Patent ID: 8021334

Claim:
A drug delivery device for metered delivery of a liquid medicament to an outlet, the device comprising: (a) a pressurized reservoir configured for storing and supplying the liquid medicament at a pressure above atmospheric pressure; (b) a flow path in fluid communication with said pressurized reservoir and the outlet, said flow path including: (i) a first valve assuming a normally-closed flow-blocking state and selectively actuatable to an open state which permits fluid flow through said first valve, (ii) a flow restriction configured to limit fluid flow along said flow path, and (iii) a second valve assuming a normally-closed flow-blocking state and selectively actuatable to an open state which permits fluid flow through said second valve, such that, when both said first valve and second valve are in said open state, the liquid medicament flows from the pressurized reservoir along said flow path to the outlet at a rate limited primarily by said flow restriction; (c) a pressure measurement arrangement deployed in pressure-sensing engagement with a first point and a second point along said flow path, at least part of said flow restriction being between said first and second points, one of said first and second points being intermediate to said first and second valves; and (d) a controller electronically associated with said pressure measurement arrangement and said first and second valves, and configured to selectively open said first and second valves to deliver a defined quantity of the liquid medicament to the outlet.