A
safety shield system for a needle cannula of a pen needle
injector or similar device, wherein a
safety shield may be retracted from a first position enclosing the needle cannula to a second position exposing the needle cannula for injection. The
safety shield system permits retraction of the safety shield during use, but extends the shield enclosing the needle cannula in a locked position following use. The shield
system is utilized with a pen needle
injector having a double-ended needle cannula mounted in a hub member received on an open end of the pen needle
injector. The
assembly is disposed of by removing the system and storing the
assembly in the cup-shaped
top cap enclosing the exposed end of the needle cannula within the cap. The
top cap includes internal radial ribs preventing retraction of the shield prior to removing the
top cap preventing inadvertently piercing the top cap during
assembly. In addition, a bottom cap may be interlocked to the top cap to completely encompass the needle cannula, thereby ensuring safe disposal of the assembly.