Abstract:
The present invention relates to drug delivery devices. The drug delivery device according to the invention includes a housing with a needle holder suitable for attaching a needle unit to the housing at the distal end, and a cap being capable of covering the distal end of the drug delivery device and comprising a retaining member capable of securing the cap by engaging with the housing, the retaining member is prevented from engaging with the housing with the needle unit being attached to the needle holder. Furthermore, using a cap for covering the distal end of the drug delivery device is disclosed.

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/EP2009/067605 filed Dec. 21, 2009, which claims priority to EP Patent Application No. 08022316.7 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]    The present invention relates to drug delivery devices. Furthermore, the present invention relates to using a cap for covering a distal end of a drug delivery device. 
       BACKGROUND 
       [0003]    Drug delivery devices are generally known for the administration of a medicinal product, for example insulin, growth hormones or other drugs suitable for self-administration. Some drug delivery devices are configured to deliver a plurality of doses. Additionally, some drug delivery devices are configured to allow setting of different dose sizes which are to be delivered. 
         [0004]    In the document EP-A1-1923084, a drug delivery device is shown where a user may activate the drug delivery device. The drug delivery device includes a drive mechanism suitable for use in pen-type injectors, wherein a number of pre-set doses of medicinal product can be administered. A needle unit can be attached to the drug delivery device for dispensing the medicinal product into a patient&#39;s skin. After usage of the drug delivery device, the distal end of the device can be covered by a cap. 
         [0005]    It is generally advisable that a needle unit is removed after using the drug delivery device and that the drug delivery device is covered by a cap after usage so as to prevent contact with the needle and/or contamination of the device. 
         [0006]    In US 2003/0191438 A1 a medical needle shield is shown that includes a shield being extensible from a retracted position to an extended position, wherein the shield includes a first segment mounted to a medical needle device having a needle extending from the device, whereby a further segment substantially encloses a distal end of the needle. 
         [0007]    In U.S. Pat. No. 4,935,012 a safety device for protecting medical personnel and the like against needle stick injuries and/or exposure to communicable diseases or other harmful agents is shown. The safety device comprises an elongated protective sleeve supported by front and rear bearing members for sliding movement about a medical needle and its associated support structure. 
         [0008]    Further safety shield systems for pen needles are known from the documents US 2002/0133122 A1 and US 2007/0293818 A1. 
       SUMMARY 
       [0009]    It is an aim of the present invention to provide for an improved drug delivery device. In particular, a drug delivery device should be provided, which encourages a user to remove the needle after operation of the device. 
         [0010]    For this aim, a drug delivery device comprises a housing with a needle holder suitable for attaching a needle unit to the housing at the distal end, and a cap being capable of covering the distal end of the drug delivery device and comprising a retaining member capable of securing the cap by engaging with the housing, the retaining member is prevented from engaging with the housing with the needle unit being attached to the needle holder. 
         [0011]    In particular, the cap may be configured to be capable of covering the distal end of the drug delivery device. The cap may be a unitary part. The cap may be a single injection moulded piece. The retaining member may be configured to be capable of securing the cap by engaging with the housing. The retaining member may be configured to secure the cap to the housing. 
         [0012]    In such a drug delivery device, the engagement of the retaining members of the cap with the housing is prevented when the needle unit is attached to the drug delivery device. Consequently, a user experiences a feedback when attempting to place the cap on the drug delivery device. This is achieved by preventing the retaining member from engaging with the housing as long as the needle unit is attached to the needle holder. 
         [0013]    Furthermore, the risk of needle stick injuries is reduced because the cap has features which abut the needle unit before the needle cannula risks piercing the distal end of the cap. 
         [0014]    In a first embodiment, the cap comprises at least one protruding element on the inner surface of the cap, wherein the protruding element is configured to abut or abuts the needle unit so as to prevent the retaining member from engaging with the housing. 
         [0015]    The at least one protruding element on the inner surface can abut the needle unit while attempting to place the cap on the drug delivery device. The arrangement of the protruding element is chosen such that the retaining members of the cap are prevented from engaging with respect to the housing, as the cap can not reach its final position. The at least one protruding element on the inner surface effectively stops further engagement of the cap with the housing by abutting the needle unit. In addition, the cap can be designed such that a relatively short cap is suitable for both long and short needle cannula. This can be achieved, for example, by placing the at least one protruding element on the inner surface close to an end of the cap which faces the proximal end. 
         [0016]    In a further embodiment, the at least one protruding element is formed as a step along the inner side wall of the cap. 
         [0017]    According to this embodiment, the protruding element can be easily implemented into a cap. Hence, the design of the cap is simplified and conventional techniques can be employed for producing the cap. For example, the cap can be provided as a single injection moulded piece fabricated from thermoplastic materials, e.g. polypropylene, polystyrene, polyamide, polyethylene, or the like. The cap may be a unitary or one-piece cap. 
         [0018]    In one embodiment, the at least one protruding element is formed as at least one rib or bar on the inner side wall of the cap. The at least one rib or bar may be arranged along a longitudinal axis being arranged between the distal end and the proximal end of the cap. 
         [0019]    In this example, the protruding element provides for a reinforcement of the cap by strengthening the cap on the inner surface. Accordingly, the manufacturability of the drug delivery device is facilitated as rather thin side walls of the cap can be employed. In addition, the cap according to this example can be implemented as a single injection moulded piece without the need for performing significant design changes to a conventional cap. 
         [0020]    According to a further embodiment, the at least one rib on the inner side wall of the cap is capable of providing guidance when attempting to engage the cap on the housing. 
         [0021]    The rib of the cap can be arranged such that it fits into respective grooves on the housing or the needle holder when attempting to engage the cap on the housing. Hence, the rib provides an orientation feature which prevents the user from placing the cap with a false orientation with respect to the housing. Rotation of the cap with respect to the housing may be prevented by means of mechanical cooperation of the rib and the respective groove. It should be noted that it is within the scope of the invention to provide a plurality of ribs. In addition, the plurality of ribs on the inner surface of the cap can be implemented such that a single orientation or a plurality of orientations of the cap with respect to the housing is possible. 
         [0022]    In a further embodiment, needle connection means are provided which allow the attachment of the needle unit to the needle holder by rotating one relative to the other. 
         [0023]    The needle holder may comprise an outer thread, the outer thread being capable of engaging with a corresponding inner thread of the needle unit 
         [0024]    According to another embodiment, the needle connection means comprise a bayonet connection. 
         [0025]    A needle holder and a needle unit of this kind can be easily implemented in drug delivery devices. Furthermore, attaching the needle unit is simplified as the corresponding threads offer a simple mechanical connection. Due to the threaded connection, the outer diameter of the needle unit is significantly larger when compared to the outer diameter of the needle holder. Consequently, the protruding element or the protruding elements can be adapted to the space occupied by the needle unit around the needle holder in a radial direction. Accordingly, the design of the cap can be adapted for different kinds of needle units. 
         [0026]    In one embodiment, the protruding element is arranged such that it contacts the needle unit in a region between the outer diameter of the needle holder and the outer diameter of the needle unit. 
         [0027]    The actual design of the cap is independent of the precise dimensions of the needle unit, as long as the protruding element is capable of contacting the needle unit in a region between the outer diameter of the needle holder and the outer diameter of the needle unit. Accordingly, different types of needle units can be employed, which can in addition be suitable for accommodating long or short needles. 
         [0028]    In one embodiment, the protruding element abuts a front side of the needle unit facing the distal end of the drug delivery device when the needle unit is attached to the needle holder. 
         [0029]    According to this embodiment, the design of the cap is independent from the outer diameter of the needle holder and the outer diameter of the needle unit. Consequently, a wide range of different needle units can be used for such a drug delivery device. In order to accommodate a long needle cannula, a correspondingly long cap should be used. 
         [0030]    During placement of the cap on the housing, the danger of needle stick injuries is reduced by providing a cavity in which the needle is located. The cavity is capable of surrounding the needle unit without abutting the needle cannula of the needle unit on its inner surface when attempting to engage the cap on the housing. The cavity may be configured to surround the needle unit without abutting the needle cannula. 
         [0031]    In one embodiment, the retaining member of the cap is arranged at the end of the cap facing the proximal end of the housing. 
         [0032]    In this embodiment, the retaining member can be provided in a region of the cap which can be fabricated from relatively flexible material. This allows the engagement of the cap with the housing requiring only a relatively weak force which needs to be applied by the user. Accordingly, operability of the drug delivery device is enhanced. 
         [0033]    According to a further embodiment, the retaining member is capable of engaging into a corresponding mating retaining member on the housing. 
         [0034]    In this example, the retaining member can be fabricated as a pair of mating means which allow an easy implementation, in particular when providing the cap as a single injection moulded piece. Accordingly, the manufacturability of the drug delivery device is simplified. 
         [0035]    According to a further embodiment, the retaining member and the corresponding mating retaining member comprise a clip feature or a clamp capable of engaging in a corresponding recess. 
         [0036]    This allows a simple fixture of the cap with respect to the housing. 
         [0037]    According to a further embodiment, the cap comprises at least one protrusion being arranged on an end face of the cap. 
         [0038]    In this example, the cap can be implemented such that the protrusion fits into a corresponding part of the housing. Hence, orientation of the cap with respect to the housing can be defined by the protrusion. Rotation of the cap with respect to the housing may be prevented in this way. 
         [0039]    According to a further embodiment, the cap comprises two protrusions which are located at symmetric positions around a longitudinal axis being arranged between the distal end and the proximal end of the cap. 
         [0040]    In this example, the number of possible orientations of the cap with respect to the housing is reduced which facilitates engaging the cap with the housing. Furthermore, the user is encouraged to place the cap with two possible orientations only. Consequently, an engagement of the cap by the user in arbitrary positions relative to the housing is prevented. 
         [0041]    According to a further embodiment, the housing comprises a cartridge holder capable of enclosing a cartridge containing a medicament and wherein the cap can be attached such that it covers at least a part of the cartridge holder. 
         [0042]    In this example, the housing comprises a cartridge holder which can be fabricated as a separate piece together with a body wherein a drive mechanism can be arranged. Accordingly, the manufacturability of the drug delivery device is facilitated. 
         [0043]    For the above mentioned aim, a cap is used for covering the distal end of the drug delivery device having a housing with a needle holder suitable for attaching a needle unit at the distal end of the housing, the cap comprising a retaining member capable of securing the cap by engaging with the housing, the retaining member is prevented from engaging with the housing with the needle being attached to the needle holder. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0044]    Other features will become apparent from the following detailed description when considered in conjunction with the accompanying drawings. 
           [0045]    In the drawings: 
           [0046]      FIG. 1  schematically shows a simplified side view of a drug delivery device according to an embodiment; 
           [0047]      FIG. 2  schematically shows a simplified cross sectional side view of a drug delivery device according to an embodiment; 
           [0048]      FIG. 3  schematically shows a simplified cross sectional side view of a drug delivery device according to an embodiment; 
           [0049]      FIG. 4  schematically shows a cross sectional view of a part of a drug delivery device according to an embodiment; 
           [0050]      FIG. 5  schematically shows a cross sectional view of a part of a drug delivery device according to an embodiment, and 
           [0051]      FIG. 6  schematically shows a simplified side view of a drug delivery device according to an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0052]    In  FIG. 1  an embodiment of a drug delivery device  5  is shown, which is an injector for a liquid medication. The drug delivery device  5  may be configured to deliver a plurality of fixed or user-settable doses of a drug. The drug delivery device  5  may be a pen-type device. The drug delivery device  5  comprises a housing  10 , which can be formed from a single or multiple pieces. 
         [0053]    In the embodiment shown in  FIG. 1 , the housing  10  comprises a body  12  and a cartridge holder  14 , wherein a cartridge  16  containing a medical product or drug can be located. The cartridge holder  14  may be secured against movement with respect to the body  12 . A needle unit  20  is located at the distal end  22  of the drug delivery device  5 . The needle unit  20  may be secured against movement with respect to the cartridge holder  14 . As will be shown below, needle unit  20  can be secured to a needle holder  24  which forms part of the cartridge holder  14  by a threaded engagement. Through needle unit  20  the medical product can be injected into a patient. 
         [0054]    Delivery of the medical product can be performed by means of a piston rod or the like (not explicitly shown), which can be moved into the distal direction with respect to the cartridge  16 . A piston (not explicitly shown) which is retained in the cartridge  16  and seals the cartridge  16  on the proximal end side may be moved in the distal direction with respect to the cartridge  16  by the piston rod. The cartridge holder  14  can be fabricated from transparent or translucent material, so as to allow viewing the position of the piston within the cartridge  16 . 
         [0055]    It should be noted that the description of the drug delivery device  5  as shown in  FIG. 1  is merely illustrative. Other elements might be necessary in order to achieve full functionality. For example a dispense button and a drive mechanism can be present, which are configured to apply the adjusted dose value and move the piston in the distal direction such that the adjusted amount of the medical product is dispensed upon pressing the dispense button. 
         [0056]    After administering a specific dose to the patient, it is usually required to remove the needle unit  20  from the drug delivery device  5 , so as to prepare the drug delivery device  5  for the next application. During preparation, a new sterile needle unit  20  can be attached to the needle holder  24 . In order to prevent contamination of the drug delivery device  5 , a cap  30  is attached to the drug delivery device  5 , which covers the distal end of the drug delivery device  5 . The cap  30  may be a single injection moulded piece. The cap  30  comprises a retaining member  32  capable of securing the cap  30  by engaging with the housing  10 , i.e. the body  12  or the cartridge holder  14 . The cap  30  may be securable against axial and rotational movement with respect to the housing  10  by means of retaining member  32 . 
         [0057]    Making now reference to  FIG. 2 , the cap  30  and the distal part of drug delivery device  5  are shown in more detail. 
         [0058]    In the embodiment shown in  FIG. 2 , the cap  30  comprises at a protruding element  34  on the inner surface  36  of the cap  30 . The protruding element  34  abuts the needle unit  20  so as to prevent the retaining member from engaging with the housing. Accordingly, the retaining members  32  of the cap  30  are prevented from engaging with respect to the housing  10 , as the cap  30  cannot reach its final position with respect to the housing  10 . In this embodiment, the protruding element  34  is formed as a ring like step running along the inner side wall of the cap  30 . However, other implementations, including a plurality of protruding elements are conceivable as well. 
         [0059]    As shown in  FIG. 2 , the needle holder  24  comprises an outer thread  26 , the outer thread  26  being capable of engaging with a corresponding inner thread  28  of the needle unit  20 . Due to the threaded connection, the outer diameter of the needle unit  20  is significantly larger as compared to the outer diameter of the needle holder  24 . Consequently, the protruding element  34  abuts the needle unit  20  in a region between the needle unit  20  and above the needle holder  24  in a radial direction. 
         [0060]    In the embodiment shown in  FIG. 2 , the protruding element  34  is located in close proximity to the inner thread of the needle holder  24  in case the needle unit  20  is not attached to the needle holder  24 . When the needle unit  20  is attached to the housing, the cap  30  encloses a cavity  38  along the inner surface  36  of the cap  30 . The cavity  38  is capable of surrounding the needle unit  20  without abutting a needle  40  of the needle unit when attempting to engage the cap  30  on the cartridge holder  14  with the needle unit  20  being attached to the needle holder  24 . Accordingly, no piercing through the cap  30  occurs when attempting to engage the cap  30  onto the housing  10 . 
         [0061]    Making now reference to  FIG. 3 , the cap  30  and the distal part of drug delivery device  5  are shown in more detail according to a further embodiment. As shown in  FIG. 3 , the cap  30  comprises a protruding element which is formed as a rib  50  on the inner side wall  36  of the cap  30 . The rib  50  is arranged along a longitudinal axis  52  being arranged between the distal end  22  and a proximal end  54 . It should be noted that a plurality of ribs  50  can be foreseen as well. 
         [0062]    The ribs  50  of the cap  30  can be arranged such that they fit into respective grooves on the housing or the needle holder when attempting to engage the cap on the housing (not shown in  FIG. 3 ). Hence, the ribs  50  provide an orientation feature which prevents users from placing the cap  30  in arbitrary orientations with respect to the housing  10 . Mechanical cooperation of the ribs  50  and the respective grooves prevents rotation of the cap  30  with respect to the housing  10 . 
         [0063]    It should be noted that the protruding elements  34  or the ribs  50  shown in  FIGS. 2 and 3  are merely illustrative. Other configurations, including a protruding element which abuts a front side of the needle unit  20  facing the distal end  22  of the drug delivery device  5  when the needle unit  20  is attached to the needle holder  24  are within of the scope of the invention. 
         [0064]    Making now reference to  FIG. 4 , the cap  30  according to an embodiment similar to that depicted in  FIG. 2  is shown in a cross sectional view. The cross section follows the line A-A′ as indicated in  FIG. 2 . In the embodiment depicted in  FIG. 4 , the protruding element  34  is formed as a ring like step running around the inner side wall  36  of the cap  30 . 
         [0065]    Making now reference to  FIG. 5 , the cap  30  according to an embodiment similar to that depicted in  FIG. 3  is shown in a cross sectional view. The cross section follows the line B-B′ as indicated in  FIG. 3 . In the embodiment depicted in  FIG. 5 , the protruding element is formed as three ribs  50  arranged along the longitudinal axis  52  between the proximal end and the distal end of the cap  30 . 
         [0066]    In  FIG. 6 , a further embodiment of the cap  30  comprises two protrusions  60  which are located at symmetric positions around the longitudinal axis  52 . The protrusions can fit into corresponding depressions on the housing. Accordingly, the number of possible orientations of the cap  30  with respect to the housing is reduced. A retaining member may be arranged near the proximal end of the cap  30 , in particular at the inner surface of the protrusions  60 . The retaining member is capable of engaging into a corresponding mating retaining member on the housing  10 . As shown in  FIG. 6 , the mating retaining member comprises a clip feature  62  or a clamp capable of engaging into a corresponding recess on the cap. However, other configurations including a clip feature or a clamp on the cap  30  and a corresponding recess on the housing are conceivable as well. 
         [0067]    Other implementations are within the scope of the following claims. Elements of different implementations may be combined to form implementations not specifically described herein.