Abstract:
A disposable syringe assembly for use in an autoinjector device, or manually includes a syringe housing which receives the syringe barrel and which is restrained against longitudinal movement with respect thereto, a shield portion mounted for generally telescopic movement relative to the syringe housing between a retracted position and an extended position in which in use it shields the syringe needle, and a lock out arrangement activated as the shield moves towards its extended position to prevent retraction therefrom. When fitted in an autoinjector the autoinjector may include drive mechanism for moving the shield portion to its locked out extended position, whereby, on completion of an injection operation, the disposable syringe assembly may be removed from the autoinjector in a shielded condition for subsequent disposal.

Description:
This application is a Section 371 National Stage of International Application PCT/GB2009/051095 filed on Aug. 28, 2009, which claims priority of U.K. patent application no. GB 0815923.8, filed Sep. 2, 2008; and U.S. provisional application no. 61/099,731, filed Sep. 24, 2008. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to syringe safety shields and in particular, but not exclusively, to such arrangements used in a disposable syringe arrangement for use in an autoinjector. 
     BACKGROUND OF THE INVENTION 
     There is a growing demand for reusable autoinjectors and for a reduction in the amount of materials or components that have to be disposed of. At the same time, safety requirements demand that, after use, the disposable components are in a safe state to reduce the risk of needle stick injuries. There is also a need for a syringe safety shield assembly that can be used either manually where an autoinjector is not available, or in an autoinjector, in each case providing needle stick protection post injection. There are many known arrangements for shrouding the needle on a syringe after a manual injection has been effected. There are also many arrangements for disposable autoinjectors which shroud the needle after use. However, there is a need for a syringe safety shield arrangement which can be used in a number of different applications, including in an autoinjector and in which there is a low number of components. 
     Although autoinjectors that provide a lock out needle shield for shielding the needle on completion of an injection are known, such devices either are designed as single use disposable autoinjectors, with the consequential environmental impact, or multiple use injectors in which the spent syringe is removed, allowing reuse of the autoinjector, but without shielding of the needle. 
     SUMMARY OF THE INVENTION 
     Accordingly, in one aspect, this invention provides an autoinjector system comprising an autoinjector device having a housing for receiving a disposable syringe assembly comprising a syringe having a syringe barrel, a needle at the forward end and a plunger, in combination with a safety shield arrangement, comprising: 
     a syringe housing receiving said syringe barrel and restrained against longitudinal movement with respect thereto, 
     a shield portion mounted for generally telescopic movement relative to said syringe housing between a retracted position and an extended position in which in use it shields said syringe needle, and 
     a lock out arrangement effective as said shield moves towards its extended position to prevent retraction therefrom, 
     the autoinjector including a drive mechanism for advancing said syringe to an injection position, for driving said plunger to expel a dose and for moving said shield portion to its locked out extended position, 
     whereby, on completion of an injection operation, said disposable syringe assembly may be removed from said autoinjector in a shielded condition for subsequent disposal. 
     Thus on completion of injection the syringe is shielded to allow safe disposal, and the number of components thrown away is low, thereby reducing environmental impact. The safety shield arrangement may also be used to shield a syringe that is used manually. 
     Thus, in another aspect there is provided a safety shield arrangement for use with a syringe having a syringe barrel, a needle at the forward end of the barrel and a plunger, said arrangement comprising: 
     a syringe housing for being coupled to said syringe barrel in use and restrained against longitudinal movement with respect thereto, 
     a shield portion mounted for a generally telescopic movement relative to said syringe housing between a retracted position and an extended shielding position in which in use it shields said syringe needle, and 
     a lock out arrangement effective as said shield moves towards its extended position to prevent retraction therefrom. 
     Preferably said syringe housing has engagement means resiliently to retain the syringe therein, such as for example surfaces providing a snap-fit for ease of assembly. 
     The lock out arrangement may comprise a resiliently deformable latch on one of said syringe housing and said shield portion, with the latch being snap-engageable with a latch surface on the other of said syringe housing and said shield portion. The extent of forward extension movement of said shield relative to said syringe housing may be limited by cooperating stop surfaces. A latch may be provided for releasably retaining the shield portion in a retracted position prior to forward extension thereof. 
     Where an autoinjector is used with a syringe with a safety shield which is subsequently disposed of, such that the needle shield is not a permanent component of the autoinjector, the sequencing of operation of the autoinjector is an important aspect. 
     Thus in yet another aspect there is provided an autoinjector adapted to receive in use a removable syringe assembly, including a syringe having a barrel, a needle at the forward end of the barrel and a plunger for expelling a dose through said needle, and a shield for being moved forwardly to shield the needle after injection, said device comprising: 
     a housing, 
     a drive mechanism including a drive member releasable for forward movement in use to drive said syringe plunger forwardly, 
     a syringe carriage for imparting forward movement of the syringe barrel relative to said housing, 
     a shield carriage for imparting forward movement of the shield relative to said syringe carriage, and 
     a control element associated with said drive member arranged to prevent forward movement of said shield carriage until after release of said drive member. 
     The autoinjector preferably includes a syringe carriage bias means urging the syringe carriage forward relative to the housing, with there also being shield carriage bias means for urging said shield carriage forwardly relative to said syringe carriage. In this way the movement of the syringe and shield during the injection stages is assisted by the respective biases. Advantageously, said control element cooperates with said drive member and at least one of said syringe carriage and said shield carriage when the drive member is in a primed position to retain both the syringe carriage and the shield carriage in retracted positions but when released allows movement of both relative to the drive member and to each other, such that each is independently movable. 
     Whilst the invention has been described above, it extends to any inventive combination of the features set out above, or in the following description or claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may be performed in various ways, and an embodiment thereof will now be described by way of example only, reference being made to the accompanying drawings in which: 
         FIG. 1  is a general perspective view of a syringe fitted with a safety shield in accordance with this invention, for use in an autoinjector or manually; 
         FIG. 2  is an exploded view of the arrangement of  FIG. 1 ; 
         FIG. 3  is a view similar to  FIG. 1  but with the syringe removed and the shield fully extended; 
         FIGS. 4(   a ), ( b ) and ( c ) are detailed views on the end of the syringe housing with the housing alone, with the housing, syringe and shield and on the shield alone; 
         FIGS. 5(   a ) and ( b ) are detailed views showing the latching arrangement for releasably latching the shield in a retained position on the syringe housing; 
         FIGS. 6(   a ) and ( b ) are views on the underside of the syringe housing and the shield respectively showing the lock out features; 
         FIGS. 7(   a ) and ( b ) are detailed sectional views showing the shield releasably latched in its retracted position and locked out in its extended position respectively; 
         FIG. 8  is a top perspective view of an autoinjector for receiving the syringe safety shield arrangement of  FIG. 1 , but with the upper housing of the autoinjector removed; 
         FIG. 9  is a perspective view from the front and above of the autoinjector of  FIG. 8 , but with the upper housing in place; 
         FIG. 10  is a view on the main drive components of the autoinjector of  FIGS. 8 and 9  removed from the autoinjector housing and rotated through 90°; 
         FIG. 11  is a perspective view from above of the syringe carriage; 
         FIG. 12  is a perspective view from below of the syringe carriage; 
         FIGS. 13(   a ) and ( b ) show the syringe carriage and shield driver in the loaded position, when viewed from above and below respectively; 
         FIGS. 14(   a ) and ( b ) are views on the syringe carrier and shield driver when in the fired position taken from above and below respectively; 
         FIGS. 15(   a ) and ( b ) are detailed views of the shield carriage and its engagement with the shield respectively; 
         FIGS. 16(   a ) and ( b ) are perspective side and rear views of the components that apply drive to the syringe plunger, the syringe barrel and the shield taken from one side and below respectively in the loaded position; 
         FIGS. 17(   a ) and ( b ) are views similar to  FIGS. 16(   a ) and ( b ) but showing the components in the fired position; 
         FIGS. 18(   a ), ( b ) and ( c ) are detailed views on the trigger assembly of the autoinjector, and 
         FIGS. 19  ( a ) to ( f ) are views showing the cycle of operation of the autoinjector of  FIGS. 9 to 18 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to  FIGS. 1 to 7 , a safety syringe shield arrangement will firstly be described. This arrangement is designed to be fitted in the autoinjector that is later described with reference to  FIGS. 8 to 19  but it also may be used to provide shielding for manual use syringes. 
     In  FIG. 1 , there is shown a syringe  10  having a plunger  12 , a barrel  14  (see  FIG. 2 ) with an outturned flange  16  with the syringe needle being covered prior to injection by a cap  18 . The syringe is fitted inside a shroud assembly comprising a syringe carrier  22  of open trough form having a fitting  24  at its rear end for engaging the flange  16  of the syringe barrel and having outwardly directed barbs  26  connected on thin flexible strips defined by slits  28  in the carrier. The shield  30  has a lower cylindrical portion of diameter to fit telescopically over the carrier  22  and an upper cylindrical portion of slightly lesser diameter designed telescopically to slide over the barrel of the syringe  14 . The shield has two slots  32  which, when the syringe carrier  22  is slid inside the shield  30  cooperate with the barbs  26  to limit extension movement of the shield  30 . The slits  28  on the syringe carrier allow the barbs  26  to deflect inwardly to allow assembly but, once the syringe  10  is inserted inward deflection of the barbs is prevented by the syringe barrel  14 . 
       FIGS. 4(   a ), ( b ) and ( c ) are detailed views on the end showing how the flange of the syringe can be snapped into engagement with the fitting  24 . Also visible in  FIG. 4(   c ) is a retention latch  34  which lightly clips the shield  30  in a retracted position relative to the syringe carrier  22 . This can be seen in more detail in  FIGS. 5 and 6 . It will be seen that the retention latch  34  is at the end of a flexible finger  36  which allows the latch to disengage when sufficient pull is applied to the shield  30 . The retention latch engages in a recess  36  forming part of the end fitting of the syringe carrier  22 . 
     Referring now in more detail to  FIGS. 6 and 7 , the radially inner surface of the finger  36  is provided with a lock out latch  38  that runs in a slot  40  on the syringe carrier. At its forward end, the slot  40  terminates in a ramp surface, forwardly of which is a lock out recess  43 . Forward of the flexible finger  36 , and on a relatively inflexible portion of the shield  30 , is a drive lug  42  for use in the autoinjector to drive the shield forward on completion of an injection. 
     The above syringe safety shield arrangement therefore allows the syringe to be snap-fitted into the syringe carrier  22  and, after injection, the shield  30  to be pulled forwardly until locked out by engagement of the lock out latch  38  in the lock out recess  43 . 
     Referring now to the autoinjector  50  illustrated in  FIGS. 8-17 , this includes an outer casing  52  closed at the rear end but providing an open access forward end into which a module comprising a syringe fitted into the safety shield described above can be fitted for injection. The autoinjector is primed by sliding a cover portion  54  rearwardly to cock a plunger  56 , the arrangement is then fired by pushing a button  58  on the rear end of the device sub-flush. 
     Referring to  FIGS. 8 and 10 , inside the casing is mounted a syringe carriage  60  which is biased forwardly by twin syringe carriage springs  62 . The plunger  56  is urged forward by a constant force spring  64 , the front end of which is anchored on the inside of the housing  52 . A slotted reset arm  66  is secured to the plunger and moves longitudinally with it, to control movement of the syringe and various components to be described below. A shield carriage  68  is slideably disposed on the underside of the syringe carriage and has a drive interface  70  designed to receive in use the drive lug  42  of the shield  30  in a releasable snap-fit. The shield carriage has twin side ribs  72  which cooperate with a T-shaped formation  74  on the forward end of the reset arm  66 . The shield carriage  68  is biased forwardly by twin shield carriage springs  76 . The inner surface of the syringe carriage  60  has an arcuate recess  78  designed to receive the end fitting  24  on the syringe carrier  22 . Extending rearwardly from the arcuate recess  78  are twin flexible arms  80  which engage within the housing. On the underside of the syringe carriage are provided laterally extending anchorage lugs  82  on which the forward ends of the shield carriage springs  76  are anchored. To the rear of the lateral anchorage lugs  82  are two downwardly extending anchorage lugs  84  on which the rear ends of the syringe carriage springs are anchored. On the underside of the formation defining the annular recess  78  is a peg  86  which slides in a slot  88  in the slotted reset arm  66 . 
     The reset arm  66  provides a sequencing function, restraining the syringe carriage  60  and the shield carriage  68  against forward movement until the plunger  56  has been released to move forwardly under the influence of the constant force spring  64 . Thus, in the primed state shown in  FIG. 10 , the plunger is in its rearward position and engagement of the peg  86  on the syringe carriage in the forward end of the slot  62  restrains movement of the syringe carriage under the influence of the carriage springs  62 . In addition, engagement of the T-formation  74  with the rib  72  on the shield carriage means that the shield carriage is prevented from forward movement with respect to the syringe carriage. The reset arm in this position therefore retains both the syringe carriage and the shield carriage in fully retracted positions. However, once the plunger is released and driven forwardly by the constant force spring  64 , the reset arm  66  moves forward thus allowing the syringe carriage and the shield carriage to move forwardly under the influence of their respective carriage springs. When freed the syringe carriage and the shield carriage are free to move forwardly relative to the housing and to move relatively to each other. Once the syringe carriage reaches its forwardmost position it stops and the plunger  56  then engages the syringe plunger to expel a dose. Upon removing the autoinjector from the injection site, the residual bias in the shield carriage springs  76 , pulls the shield forwardly to shield the needle, and to lock out.  FIGS. 17(   a ) and ( b ) show the components in this condition, with the syringe removed. It will be seen here that the plunger  56  is extended, and the drive interface  70  is at the forward end limit of its travel. 
       FIGS. 18  ( a ) to ( c ) show the trigger arrangement in this embodiment. The drive plunger  56  has two flexible barbs  90  that can slide past and be captured by complementary barbs  92  on the inner wall of the housing, to retain the plunger in an energised position when pulled back against the spring bias of the constant force spring  64 . The firing button  58  is connected to an inner sleeve  94  which, when the firing button  58  is pressed against the bias of a leaf spring  96  squeezes the barbs  90  inwardly so they disengage from the barbs  92  on the housing, thus allowing the plunger to move forward under the influence of the constant force spring  64 . 
     Referring now to  FIGS. 19(   a ) to ( f ) the operation of the autoinjector will now be described. In  FIG. 19(   a ) a syringe with a safety shield arrangement as described above is fitted into an autoinjector which has been previously primed by sliding back the cover  54 . The syringe is located by inserting it into the syringe carriage with the fitting  24  being received in the recess  78  and the drive lug  42  on the shield being received in the drive interface  70 . The device is offered up to the injection site ( FIG. 19(   b )) and the trigger depressed. The plunger  56  shoots forward allowing the syringe carriage and the shield carriage to move the syringe and shield assembly forward. On reaching its forwardmost position, the syringe carriage is arrested and the plunger  56  then expels a dose from the syringe ( FIG. 19(   c )). Upon then removing the autoinjection from the injection site, the needle shield is moved forwardly by the shield carriage moving forwardly relative to the syringe carriage ( FIG. 19(   d )) until the needle shield is fully extended and locked out by the lock out latch  38  latching into the lock out recess  43 . The syringe with the safety shield extended and locked out may then be removed ( FIG. 19(   d )) and disposed of safely. The autoinjector may then be re-primed by sliding the cover  54  rearwardly ( FIG. 19(   e )).