The capsule (11), which can be screwed onto the threaded neck (3) of the bottle, coaxially forms the cylinder (15) of the syringe device; an element (21) inside the capsule (11) and surrounding the cylinder (15) forms an annular leaktight seal (21A) which can be tightened onto the edge (3B) of the neck (3) and fits inside the bottle neck by means of a shaped extension piece (21B); said element (21) accommodates, via a central hole, the cylinder (15) of the syringe device and surrounds it with an annular lip (21C) which extends toward the center of the bottle so as to wipe the outer surface of the cylinder as the capsule (11) with the syringe device is pulled out. The capsule is fitted with a safety cap (29) and a seal (33).