through a second needle inserted through the membrane of the ampoule and provided with a micro-filter. In one embodiment, the needle unit is displaceable to cause the ends of the needles to pierce the respective membranes, and locked in place by a spring biased locking mechanism. A branch passage from the needle is connected to a cylinder containing a piston coupled to the locking mechanism. When the ampoule is full, pressure in the branch passage will rise, actuating the piston and releasing the locking mechanism.