Abstract: The present invention relates to an innovative system which definitively prevents the re-use of syringes with retractable needles, allowing at the same time to fill the tank by means of a mechanical system installed inside the piston. The operation that aims at preventing the re-use of the device takes place through a mechanical system that prevents the return of the piston towards the initial position of aspiration and restricts, therefore, its action in a single direction and prevents the return of the plunger to the initial position of injection and therefore restricts its action in a single direction. Moreover a rotating mechanical transition system prevents the repositioning of the piston in the previously used position. The filling of the container, instead, takes place through the use of a system via a flexible cannula placed inside the piston.