A combination cartridge and cartridge interface assembly comprising: a cartridge comprising: a substance therein for administration to a subject; an inner wall, a first plunger slidingly inserted in the cartridge that moves linearly in the cartridge as the cartridge is filled with the substance, wherein the first plunger is in an initial position before filling of the cartridge with the substance, and a distal end a cartridge interface assembly comprising: a driving plunger including an outer shaft, the driving plunger being initially distanced away from the first plunger when the first plunger is at the initial position; and a driver comprising: an inner shaft that mates with an outer shaft, the inner shaft and the outer shaft being movable telescopically with respect to one another, wherein rotation of said driver causes said driving plunger to linearly advance towards the first plunger, the arrangement being such that on insertion of the cartridge interface assembly in the cartridge, friction of the driving plunger against the inner wall of the cartridge is such that it is much easier for the driving plunger to move linearly than to rotate, and wherein rotation of said driver causes said driving plunger to advance distally in the cartridge until the driving plunger abuts against the plunger whereupon the driving plunger urges the first plunger towards the distal end of the cartridge during filling of the substance for metering of the substance from the cartridge. a cartridge comprising: a substance therein for administration to a subject; an inner wall, a first plunger slidingly inserted in the cartridge that moves linearly in the cartridge as the cartridge is filled with the substance, wherein the first plunger is in an initial position before filling of the cartridge with the substance, and a distal end a cartridge interface assembly comprising: a substance therein for administration to a subject; an inner wall, a first plunger slidingly inserted in the cartridge that moves linearly in the cartridge as the cartridge is filled with the substance, wherein the first plunger is in an initial position before filling of the cartridge with the substance, and a distal end a cartridge interface assembly comprising: a driving plunger including an outer shaft, the driving plunger being initially distanced away from the first plunger when the first plunger is at the initial position; and a driver comprising: an inner shaft that mates with an outer shaft, the inner shaft and the outer shaft being movable telescopically with respect to one another, wherein rotation of said driver causes said driving plunger to linearly advance towards the first plunger, the arrangement being such that on insertion of the cartridge interface assembly in the cartridge, friction of the driving plunger against the inner wall of the cartridge is such that it is much easier for the driving plunger to move linearly than to rotate, and wherein rotation of said driver causes said driving plunger to advance distally in the cartridge until the driving plunger abuts against the plunger whereupon the driving plunger urges the first plunger towards the distal end of the cartridge during filling of the substance for metering of the substance from the cartridge. an inner shaft that mates with an outer shaft, the inner shaft and the outer shaft being movable telescopically with respect to one another, wherein rotation of said driver causes said driving plunger to linearly advance towards the first plunger, the arrangement being such that on insertion of the cartridge interface assembly in the cartridge, friction of the driving plunger against the inner wall of the cartridge is such that it is much easier for the driving plunger to move linearly than to rotate, and wherein rotation of said driver causes said driving plunger to advance distally in the cartridge until the driving plunger abuts against the plunger whereupon the driving plunger urges the first plunger towards the distal end of the cartridge during filling of the substance for metering of the substance from the cartridge.