Syringe with internal safety device

A syringe comprising:

• a syringe cylinder including a proximal end having an opening and a distal end having a needle attachment piece;
• a sealing plug movably disposed within the syringe cylinder;
• a plunger received within the opening and cooperating with the sealing plug;
• and
• a safety device disposed within the syringe cylinder that prevents a sliding back of the sealing plug within the syringe cylinder in any position the sealing plug assumes within the syringe cylinder, the safety device including a retaining fixture and a locking element, the retaining fixture distally extending into the syringe cylinder from proximate the proximal end, the locking element carried at a distal end of the retaining fixture and operative to engage the plunger in any position the plunger assumes within the syringe cylinder;
• wherein the locking element is attached to the retaining fixture and protrudes from the retaining fixture in such a manner that an attachment point of the locking element is closer to the sealing plug at the retaining fixture than the free end of the locking element opposite of the attachment point;
• wherein the locking element is pivotally coupled to the retaining fixture at the attachment point, the locking element assumes a releasing position when the plunger is pushed into the syringe cylinder and a locking position when the plunger is moved in an opposite direction, wherein the locking element defines an angle of 90° with a center axis of the plunger, which is larger in the releasing position than in the locking position, the angle opening towards the upper end of the syringe cylinder opposite of the needle attachment piece.