Needleless syringe provided with modular resorvoir

Abstract

The technical field of the invention is that of needleless pre-filled disposable syringes, operating with a gas generator, and used for intradermal, subcutaneous and intramuscular injections, of a liquid active principle for therapeutic use in human and veterinary medicine. The inventive needleless syringes use a reservoir ( 5 ) consisting of a tube ( 6 ) closed by an upstream plug-piston ( 7 ) and a downstream plug-piston ( 8 ) between which is contained the liquid active principle. Said needleless syringes are characterized in that they are capable of injecting a variable amount of liquid active principle ( 9 ) by adapting, through displacement of the downstream plug-piston ( 8 ) in the tube ( 6 ) the volume included between the two plug-pistons ( 7,8 ) to the amount of active principle ( 9 ) to be injected.

1 . A needleless syringe ( 1 ) comprising several elements including a gas generator, a reservoir ( 5 ) formed by a tube ( 6 ) which is closed off by an upstream plunger stopper ( 7 ) and a downstream stopper between which the liquid active principle ( 9 ) is contained, said reservoir ( 5 ) being able to have a volume which can be varied by displacement of the downstream plunger stopper ( 8 ) in said tube ( 6 ), and an injection device ( 10 ), characterized in that 
 i) the gas generator is a pyrotechnic generator having a pyrotechnic charge ( 3 ) and an initiation system,    ii) the elements of said syringe ( 1 ) are arranged in such a way as to ensure, irrespective of the amount of active principle ( 9 ) contained in the reservoir ( 5 ), the injection of all of said principle ( 9 ) through the skin, by virtue of the production, at the outlet of the injection device ( 10 ), of a pressure profile of the type consisting of an intense phase to permit penetration of the principle ( 9 ) through the skin, followed by a less intense phase to ensure its passage through the latter.    
     
     
         2 . The needleless syringe as claimed in  claim 1 , characterized in that the downstream plunger stopper ( 8 ) is at first located entirely within the tube ( 6 ).  
     
     
         3 . The needleless syringe as claimed in  claim 1 , characterized in that the pyrotechnic charge ( 3 ) is formed by the mixture of a first powder and a second powder, the first powder having a dynamic vivacity greater than that of the second powder.  
     
     
         4 . The needleless syringe as claimed in  claim 3 , characterized in that the first powder has a dynamic vivacity of greater than 8 (MPa.s) −1 , and the second powder has a dynamic vivacity of less than 16 (MPa.s) −1 .  
     
     
         5 . The needleless syringe as claimed in  claim 1 , characterized in that the volume of the reservoir ( 5 ) between the two plunger stoppers ( 7 ,  8 ) can vary from 0.1 ml to 2 ml.  
     
     
         6 . The needleless syringe as claimed in  claim 1 , characterized in that the upstream plunger stopper ( 7 ) is situated, in a fixed manner, at one of the two ends of the tube ( 6 ).  
     
     
         7 . The needleless syringe as claimed in  claim 6 , characterized in that at least one plunger ( 4 ) is lodged between the gas generator ( 2 ) and the upstream plunger stopper ( 7 ).  
     
     
         8 . The needleless syringe as claimed in  claim 7 , characterized in that the upstream plunger stopper ( 7 ) is in contact with the plunger ( 4 ).  
     
     
         9 . The needleless syringe as claimed in  claim 1 , characterized in that the tube ( 6 ) is made of glass and has a thickness of between 0.5 mm and 4 mm.  
     
     
         10 . The needleless syringe as claimed in  claim 1 , characterized in that the two plunger stoppers ( 7 ,  8 ) are made of a deformable material.  
     
     
         11 . The needleless syringe as claimed in  claim 1 , characterized in that the injection device ( 10 ) comprises at least two peripheral injection conduits ( 20 ) which are situated outside a hollow component ( 15 ) serving as receptacle for the downstream plunger stopper ( 8 ), the depth of said component ( 15 ) permitting. the clearance of the inlets of the peripheral conduits ( 20 ) when said downstream plunger stopper ( 8 ) comes into contact with the bottom of said hollow component ( 15 ).  
     
     
         12 . The needleless syringe as claimed in either one of claims  1  and  9 , characterized in that the length of the tube ( 6 ) is constant.  
     
     
         13 . The needleless syringe as claimed in  claim 7 , characterized in that the plunger ( 4 ) is lodged in a hollow body ( 13 ) with the same internal diameter as that of the tube ( 6 ) and situated in its continuation, said hollow body ( 13 ) and said tube ( 6 ) being held in an envelope ( 14 ).  
     
     
         14 . The needleless syringe as claimed in  claim 1 , characterized in that the reservoir ( 5 ) comprising the tube ( 6 ) and the two plunger stoppers ( 7 ,  8 ) constitutes a component which is autonomous of said syringe ( 1 ).  
     
     
         15 . The needleless syringe as claimed in  claim 11 , characterized in that a free space ( 19 ) exists between the downstream plunger stopper ( 8 ) and the bottom of the hollow component ( 15 ).