A combinatorial drug delivery device for delivering a predetermined selection of drug components, each of the drug components being contained in a drug vial, the device comprising: a plurality of serially-connected modules, wherein each of the modules is similarly formed and includes: a body having an interior volume formed to accommodate a drug vial; a cannula protruding into the interior volume, the cannula terminating at a free end, first and second openings being formed in the free end with first and second lumens (30A, 30B) extending therefrom and through the cannula; a socket located on an exterior portion of the body; a first passageway extending between, and in communication with, the socket and the first lumen; a boss protruding from an exterior portion of the body; and, a second passageway extending from, and in communication with the second lumen, the second passageway extending through the boss to terminate at an exit opening formed therein; a housing having a discharge passageway, wherein a first of the serially-connected modules is coupled to the housing with the second passageway of the first module being in communication with the discharge passageway, and, wherein a second of the serially-connected modules is coupled to the first module with the second passageway of the second module being in communication with the first passageway of the first module, the first module being located between the second module and the housing; and, a source of negative pressure for drawing the drug components from the drug vials of the serially-connected modules and into the discharge passageway, wherein the source of negative pressure is solely located inside the housing. a plurality of serially-connected modules, wherein each of the modules is similarly formed and includes: a body having an interior volume formed to accommodate a drug vial; a cannula protruding into the interior volume, the cannula terminating at a free end, first and second openings being formed in the free end with first and second lumens (30A, 30B) extending therefrom and through the cannula; a socket located on an exterior portion of the body; a first passageway extending between, and in communication with, the socket and the first lumen; a boss protruding from an exterior portion of the body; and, a second passageway extending from, and in communication with the second lumen, the second passageway extending through the boss to terminate at an exit opening formed therein; a body having an interior volume formed to accommodate a drug vial; a cannula protruding into the interior volume, the cannula terminating at a free end, first and second openings being formed in the free end with first and second lumens (30A, 30B) extending therefrom and through the cannula; a socket located on an exterior portion of the body; a first passageway extending between, and in communication with, the socket and the first lumen; a boss protruding from an exterior portion of the body; and, a second passageway extending from, and in communication with the second lumen, the second passageway extending through the boss to terminate at an exit opening formed therein; a housing having a discharge passageway, wherein a first of the serially-connected modules is coupled to the housing with the second passageway of the first module being in communication with the discharge passageway, and, wherein a second of the serially-connected modules is coupled to the first module with the second passageway of the second module being in communication with the first passageway of the first module, the first module being located between the second module and the housing; and, a source of negative pressure for drawing the drug components from the drug vials of the serially-connected modules and into the discharge passageway, wherein the source of negative pressure is solely located inside the housing.