Abstract:
A syringe for dispensing a medicament comprises a cartridge, a plug and an activator member. The syringe comprises a main chamber containing a first liquid and an auxiliary chamber containing a second liquid. To activate the syringe and merging the first and second liquid to form the medicament the auxiliary chamber and the main chamber are connectable for fluid communication with each other. A movement of the activator member and/or the plug causes the second liquid to be transferred from the auxiliary chamber into the main chamber. The syringe helps facilitating the preparation of a medicament that has to be mixed from different liquids shortly prior to use.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a syringe for dispensing a medicament which can be mixed within the syringe from at least two liquids. In particular the invention relates to a syringe which has a main chamber containing a first liquid and an auxiliary chamber containing the second liquid. The syringe is adapted to connect the main chamber and the auxiliary chamber for fluid communication and for transferring the second liquid from the auxiliary chamber into the main chamber with the first liquid. 
       BACKGROUND ART 
       [0002]    There are medicaments which are prepared by mixture from at least two components only short before use. For example local anesthesia are often provided as a liquid prefilled in a syringe or cartridge and, prior to use, a buffer solution is added to the liquid local anesthesia, for example to obtain a desired pH value of the mixture. Typically a doctor, for example a dentist, manually mixes local anesthesia and the buffer by dispensing both liquids into a common container and aspirating both liquids back into the syringe. 
         [0003]    There are further syringes which facilitate mixing of an anesthesia and a buffer. For example U.S. 2009/292271 A1 discloses a device for delivering a buffer solution into a buffer cartridge that comprises a needle assembly and a pusher. The septa of a buffer cartridge and an anesthetic cartridge are advanced onto a transfer needle, and the pusher advances a plunger into the buffer cartridge to deliver buffer through the transfer needle into the anesthetic cartridge. A separate exhaust needle allows excess anesthetic from the anesthetic cartridge to be exhausted. A compression member is usually provided to maintain a force against the plunger on the buffer cartridge to pressurize and stabilize the contents during sterilization and/or storage. Although existing syringes provide useful advantages there is still a need for a syringe which is easy to use and relatively inexpensive. 
       SUMMARY OF THE INVENTION 
       [0004]    In one aspect the invention relates to a syringe for dispensing a medicament. The syringe comprises:
   a cartridge forming a main chamber and having a first tubular portion extending along a longitudinal axis and being in fluid communication with the main chamber;   a plug forming an auxiliary chamber;   the plug comprising an activator member which is movable to activate the syringe by causing a first liquid and a second liquid to merge to form the medicament;   the plug being received within the first tubular portion for sealing the main chamber;   the so sealed main chamber being substantially air free filled with the first liquid and the auxiliary chamber containing the second liquid;   the plug being movable within the first tubular portion in at least a first direction along the longitudinal axis for extruding at least part of the medicament;   the activator member being movable in the first direction to cause the auxiliary chamber and the main chamber to connect for fluid communication with each other such that the first and second liquid can merge; and   wherein the syringe is adapted such that a further movement of the activator member toward the first direction causes at least part of the second liquid to be transferred from the auxiliary chamber into the main chamber and thereby the plug to displace within the first tubular portion in a second direction opposite to the first direction.   
 
         [0013]    The invention is advantageous in that it allows a preparation of a medicament mixed form two or more components at a minimized number of preparation steps. Further the invention helps maximizing the reliability in the preparation of a medicament in that the syringe of the invention provides the correct combination and quantities of the components. The risk of mixing tolerances or false combinations of components thus is minimized Further the invention is advantageous in that the preparation of the medicament by use of a syringe of the invention can be performed at a minimized amount of time. 
         [0014]    In one embodiment the plug has a second tubular portion extending along the longitudinal axis and being in fluid communication with the auxiliary chamber. The activator member may be slidably received within the second tubular portion for sealing the auxiliary chamber. Further the activator member may be movable within the second tubular portion in the first direction for activating the syringe. 
         [0015]    In an embodiment the cartridge has a tubular side wall which also forms the first tubular portion. Such cartridge side wall may have a substantially uniform cross-section along the longitudinal axis of the syringe. The cartridge side wall preferably directly delimits the main chamber, meaning that the first liquid is preferably in direct contact with the cartridge side wall. The cartridge side wall may at least inwardly extend at a generally uniform cross-section along the longitudinal axis. The cartridge side wall may for example extend at a circular cross-section at least inwardly, and in more particular may inwardly and outwardly extend at a circular cross-section, or, in other words may extend at a ring-shaped cross-section. The cartridge side wall thus may have an inner cartridge diameter, preferably a generally constant or uniform diameter over its length along the longitudinal axis. 
         [0016]    In a further embodiment the plug has a front wall which separates the main chamber and the auxiliary chamber from each other. The activator member may have a piercing member, for example an elongated spike, protruding from the activator member. At a stage accommodated within the plug the piercing member further preferably protrudes toward the plug front wall. Thus the piercing member is adapted for piercing the plug front wall and connecting the auxiliary chamber and the main chamber for fluid communication. For example a movement of the activator member toward the plug front wall preferably causes the piercing member to penetrate through the plug front wall and thereby creates the connection between the main chamber and the auxiliary chamber. The auxiliary chamber may be air free or substantially air free filled with the second liquid. Due to normal incompressibility of liquids thus the activator member and the plug are hindered in a movement toward each other by the second liquid. However it has been found that urging the activator member toward the plug and thereby causing the second liquid to be pressurized results in the plug and eventually the activator member to deform so that the piercing member reaches and pierces the front wall upon reaching a certain pressure in the second liquid. In particular urging only the activator member and the cartridge toward each other first causes the front wall to be pierced and further urging only the activator member and the cartridge toward each other causes the activator member to move into the plug. Thereby the second liquid is transferred into the first liquid. 
         [0017]    In a further embodiment the plug comprises a side wall which at least inwardly extends at a generally uniform cross-section along the longitudinal axis. The plug side wall preferably also forms the second tubular portion. Further the auxiliary chamber is preferably formed between the plug front wall, at least part of the plug side wall and the activator member. 
         [0018]    In an embodiment the plug side wall directly delimits the auxiliary chamber, meaning that the second liquid is preferably in direct contact with the plug side wall. The plug side wall may extend at a circular cross-section at least inwardly, and in more particular may inwardly and outwardly extend at a circular cross-section, or, in other words may extend at a ring-shaped cross-section. The plug side wall thus preferably has an inner plug diameter which is smaller than the inner cartridge diameter. 
         [0019]    In a further embodiment the plug has a deformable dome shaped rear portion. The deformable dome shaped rear portion in this embodiment preferably forms the activator member. Further the deformable dome shaped rear portion preferably forms a wall of the auxiliary chamber. The activator member is movable along the longitudinal axis by deformation of the activator member, particularly the activator member is movable along the longitudinal axis by inversion of the activator member. The activator member, for example when accommodated within the cartridge, is further preferably oriented and adapted for a movement in the first direction for activating the syringe. 
         [0020]    In a further embodiment the plug has a front seal. The front seal preferably separates the main chamber and the auxiliary chamber from each other, and in particular preferably delimits part of the main chamber and further delimits part of the auxiliary chamber. The plug front seal is preferably adapted to rupture upon pressure exerted to the plug front seal from the auxiliary chamber such that the auxiliary chamber and the main chamber are connected for fluid communication. For example the plug front seal may be made of a plastic film or foil, optionally comprising a layer of aluminum. The plug front seal may further have a predetermined breaking point which facilitates rupturing of the seal upon exertion of a pressure. The auxiliary chamber in this embodiment thus is preferably formed between the plug front seal and the activator member, and the second liquid may be in direct contact with the plug front seal and the activator member. 
         [0021]    In one embodiment the cartridge comprises a cartridge front having an openably sealed outlet for the medicament. The cartridge may for example be formed by a tubular body which is open on both sides and having a bottle neck on only one side. The bottle neck may be closed by a cartridge seal that can be pierced for opening. Such a cartridge may be made of glass, or of plastic material, for example. The cartridge may be adapted for use with a syringe mount having a plunger, and operating elements, like fingerplates, for manual use. The syringe mount may be used to dispense the medicament from the syringe by advancing the plug of the syringe via the plunger of the syringe mount. The main chamber thus is preferably formed between the cartridge front, the cartridge side wall and the plug. In a further embodiment the syringe comprises a pistil for mixing the first and second fluid upon shaking of the syringe. 
         [0022]    In an alternative aspect the invention relates to a syringe for dispensing a medicament, which syringe comprises:
   a cartridge forming a main chamber and an auxiliary chamber;   the cartridge having a first tubular portion extending along a longitudinal axis and being in fluid communication with the auxiliary chamber;   a plug being movable to activate the syringe by causing a first liquid and a second liquid to merge to form the medicament;   the plug being received within the first tubular portion for sealing the auxiliary chamber;   an activator member separating the main chamber and the auxiliary chamber from each other and sealing the main chamber;   the so sealed main chamber being substantially air free filled with the first liquid and the auxiliary chamber containing the second liquid;   the plug being movable within the first tubular portion in at least a first direction along the longitudinal axis for extruding at least part of the medicament;   the activator member adapted to connect the auxiliary chamber and the main chamber for fluid communication with each other such that the first and second liquid can merge; and   wherein the syringe is adapted such that a movement of the activator member toward a second direction opposite of the first direction causes at least part of the second liquid to be transferred from the auxiliary chamber into the main chamber.   
 
         [0032]    In one embodiment the activator member is formed by a hollow body forming an outer ridge for sealing with an inner cartridge surface. The activator member and the plug are preferably disposed within the cartridge of the syringe. The syringe may be adapted such that a movement of the plug toward the first direction creates a pressure in the cartridge. Further the syringe is preferably adapted such that the so created pressure causes the hollow body of the activator member to compress. By compression of the activator member the ridge of the activator member preferably retracts from the inner cartridge surface. Consequently a gap is formed between the activator member and the cartridge, and thus the syringe is activated. The activator member may be resiliently suspended at the plug under pretension for a movement of the plug and the activator toward one another. Such a suspension may comprise or consist of a spring or an elastic band, for example. The activation of the syringe accordingly preferably allows, or automatically causes, the activator member to move in the second direction toward the plug by the pretension. 
         [0033]    In a further embodiment the activator member comprises a weight for causing the activator member to move by force of gravity. Thus a user may orient the syringe after activation so that the weight urges the activator member toward the second direction. In this embodiment the resilient suspension is optional. 
         [0034]    In one embodiment the activator member has a retraction cord which extends through the plug to an exterior of the syringe. The retraction cord may be adapted to be grasped by a user of the syringe. The retraction of the activator member via the cord preferably causes the activator to move in the second direction toward the plug. The activator member may be deformable and due to pressure exerted by the second liquid on the activator member assume a dome shape creating a gap between the cartridge and the activator member as the activator member is urged toward the second direction. The so formed gap preferably establishes the fluid communication between the auxiliary chamber and the main chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0035]      FIGS. 1 to 3  show cross-sectional views of a syringe according to an embodiment of the invention at different stages of operation; 
           [0036]      FIG. 4  shows a variant of the embodiment shown in  FIGS. 1 to 3 ; 
           [0037]      FIGS. 5 ,  6  show cross-sectional views of a syringe according to a further embodiment of the invention at different stages of operation; 
           [0038]      FIGS. 7 to 9  show cross-sectional views of a syringe according to still a further embodiment of the invention at different stages of operation; 
           [0039]      FIG. 10  shows a partial cross-sectional view of a syringe according to an embodiment of the invention; 
           [0040]      FIG. 11 ,  12  show cross-sectional views of the syringe of  FIG. 10  at different stages of operation; and 
           [0041]      FIGS. 13 ,  14  show cross-sectional views of a syringe according to another embodiment of the invention at different stages of operation. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0042]      FIGS. 1 to 3  illustrate a syringe  10  for dispensing a medicament. The syringe  10  comprises a cartridge  11 , a plug  12  and an activator member  13 . The cartridge  11  forms a main chamber  14 , and the plug  12  forms an auxiliary chamber  15 . A first liquid  18  is contained within the main chamber  14 , and a second liquid  19  is contained in the auxiliary chamber  15 . The main chamber  14  is sealed by the plug  12  at a rear end  16  of the cartridge  11 . The cartridge  11  in the example has a substantially tubular wall laterally delimiting the main chamber  14 , and particularly at the rear end  16  the cartridge  11  has a first tubular portion  17  which extends along a longitudinal axis A of the syringe  10 . Accordingly the first tubular portion  17  is in fluid communication with the main chamber  14 . The plug  12  is received within the first tubular portion  17  and thus seals the main chamber  14 . 
         [0043]    The plug  12  receives the activator member  13 . The activator member  13  is movable in a first direction (in the Figure from the right toward the left) to activate the syringe  10  by causing the first liquid  18  and the second liquid  19  to merge. In particular in the example the plug  12  has a second tubular portion  20  that extends along the longitudinal axis A and being in fluid communication with the auxiliary chamber  15 . The activator member  13  is slidably received within the second tubular portion  20  for sealing the auxiliary chamber  15 . Further the activator member  13  is movable within the second tubular portion  20  in the first direction for activating the syringe. The plug  12  has a front wall  21  which separates the main chamber  14  and the auxiliary chamber  15  from each other. Further the activator member  13  has a piercing member  22  that protrudes from the activator member toward the plug front wall  21  for piercing the plug front wall  21  upon movement of the activator member  13  in the first direction. Thus the auxiliary chamber  15  and the main chamber  14  can be connected for fluid communication such that the first and second liquid  18 ,  19  can merge to form the medicament. 
         [0044]    As illustrated in  FIG. 2  the syringe is adapted such that a further movement of the activator member  13  toward the first direction causes at least part of the second liquid  19  to be transferred from the auxiliary chamber  15  into the main chamber  14 . Thereby the plug  12  displaces within the first tubular portion  17  in a second direction (in the Figure from the left toward the right) opposite to the first direction. Because the main chamber  14  is substantially air free filled with the first liquid  18 , any transfer of the second liquid  19  from the auxiliary chamber  15  toward the main chamber  14  forces the plug  12  to move and thus to provide the volume required for the merged first and second liquid  18 ,  19 . It has been found that urging the activator member  13  toward the first direction against the cartridge  11  without urging the plug  12  in the same direction causes the plug  12  to move opposite of the first direction. 
         [0045]    Once substantially all of the second liquid  19  is transferred into the main chamber  14 , as illustrated in  FIG. 3 , the plug  12  may be moved within cartridge  11  in the first direction along the longitudinal axis A for extruding the medicament. The cartridge  11  at front end  23  preferably has an openably sealed outlet  24  for the medicament. The skilled person will recognize different embodiments of seals that are openable, for example by a user. In a preferred embodiment the cartridge  11  has a seal film that can be pierced open, for example by an injection needle. Preferably the cartridge  11  is made of a glass or plastic material, and the plug  12  and the seal film may be made of a resilient plastic or rubber material. The activator member  13  (and the piercing member  22 ) may be made of a comparatively rigid plastic material or a metal. 
         [0046]      FIG. 4  shows the syringe  10  which has a pistil  25  movably disposed within the cartridge  11 . The pistil  25  is of a ring-shaped cross-section and by movement causes the liquids  18 ,  19  to flow through the opening left within the ring-shape. Therefore the liquids  18 ,  19  are agitated so that they mix with one another. The pistil  25  may accordingly be used to mix the first and second liquid  18 .  19  once they are merged within the main chamber  14 . 
         [0047]      FIG. 5  shows a syringe  110  which is identical to the syringe  10  except for the plug configuration. The syringe  110  has a plug  112  which has a deformable dome shaped rear portion forming the activator member  113 . The activator member  113  also forms a wall of an auxiliary chamber  115 . In the example shown the activator member  113  is movable in a first direction (in the Figure from the right toward the left) along a longitudinal axis B of the syringe  110  by deformation of the activator member  113 . In particular the activator member  113  may be inverted as illustrated in  FIG. 6  for activating the syringe. 
         [0048]    The plug  112  has a front seal  121  which separates the main chamber  114  and the auxiliary chamber  115  from each other. The front seal  121  is adapted to rupture upon pressure exerted to the front seal from the auxiliary chamber  115 . For example the front seal  121  may be formed from a relatively thin film or foil. The front seal  121  may further comprise one or more predetermined breaking zones or lines. Thus a controlled rupturing of the front seal  121  may be facilitated. Upon rupturing of the front seal the auxiliary chamber  115  and the main chamber  114  are connected for fluid communication. In this example the auxiliary chamber  114  is formed between the plug front seal  121  and the activator member  113  only. 
         [0049]      FIG. 7  shows a syringe  210  for dispensing a medicament. The syringe  210  comprises a cartridge  211  forming a main chamber  214  and an auxiliary chamber  215 . The main chamber  214  comprises a first liquid and the auxiliary chamber  215  comprises a second liquid  219 , the first and second liquid being adapted to form the medicament. The cartridge  211  generally has a tubular shape and in particular has at a rear end  216  a first tubular portion  217 . The tubular portion  217  extends along a longitudinal axis C and is in fluid communication with the auxiliary chamber  215 . The syringe  210  further comprises a plug  212  which is movable to activate the syringe by causing the first liquid  218  and the second liquid  219  to merge to form the medicament. The plug  212  is received within the first tubular portion for sealing the auxiliary chamber  215 . 
         [0050]    The syringe  210  further has an activator member  213  that separates the main chamber  214  and the auxiliary chamber  215  from each other. Further the activator member  213  seals the main chamber  214 . In the example shown the activator member  213  is formed of a hollow body. The hollow body is formed of walls having a shape of a double cone connecting to each other at their wide ends. The hollow body is preferably made of a resilient material, for example rubber, and may contain a gas (for example air) hermetically sealed within and by the walls of the hollow body. At the area at which the cones connect to a double cone a sealing ridge  213   a  is formed. Accordingly the activator member  213  seals the main chamber  214  due to the ridge  213   a  sealing with an inner surface  211   a  of the cartridge  211 . Optionally the gas within the activator member  213  may have an overpressure relative to the normal atmospheric pressure (or the pressure outside of the syringe  210 ) to maximize the sealing effect. The so sealed main chamber  114  is substantially air free filled with the first liquid  218 . 
         [0051]    The plug  212  is movable within the first tubular portion  217  in at least a first direction (in the Figure from the right toward the left) along the longitudinal axis C for extruding at least part of the medicament. A movement of the plug  212  further creates a pressure within the auxiliary chamber  214  and the main chamber  215  and consequently causes the activator member  213  to shrink. Thus upon reaching a certain pressure in the auxiliary chamber  214  and the main chamber  215  the sealing ridge  213   a  retracts from the inner surface  211   a  of the cartridge (shown in  FIG. 8 ) so that the auxiliary chamber  214  and the main chamber  215  become connected for fluid communication with each other. Thus the first and second liquid  218 ,  219  can merge. 
         [0052]    The syringe  210  is further adapted such that a movement of the activator member  213  toward a second direction opposite of the first direction causes at least part of the second liquid  219  to be transferred from the auxiliary chamber  215  into the main chamber  214  (shown in  FIG. 9 ). In the example the activator member  213  comprises a weight  213   b.  A user may thus by appropriate orientation of the syringe  210  cause the activator member  213  to move toward the second direction (toward the plug  212 ) by force of gravity. In the Figure the syringe  210  may for example be oriented with its longitudinal axis C generally vertically and with the plug  212  oriented downwards. Upon exerting a pressure onto the liquids  218 ,  219  by movement of the plug  212  into the cartridge  211  the activator member  213  preferably shrinks and the weight  213   b  urges the activator downwards toward the plug  212 . Thereby the second liquid  219  is transferred from the auxiliary chamber  215  into the main chamber  214 . The movement of the activator member  213  thus causes the auxiliary member to reduce in volume and the main chamber to increase in volume. Thus the second liquid  219  bypasses the activator member  213  into the main chamber  214  via a gap between the cartridge  211  and the activator member  213 . 
         [0053]      FIG. 10  shows a syringe  310  having (compared to the embodiment shown in  FIGS. 7 to 9 ) an alternative activator member  313 . The activator member  313  is generally cylindrical and having a circumferential bulge  313   a  forming a diameter maximum of the activator member  313  at about half of the cylinder length. The diameter maximum is dimensioned such that the activator member  313  seals with an inner surface  317   a  of a tubular portion  317  of the cartridge  311 . In the example at least the portion of the activator member  313  forming the bulge is made of a resilient material, which thus upon creating a pressure in the main chamber  314  and/or the auxiliary chamber  115  is adapted to collapse. Accordingly the auxiliary chamber  315  and the main chamber  314  are connected for fluid communication upon pressurizing the activator member  313 . The shape of the activator member  313  preferably prevents the activator member  313  from inadequate canting, for example from turning in a position in which a gap is formed between the bulge  313   a  of the activator member  313  and the cartridge  311 . The skilled person will recognize that instead of an ideal the cylinder shape a barrel shape, or similar or equivalent shape may be used for the activator member  313 . 
         [0054]      FIG. 11  shows a syringe  410  having an activator member  413  which is identical with the activator member  313  of  FIG. 10 . In the example the activator member  413  is however connected to a plug  412  via a spring  425  that is held under pretension by a liquid  419  filled with auxiliary chamber  415 . Because the activator member  413  seals with the cartridge  411  the liquid  419  cannot escape from the auxiliary chamber  415  although it is pressurized by the spring  425 . However upon moving the plug  412  to create a (further) pressure in the auxiliary chamber  415  and/or main chamber  414  a gap is formed between the activator member  413  and the cartridge  411  so that the liquid  419  can bypass the activator member  413 . Hence at that stage the activator member  413  is automatically retracted by the spring  425  causing also the liquid  419  to transfer into the main chamber  414  (shown in  FIG. 12 ). 
         [0055]      FIG. 13  shows a syringe  510  having an activator member  513  and a plug  512  which are disposed spaced from each other within a tubular portion  517  of a cartridge  511 . The syringe  510  is adapted such that the plug  513  is movable in a first direction (in the Figure from the right toward the left) for dispensing a medicament contained within the syringe  510  and merged within the syringe from separately stored first and second liquids  518 ,  519 . The space delimited by the activator member  513  the plug  512  and the cartridge  511  forms an auxiliary chamber  515  in which the second liquid  519  is contained. The first liquid  518  is contained in a main chamber  514  formed by a continuation of the tubular portion  517  of the cartridge  511 . The activator member  513  in the example has a retraction cord  525  which protrudes from the activator member through the plug  512  to an exterior of the syringe  510 . Thus a user can grasp the retraction cord  525  for pulling back the activator member  513  relative to the plug  512  in a second direction opposite of the first direction. To avoid retraction of the plug  512  together with the retraction of the activator member  513  the plug  512  is preferably held in place during retraction of the activator member  513 . For this purpose the cartridge  511  may have a retainer  526  which prevents a movement of the plug  512  in the second direction. 
         [0056]    The activator member  513  is adapted to seal with an inner surface of the cartridge  511 , particularly with an inner surface  517   a  of the tubular portion  517 . Further the activator member  513  may be generally disk shaped, for example having a thickness that is smaller than its diameter, and may be made of a resilient material. Thus the activator member  513  is adapted to deform toward a dome shape upon retraction by the retraction cord against pressure built up in the auxiliary chamber  515  in the second liquid  519 . Such pressure acts upon the circumferential portion of the activator member  513  and thus causes the circumferential portion of the activator member  513  to bend away from that pressure, thus preferably assuming the dome shape. At some point as a certain pressure is reached the dome shape results in the diameter of the activator member  513  to become smaller than the diameter of the inner surface  517   a  of the cartridge so that a gap is created between the activator member  513  and the cartridge. Accordingly a fluid communication is established between the main chamber  514  and the auxiliary chamber  515  via the gap. A further movement of the activator member  513  toward the second direction finally results in the second liquid  519  to be transferred from the auxiliary chamber  515  into the main chamber  514  where it merges with the first liquid  518  to form the medicament (shown in  FIG. 14 ). In the example the activator member  513  and the plug  512  are additionally connected to each other by a sleeve  527  within which the retraction cord is accommodated. Thus the retraction cord  525  is prevented from getting in contact with the second liquid  519 . Accordingly also a user may be prevented from getting in contact with the second liquid  519  when the retraction cord  525  is retracted out of the syringe  510 . This is particularly advantageous in an embodiment in which the retraction cord  525  is adapted to tear off after activation of the syringe  510  as indicated in  FIG. 14 .