This invention relates to a method for mixing a first injectable liquid pharmaceutical composition and a second injectable composition within an injection device, said injection device including:• a generally cylindrical barrel or a generally cylindrical shell in which a carpule is lodged,• at one first end of the generally cylindrical barrel or the generally cylindrical shell, a plunger, the plunger being mounted on the barrel or shell,• at a second end opposite the first end of the generally cylindrical barrel or the generally cylindrical shell, is provided a needle assembly support member, on which may be mounted a needle assembly, said needle assembly comprising means to be mounted on the needle support member, and further comprising:• at least one hollow canula for transportation of liquid from the barrel or carpule to the body of the patient• and at least one hub surrounding part of the canula and attached to canula said hub possibly including a hollow partcharacterized in that the first injectable composition is within the cylindrical barrel or the carpule and the second injectable composition is associated with the needle assembly, and further characterized in that the mixture of said first and said second composition occurs in the hub, in the carpule, or in the canula. The invention also relates to said device.
