Needleless syringe functioning with a double-composition pyrotechnic charge

Abstract

The technical field of the invention is that of pre-filled and disposable needleless syringes, used for intradermal, subcutaneous and intramuscular injections of liquid active principle for therapeutic use in human and veterinary medicine. The inventive syringes ( 1 ) are mainly characterized in that they function with a pyrotechnic charge ( 6 ) consisting of a mixture of powder with high burning rate and a powder with low burning rate. Indeed, the combustion of the powder with a high burning rate enables to communicate instantly, through a piston ( 3 ), a very high speed to the active principle ( 4 ), whereas the combustion of the powder with a low burning rate enables to maintain a threshold pressure level to proceed with the injection, so as to ensure that the active principle ( 4 ) penetrates through the skin. Thus, the injection is properly and homogeneously without any loss of active liquid ( 4 ).

1 . A needleless syringe comprising, in succession, a pyrotechnic gas generator, at least one piston, a reserve of liquid active principle, and an ejection nozzle, wherein the pyrotechnic gas generator comprises a haphazard mixture of at least two pyrotechnic charges. 
   
   
       2 . The needleless syringe as claimed in  claim 1 , wherein the pyrotechnic gas generator comprises a haphazard mixture of a first pyrotechnic charge and of a second pyrotechnic charge. 
   
   
       3 . The needleless syringe as claimed in  claim 2 , wherein the first pyrotechnic charge is a powder and the second pyrotechnic charge is a powder, wherein the powder of the first pyrotechnic charge is different than the powder of the second pyrotechnic charge. 
   
   
       4 . The needleless syringe as claimed in  claim 2 , wherein the first pyrotechnic charge is a gunpowder and the second pyrotechnic charge also is a gunpowder.