A one-piece dispensing device for the contamination-free administration of medicaments (cytostatica) is particularly suitable for use in ambulant treatment. The invention provides a connector for connecting medicament (cytostatica) containers to instruments by which the medicaments are administered. The connector is designed to prevent, without a complex apparatus, contamination of the surroundings during connection of the container and until its disposal. The dispensing device has at least one coupling member to create a non-releasable connection with a medicaments container. The coupling member has an insertion pin and barbed surfaces to accommodate the medicaments container. The coupling member is non-releasably connected via a tube to a flexible container which is to be filled with gas. The flexible container is non-releasably connected to a further tube outlet and a mechanically actuated stop valve is incorporated in each of the connecting tubes.