Patent ID: 7670314

Claim:
A manually-powered injection device for painless intramuscular injection of an injectable liquid composition from with a reservoir, comprising: a) a housing having a base for semi-permanent attachment to the skin of a patient, b) an injection needle disposed substantially perpendicular to the base and within the housing, the needle having an injection end, and configured for axial movement manually between a first position wherein the injection end is within the housing and a second position wherein the injection end extends outwardly from the base to a distance sufficient for intramuscular insertion thereof, the injection needle having an outside diameter greater than 0.10 mm and less than about 0.38 mm that effects a painless insertion of the needle, c) a means for retaining a reservoir containing an injectable liquid composition, d) a means for providing liquid communication between the retained reservoir and the injection needle, and e) a manually-powered spring that exerts pressure upon the injectable liquid composition within the retained reservoir to inject the injectable liquid at a substantially constant volumetric flow rate of about 0.5 μL/s to about 20 μL/s from the reservoir through the needle, which effects a painless injection.