A closure system for an applicator projection on a container for pharmaceutical preparations, said applicator projection extending along a theoretical longitudinal axis, having a through-opening and being formed for the connection of an applicator, comprising - a closure element with at least one region having a sealing surface for sealing the through-opening of the applicator projection, - sleeve-shaped connecting element for a friction-locked and/or interlocking connection with the container in the end region on the applicator side; - a closure securing unit which is arranged coaxially to the connecting element, surrounds said element in the circumferential direction and comprises a securing ring and a securing part which is severably connected to the securing ring via connecting means under irreversible destruction thereof, wherein the closure securing unit is formed to surround at least the end region of the applicator projection and the closure element in the circumferential direction around the longitudinal axis over a section of the extension in the longitudinal direction, and to fix the sleeve-shaped connecting element to the container by relative movement in the longitudinal direction in relation to the connecting element from a first to a second mounting position; characterized in that the closure element is at least indirectly detachably connected in a friction-locked and/or interlocking manner to a connecting part formed by the applicator projection or a functional element that carries said applicator projection or the securing ring, wherein the closure element, in a first functional position defined as the closure position, tightly seals the through-opening on the applicator projection in a pressure-tight, media-tight and microbially-tight manner, and the interlocking and/or friction-locked connection (22, 51) is arranged and formed in such a way that it is capable, after the severing of the securing part from the securing ring, of enabling a relative movement between the components involved in the connection (22, 51), especially the closure element and the connecting part, with a directional component in the direction of the longitudinal axis from the first functional position (closure position) to at least one further functional position (splash-protection and/or ventilation position) under at least partial maintenance of said connection (22, 51), wherein in the at least one further functional position the pressure-tight, media-tight and microbially-tight sealing of the through-opening on the applicator projection is eliminated by the closure element by forming an intermediate space formed between the closure element, the applicator projection and/or the connecting part. - a closure element with at least one region having a sealing surface for sealing the through-opening of the applicator projection, - sleeve-shaped connecting element for a friction-locked and/or interlocking connection with the container in the end region on the applicator side; - a closure securing unit which is arranged coaxially to the connecting element, surrounds said element in the circumferential direction and comprises a securing ring and a securing part which is severably connected to the securing ring via connecting means under irreversible destruction thereof, wherein the closure securing unit is formed to surround at least the end region of the applicator projection and the closure element in the circumferential direction around the longitudinal axis over a section of the extension in the longitudinal direction, and to fix the sleeve-shaped connecting element to the container by relative movement in the longitudinal direction in relation to the connecting element from a first to a second mounting position;