Abstract: Syringe having a plunger, a barrel and a restrictor mechanism between the shaft of the plunger and the barrel and including a first part engaged with the barrel for limiting movement of the first part with respect to the barrel in a first direction, and a second part. The restrictor mechanism and/or plunger shaft carries a formation for limiting movement of the restrictor mechanism with respect to the plunger in the first direction. The restrictor mechanism as a further member which restricts movement of the restrictor mechanism with respect to the barrel or plunger shaft in a second direction. A latch member prevents he further member from restricting movement of the restrictor mechanism with respect to the barrel or plunger shaft in the second direction until a predetermined point in an operation cycle of the syringe.

Abstract: A disposable syringe (2) is disclosed. Withdrawal of a plunger handle (18) in the direction of arrow B to fill the syringe causes a moveable safety bobbin (20) to lock, and shaft (16) slides in the direction of arrow B relative to safety bobbin (20) and washer (22). Subsequent depression of plunger handle (18) in the direction of arrow A causes safety bobbin (20) to move along barrel (4), from which position it can not be withdrawn. This therefore prevents subsequent withdrawal of piston (14) and therefore prevents re-use of the syringe.

Abstract: An auto-disable syringe (50,150) is disclosed which prevents re-use of the syringe whatever dose is delivered on the first use. A restrictor bobbin comprises an element (1,100) which spans the barrel of the syringe and which, after initial distal movement of the plunger (52, 152) rotates and wedges in the barrel when the plunger is moved proximally. The wedged restrictor bobbin (1, 100) prevents further substantial proximal movement of the plunger (52, 152) whilst allowing further distal movement. A small degree of repeated proximal and distal movement is permitted to allow for an aspiration step.