This medical device (2) comprises a pre-filled syringe (3) comprising a syringe body (4) and a piston (16) mounted sliding in the syringe body (4), the syringe body (4) and the piston (16) delimiting an internal chamber (17) containing a fluid to be administered; and a package (21) in which the pre-filled syringe (3) is arranged, the package (21) comprising first and second package portions (22, 23) mounted movable relative to each other between a storage configuration in which the first and second package portions (22, 23) prevent the pre-filled syringe (4) from being removed from the package (21), and an open configuration in which the first and second package portions (22, 23) allow the pre-filled syringe (3) to be removed from the package (21), a movement of the first and second package portions (22, 23) from the storage configuration to the open configuration causing the piston (16) to move from a first piston position to a second piston position.