Needle cannula, a method of producing a needle cannula and use of a needle cannula

Abstract

An elongated tubular needle for injecting a fluid into a human body or retracting a fluid from the human body, comprising; a tubular needle cannula ( 1 ) having a skin piercing distal end ( 4 ), an opposite proximal end ( 5 ), and a tubular sidewall ( 2 ) there between having an outside diameter at the skin piercing end ( 4 ) which is smaller than the outside diameter at the opposite proximal end ( 5 ) thereof, and a cylindrical lumen ( 3 ) extending through the needle cannula ( 1 ) and having approximately the same uniform inside diameter through the needle cannula ( 1 ).

We claim:  
     
         1 . A method of manufacturing a tapered injection needle cannula having a distal skin piercing end, an opposite proximal end and a sidewall there between, said method comprising the steps of: 
 i. Gripping a tubular needle cannula having the same outer diameter of more than 0.25 mm along the outer surface,    ii. exposing at least a distal part of the needle cannula to tapering means thereby reducing the outer diameter to less than 0,25 mm while maintaining the original outer diameter on the remaining part of the needle cannula thereby giving the needle cannula a tapered appearance at least along the outer surface of the distal part of the needle cannula.    
     
     
         2 . A method of manufacturing a tapered injection needle cannula of  claim 1 , wherein the tapering means comprises mechanical means.  
     
     
         3 . A method of manufacturing a tapered injection needle cannula of  claim 2 , wherein the mechanical tapering means comprises forging.  
     
     
         4 . A method of manufacturing a tapered injection needle cannula of  claim 2 , wherein the mechanical tapering means comprises grinding.  
     
     
         5 . A method of manufacturing a tapered injection needle cannula of  claim 2 ,  3  or  4 , wherein the mechanical tapering means works solely on the outer surface of the needle cannula.  
     
     
         6 . A method of manufacturing a tapered injection needle cannula of  claim 5 , wherein the mechanical tapering means works solely on the distal part of the needle cannula.  
     
     
         7 . A method of manufacturing a tapered injection needle cannula of  claim 1 , wherein the tapering means comprises chemical means.  
     
     
         8 . A method of manufacturing a tapered injection needle cannula of  claim 7 , wherein the chemical tapering means comprises a bath of a metal eroding substance.  
     
     
         9 . A method of manufacturing a tapered injection needle cannula of  claim 7  or  8 , wherein the chemical tapering means works solely on the outer surface of the needle cannula.  
     
     
         10 . A method of manufacturing a tapered injection needle cannula of  claim 9 , wherein the chemical tapering means works solely on the distal part of the needle cannula.  
     
     
         11 . A method of manufacturing a pen needle assembly for an insulin injection device comprising the steps of: 
 i. molding a polymeric hub comprising a circular base having a central through hole and an annular sleeve extending perpendicular from the periphery of the base,    ii. inserting a tapered injection needle cannula according to any of the previous claims into the central through hole of the base,    iii. securing the injection needle cannula to the base in such a way that the distal end of the injection needle cannula extends from the base in a direction opposite the sleeve and that the proximal end of the injection needle cannula is located within the boundaries of the sleeve.    
     
     
         12 . A method of manufacturing a needle cannula comprising: 
 a. obtaining a piece of material suitable for use as a needle cannula, the piece of material having a distal end and a proximal end;    b. forging a needle cannula out of the piece of material wherein the cannula has a tapered distal end and wherein the forging step results in the cannula having taper distal portion with an outside diameter less than 0.25 mm.    
     
     
         13 . The method of  claim 12  wherein the needle cannula is forged such that needle as a cylindrical lumen.