(a) a fluid storage chamber for storing said liquid medicament, said fluid storage chamber having an output orifice through which said liquid medicament can be expelled;

(b) a single expandable pump chamber functionally connected to said fluid storage chamber by a moveable barrier, wherein the rate of movement of said moveable barrier caused by expansion of said pump chamber is adjustable to produce variable dosing under patient control;

(c) a hydraulic fluid reservoir functionally connected to a first actuator and having a high viscosity fluid stored therein, said hydraulic fluid reservoir fluidly connected to said pump chamber by a fixed aperture;

(d) a second actuator which physically acts on said pump chamber, wherein said second actuator is controlled independently of said first actuator; and

(e) a needle functionally connected to the output orifice for delivery of liquid medicament expelled from said fluid storage chamber to an individual,

wherein said pump chamber continuously expands upon actuation of said system with said first actuator;

wherein operating said first actuator causes said high viscosity fluid to flow into said pump chamber through said fixed aperture at a constant rate, thereby displacing said moveable barrier to compress said fluid storage chamber and causing a quantity of said liquid medicament to be expelled through said orifice;

wherein operating said second actuator independently causes displacement of said moveable barrier to compress said fluid storage chamber, thereby causing a quantity of said liquid medicament to be expelled; and

wherein concurrently operating both of said first and second actuators causes displacement of the moveable barrier to compress said fluid storage chamber at an increased rate relative to operating either actuator alone.