Abstract:
A drug delivery device ( 1 ) comprises a housing ( 2 ) and a cap ( 3 ) attachable onto the housing ( 2 ). The cap ( 3 ) comprises one or more snap features ( 33 ) to attach the cap ( 3 ) onto the housing ( 2 ) and one or more orientation features ( 34 ) to define the orientation of the cap ( 3 ) relative to the housing ( 2 ). At least one of the orientation features ( 34 ) is located at a rigid part of the cap ( 3 ) and at least one of the snap features ( 34 ) is located at a less rigid part of the cap ( 3 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a U.S. National Phase Application pursuant to 35 U.S.C. §371 of International Application No. PCT/EP2009/067477 filed Dec. 18, 2009, which claims priority to EP Patent Application No. 08022318.3 filed on Dec. 23, 2008. The entire disclosure contents of these applications are herewith incorporated by reference into the present application. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This disclosure relates to a drug delivery device comprising a cap which can be attached to a housing of the device. In particular, it relates to a cap which can be attached to the housing only in a single orientation relative to the housing. 
       BACKGROUND 
       [0003]    The patent application EP 1923083 A1 discloses an injection device for setting and dispensing a fixed dose of a medicament. Here, a removable cap can be releasably retained over a distal end of a cartridge retaining part. 
         [0004]    The patent EP 1007115 B1 discloses an injection device comprising a cap having a curved edge at its open end. 
         [0005]    It is an aim of the present invention to provide a drug delivery device, wherein a cap can be attached to a housing in a defined orientation and wherein an attachment in a wrong orientation is efficiently prevented. 
       SUMMARY 
       [0006]    According to a first aspect of the present invention, a drug delivery device is provided comprising a housing and a cap attachable onto the housing. The cap comprises one or more snap features to attach the cap onto the housing and one or more orientation features to define the orientation of the cap relative to the housing when the cap is attached to the housing. At least one of the orientation features is located at a rigid part of the cap and at least one of the snap features is located at a less rigid part of the cap. 
         [0007]    The drug delivery device may be a pen-type injection device comprising a cartridge holder configured to receive a cartridge containing a drug. The drug may be medication. Preferably, the cap is attachable onto the device such that it covers at least a part of the cartridge holder. This is useful for protecting the cartridge, in particular when the cartridge is made of a breakable material like glass, or for protecting a needle unit at the distal end of the cartridge holder. 
         [0008]    The cap may comprise a window through which information provided by the cartridge or the cartridge holder is visible for the user. As examples, the information may be related to the type or name of the drug contained in the cartridge or may be an indication of the filling status of the cartridge. In the case that the information is visible only when the cap is attached in a certain orientation relative to the housing, the appropriate rotational orientation of the cap has to be ensured. 
         [0009]    For this aim, the cap comprises one or more orientation features. In a preferred embodiment, the housing comprises one or more mating orientation features which interact with at least one of the orientation features of the cap. Preferably, for each orientation feature on the cap a mating orientation feature on the housing is provided. 
         [0010]    If all orientation features were located at a flexible part of the cap, i.e., a part where the cap can easily be elastically deformed, the cap might be attachable to the housing also in a wrong orientation. Here, the cap may be forced onto the housing by a deformation at its flexible part where the orientation features are located and thereby, the orientation features bump over the mating orientation features of the housing. However, for an orientation feature which is located at a rigid part of the cap, such an elastic deformation and the resulting “bump over” may be prevented. 
         [0011]    At least one of the snap features of the cap is located at a less rigid part of the cap. In a preferred embodiment, the housing comprises at least one mating snap feature which is engageable with at least one of the snap features of the cap. For the engagement of a snap feature with a mating snap feature, a certain elastic deformability of the cap may be required. Preferably, for every snap feature on the cap a mating snap feature on the housing exists. 
         [0012]    Accordingly, the separate positioning of at least one orientation feature at a rigid part of the housing and of at least one snap feature at a less rigid part of the housing allows a reliable attachment of the cap at the right orientation relative to the housing. 
         [0013]    The drug delivery device may have a longitudinal axis. In this case, the cap may extend along the longitudinal axis, and the rigidity of the cap may vary along the longitudinal axis. Here, the snap feature located at a less rigid part of the cap and the orientation feature located at a rigid part of the cap may have an offset along the longitudinal axis. 
         [0014]    The cap may comprise an open end and a closed end. Preferably, at least one of the snap features is located near the open end of the cap and the orientation feature located at a rigid part of the cap is displaced from the snap feature in a direction towards the closed end of the cap. Preferably, the cap is more rigid at its closed end than at its open end. This means that the cap can be more easily elastically deformed at its open end than at its closed end. As an example, the cap may be of a plastic material such as polypropylene which may be easily deformable at the open end of the cap. 
         [0015]    In one embodiment, the orientation feature comprises a rib. 
         [0016]    The rib may extend towards a longitudinal axis of the drug delivery device. Preferably, the housing comprises a groove where the rib can engage. 
         [0017]    The cap may comprise several orientation features, wherein the orientation features in combination ensure that the cap is attached in the right orientation onto the housing. Here, some of the orientation features may be located at a rigid part of the cap and others may be located at a less rigid part of the cap. 
         [0018]    In a preferred embodiment, the drug delivery device comprises a plurality of orientation features which have an angular offset around the longitudinal axis. 
         [0019]    Preferably, these orientation features simultaneously interact with mating orientation features of the housing or with parts of the housing which prevent an attachment of the cap. By the simultaneous interaction of many orientation features a maximum counterforce can be achieved when a user tries to attach the cap in a wrong orientation. 
         [0020]    In a preferred embodiment, several orientation features are located at the same axial position and at an angular offset relative to the longitudinal axis. 
         [0021]    In this case, the misplacement of the cap can be prevented efficiently even if a clearance between the inside diameter of the cap and the outside diameter of the housing exists. If only one orientation feature was present at a certain position about the longitudinal axis, there would be a high risk that the cap would be assembled on the housing off axis without the orientation feature preventing the full assembly. However, in the case that several orientation features, e. g. two diametrically opposed orientation features, are provided at certain positions, these may prevent the assembly unless the correct orientation is found. 
         [0022]    In a preferred embodiment, several orientation features are located equiangular around the longitudinal axis of the device. 
         [0023]    In this case, due to the symmetry, several orientations of the cap relative to the housing may be allowed. In order to allow only one single orientation, some of the orientation features may be located at other positions of the cap. When placing several orientation features at equiangular positions, either all or none of these orientation features interact with mating orientation features. Thereby, a maximum counterforce is exerted when a user tries to assemble the cap in the wrong orientation. In a preferred embodiment, the cap comprises three orientation features which are located at equiangular positions around the longitudinal axis. 
         [0024]    In one embodiment, the mating orientation features on the housing comprise a lead-in to assist the assembly of the cap and the housing in the correct orientation. 
         [0025]    Thereby, the cap may be guided into the right orientation when a user tries to assemble the cap onto the housing in an orientation slightly deviating from the right orientation. The lead-in may also allow a twisting off of the cap from the housing. 
         [0026]    In one embodiment, the cap comprises at least one orientation feature which is located at the open end of the cap in addition to one or more orientation features at the rigid, closed end of the cap. 
         [0027]    The sum of the orientation features which are arranged at a rigid part of the cap and the orientation features arranged at the open end of the cap may define a single orientation of the cap on the housing. 
         [0028]    As an example, the end face at the open end of the cap comprises at least one protrusion. In a preferred embodiment, the end face of the cap comprises two protrusions which are located at equiangular positions around the longitudinal axis. Here, two possible orientations of the cap are allowed. However, in combination with orientation features at the rigid part of the cap, only a single orientation is possible. 
         [0029]    Preferably, at least one orientation feature at the rigid part of the cap is located such that the snap feature at the cap does not fully reach a mating snap feature at the housing before the right orientation has been found. 
         [0030]    At least one of the snap features of the cap may be located at the protrusion at the open end of the cap. 
         [0031]    The drug delivery device may comprise several snap features. Preferably, the snap features are located at a less rigid part of the cap. Also here, some of the snap features may be located at a more rigid part of the cap. 
         [0032]    Other features will become apparent from the following detailed description when considered in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0033]      FIG. 1  shows a pen-type injection device comprising a cap, 
           [0034]      FIG. 2A  shows a cap having orientation features and snap features, 
           [0035]      FIG. 2B  shows a cartridge holder having mating snap features and mating orientation features, 
           [0036]      FIG. 3  shows an assembly of a cap and a housing in the right orientation, 
           [0037]      FIG. 4A  shows an attempted assembly of a cap and a housing in a first wrong orientation, 
           [0038]      FIG. 4B  shows an attempted assembly of a cap and a housing in a second wrong orientation, 
           [0039]      FIG. 5  shows the front part of a cartridge holder. 
       
    
    
     DETAILED DESCRIPTION 
       [0040]      FIG. 1  shows a pen-type injection device  1  having a longitudinal axis  1 . 
         [0041]    The injection device  1  comprises a housing  2  with a rear part  21  and a cartridge holder  4 , wherein a cartridge  5  is retained. A cap  3  is attached onto the housing  2  and covers the cartridge holder  4 . 
         [0042]    Through a window  36  in the cap  3 , the transparent cartridge holder  4  and the cartridge  5  are visible. A user may set a dose by twisting a dose dial element  23  and inject a dose by pushing a dose button  22 . Thereby, a piston  51  in the cartridge  5  is moved forward and the medicament is pressed out of the cartridge  5 . The user is informed on the filling status of the cartridge  5  by the position of the piston  51  inside the cartridge  5 . A scale  52  at the cartridge holder  5  indicates how many doses are left in the injection device  1 . In other embodiments, the scale may be located at the cartridge  5 . In order to ensure that the scale  52  is always visible to a user, the cap  3  has to be attached onto the housing  2  in the appropriate orientation. 
         [0043]      FIG. 2A  shows a cap  3  having orientation features  34  and snap features  33 , whereby the orientation features  34  ensure that the cap  3  can be attached onto the housing  2  only at one specific orientation. The cap  3  comprises a closed end  32  and an open end  31 , wherein the closed end  32  is more rigid than the open end  31 . 
         [0044]    Some of the orientation features  34  are formed as ribs  34   a  and are located near the closed end  32  of the cap  3 . Here, three ribs  34   a  are arranged at equiangular positions around the longitudinal axis  1 . 
         [0045]    At its open end  31 , the cap  3  comprises orientation features  34  in the form of two protrusions  34   b  having curved end faces. The protrusions  34   b  are arranged at diametrically opposed positions. 
         [0046]    At the inner surface of each protrusion  34   b,  a snap feature  33  is located. The end face  35  of the cap  3  also comprises two flat sections  35   a  arranged between the curved sections  35   b  of the protrusions  34   b.    
         [0047]      FIG. 2B  shows a cartridge holder  4  which can be attached to the rear part  21  of the housing  2  of an injection device  1 . For this aim, the cartridge holder  4  comprises locking means  46  which engage with mating locking means at the rear part  21  of the housing  2  when the rear part  41  of the cartridge holder  4  is inserted into the housing  2 . 
         [0048]    At its front part  42 , the cartridge holder  4  comprises a thread  48 , where a needle unit (not shown here) can be attached. The cartridge holder  4  can be covered by the cap  3  as shown in  FIG. 1 . 
         [0049]    For a releasable attachment of the cap  3 , the cartridge holder  4  comprises mating snap features  43  which are engagable with the snap features  33  of the cap  3 . 
         [0050]    Moreover, the cartridge holder  4  comprises mating orientation features  44  which, by interaction with the orientation features  34  of the cap  3 , ensure that the cap  3  can be attached onto the housing  2  only at a single orientation. 
         [0051]    At a front face  49  near the thread  48 , the cartridge holder  4  comprises three grooves  44   a  where the ribs  34   a  of the cap  3  can engage. The grooves  44   a  have a generous lead-in to aid the location of the ribs  34   a  and to enable the user to twist off the cap  3  in order to remove it. In particular, the grooves  44   a  are broader than the ribs  34   a,  such that the ribs  34   a  may engage also when an orientation near the correct orientation has been found, and have inclined side faces. 
         [0052]    Towards the rear part  41  of the cartridge holder  4 , two diametrically opposed recesses  44   b  are formed. By the recesses  44   b,  mating orientation features  44  for the protrusions  34   b  of the cap  3  are provided. At the recesses  44   b,  the cartridge holder  4  has a flank profile  45  which matches the end face  35  of the cap  3 . Accordingly, the flank profile  45  comprises a mating flat section  45   a  and a mating curved section  45   b,  whereby the twisting off of the cap  3  is enabled. 
         [0053]      FIG. 3  shows an assembly of the cap  3  and the housing  2  in the appropriate orientation. Here, the cartridge holder  4  as shown in  FIG. 2B  has been fixed to the rear part  21  of the housing  2  by its locking means  46  and is covered by the cap  3 . Both the cap  3  and the rear part  21  of the housing  2  comprise a rail  37 ,  24 , whereby a user can easily visually identify the correct orientation of the cap  3  on the housing  2 . The front part  32  of the cap  3  and the underlying cartridge holder  4  and cartridge  5  is shown in a cross sectional view at the locations marked by the lines A-A in  FIGS. 2A and 2B . 
         [0054]    In  FIG. 3 , the ribs  34   a  of the cap  3  are in the correct orientation to engage with the mating grooves  44   a  of the cartridge holder  4 . Also the protrusions  34   b  of the cap  3  are in the correct orientation to engage with the recesses  44   b  of the cartridge holder  4 . In this orientation, the cap  3  can be fully assembled onto the housing  2  such that the snap features  33  of the cap  3  can engage with the mating snap features  43  at the cartridge holder  4 . By the engagement of the snap features  33  and the mating snap features  43 , the cap  3  is attached to the housing  2 . 
         [0055]      FIG. 4A  shows an attempted assembly of a cap  3  and a housing  2  in a first wrong orientation. Here, the cap  3  is out of position by 180°, which can easily be seen by the mismatch of the rail  37  on the cap  3  and the rail  24  on the housing  2 . At this orientation, the ribs  34   a  of the cap  3  cannot engage with the grooves  44   a.  A further assembly of the cap  3  on the housing  2  is blocked by the abutment of the front end of the ribs  34   a  and a front face  49  of the cartridge holder  4 , although the protrusions  34   b  would allow an assembly of the cap  3  onto the housing  2 . The ribs  34   a  are located such that an assembly is blocked before the snap features  33  on the cap  3  can engage with the mating snap features  43 . Thus, in a wrong orientation, the orientation features  34  prevent both the full assembly and the attachment of the cap  3  onto the housing  2 . 
         [0056]      FIG. 4B  shows an attempted assembly of a cap  3  and a housing  2  in a second wrong orientation. Here, the cap  3  as shown in  FIG. 4A  has been rotated such that the ribs  34   a  are about to engage with the grooves  44   a.  However, at this orientation, the curved end faces of the protrusions  34   b  abut with the flat sections  45   a  of the cartridge holder  4 , whereby the engagement of the ribs  34   a  is prevented due to the axial offset caused by the position of the protrusions  34   b.  The cap  3  can be rotated relative to the housing  2  with the protrusions  34   b  abutting the flank profile  45  until the correct orientation has been found and the cap  3  can be pushed fully home. In that case, the snap features  33  of the cap  3  engage with the mating snap features  43  of the cartridge holder  4 . The cap  3  may be removed by applying a twisting, or a combined twisting and pulling action to the cap  3  relative to the housing  2 . 
         [0057]      FIG. 5  shows the front part  42  of a cartridge holder  4 . Here, at the front face  49  only a limited material thickness d for the grooves  44   a  is available. Therefore, preferably, at least two or more orientation features  34  on the cap  3  and mating orientation features  44  on the cartridge holder  4  are provided. In this case, also when the cap  3  is assembled off axis, at least one of the orientation features  34  will block the full assembly of the cap until the correct orientation has been found. 
         [0058]    Other implementations are within the scope of the following claims. Elements of different implementations may be combined to form implementations not specifically described herein.