Abstract:
A frontloaded injection device comprising a cartridge holder into which a replaceable cartridge containing a fluid is inserted. The cartridge holder comprises a closing element such as a pair of claws which are displaceable in a radial direction. The closing element is provided at the front of the injection device and locks the cartridge by gripping at the neck part of the cartridge after the cartridge has been loaded into the cartridge holder from the front of the injection device. The closing element is preferably biased in an outwardly radial direction when the locking element is moved axially out of the cartridge holder.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority under 35 U.S.C.  119  of Danish application no. PA 2002 01269 filed Aug. 29, 2002, and U.S. provisional application No. 60/416,858 filed Oct. 8, 2002, the contents of which are fully incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The invention relates to injection devices comprising a cartridge holder and a dose setting and injection part by which set doses can be apportioned from a cartridge in the cartridge holder as a piston rod is successively moved into a first end of said cartridge to press a piston closing said first end of the cartridge into the cartridge which has a second end closed by a membrane, whereby a liquid stored between the piston and the membrane can be pressed out through a hollow needle which is mounted on the device so that it pierces said membrane, access to the cartridge holder being obtained by opening a first end thereof through which the first end of the cartridge can be inserted with its piston facing the piston rod which extends into the cartridge holder from a second end thereof.  
           [0003]    By most known injection devices using changeable cartridges the cartridge holder may be unscrewed from the device to obtain access to the cartridge holder. This will make the user stand with two parts: A cartridge holder with an empty cartridge; and a dose setting and injection part with a protruding piston rod. The cartridge in the cartridge holder is then changed and the cartridge holder can be remounted on the dose setting and injection part. However, first the extending piston rod must be pushed or screwed back into the dose setting and injection part. This returning of the projecting piston rod can cause some problems as an attempt to screw back a piston rod, which is designed to be pushed back, and visa versa, may damage the piston rod or components in the dose setting and injection system. Consequently an injection device in which the piston rod cannot be reached by the user is preferred.  
           [0004]    In a so-called front loaded device as the one described in the opening of this application the piston rod remains hidden by the cartridge holder when the front end of this holder is opened to change the cartridge. When a new cartridge is passed into the cartridge holder the piston of this cartridge abuts the piston rod and press it backward into the device when the cartridge is pressed into the cartridge holder from the open first end of this cartridge holder. The open first end of the cartridge holder may the be closed by a screw plug as it is described in EP 513 128.  
           [0005]    As loose parts as screw plug offers possibility for skew mounting or loss of this part it is an objective of the invention to provide a closing mechanism which is integrated in the device.  
         SUMMARY OF THE INVENTION  
         [0006]    This is obtained by a device as described in the opening of this application, which device is characterised in that at least one closing element is provided at the first end of the cartridge holder which closing element in its closed position forms a support for the second end of a cartridge to bar for an axial movement of the cartridge out of the cartridge holder and which closing element is displaceable in a radial direction relative to the cartridge holder so that said closing element can be moved to a position allowing a cartridge to pass axially into or out of the cartridge holder.  
           [0007]    The cartridge holder may be provided with at least one axial element which has at its end at the second end of the cartridge holder an inward protrusion perpendicular to said axial element, which protrusions form the closure of the cartridge holder and may be moved in a radial direction relative to the cartridge holder by deflecting the end of the element carrying said inward protrusion away from its axial position and the cartridge holder  
           [0008]    In an embodiment a closure at the second end of the cartridge holder may be formed by a number of axial elements arranged to form a cylinder accommodating a each axial element having an inward protrusion perpendicular to said axial element.  
           [0009]    The said axial elements may be biased to be deflected outwardly and may be held in an axial position by an encompassing cartridge holder having an inner diameter corresponding to the outer diameter of the arrangement of the axial elements when these are in their axial position.  
           [0010]    A longitudinal displacement of the cartridge holder may be obtained by a closing mechanism comprising a ring which is mounted on the device and can be rotated between to rotational positions, the ring having pins extending through slots in the cartridge holder and into tracks a tubular element on which the longitudinal elements are arraged, the tracks being helically designed so that the tubular element is displaced in an axial direction when the ring is rotated from one rotational position to the other.  
           [0011]    In another embodiment of the invention at least one closing element is mounted at a front end of the cartridge holder axially displaceable relative to said cartridge holder.  
           [0012]    A connection may be established between the locking device and the dose setting part of the device to set the piston free to be moved backward when the closure of the cartridge holder is opened and to lock it to the dose setting part to be governed by this part when the closure is closed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    In the following the invention is further described with references to the drawing, wherein  
         [0014]    [0014]FIG. 1 shows schematically a side view of a front loadable syringe according to the invention,  
         [0015]    [0015]FIG. 2 shows a sectional view along the line II-II in the syringe in FIG. 1,  
         [0016]    [0016]FIG. 3 shows a sectional view of the syringe in FIG. 2 rotated 90° about its axis,  
         [0017]    [0017]FIG. 4 shows an exploded view of the syringe in FIG. 1,  
         [0018]    [0018]FIG. 5 shows an enlarged view of the encircled part in FIG. 2,  
         [0019]    [0019]FIG. 6 shows a detail of another embodiment of a front loaded device with its closure open,  
         [0020]    [0020]FIG. 7 shows the embodiment in FIG. 6 with its closure closed. 
     
    
     DETAILED DESCRIPTION  
       [0021]    [0021]FIG. 1 schematically shows a syringe according to the invention which syringe comprises a housing  1  for a dose setting and injection part, a cartridge holder  2  mounted on the housing  1 , and an operation ring  3  surrounding the housing at the transition between the housing  1  and the cartridge holder  2 . The housing  1  has a window  4  wherein a set dose is shown, but details of the dose setting and injection system are not shown. The cartridge holder  2  has a window  5  through which a cartridge in the cartridge holder can be visually inspected. The cartridge may be provided with a plastic top  6  onto which a not shown needle hub with an injection needle can be mounted. The possible provision of a needle is hinted by a needle cap  7 .  
         [0022]    [0022]FIGS. 2 and 3 shows sectional views of the syringe in FIG. 1 whereas FIG. 4 shows an exploded view of this syringe. In FIG. 3 it is seen that a cartridge  8  mounted in the cartridge holder  2  has a piston  9  which can be moved into the cartridge by a not shown piston rod which is successively moved outward from the dose setting and injection system when doses are set and injected. The function of the dose setting system implies that the piston rod cannot rotate relative to the housing during dose setting and injection. When the piston rod is allowed to rotate the extending part of it can easily be pressed back into the dose setting and injection system.  
         [0023]    As it is seen in FIG. 4, the cartridge holder  2  is a tubular element provided with windows  5  for cartridge inspection and having at its end adjacent to the housing  1  of the dose setting and injection system a F-shaped cut out  11  which allows mounting of an operation ring  3  which has on its inner wall pins  10  with an axial distance corresponding to the distance between the horizontal parts of the F-shaped cut out. The mounting is obtained by passing the pins  10  along the vertical part of the F-shaped cut out  11 . In FIG. 4 only one F-shaped cut out is seen but a similar cut out is provided rotationally displaced  1800  from the shown cut out.  
         [0024]    A clamping member  12  has a tubular bottom part which has diametrically opposed axial cut outs  13  in which correspondingly diametrically opposed protrusions  14  at the perimeter of a ring  15  are guided to form an axially displaceable bottom in the clamping member  12 . Said bottom part further has diametrically opposed cut outs  16  which are not perpendicular to the axis of the clamping member  12  but rather form apart of a helix. The bottom part further carries two diametrically opposed tongues  17  which are biased to diverge outwardly away from the axis of the clamping member  12 . At their outer ends the tongues  17  are provided with closing members  18  which are moved radial inward when the tongues  17  are forced to attain an axial direction.  
         [0025]    The clamping member  12  is mounted in the cartridge holder  2  which has at its end opposite the dose setting and injection system longitudinal cut outs  19  in which ribs  20  at outer wall of the end of the tongues  17  can be guided. The operation ring  3  is mounted so that a pair of diametrically opposed pins  10  on this ring grips through the upper vertical part of the F of the F-shaped cut out into the cut out  16  in the bottom part of the clamping member  12 .  
         [0026]    A coupling ring  21  having in its outer wall diametrically opposed recesses  22 , each comprising two axially displaced parts perpendicular to the axis of the syringe connected by a part which is not perpendicular to said axis, is mounted in the cartridge holder  2  so that a set of diametrically opposed pins on the inner wall of the operation ring  3  grips through the lover vertical part of the F of the F-shaped cut outs into said recesses  22 . The coupling ring  21  further has at its outer cylindrical wall splines  23  which engage axial recesses in the cartridge holder to make the coupling ring inrotatable in the cartridge holder. A spring  24  is mounted between the coupling ring  21  and the bottom ring  15  of the clamping member  12 . Finally the coupling ring  21  is at its end surface turning away from the cartridge holder provided with circumferential three angled teeth which can cooperate with similar teeth on a piston rod guide ring  25  which has a not round central opening through which a correspondingly not round not shown piston rod projects from the dose setting and injection system.  
         [0027]    When the described components has been mounted in the cartridge holder  2  this holder is by gluing or welding or any other method secured to the housing  1 .  
         [0028]    In the FIGS. 2 and 3 the syringe is ready for use with a cartridge held in the cartridge holder. The operation ring  3  is in a position wherein its pins  10  gripping through the F-shaped cut out into the recess  16  of the syringe clamping member  12  engaging the parts at the foremost ends of these recesses  16  which parts are shaped as not helical landings which runs perpendicular to the axis of the clamping member  12 . Thereby the clamping member  12  is held in a retracted position in the cartridge holder in which position the closing members  18  is in their radially innermost position in which they grip over a neck part of the cartridge  8  and bar for an outward movement of said cartridge  8 . At the same time the pins gripping through the lover vertical part of the F of the F-shaped cut out into the recess  22  of the coupling ring  21  keep this ring  21  in a position wherein its triangular teeth engages the teeth of the piston rod guide ring  25  through which the not shown piston rod is guided, and this way the piston rod is locked against rotation relative to the housing  1 .  
         [0029]    When in FIG. 4 the operation ring  3  is rotated to the left the, pins engaging the recess  16  of the clamping member will move this member outward in the cartridge holder. The tongues  17  which were forced to their axial position by the cartridge holder will now diverge bringing the closing members away from the cartridge and provide an opening through which the cartridge can be drawn out through the end of the cartridge holder  2 . At the same time the other set of pins  10  which engages the recesses of the coupling ring  21  will against the force of the spring  24  move this ring away from the dose setting and injection system and bring its teeth out of engagement with the teeth of the piston rod guide ring  25 . This will allow the piston rod guide ring  25  and the not shown piston rod to rotate so that the piston rod can by the insertion of a new cartridge be pressed back in to the dose setting and injection system. When a new cartridge has been moved into the cartridge holder, the operation ring  3  is rotated rightward whereby its pins  10  engaging the helical cut out  16  will draw the clamping member  12  into the cartridge holder and the closing members  18  will be moved radially inward in front of the cartridge to maintain it in the cartridge holder. At the same time the coupling ring  21  is by the other set of pins which engage the recesses  22  in this coupling ring moved toward the housing  1  whereby the coupling teeth of this ring is brought into engagement with the teeth on the piston rod guide ring  25 . This will lock the piston rod against rotation whereby dose setting and injection is again allowed.  
         [0030]    [0030]FIGS. 6 and 7 shows another embodiment of a front loaded injection device wherein a closing element  30  can be moved relative to a second closing element which is integral with the device. The closing element  30  is moved radially relative to a cartridge holder  31  providing an opening which allows insertion of a cartridge  32 . By pressing the plastic top  33  mounted on a neck part of the cartridge, the cartridge is moved so far into the cartridge holder  31  that the closing element can be moved axially relative to the cartridge towards the second closing element so that the diameter of the opening formed by the two closing elements is smaller than the diameter of the cartridge which is in this way supported at its neck part.