Needleless hypodermic injection system, application device and medication cartridge therefor

Abstract

A needleless hypodermic injection system for injecting a liquid medication, which system comprises a disposable cartridge which contains a medication and which comprises a propellant and an igniter, and a reusable application device which comprises a pressure chamber for receiving the medication cartridge, actuation means including an ignition system and means for ensuring reliability and safety of the system. The reusable application device comprises: (a) a housing including a fist housing section and a second housing section which are adapted to be assembled together by a screwing operation, the first housing section comprising a front part having an injection outlet and a chamber adapted to receive a the cartridge contains the medication to be injected and also contains a propellant and an igniter, and (b) means for selectively activating said igniter of said cartridge when predetermined conditions are fulfilled.

1 . An application device for needleless hypodermic injection of a liquid medication said application device comprising 
 a) a housing having a length axis and an outer contact surface which is adapted to be applied on a skin surface through which an injection is to be applied;    b) said housing containing ejection means causing ejection of said liquid medication in order to perform an injection and actuator means for activating said ejection means; and    c) position detecting means for detecting whether said contact surface of said housing exerts a predetermined pressure on said skin surface and whether at the same time said length axis of said housing is positioned substantially normal to said skin surface, the distribution of said pressure over the area of said contact surface being substantially uniform, said means for detecting enabling said actuator means when the latter conditions are satisfied.    
   
   
       2 . A device according to  claim 1 , wherein the ejection means comprise a propellant and means for its ignition.  
   
   
       3 . A device according to  claim 1 , wherein said position detecting means exclusively comprise mechanical and electro-mechanical means, but no electronic means sensitive to electrical noise or other perturbating electrical signals.  
   
   
       4 . A device according to  claim 1 , wherein said position detecting means comprise a first switch adapted to be mechanically actuated by a movable part of said position detecting means to establish an electrical connection when said position detecting means senses application of the contact surface of the housing on said skin surface with a predetermined pressure applied on the skin surface.  
   
   
       5 . A device according to  claim 1 , wherein said housing is so configured and dimensioned that it is adapted to be held and used by a user with only one hand.  
   
   
       6 . A device according to  claim 1 , further comprising means providing a visual or audible indication to the user when said actuator means is enabled.  
   
   
       7 . A device according to  claim 1 , wherein the position detecting means comprise a purely mechanical object sensor, and a first switch adapted to be mechanically actuated by a movable part of the position detecting means to establish an electrical connection when said object sensor senses application of the contact surface of the housing on a body part.  
   
   
       8 . A reusable application device for needleless hypodermic injection of a liquid medication said application device comprising 
 a) a housing having a length axis and an outer contact surface which is adapted to be applied on a skin surface through which an injection is to be applied wherein 
 the housing comprises a first section and a second section which are adapted to be connected with each other to form a housing assembly,  
 said first housing section comprising a chamber for receiving a cartridge containing a medication unit which contains a liquid medication,  
 said first housing section having a symmetry axis which extends along its length and a front part having the outer contact surface which is adapted to be applied on a skin surface, said contact surface having an opening through which liquid medication ejected from said cartridge can pass and be injected through said skin surface;  
   b) said housing containing ejection means causing ejection of said liquid medication in order to perform an injection and actuator means for activating said ejection means wherein 
 a first part of the ejection means is contained in said cartridge and a second part of said ejection means is contained in said second housing section;  
   c) assembly detecting means which reach a first predetermined state when said first housing section is properly and completely assembled with said second housing section to form said housing assembly, said assembly detecting means being located within said housing assembly;    d) position detecting means for detecting whether said contact surface of said housing exerts a predetermined pressure on said skin surface and whether at the same time said length axis of said housing is positioned substantially normal to said skin surface, the distribution of aid pressure overt the area of said contact surface being substantially uniform, said means for detecting enabling said actuator means when the latter conditions are satisfied wherein 
 the position detecting means are located in part within said first housing section and in part in said section housing section, said position detecting means reaching a second predetermined state when the following conditions are simultaneously satisfied by the relative position of said housing assembly with respect to said skin surface,  
 d.2) said contact surface of said first section exerts a predetermined pressure on said skin surface, the distribution of said pressure over the area of said contact surface being substantially uniform, and  
 d.3) said symmetry axis of said first section is positioned substantially normal to said skin surface; and  
   e) the actuator means are normally disabled and become operable only upon being enabled by a combination of predetermined effects provided by 
 said assembly detecting means after they reach said first predetermined state, and  
 said position detecting means when they reach said second predetermined state.  
   
   
   
       9 . A device according to  claim 8 , wherein said second housing section comprises means which are adapted to cooperate with a corresponding part of said first housing section for clamping with a predetermined preload and for hermetically closing a cartridge inserted into said cartridge receiving chamber.  
   
   
       10 . A device according to  claim 8 , wherein said first housing section and said second housing section are so shaped, dimensioned and configured that proper and complete assembly therefore is accurately defined and recognizable by visual and tactile inspection.  
   
   
       11 . A device according to  claim 8 , wherein said first housing section and said second housing section are adapted to be assembled together by assembling steps which include a screwing operation.  
   
   
       12 . A device according to  claim 8 , wherein injection is caused by an electrical circuit comprising 
 a battery,    a first switch    a second switch adapted to be actuated by a user,    interconnection conductors, and    two electrical terminals which correspond to    respective terminals of an igniter,    said electrical circuit being so configured that    electrical current can flow from the battery to the igniter only when the following conditions are met:    i) said cartridge is properly positioned within said chamber of said first housing section.    ii) said first and said second housing section are completely and properly assembled, whereby said two terminals of said electrical circuit contact said respective terminals of said igniter.    iii) said first switch is actuated by said object sensor and thereby establishes an electrical connection, and    iv) said second switch is actuated by a user.    
   
   
       13 . A device according to  claim 8 , wherein said assembly detecting means exclusively comprise mechanical means.  
   
   
       14 . A needleless hypodermic injection system for injecting a liquid medication, which system comprises: 
 a) an application device according to  claim 1  
 i) a housing having a length axis and an outer contact surface which is adapted to be applied on a skin surface through which an injection is to be applied;  
 ii) said housing containing ejection means causing ejection of said liquid medication in order to perform an injection and actuator means for activating said ejection means; and  
 iii) position detecting means for detecting whether said contact surface of said housing exerts a predetermined pressure on said skin surface and whether at the same time said length axis of said housing is positioned substantially normal to said skin surface, the distribution of said pressure over the area of said contact surface being substantially uniform, said means for detecting enabling said actuator means when the latter conditions are satisfied; and  
   b) a disposable cartridge which contains a medication and which comprises a propellant and an igniter.    
   
   
       15 . A medication cartridge for a needleless hypodermic injection system according to  claim 14  for injecting a liquid medication, said cartridge comprising a housing adapted to contain: 
 a) a first chamber containing a medication unit configured and dimensioned to store a volume of liquid to be injected, said medication unit having a first region and a second region that are in liquid communication with each other, said first region being deformable and said second region having an injection outlet,    b) a second chamber containing a propellant, said first chamber being divided by an elastic barrier in two zones, a first zone containing said medication unit and a second zone which is in communication with said second chamber, so that upon ignition of the propellant in the second chamber gas generated thereby expands into said second zone of said first chamber, exerts pressure on and deforms said barrier which in turn transfers that pressure to and deforms said deformable first region of said medication unit and thereby causes ejection of said medication through said injection outlet, and    c) means for mechanically setting the volume available within said cartridge for gas expansion, so that said volume has a selected predetermined size.    
   
   
       16 . A medication cartridge according to  claim 15 , further comprising an envelope which surrounds said elastic barrier and protects it from direct contact with hot gas generated by ignition of said propellant in said second chamber.  
   
   
       17 . A medication cartridge according to  claim 16 , wherein said envelope also forms a gas seal between said housing and said medication unit containing said liquid medication.