An injection kit comprising: - a re-usable syringe; - a tubular vial; - a needle mounted within a through cavity of a bushing member that can be coupled to said re-usable syringe; said tubular vial comprising: - a tubular casing; - a diaphragm at a first end of said tubular casing, and - a piston sealingly arranged within said tubular casing and axially movable between a second end of said tubular casing, opposite to said first end, and said first end; said piston for a tubular vial, comprising: - a longitudinal axis; - a skirt coaxial to said longitudinal axis and configured for guiding the piston along an inner surface of a tubular vial; and - an axial extension comprising an axial cavity and including an outer surface and an inner surface, the inner surface facing said axial cavity, wherein: said axial extension comprises at least one through opening extending from said outer surface to said inner surface; the intersection of said at least one through opening with said outer surface has an open perimeter; and the intersection of said at least one through opening with said inner surface has an open perimeter; characterized in that said axial extension moreover comprises at least one further through opening extending from said outer surface to said inner surface, and wherein: the intersection of said at least one further through opening with said outer surface has a closed perimeter; and the intersection of said at least one further through opening with said inner surface has a closed perimeter; - said needle is configured for irreversibly coupling with said piston upon a displacement of said piston in a direction proceeding from the second end of said tubular casing towards the first end of said tubular casing; - said needle comprises a proximal end configured for penetration into the body of a patient and a distal end configured for penetration into the diaphragm of the tubular vial; and - said needle further comprises a jacket including a distal stud having a shoulder, said shoulder being configured for bearing upon a shoulder provided in the axial cavity of said axial extension, and wherein said distal end of the needle protrudes over said distal stud, and further wherein a free end of the axial extension of said piston is configured for overstepping said distal stud upon coupling with said needle. - a re-usable syringe; - a tubular vial; - a needle mounted within a through cavity of a bushing member that can be coupled to said re-usable syringe; - a tubular casing; - a diaphragm at a first end of said tubular casing, and - a piston sealingly arranged within said tubular casing and axially movable between a second end of said tubular casing, opposite to said first end, and said first end; - a longitudinal axis; - a skirt coaxial to said longitudinal axis and configured for guiding the piston along an inner surface of a tubular vial; and - an axial extension comprising an axial cavity and including an outer surface and an inner surface, the inner surface facing said axial cavity, wherein: said axial extension comprises at least one through opening extending from said outer surface to said inner surface; the intersection of said at least one through opening with said outer surface has an open perimeter; and the intersection of said at least one through opening with said inner surface has an open perimeter; characterized in that said axial extension moreover comprises at least one further through opening extending from said outer surface to said inner surface, and wherein: the intersection of said at least one further through opening with said outer surface has a closed perimeter; and the intersection of said at least one further through opening with said inner surface has a closed perimeter; said axial extension comprises at least one through opening extending from said outer surface to said inner surface; the intersection of said at least one through opening with said outer surface has an open perimeter; and the intersection of said at least one through opening with said inner surface has an open perimeter; characterized in that said axial extension moreover comprises at least one further through opening extending from said outer surface to said inner surface, and wherein: the intersection of said at least one further through opening with said outer surface has a closed perimeter; and the intersection of said at least one further through opening with said inner surface has a closed perimeter; the intersection of said at least one further through opening with said outer surface has a closed perimeter; and the intersection of said at least one further through opening with said inner surface has a closed perimeter; - said needle is configured for irreversibly coupling with said piston upon a displacement of said piston in a direction proceeding from the second end of said tubular casing towards the first end of said tubular casing; - said needle comprises a proximal end configured for penetration into the body of a patient and a distal end configured for penetration into the diaphragm of the tubular vial; and - said needle further comprises a jacket including a distal stud having a shoulder, said shoulder being configured for bearing upon a shoulder provided in the axial cavity of said axial extension, and wherein said distal end of the needle protrudes over said distal stud,