Tamper evident syringe and cap

A syringe that provides evidence of tampering, comprising:

• a syringe barrel having a chamber that holds a fluid;
• an adapter section formed on the syringe barrel, the adapter section including outer and inner walls that form a first groove, wherein the inner wall includes barrel threads and the outer wall includes a first projection, the adapter section further including a fluid passageway that enables fluid communication with the chamber;
• a moveable plunger having a plunger flange that moves forward within the chamber to decrease a volume of the chamber to cause the fluid to be forced out of the fluid passageway;
• a cap having cap threads that threadably engage the barrel threads to removably attach the cap to the adapter section wherein the cap encloses the fluid passageway and wherein the cap further includes a second groove;
• and
• a locking element having a sidewall that includes a second projection, wherein the locking element is received by the first groove and wherein the locking element is removably attached to the cap by an interference fit between the sidewall and the second groove,
• wherein rotation of the cap causes upward movement of the cap that overcomes the interference fit between the cap and locking element thereby removing the cap from the adapter section and wherein the locking element is prevented from being removed from the first groove due to contact between the first and second projections wherein presence of the locking element in the first groove after the cap is removed provides evidence of tampering and
• wherein a depth of the first groove is larger than a height of the locking element such that the locking element does not extend beyond the first groove to inhibit re-insertion of the locking element back into the first groove after the cap is removed.

A method of detecting tampering of a syringe, the method comprising:

• providing a syringe barrel having a chamber that holds a fluid;
• providing an adapter section on the syringe barrel, the adapter section including outer and inner walls that form a first groove, wherein the inner wall includes barrel threads and the outer wall includes a first projection, the adapter section further including a fluid passageway that enables fluid communication with the chamber;
• providing a moveable plunger having a plunger flange that moves forward within the chamber to decrease a volume of the chamber to cause the fluid to be forced out of the fluid passageway;
• providing a cap having cap threads that threadably engage the barrel threads to removably attach the cap to the adapter section wherein the cap encloses the fluid passageway and wherein the cap further includes a second groove;
• and
• providing a locking element having a sidewall that includes a second projection, wherein the locking element is received by the first groove;
• forming an interference fit between the sidewall and the second groove to removably attached the cap;
• providing upward movement of the cap to overcome the interference fit between the cap and locking element thereby removing the cap from the adapter section;
• providing contact between the first and second projections during upward movement of the cap;
• and
• preventing removal of the locking element from the first groove due to contact between the first and second projections wherein presence of the locking element in the first groove after the cap is removed provides evidence of tampering.