Drug delivery device

Abstract

There is provided drug delivery devices comprising a drug container assembly with a needle and automatic needle insertion and drug delivery mechanisms. Aspects of the devices described include a noise-generation mechanism to indicate the completion of drug delivery, a mechanism for triggering drug delivery following needle insertion, front-end activation of the device and a safety mechanism for covering the needle after use and methods of assembly of the devices.

What is claimed is: 
     
         1 . A needle assembly comprising:
 a hypodermic needle;   a needle hub to which the needle is fixed at a first end;   a needle shield coupled to the needle hub and covering a second end of the needle; wherein the needle shield comprises a rigid body, the rigid body providing a sterile barrier around at least a portion of the needle; and   a compliant element within the rigid body, the compliant member providing a liquid tight seal around the second end of the needle,   wherein the rigid body is configured to provide an interference fit with the needle hub and thereby provides a seal around the needle hub.   
     
     
         2 . A needle assembly according to  claim 1 , wherein the rigid body is formed from a moulded plastics material. 
     
     
         3 . A needle assembly according to  claim 2 , wherein the rigid body is formed from a high density polyethylene or polypropylene. 
     
     
         4 . A needle assembly according to  claim 1 , comprising at least one circumferential rib on an interior surface of the rigid body. 
     
     
         5 . A needle assembly according to  claim 1 , comprising at least one circumferential rib on an external surface of the needle hub. 
     
     
         6 . A needle assembly according to  claim 4 , comprising at least two circumferential ribs on the interior surface of the rigid body. 
     
     
         7 . A needle assembly according to  claim 6 , wherein a radius of curvature at a contact point of each rib before the rigid body is fitted to the needle hub is less than 0.6 mm. 
     
     
         8 . A needle assembly according to  claim 1 , wherein the needle hub has a surface finish having a maximum distance between peak and trough of 2 microns or less. 
     
     
         9 . A needle assembly according to  claim 1 , wherein the needle hub has a circular cylindrical outer surface to which the rigid body is coupled. 
     
     
         10 . A needle assembly according to  claim 1 , wherein the needle hub is formed from a moulded plastics material. 
     
     
         11 . A needle assembly according to  claim 10 , wherein the needle hub is formed from a cyclic olefin polymer. 
     
     
         12 . A needle assembly according to  claim 1 , wherein the rigid body comprises an external surface having at least one protrusion or recess. 
     
     
         13 . A needle assembly according to  claim 1 , wherein at least a portion of the rigid body is transparent. 
     
     
         14 . A needle assembly according to  claim 1 , wherein the compliant element is only partially enclosed by the rigid body and needle hub. 
     
     
         15 . A needle assembly according to  claim 1 , wherein the compliant element is fully enclosed by the rigid body and needle hub. 
     
     
         16 . A needle assembly according to  claim 1 , wherein the compliant element is retained in the rigid body by at least one protrusion on the rigid body. 
     
     
         17 . A needle assembly according to  claim 1 , comprising at least one vent in the compliant element or the rigid body for allowing air to escape from the rigid body during insertion of the compliant element into the rigid body. 
     
     
         18 . An autoinjector or syringe comprising the needle assembly according to  claim 1 . 
     
     
         19 . An autoinjector or syringe according to  claim 18 , wherein the autoinjector or syringe comprises a cap and the needle assembly comprises a bulb configured to engage with the cap so as to ensure that, when the cap is removed, the needle shield is also removed. 
     
     
         20 . A method of manufacturing a needle assembly comprising:
 fixing a first end of a needle to a needle hub;   coupling a needle shield to the needle hub, the needle shield covering a second end of the needle;   wherein the needle shield comprises a rigid body and a compliant element, wherein the rigid body is configured to provide an interference fit with the needle hub and thereby provide a seal around the needle hub, the rigid body providing a sterile barrier around at least a portion of the needle, the step of coupling including inserting the second end of the needle into the compliant element such that the compliant element provides a liquid tight seal around the second end of the needle.