SYRINGE ASSEMBLY HAVING DISABLING MECHANISM

摘要

A syringe assembly (20) having passive disabling structure includes a bar rel (21) and a plunger rod assembly (43, 81, 71). The plunger rod (43) assem bly includes a plunger rod and a stopper (81) connected by an indexing locki ng element (71). The number of strokes of the syringe plunger before the sto pper, is locked into the barrel rendering the syringe assembly unusable is d etermined by the number of detents on the plunger rod and stopper which enga ge the locking mechanism. Upon completion of the final delivery stroke, any attempt to withdraw the plunger rod from the barrel will cause the locking e lement to engage the barrel and trap the stopper in the barrel preventing fu rther use of the syringe.