A syringe (1) for mixing and ejecting an active pharmaceutical ingredient is disclosed. The syringe (1) comprises a syringe body (2) defining a first lumen (8), a first plunger (4) arranged movably in said first lumen (8), said first plunger (4) being hollow, thereby defining a second lumen (9) being separated from the first lumen (8), and a second plunger (5) arranged movably in said second lumen (9). A liquid diluent is contained in one of the first lumen (8) and the second lumen (9), and an active pharmaceutical ingredient is contained in the other of the first lumen (8) and the second lumen (9). The second plunger (5) is movable in such a manner that the active pharmaceutical ingredient and the liquid diluent are brought together, e.g. in the first lumen (8) or in the second lumen (9), thereby causing the active pharmaceutical ingredient to be diluted by the diluent, and the first plunger (4) and/or the second plunger (5) is/are movable in such a manner that diluted active pharmaceutical ingredient can be ejected from the syringe (1). The syringe (1) provides a single device for mixing and ejecting the active pharmaceutical ingredient. This reduces the risk of contamination, and the syringe (1) can be easily operated by an untrained user.
