Patent Publication Number: US-2023145661-A1

Title: Injector Device

Description:
FIELD OF INVENTION 
     The present invention relates to an injector device for a medicament. 
     BACKGROUND 
     Injection devices, for example auto-injectors, typically have a sealed container of medicament, and a needle for injection of the medicament into a patient. In one type of device, the medicament container may comprise a medicament cartridge and the needle may be initially separated from the cartridge. An initial action moves the cartridge and needle together so that the needle pierces the cartridge. In another type of device, the medicament container may comprise a syringe containing a medicament and the needle may be secured to the syringe. In both cases, a plunger or piston within the cartridge or syringe can then be moved into the cartridge or syringe to dispense medicament through the needle for injection to a patient. 
     SUMMARY 
     It is an object of the present invention to provide an advantageous injector device having a piston rod release mechanism. 
     According to the present invention, there is provided an injector device comprising an elongate housing having a proximal end and a distal end, and configured to receive a container of medicament, a plunger rod moveable longitudinally within the housing between a primed position and a completed position, the plunger rod being configured to be engageable with a container of medicament when received in the housing; wherein the housing comprises an indicator located in a proximal region of the housing; the indicator comprising a spindle, the spindle comprising a shaft and a dial, and wherein the shaft of the spindle comprises a threaded arrangement configured to engage with a threaded arrangement on the plunger rod such that longitudinal movement of the plunger rod from the primed position towards the completed position is configured to cause the dial of the spindle to rotate to provide a user with information associated with the progress of the injection process dependent upon the longitudinal position of the plunger rod. 
     Preferably, the distal end of the housing is relatively closer to a site of injection and the proximal end is relatively further away from the injection site. 
     Preferably, the spindle is constrained from movement in the longitudinal direction and is rotatable relative to the plunger rod 
     In some embodiments, the spindle may be prevented from moving in the longitudinal direction by the housing. 
     In some embodiments, the dial may be located at the proximal end of the housing such that the distal surface of the dial contacts the proximal end of the housing and the proximal surface of the dial faces outwardly of the device to provide a user with information associated with the progress of the injection process, in use. 
     In other embodiments, the dial may be located inside the housing at the proximal end of the housing such that a proximal surface of the dial faces out of the housing to provide a user with information associated with the progress of the injection process. 
     In some embodiments, the proximal surface of the dial may comprise a surface formation configured to provide tactile feedback to a user associated with the progress of the injection progress. 
     The housing may comprise a cover extending from the proximal end of the housing and over the proximal surface of the dial, the cover being configured such that the dial can provide visual feedback to a user associated with the progress of the injection progress. 
     In one embodiment, the dial is housed inside the proximal end of the housing, and the housing further comprises a display window in its side face through which a side face of the dial can be seen, the side face of the dial comprising indicia configured to provide visual feedback to a user associated with the progress of the injection progress. 
     Preferably, the threaded arrangement comprises a continuous thread on at least one of the plunger rod and the shaft of the spindle, the continuous thread being configured to provide constant feedback on the progress of the injection process. 
     Preferably, the continuous thread on at least one of the plunger rod and the shaft of the spindle extends over a distance greater than or equal to the longitudinal distance between the primed position and the completed position of the plunger rod. 
     In some embodiments, the threaded arrangement may comprise a non-continuous thread on one of the plunger rod and the shaft of the spindle, the non-continuous thread being configured to provide event specific feedback on the progress of the injection process. 
     The plunger rod may be hollow and may comprise an open proximal end configured to receive the shaft of the spindle, the plunger rod comprising a thread on its inner surface and the shaft comprising a thread on its outer surface. 
     The injector device may further comprise a container of medicament received within the housing between the plunger rod and the distal end of the injector device. 
     In some embodiments, the indicator may comprise a display window located in a side wall of the housing, and a proximally extending projection extending from the plunger rod, wherein the projection is coupled to the proximal end of the plunger rod, the projection being visible through the display window in at least the primed position. 
     The indicator may further comprise an indication element, the projection being located between the display window and the indication element to obscure a user&#39;s view of the indication element in at least the primed position. 
     The projection may be axially coupled to the plunger rod and configured to move between a first indicating position and a second indicating position when the plunger rod is moved from the primed position to the completed position and wherein movement of the projection towards the second indicating position makes a greater portion of the indication element visible through the display window. 
     The projection may be in the first indication position, a proximal end of the projection is located at a proximal end of the display window. 
     When the projection is in the first indicating position, only the projection may be visible through the display window. 
     When the projection is in the second indicating position, a proximal end of the projection may be located at a distal end of the display window. 
     When the projection is in the second indicating position, only the indication element may be visible in the display window. 
     The projection may be rotationally decoupled from the plunger rod such that the projection remains aligned with the display window throughout the injection process. 
     An inner surface of the housing may comprise a guide mechanism configured to restrict rotational motion of the projection about the longitudinal axis of the plunger rod. 
     The housing may further comprise a second indicator comprising a second display window in the distal region of the housing, a container of medicament being visible through the second display window when the plunger rod is in its primed position and when the container of medicament is received in the housing, and wherein when the plunger rod is moved longitudinally into the completed position the distal end of the plunger rod is located at the distal end of the second display window. 
     The plunger rod and the indication element may comprise the same indicia and the projection comprises a different indicia to the plunger rod and indication element. 
     The injector device may further comprise an external sleeve configured to extend around the housing, the external sleeve being moveable longitudinally from a first position at the proximal end of the housing in which the external sleeve covers the indicator to a second position at the distal end of the housing in which the external sleeve exposes the indicator. 
     Another object of the present invention is to provide a method of using an injector device, the method comprising: actuating the injector device such that a plunger rod is moved longitudinally within the housing from a primed position to a completed position; and providing information associated with the longitudinal position of the plunger rod with an indicator. 
     These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG.  1 A  is a schematic side view of an injector device that embodies the invention, and a removable cap; 
         FIG.  1 B  is a schematic side view of the injector device of  FIG.  1 A , with the cap removed from the housing; 
         FIG.  2    is a perspective view of an injector device according to the present invention in its primed position; 
         FIG.  3    is a schematic perspective view of the injector device of  FIG.  2    in its completed position; 
         FIG.  4    is a schematic side view of the injector device of  FIG.  2    held in use; 
         FIG.  5    is a schematic side view of the injector device of  FIG.  2    further comprising an external sleeve held at the beginning of an injection process; 
         FIG.  6    is a schematic side view of the injector device of  FIG.  5    held during an injection process; 
         FIG.  7    is a schematic cross-sectional view of an injector device according to the present invention in its primed position; 
         FIG.  8    is a schematic cross-sectional view of the injector device of  FIG.  7    wherein a plunger rod has been moved towards the completed position; 
         FIG.  9    is a schematic cross-sectional view of an alternative arrangement of a dial at the proximal end of the injector device of  FIG.  7   ; 
         FIG.  10    is a schematic cross-sectional view of an alternative arrangement of a dial at the proximal end of the injector device of  FIG.  7   ; 
         FIG.  11    shows a collection of embodiments of indicia on the dial arrangement of the injector device of  FIG.  7   ; 
         FIG.  12    shows a schematic cross-sectional view of an alternative threaded engagement of the injector device of  FIG.  7   ; and 
         FIG.  13    shows a schematic cross-sectional view of an alternative arrangement of a plunger rod and a spindle of the injector device of  FIG.  7   . 
     
    
    
     DETAILED DESCRIPTION 
     A drug delivery device, as described herein, may be configured to inject a medicament into a patient. For example, delivery could be sub-cutaneous, intra-muscular, or intravenous. Such a device could be operated by a patient or care-giver, such as a nurse or physician, and can include various types of safety syringe, pen-injector, or auto-injector. The device can include a cartridge-based system that requires piercing a sealed ampule before use. Volumes of medicament delivered with these various devices can range from about 0.5 ml to about 3 ml. Another device can include a large volume device (“LVD”) or patch pump, configured to adhere to a patient&#39;s skin for a period of time (e.g., about 5, 15, 30, 60, or 120 minutes) to deliver a “large” volume of medicament (typically about 2 ml to about 50 ml). Yet another device may comprise a pre-filled syringe within a housing of the device. The syringe may be fixed within the housing or may be moveable within the housing, for example from a retracted position to an operation extended position. 
     In combination with a specific medicament, the presently described devices may also be customized in order to operate within required specifications. For example, the device may be customized to inject a medicament within a certain time period (e.g., about 3 to about 20 seconds for auto-injectors, and about 10 minutes to about 60 minutes for an LVD). Other specifications can include a low or minimal level of discomfort, or to certain conditions related to human factors, shelf-life, expiry, biocompatibility, environmental considerations, etc. Such variations can arise due to various factors, such as, for example, a drug ranging in viscosity from about 3 cP to about 50 cP. Consequently, a drug delivery device will often include a hollow needle ranging from about 25 to about 31 Gauge in size. Common sizes are 17 and 29 Gauge. 
     The delivery devices described herein can also include one or more automated functions. For example, one or more of combining the needle and cartridge, needle insertion, medicament injection, and needle retraction can be automated. Energy for one or more automation steps can be provided by one or more energy sources. Energy sources can include, for example, mechanical, pneumatic, chemical, or electrical energy. For example, mechanical energy sources can include springs, levers, elastomers, or other mechanical mechanisms to store or release energy. One or more energy sources can be combined into a single device. Devices can further include gears, valves, or other mechanisms to convert energy into movement of one or more components of a device. 
     The one or more automated functions of an auto-injector may each be activated via an activation mechanism. Such an activation mechanism can include an actuator, for example, one or more of a button, a lever, a needle sleeve, or other activation component. Activation of an automated function may be a one-step or multi-step process. That is, a user may need to activate one or more activation components in order to cause the automated function. For example, in a one-step process, a user may depress a needle sleeve against their body in order to cause injection of a medicament. Other devices may require a multi-step activation of an automated function. For example, a user may be required to depress a button and retract a needle shield in order to cause injection. 
     In addition, activation of one automated function may activate one or more subsequent automated functions, thereby forming an activation sequence. For example, activation of a first automated function may activate at least two of combining the needle and cartridge, needle insertion, medicament injection, and needle retraction. Some devices may also require a specific sequence of steps to cause the one or more automated functions to occur. Other devices may operate with a sequence of independent steps. 
     Some delivery devices can include one or more functions of a safety syringe, pen-injector, or auto-injector. For example, a delivery device could include a mechanical energy source configured to automatically inject a medicament (as typically found in an auto-injector) and a dose setting mechanism (as typically found in a pen-injector). 
     According to some embodiments of the present disclosure, an exemplary drug delivery device  10  is shown in  FIGS.  1 A and  1 B . Device  10 , as described above, is configured to inject a medicament into a patient&#39;s body. Device  10  includes a housing  11  which typically contains a cartridge or pre-filled syringe that defines a reservoir containing the medicament to be injected, and the components required to facilitate one or more steps of the delivery process. 
     The device  10  can also include a cap  12  that can be detachably mounted to the housing  11 . Typically, a user must remove cap  12  from housing  11  before device  10  can be operated. 
     As shown, housing  11  is substantially cylindrical and has a substantially constant diameter along the longitudinal axis A-A. The housing  11  has a distal region D and a proximal region P. The term “distal” refers to a location that is relatively closer to a site of injection, and the term “proximal” refers to a location that is relatively further away from the injection site. 
     Device  10  can also include a needle sleeve  19  coupled to housing  11  to permit movement of sleeve  19  relative to housing  11 . For example, sleeve  19  can move in a longitudinal direction parallel to longitudinal axis A-A. Specifically, movement of sleeve  19  in a proximal direction can permit a needle  17  to extend from distal region D of housing  11 . 
     Insertion of needle  17  can occur via several mechanisms. For example, needle  17  may be fixedly located relative to housing  11  and initially be located within an extended needle sleeve  19 . Proximal movement of sleeve  19  by placing a distal end of sleeve  19  against a patient&#39;s body and moving housing  11  in a distal direction will uncover the distal end of needle  17 . Such relative movement allows the distal end of needle  17  to extend into the patient&#39;s body. Such insertion is termed “manual” insertion as needle  17  is manually inserted via the patient&#39;s manual movement of housing  11  relative to sleeve  19 . 
     Another form of insertion is “automated”, whereby needle  17  moves relative to housing  11 . Such insertion can be triggered by movement of sleeve  19  or by another form of activation, such as, for example, a button  13 . As shown in  FIGS.  1 A and  1 B , button  13  is located at a proximal end of housing  11 . However, in other embodiments, button  13  could be located on a side of housing  11 . 
     Other manual or automated features can include drug injection or needle retraction, or both. Injection is the process by which a bung or piston  14  is moved from a proximal location to a more distal location within the reservoir of the cartridge  18  in order to force a medicament from the cartridge  18  through needle  17 . In some embodiments, a drive spring (not shown) is under compression before device  10  is activated. A proximal end of the drive spring can be fixed within proximal region P of housing  11 , and a distal end of the drive spring can be configured to apply a compressive force to a proximal surface of piston  14 . Following activation, at least part of the energy stored in the drive spring can be applied to the proximal surface of piston  14 . This compressive force can act on piston  14  to move it in a distal direction. Such distal movement acts to compress the liquid medicament within the cartridge  18 , forcing it out of needle  17 . 
     Following injection, needle  17  can be retracted within sleeve  19  or housing  11 . Retraction can occur when sleeve  19  moves distally as a user removes device  10  from a patient&#39;s body. This can occur as needle  17  remains fixedly located relative to housing  11 . Once a distal end of sleeve  19  has moved past a distal end of needle  17 , and needle  17  is covered, sleeve  19  can be locked. Such locking can include locking any proximal movement of sleeve  19  relative to housing  11 . 
     Another form of needle retraction can occur if needle  17  is moved relative to housing  11 . Such movement can occur if the cartridge  18  within housing  11  is moved in a proximal direction relative to housing  11 . This proximal movement can be achieved by using a retraction spring (not shown), located in distal region D. A compressed retraction spring, when activated, can supply sufficient force to the cartridge  18  to move it in a proximal direction. Following sufficient retraction, any relative movement between needle  17  and housing  11  can be locked with a locking mechanism. In addition, button  13  or other components of device  10  can be locked as required. 
     Referring now to  FIG.  2   , an embodiment of an injector device  20  of the present invention is shown. The injector device  20  of the present invention is similar to the device  10  described above and so features and components of the device  20  that are the same as the features and components of the above described device  10  will retain the same terminology and reference numbers. 
     The injector device  20  comprises a housing  11  configured to receive a container of medicament  18 , i.e. a cartridge. The container of medicament  18  may refer to a container, as such, for receiving a medicament or a container at least partially filled with medicament. The housing  11  is elongate and comprises a proximal end P and a distal end D. The container of medicament  18  is received in a distal region D′ of the housing  11 . That is, the container of medicament  18  is located closer to the distal end D of the housing  11  than the proximal end P of the housing  11 . 
     For the purposes of the following description, the distal region D′ may be considered to be a part of the housing  11  closer to the distal end D of the housing  11  than the proximal end P of the housing. The proximal region P′ of the housing  11  may be considered to be a part of the housing  11  that is closer to the proximal end P of the housing  11  than the distal end D of the housing  11 . 
     In  FIGS.  2  and  3   , the housing  11  of the injector device  20  is shown partially transparent in order to show the internal components of the injector device  20  more clearly. For the sake of clarity, some components of the injector device  20  are not shown in  FIGS.  2  and  3   , such as the cap  12  and the needle sleeve  19 , for simplicity. 
     The injector device  20  further comprises a plunger rod  21  which is moveable longitudinally within the housing  11  between a primed position, shown in  FIG.  2   , and a completed position, shown in  FIG.  3   . Preferably, the plunger rod  21  is located predominantly, if not completely, in the proximal region P′ when in its primed position and the plunger rod  21  is located predominantly in the distal region D′ when in its completed position. Therefore, the plunger rod  21  is moveable from a proximal region P′ of the housing  11  to the distal region D′ of the housing  11  during the injection progress. In any case, when the plunger rod  21  is located in its completed position, the plunger rod  21  is located closer to the distal end D of the housing  11  than when the plunger rod  21  is in its primed position. 
     The injector device  20  further comprises a container of medicament  18 . The plunger rod  21  comprises a distal end  22  and a proximal end  23 . The container of medicament  18  is received within the housing  11  between the plunger rod  21  and the distal end D of the injector device  20 . 
     The plunger rod  21  comprises a bung  14  located at its distal end  22 . The bung  14  is configured to contact the side wall(s) of the container of medicament  18  to form a seal so that the medicament is urged out of the container  18  and through the needle  17  when the plunger rod  21  is moved longitudinally in the distal direction from the primed position towards the distal position. 
     The injector device  20  further comprises an indicator  24 . The indictor  24  is located in the proximal region P′ of the housing  11 . Preferably, the indicator  24  is located in the region of the proximal end P. That is, preferably the indicator  24  is located close to, if not at, the proximal end P of the housing  11 . The indicator  24  is configured to provide a user with information associated with the progress of the injection progress dependent upon the longitudinal position of the plunger rod between the primed and completed positions. 
     In the present embodiment, the indicator  24  comprises a display window  25 . The display window  25  is located in a side wall of the housing  11 . The display window  25  comprises a distal end  28   a  and a proximal end  28   b.  The display window  25  is located in the proximal region P′ of the housing  11 . Preferably, the display window  25  is fully located in the proximal region P′ of the housing  11 . Even more preferably, the display window is located close to the proximal end P of the housing  11 . That is, preferably, the proximal end  28   b  of the display window  25  is located next to the proximal end P of the housing  11 . Having the display window  25  positioned near the proximal end P of the housing  11  allows a user to grip the injector device  20  closer to the distal end D of the housing  11  which improves the stability of the device  20  during injection due to the user&#39;s hand being closer to the injection site. The display window  25  being positioned near the proximal end P of the housing  11  also allows a user to hold the device  20  close to its distal end D whilst still enabling the user to see the indicator  24  and the information associated with the progress of the injection process, as shown in  FIG.  4     
     In  FIGS.  2  and  3   , the display window  25  is illustrated as a rectangular aperture  27  in the side wall of the housing  11 . The display window  25  has its longitudinal axis extending parallel to the longitudinal axis of the housing  11 . The longitudinal length of the display window  25 , i.e. the distance between the distal end  28   a  and the proximal end  28   b  is substantially equal to the longitudinal distance that the plunger rod  21  must travel between its primed and completed positions. 
     It will be understood that the display window  25  could be any other shape, including, but not limited to, triangular, circular, or a curved line. In addition, it will be understood that there may be more than one display window  25  located in the side wall of the housing  11 , preferably spaced by a longitudinal gap. The display window  25  may comprise a cover  29  configured to prevent debris from entering the housing  11  of the injection device  20 . The cover  29  may be configured such that a user can see through the display window  25  and into the device  20 . That is, the cover maybe transparent or translucent. 
     The indicator  24  further comprises a proximally extending projection  30 . The projection  30  comprises a distal end  31  and a proximal end  32 . The projection  30  is connected to the plunger rod  21  and extends away from the plunger rod  21  in the proximal direction. Preferably, the distal end  31  of the projection  30  is connected to the plunger rod  21 . The projection  30  is configured to be visible through the display window  25  when the plunger rod  21  is in its primed position, at least. 
     The projection  30  comprises an outwardly facing surface  33  which is configured to be viewed through the display window  25  when the plunger rod  21  is in its primed position, at least. The outwardly facing surface  33  is located on a longitudinally projecting arm  34  of the projection. 
     Preferably, the distal end  31  of the projection  30  is connected to the plunger rod  21  in the proximal region of the plunger rod  21 , that is, close to the proximal end  23  of the plunger rod  21 . The distal end  31  of the projection  30  may comprises a flange  35  which connects the distal end  31  of the arm  34  of the projection  30  to the proximal region of the plunger rod  21 . 
     As illustrated in  FIG.  2   , the projection  30  extends in the proximal direction such that the majority of the projection  30  is located further from the distal end D of the housing  11  than the proximal end of the plunger rod  21 . That is, the proximal end  32  of the arm  35  of the projection  30  is spaced from the proximal end  23  of the plunger rod  21  and is located closer to the proximal end P of the housing  11 . 
     The injector device  24  further comprises an indication element  36 . The indication element  36  is located in the same longitudinal position as the display window  25 . In some embodiments, the indication element  36  may cover an area slightly larger than the area of the display window  25 . The indication element  36  is also located radially inwardly of the display window  25  and the arm  34  of the projection  30  extending from the plunger rod  21 . The arm  34  of the projection  30  is located between the display window  25  and the indication element  36 . The arm  34  of the projection  30  is configured to obscure a user&#39;s view of the indication element  36 , when the plunger rod  21  is in its primed position, at least. 
     The projection  30  is axially coupled to the plunger rod  21 . The projection  30  is configured to move between a first indication position A, shown in  FIG.  2   , and a second indication position B, shown in  FIG.  3   , when the plunger rod  21  is moved from the primed position, shown in  FIG.  2   , to the completed position, shown in  FIG.  3   . Therefore, movement of the plunger rod  21  in the longitudinal direction causes the same amount of movement of the projection  30  in the longitudinal direction. In addition, movement of the projection  30  from the first indicating position A towards the second indicating position B makes a greater portion of the indication element  36  visible through the display window  25 . 
     In one embodiment, when the projection  30  is located in the first indication position A, as shown in  FIG.  2   , the proximal end  32  of the arm  34  of the projection  30  is located at the proximal end  28   b  of the display window  25 . In such an embodiment, most of the indication element  36  may be obscured from view through the display window  25  by the arm  34  of the projection  30  to indicate that the plunger rod  2  is in its primed position. In another embodiment, when the projection  30  is located in the first indication position A, only the arm  34  of the projection  30  may be visible through the display window  25  to indicate that the plunger rod  21  is in its primed position. 
     In one embodiment, when the projection  30  is located in the second indicating position B, the proximal end  32  of the projection  30  is located at the distal end  28   a  of the display window  25 . In such an embodiment, most of the indication element  36  may be visible through the display window  25 . That is, only a small portion of the indication element  36  may be obscured from view through the display window by the arm  34  of the projection  30  when the projection  30  is located in the second indicating position B to indicate that the plunger rod  21  is in its completed position. In another embodiment, when the projection  30  is located in the second indication position B, only the indication element  36  may be visible through the display window  25  to indicate that the plunger rod  21  is in its completed position, as shown in  FIG.  3   . That is, when the projection  30  is in its second indicating position B, the arm  34  of the projection  30  may not be visible through the display window  25 . 
     In one embodiment, the plunger rod  21  may be constrained to purely longitudinal motion. In such an embodiment, the projection  30  may be integrally formed with the plunger rod  21 . Alternatively, the projection  30  may be fixedly attached to the proximal region of the plunger rod  21 . In such embodiments, purely longitudinal motion of the plunger rod  21  from the primed position, shown in  FIG.  2   , to the completed position, shown in  FIG.  3   , means that the projection  30  only moves longitudinally and so is always in line with the display window  25  during the injection process. 
     In another embodiment, the plunger rod  21  may move rotationally during its longitudinal motion from the primed position to the completed position. In such an embodiment, the projection  30  may be rotationally decoupled from the plunger rod  21  such that the projection  30  remains aligned with the display window  25  throughout the injection process. Therefore, any rotational motion of the plunger rod  21  will not cause rotation of the projection  30  and therefore will not remove the projection  30  from the display window through rotational motion. 
     The projection  30  may be constrained to longitudinal movement by a guide mechanism  40 , shown in  FIG.  3   . The guide mechanism  40  may comprise a guide element  41 . The guide element  41  may be located on an inner surface  42  of the housing  11 . The guide element  41  may be configured to prevent rotational motion of the projection about the longitudinal axis of the plunger rod  21 . In one embodiment, the guide element  41  may protrude inwardly from the inner surface  42  of the housing  11 . The guide element  41  may extend longitudinally along the inner surface  42  of the housing  11 . The guide element  41  may extend along the periphery of the display window  25  to prevent rotation of the projection  30  away from the display window  25 . One guide element  41  may be located on either side of the display window  25  to prevent rotation in both directions about the longitudinal axis. 
     The guide mechanism  40  may be used to prevent rotation of solely the projection  30  or of the projection  30  and the plunger rod  21  when the projection is fixedly attached to the plunger rod  21 . 
     In embodiments where the plunger rod  21  and projection  30  are formed separately and then fixed together, the projection  30  may further comprise a connecting element  44 . The connecting element  44  is located on the end of the flange  35  opposite to the arm  34 . The connecting element  44  may comprise, for example, but not limited to, a snap-fit connection having two arms which fit around the proximal region of the plunger rod  21  or an annular ring which locates in a groove on the plunger rod  21 . These types of connecting elements  44  allow for rotation of the plunger rod  21  relative to the projection  30 . 
     In one embodiment, the projection  30  may comprise an annular element (not shown), instead of a longitudinally extending arm  34 . The annular element may extend up to 360 degrees around the longitudinal axis so that any rotation of the projection  30  relative to the plunger rod  21  does not remove the projection  30  from the display window  25 . 
     The outward facing arm  34  of the projection  30  and the indicating element  36  comprise different indicia configured to help a user determined the progress of the injection process at any time. The outward facing arm  34  of the projection  30  comprises a first indicia and the indicating element  36  comprises a second indicia, different to the first indicia. The indicia may be, for example, but not limited to, one or more colours, colour gradients, patterns, images, or number scale, etc. 
     The injector device  20  may be mechanically driven. The indicator  24  may be a mechanical indicator. For example, the injector device  20  shown in  FIGS.  2  and  3    comprises a biasing element  46 . In the present embodiment, the biasing element is a helical spring  47 . When the injector device  20  is actuated and the plunger rod  21  is free to move distally, the biasing element  46  urges the plunger rod  21  towards the distal end D of the housing  11 . The spring  47  may abut the flange  35  of the projection  30  or the proximal end  23  of the plunger rod  21  in order to urge the plunger rod  21  towards its completed position. The longitudinal motion of the plunger rod  21  in the distal direction also causes longitudinal motion of the projection  30  in the distal direction and causes the proximal end  32  of the arm  34  of the projection to move from the proximal end of the display window  25  in the distal direction towards the distal end  28   a  of the display window  25  to reveal the indication element  36 . As the spring  47  extends further, the proximal end  32  of the projection  30  moves closer to the distal end  28   a  of the display window  25  and reveals more of the indication element  36 . 
     In one embodiment, the housing  11  of the injector device  20  may further comprise a second indicator  50 . The second indicator  50  comprises a second display window  51  having a distal end  52  and a proximal end  53 . The second display window it located at the distal region D′ of the housing  11 . That is the second indicator is located proximate to the distal end D of the housing  11 . The second display window  51  may also comprise a cover  54 . When the plunger rod  21  is in its primed position and a container of medicament  18  is received in the housing  11 , the container of medicament  18  is visible through the second display window  25 . 
     As the plunger rod  21  is moved longitudinally towards the completed position, the distal end  23  of the plunger rod  21  moved through the second display window  51 . When the plunger rod  21  is moved into its completed position, the distal end  23  of the plunger rod  21  may be located at the distal end of the second display window  51 . 
     The plunger rod  21 , projection  30 , and indication element  36  may comprise indicia. In one embodiment, the plunger rod  21  and projection  30  may comprise a first indicia and the indication element  36  may comprise a second indicia, different to the first indicia. In such an arrangement, the indicia will indicate to a user how far the plunger rod  21  has travelled by the movement of the first indicia through the first and second display windows  25 ,  52  and by the increasing size of the area of the indication element  36  as the plunger rod  21  is moved from its primed position to its completed position. 
     In an alternative embodiment, the plunger rod  21  and the indication element  36  may comprise a first indicia and the projection  30  may comprise a second indicia, different to the first indicia. Preferably, the second indicia on the projection  30  is similar to the appearance of the medicament in the container of medicament  18 . In such an arrangement, the progress of the injection process will be apparent to a user as the second indicia signifies how far the plunger rod has left to travel and a first indicia signifies how close to the end of the process the plunger rod  21  is. 
     Referring briefly to  FIGS.  5  and  6   , the injector device  20  may further comprise an external sleeve  55 . The external sleeve  55  is configured to extend around the housing  11 . Furthermore, the external sleeve  55  is configured to be moveable longitudinally from a first position at the proximal end P of the housing  11 , shown in  FIG.  5   , to a second position at the distal end D of the housing  11 , shown in  FIG.  6   . 
     Referring to  FIG.  5   , when the external sleeve  55  is in its first position, the second display window  51  is visible and the container of medicament  18  within the housing  11 , whilst the first display window  25  is hidden behind the external sleeve. Now, referring to  FIG.  6   , when the external sleeve  55  is in its second position, the second display window  51  is hidden and the first display window  25  is visible. 
     The external sleeve  55  is moveable by a user when they grip the injector device  20 . The force required to move the external sleeve  55  is less than the force required to retract the needle sleeve  19  into the housing  11  so that when a user pushes the distal end D of the device  20  into their body, the external sleeve moves longitudinally to the distal end of the hosing  11  before the needle sleeve  19  is retracted. This ensures that a user holds the injector device  20  close to the distal end D of the housing  11  to improve stability of the device  20  during the injection process. 
     Referring now to  FIGS.  7  and  8   , an embodiment of an injector device  110  of the present invention is shown. The injector device  110  of the present invention is similar to the injector device  10  described above and so features and components of the device  110  that are the same as features and components of the above described device  10  will retain the same terminology and corresponding reference numbers. 
     The injector device  110  comprises a housing  111  configured to receive a container of medicament  118 , i.e. a cartridge. The container of medicament  18  may refer to a container, as such, for receiving a medicament or a container at least partially filled with medicament. The housing  111  is elongate and comprises a proximal end P and a distal end D. The container of medicament  118  is received in a distal region D′ of the housing  111 . That is, the container of medicament  118  is located closer to the distal end D of the housing  111  than the proximal end P of the housing  111 . 
     For the purposes of the following description, the distal region D′ may be considered to be a part of the housing  111  closer to the distal end D of the housing  111  than the proximal end P of the housing  111 . The proximal region P′ of the housing  111  may be considered to be a part of the housing  111  that is closer to the proximal end P of the housing  111  than the distal end D of the housing  111 . 
     In  FIGS.  7  to  10   , the housing  111  of the injector device  110  is shown in schematic cross-sectional drawings in order to show internal components of the injector device  110  more clearly. For the sake of clarity some components of the injector device  110  are not shown in the  FIGS.  7  to  10   , such as the cap  12  and the needle sleeve  19 , for simplicity. 
     The injector device  110  further comprises a plunger rod  121  which is moveable longitudinally within the housing  111  between a primed position, shown in  FIG.  7   , and a completed position, the plunger rod  121  having almost reached this position in  FIG.  8   . Preferably, the plunger rod  121  is located predominantly, if not completely, in the proximal region P′ when in its primed position and the plunger rod  121  is located predominantly, if not completely, in the distal region 
     D′ when in its completed position. Therefore, the plunger rod  121  is moveable from a proximal region P′ of the housing  111  to the distal region D′ of the housing  111  during the injection progress. In any case, when the plunger rod  121  is located in its completed position, the plunger rod  121  is located closer to the distal end D of the housing  111  than when the plunger rod  121  is in its primed position. 
     The injector device  110  further comprises a container of medicament  118 . The plunger rod comprises a distal end  122  and a proximal end  123 . The container of medicament  118  is received within the housing  111  between the plunger rod  121  and the distal end D of the injector device  110 . 
     The plunger rod  121  comprises a bung  114  located at its distal end  122 . The bung  114  is configured to contact the side wall(s) of the container of medicament  118  to form a seal so that the medicament is urged out of the container of medicament  118  and through the needle  117  when the plunger rod  121  is moved longitudinally in the distal direction from the primed position towards the distal position. 
     The injector device  110  further comprises an indicator  124 . The indictor  124  is located in the proximal region P′ of the housing  111 . Preferably, the indicator  124  is located in the region of the proximal end P. That is, preferably the indicator  124  is located close to, if not at, the proximal end P of the housing  111 . The indicator  124  is configured to provide a user with information associated with progress of the injection process dependent upon the longitudinal position of the plunger rod  121  between the primed and completed positions. 
     The indicator  124  of the injector device  110  comprises a spindle  126 . The spindle  126  comprises a shaft  127  and a dial  128 . The dial  128  is configured to rotate to provide a user with information associated with the progress of the injection process dependent upon the longitudinal position of the plunger rod  121 . The dial  128  comprises a display surface  129 . The display surface  129  of the dial  128  provides the information associated with the progress of the injection process. The dial  128  is fixedly attached to the shaft  127  such that rotational motion of the shaft  127  causes the dial  128  rotate. 
     As shown in  FIGS.  7  and  8   , the shaft  127  of the spindle  126  comprises a distal end  131  and a proximal end  132 . The shaft  127  is fixedly attached to the dial  128  at its proximal end  132 . In the present embodiment, the dial  128  has a larger diameter than the shaft  127  of the spindle  126 . The larger diameter of the dial  128  allows for a larger display surface  129  for providing information associated with the progress of the injection process to the user. The dial  128  comprises a distal surface  133  and an opposing proximal surface  134 . The proximal surface  134  of the dial  128  faces outwards of the device  110 . In the present embodiment, the proximal surface  134  is the display surface  129 . That is, the proximal surface  134  provides the information associated with the progress of the injection process. 
     The plunger rod  121  comprises a first threaded arrangement  135  and the shaft  127  of the spindle  126  comprises a second threaded arrangement  136 . The second threaded arrangement  136  on the shaft  127  is configured to engage with the first threaded arrangement  135  on the plunger rod  121 . The engagement between the threaded arrangements  135 ,  136  on the plunger rod  121  and shaft  127  of the spindle  126  is configured such that longitudinal movement of the plunger rod  121  from the primed position towards the completed position causes the shaft  127  and therefore the dial  128  to rotate to provide a user with information associated with the progress of the injection process, as will be described in more detail hereinafter. 
     The spindle  126  is constrained from movement in the longitudinal direction. That is, the spindle  126  is prevented from moving longitudinally. In some embodiments, the spindle  126  is prevented from moving in the longitudinal direction by the housing  111 . There are many ways in which the housing  111  can be configured to prevent longitudinal movement of the spindle  126 . 
     For example, in one embodiment shown in  FIGS.  7  and  8   , the dial  128  contacts the proximal end P of the housing  111 . That is, the dial  128  is located at the proximate end of the housing  111  such that distal surface  133  of the dial  128  contacts the proximal end of the housing  111 . 
     The housing  111  comprises a side wall  138  which extends longitudinally and at the proximal end P of the housing  111 , the side wall  138  comprises an end surface  139 . In the present embodiment, the end surface  139  is annular when viewed from the proximal end P of the housing  111 . However, in some embodiments, the end wall  139  may comprises an end plate which extends across the proximal end P of the housing  111 . 
     Furthermore, the dial  128  is positioned such that the distal surface  133  of the dial  128  contacts the end surface  139  at the proximal end of the housing  111 . Thus, when the plunger rod  121  is moved longitudinally from the primed position towards the completed position, the end surface  139  of the housing  111  prevents the spindle  126  from moving longitudinally towards the completed position by acting against the distal surface  133  of the dial  128 . In an embodiment where the dial  128  is located at the proximal end of the housing  111 , the proximal surface  134  of the dial  128  is the proximal most end of the device  110 . 
     Other example configurations to prevent longitudinal movement of the spindle  126  include an inner surface  142  of the housing  111  comprising a groove (not shown) ( 143 ) into which a projection (not shown) ( 144 ) extending from the shaft  127  or a side face  145  of the dial  128  locates. Such a groove can prevent longitudinal movement of the spindle  126  towards and away from the completed position. Alternatively, a projection  144  may extend from the inner surface  142  of the housing  111  into a groove  143  located in the shaft  127  of the spindle  126 , shown in  FIG.  10   , or in a side face  141  of the dial  128 . In some embodiments, the projection may be formed by a end plate which forms the end surface  139  of the housing  111 . 
     In an alternative embodiment as shown in  FIG.  9   , the dial  128  may be located inside the housing  111  such that the proximal surface  134  of the dial  128  faces out of the housing  111  to provide a user with information associated with the progress of the injection process. In such an embodiment, preferably, the dial  128  is located within the housing  111  such that the proximal surface  134  of the dial  128  does not extend beyond the plane of the proximal end P of the housing  111 . That is, the proximal surface  134  of the dial  128  does not extend beyond the end surface  139  of the housing  111 . 
     The housing  111  further comprises a cover  146 . The cover  146  extends over the proximal surface  134  of the dial  128 . The cover  146  may also extend over the proximal end P of the housing  111 . The cover  146  may comprise a peripheral protrusion  146   a  which is configured to be located in a groove  146   b  on the inner surface  142  of the housing  111 . In some embodiments, the cover  146  may not extend beyond the plane of the proximal end P of the housing  111 , i.e. the cover  146  does not extend beyond the end surface  139  o the housing  111 . In other embodiments, the cover  146  may form the proximal most end of the injector device  110 . 
     The cover  146  is configured such that the dial  128  can provide visual feedback to a user associated with the progress of the injection process. The cover  146  may be transparent, or at least translucent, to allow a user to see the dial  128  below. In some embodiments, only a part of the cover may be configured to allow a user to see the dial  128 . 
     The dials  128  shown in  FIGS.  7  to  9    may be configured in a variety of different ways in order to provide visual feedback to the user associated with the progress of the injection process. The proximal surface  134  of the dial  128  may be curved such that the proximal surface is dome shaped or in alternative embodiments, the proximal surface  134  of the dial  128  may be flat. Furthermore, the proximal surface  134  of the dial  128  may be uninterrupted. That is, the proximal surface  134  may be without holes or indents, etc. In such an embodiment, the proximal surface  134  of the dial  128  may comprise indicia configured to line up with indicia on the proximate end of the side wall  138  of the housing  111 . 
     For example, one of the proximate surface  134  and the side wall  138  may comprise an arrow pointing towards the periphery of the dial  128  and the other of the proximate surface  134  and the side wall  138  may comprise indicia which provide information associated with the progress of the injection process by way of, for example, but not limited to, a number scale, colour gradient, or words representing events that occur during the injection process. 
     Referring briefly to  FIG.  11   , yet further exemplary embodiments of the dial  128  are shown. 
     Referring to the embodiment shown in the top right of  FIG.  11   , the dial  128  may be at least partially transparent. That is, the whole dial  128  may be transparent, or at least translucent, such that a user may see through the dial  128 . Alternatively, only a part of the dial  128  may be transparent or translucent. The injector device  110  may further comprises a display plate  147  located in the housing  111  distal of the dial  128 . The display plate  147  may comprise indicia on its proximate surface  148 , i.e. the surface facing outwards of the injector device  110  and towards the dial  128 . In the example shown, one of the dial  128  and the proximate surface  148  of the display plate  147  comprises an arrow  149  and the other of the dial  128  and the proximate surface  148  comprises indicia  151  in the form of words representing events that occur during the injection process. As the plunger rod  121  is moved longitudinally towards its completed position, the dial  128  will rotate and the event to which the arrow  149  points will change to provide the user with information associated with the progress of the injection process. 
     It will be appreciated that the shaft  127  of the spindle  126  may pass through a central hole in the display plate  147 . Furthermore, it will be appreciated that it may be the display plate  147  of the housing  111  which comprises a groove  143  or projection  144  to interact with the shaft  127  of the spindle  126  to prevent longitudinal movement of the spindle  126  during the injection process. It will be further appreciated that the display plate  147  may form the end surface  139  of the housing  111  in some embodiments. 
     Referring briefly to the embodiment shown on the left of  FIG.  11   , the dial  128  may comprise a cut-out  152 . The cut-out  152  extends through the dial  128  from the proximal surface  134  to the distal surface  133  and enables a user to see the display plate  147  below the dial  128 . The cut-out  152  may have, for example, but not limited to, sector shaped. The dial  128  may also comprise a display window  153 . The display window  153  is similar to the cut-out in that it extends through the dial  128  from the proximal surface  134  to distal surface  133  to enable a user to see the display plate  147  below the dial  128 . The display window  153  may be, for example, but not limited to semi-circular or crescent shaped. However, the cut-out  152  and display window  153  may be at different radial and angular positions in the dial  128  and may be used to provide different information about the progress of the injection process. Referring briefly to the embodiment shown in the bottom right of  FIG.  11   , it can be seen that multiple cut-outs  152  can be formed in the dial  128 . 
     Both the cut-outs  152  and the display windows  153  may comprise a cover  154  configured to be placed in the cut-out  152  or display window  153  to prevent debris entering the housing  111  of the injector device  110 . The cover  154  may be transparent, or at least translucent, in order to enable a user to see through the cover  154  to the indicia located on the proximate surface  148  of the display plate  147 . The cover  154  may be formed by a transparent or translucent portion of the dial  128  rather than being an insert into a cut-out  152  or display window  153 . 
     In the above embodiments, as the dial  128  rotates relative to the display plate  147 , the cut-outs  152  and/or windows  153  are moved over the proximal surface  148  of the display plate  147  such that as the rotational position of the cut-out  152  and/or display window  153  changes, so does the indicia on the proximal surface  148  of the display plate  147  that is visible through the cut-out  152  and/or display window  153 . Therefore, the changing indicia provides visual feedback on the progress of the injection progress. 
     In the embodiments above, the dial  128  comprises cut-outs  152  and/or display windows  153  to allow a user to see indicia located on the proximate surface  148  of the display plate  147 . 
     However, in alternative embodiments, the cover  146  may comprise portions which are transparent, or at least translucent, and the indicia may be located on the proximate surface  134  of the dial  128 . Therefore, as the dial  128  rotates relative to the transparent part of the cover  146 , the indicia on the proximate surface  134  of the dial  128  pass under the transparent portion of the cover  146  in order to provide a user with information associated with the progress of the injection process. 
     In some embodiments, the dial  128  may be configured to provide tactile feedback to a user associated with the progress of the injection process, instead of visual feedback. An example of such an embodiment is illustrated in  FIG.  10   . In  FIG.  10   , the proximal surface  134  of the dial  128  comprises a surface formation  156  configured to provide tactile feedback to a user associated with the progress of the injection process. The surface formation  156  may be formed by, for example, but not limited to, one or more protrusions, one or more indents, or surface roughness. 
     In yet a further embodiment of the injector device  110 , the dial  128  may be housed inside the housing  111 . The housing  111  may comprise a display window ( 158 ) in its side wall  138  through which the side face  145  of the dial  128  can be seen. The side face  145  of the dial  128  may comprise indicia configured to provide visual feedback to a user associated with the progress of the injection process. 
     Referring back to  FIGS.  7  and  8   , the plunger rod  121  is shown in threaded engagement with the shaft  127  of the spindle  126 . In the present embodiment the first threaded arrangement  135  on the plunger rod  121  faces inwardly. That is, in the present embodiment, the plunger rod  121  comprises a hollow tubular housing  161 . The tubular housing  161  comprises a distal wall  162  and a longitudinally extending side wall  163 . In the present embodiment, the housing  161  is cylindrical and so the side wall  163  is annular when viewed from the proximal end P of the housing  111 . The tubular rod  161  comprises an open proximal end  164  and an internal cavity  165 . The internal cavity  165  is defined by an inner surface  166  of the side wall  163  and an inner surface  167  of the distal wall  162 . The first threaded arrangement  135  on the plunger rod  121  is formed on the inner surface  166  of the side wall  163  of the plunger rod  121 . 
     The plunger rod  121  is constrained to longitudinal movement. That is, plunger rod  121  can move in the longitudinal direction but is prevented from rotating about the longitudinal axis. The plunger rod  121  comprises a projection  168  configured to be located in a groove on the inner surface  142  of the housing  111 . The projection  168  extends radially outward from an outer surface  169  of the plunger rod  121 . The groove in the inner surface  142  of the housing  111  extends longitudinally and over a distance which is at least equal to the distance that the plunger rod  121  must travel between primed and completed positions. The side walls of the groove abut the projection  168  of the plunger rod  121  to prevent rotation of the plunger rod  121  relative to the housing  111 . 
     The cavity  165  formed in the plunger rod  121  is configured to at least partially receive the shaft  127  of the spindle  126 . Preferably, when the plunger rod  121  is in its primed position, the distal end  127  of the shaft  127  abuts the inner surface  167  of the distal wall  162 , i.e. the proximal surface. of the plunger rod  121 . The shaft  127  of the spindle  126  comprises a second threaded arrangement  136  on an outer surface  171  of the shaft  127 . The second threaded arrangement  136  on the outer surface  171  of the shaft  127  of the spindle  126  is configured to threadingly engage the first threaded arrangement  135  on the inner surface  166  of the plunger rod  121 . 
     In the embodiment shown in  FIG.  7    and  FIG.  8   , the shaft  127  of the spindle  126  is located inside the plunger rod  121 . However, it will be understood that in an alternative embodiment, the shaft  127  of the spindle  126  maybe located outside of the plunger rod  121 . In such an embodiment, the first threaded arrangement  135  may be located on the outer surface  169  of the plunger rod  121  and the second threaded arrangement  136  would be located on an inner surface of the shaft  127 . 
     In the present embodiment, the first threaded arrangement  135  on the plunger rod  121  comprises a continuous threaded arrangement. That is, the continuous threaded arrangement comprises a continuous thread  172 . The continuous threaded arrangement extends from a distal end  173  of the inner surface  166  of the plunger rod  121  to a proximal end  174  of the inner surface  166  of the plunger rod  121 . That is, the continuous first threaded arrangement  135  extends along the length of the inner surface  166  of the plunger rod  121 . Similarly, the second threaded arrangement  136  on the shaft  127  of the spindle  126  comprises a continuous threaded arrangement. The continuous threaded arrangement extends from the distal end  131  of the shaft  127  towards the proximal end  132  of the shaft  127 . In the present embodiment, the second threaded arrangement  136  only extends along the shaft  127  by a distance equal to the length of the inner surface  166  of the plunger rod  121 . Therefore, the first and second threaded arrangements  135 ,  136  are in contact throughout the longitudinal movement of the plunger rod  121  between the primed and completed positions. 
     The inner surface  166  of the side wall  163  of the plunger rod  121  determines the maximum longitudinal distance of travel between the primed position and the completed position of the plunger rod  121 . This is necessary because once the plunger rod  121  and spindle  126  are no longer in threading engagement, the dial  128  cannot provide accurate information about the progress of the injection process. The continuous thread on the plunger rod  121  and/or the shaft  127  of the spindle  126  is configured to ensure that the spindle  126  is constantly rotated as the plunger rod  121  is moved axially to provide constant feedback on the progress of the injection process. 
     In some embodiments, the longitudinal length of the continuous thread on one of the plunger rod  121  and the shaft  127  of the spindle  126  is equal to the longitudinal distance between the primed position of the plunger rod  121  and the completed position of the plunger rod  121 . This enables the dial  128  of the spindle  126  to provide feedback on the progress of the injection process dependent upon the position of the plunger rod  121  at any stage between the primed position and the completed position. 
     In other embodiments, the longitudinal length of the continuous thread on one of the plunger rod  121  and the shaft  127  of the spindle  126  is greater than the longitudinal distance between the primed position of the plunger rod  121  and the completed position of the plunger rod  121 . This enables the dial  128  of the spindle  126  to provide feedback on the progress of the injection process dependent upon the position of the plunger rod  121  at stages before the plunger rod  121  is moved into its primed position and/or after the plunger rod  121  has been moved into its completed position. 
     For example, the plunger rod  121  may have a loading position proximal to the primed position in which the plunger rod  121  is held until a container of medicament  118  is loaded into the housing  121 . The plunger rod  121  may then be moved distally from a loading position into the primed position in which the bung  114  is in contact with the proximal end of the container of medicament  118 . 
     It can be seen in  FIGS.  7  and  8    that the injector device  110  further comprises a biasing element  175 . In the embodiments shown, the biasing element  175  is a helical spring  176 . However, it will be clear to a person skilled in the art that any other type of biasing member  175  could be used. The helical spring  176  is located such that its longitudinal axis coincides with the longitudinal axis of the shaft  127  of the spindle  126  and the longitudinal axis of the plunger rod  121 . Thus, the helical spring  176  extends about the shaft  127  of the spindle  126 . This helps to prevent the spring  176  from bending out alignment with the longitudinal axis when it is compressed. 
     The helical spring  176  comprises a distal end  177  and a proximal end  178 . The distal end  177  of the helical spring  176  is in contact with the proximal end  123  of the plunger rod  121 . The proximal end  178  of the helical spring  176  contacts the housing  111  in the proximal region P′. In some embodiments, the proximal end  178  of the helical spring  176  may abut the display plate  147 , the inner surface  142  of the housing  111 , or a projection extending from the inner surface  142  of the housing  111 . When the plunger rod  121  is in its primed position, the biasing member  175  is in a higher state of compression than when the plunger rod  121  is in its completed position. 
     When the injector device  111  is actuated, a locking element which prevents longitudinal movement of the plunger rod  121  is released and the biasing member  175  extends from its compressed state. The proximal end  178  of the helical spring  176  is attached to the housing  111  which is fixed and so the extension of the spring  176  urges the distal end  177  of the spring  176  and therefore the plunger rod  121  distally in the longitudinal direction. Movement of the plunger rod  121  in the distal direction is constrained to longitudinal movement due to the location of a projection  168  from the plunger rod  121  in a groove in the inner surface  142  of the housing  111 . 
     The longitudinal movement of the plunger rod  121  causes the first threaded arrangement  135  to move distally. Due to the spindle  126  being prevented from movement in the longitudinal direction, the longitudinal distal movement of the first threaded arrangement  135  causes the second threaded arrangement  136  to slip against the first threaded arrangement  136 . This caused the shaft  127  of the spindle  126  and therefore the dial  128  to rotate. The rotation of the dial  128  provides feedback to the user of the progress of the injection progress. 
     Referring briefly to  FIG.  12    another embodiment of the threaded arrangements can be seen. In the alternative embodiment, the threaded arrangement comprises a non-continuous thread  181  on one of the plunger rod  121  and the shaft  127  of the spindle  126 . In  FIG.  12   , the first threaded arrangement  135  on the inner surface  166  of the plunger rod  121  is a continuous thread  172 . However, the continuous thread  172  only extends over a small longitudinal distance at the proximal end of the plunger rod  121 . The second threaded arrangement  136  on the shaft  127  of the spindle  126  comprises the non-continuous thread  181 . The non-continuous thread  181  comprises a proximal portion  182  and a distal portion  183 . 
     Therefore, upon longitudinal movement of the plunger rod  121 , the continuous first threaded arrangement  135  on the plunger rod  121  engages the proximal portion  182  of the non-continuous second threaded arrangement  136  to rotate the dial  128  until the threaded arrangements are no longer in contact. Once the plunger rod  121  and the shaft  127  are not threadingly engaged, further longitudinal movement of the plunger rod  121  does not cause rotation of the dial  128  until the continuous first threaded arrangement  135  on the plunger rod  121  engages the distal portion  183  of the non-continuous second threaded arrangement  136  to rotate the dial  128 . 
     In such an embodiment, the non-continuous thread  181  is configured to provide event specific feedback on the progress of the injection progress. This is shown by the discontinuous rotational movement of the dial  128  as the plunger rod  121  is moved longitudinally from the primed position to the completed position. For example, rotation due to the proximal portion  182  of the non-continuous thread  181  may turn the dial  128  from indicating the container of medicament  118  is loaded to indicating that the plunger rod  121  is in its primed position and rotation due to the distal portion  183  of the non-continuous thread  181  may turn the dial  128  from indicating the plunger rod  121  is in its primed position to indicating that the plunger rod  121  is in its completed position. 
     In an embodiment in which the first threaded arrangement  135  comprises a non-continuous thread  181  and the second threaded arrangement  136  comprises a continuous thread, the continuous thread may be located on the distal end  131  of the shaft  127 . 
     Furthermore, it will be appreciated that in some embodiments, the continuous thread on one of the plunger rod  121  and the shaft  127  may be replaced with a projection which extends into the continuous or non-continuous thread on the other of the plunger rod  121  and the shaft  127 . In these embodiments, the pitch of a thread may be varied along the length of the threaded arrangement. An increase in pitch may result in a lower frictional force with the thread due to the angle of the thread being more closely aligned with the longitudinal direction of movement. 
     Therefore, the pitch of the thread may increase towards the distal end of the shaft  127  in order to reduce the force required from the biasing element  173  to move longitudinally. This helps to overcome the reduced force with which the spring  174  urges the plunger rod  121  as it extends. Alternatively, the pitch may be varied, i.e. decreased, at event specific stages to cause a quicker rotation of the dial  128 . 
     Referring briefly to  FIG.  13   , it can be seen that in an alternative embodiment, the spindle  126  may be hollow and open-ended. In such an embodiment, the biasing member  173  can be accommodated in the hollow of the spindle  126 . Therefore, the distal end  175  of the spring  174  can contact the inner surface  166  of the distal wall  162  of the plunger rod  121 . 
     In some alternative embodiments, the feedback provided by the dial  128  may comprise other types of feedback to the ones discussed above. For example, the feedback provided by the dial  128  may be, but not limited to, an animation, visuals, or motions. The feedback may be intended to comfort a user or receiver of a medicament. In some embodiments, the dial may comprise a display for displaying the feedback. Alternatively, the images may be provided on the surface of the dial. 
     The feedback may begin when the device is actuated. In some embodiments, the feedback may begin before the plunger rod is moved from the primed position, for example, but not limited to, on removal of the cap or retraction of the needle shield, etc. In some embodiments, the feedback may begin at least 2 seconds before the plunger rod moves. More preferably, the feedback may begin at least 5 seconds before the plunger rod moves. 
     The feedback may finish when the injection is completed. That is, the feedback may begin when the plunger rod is moved from the primed position and the feedback may finish when the plunger rod is in the completed position. In some embodiments, the feedback may finish after the plunger rod has reach the completed position. The feedback may continue for a given time period after the injection has been completed. For example, the feedback may continue for at least 2 seconds after the injection has been completed. More preferably, the feedback may continue for at least 5 seconds after the injection has been completed. 
     It will be appreciated by a person skilled in the art that the injector device  20  shown in  FIGS.  2  to  6    may incorporate features described with reference to the injector device  111  shown in  FIGS.  7  to  13    even though they are not explicitly described in the same embodiment. Furthermore, it will be appreciated by a person skilled in the art that the injector device  111  shown in  FIGS.  7  to  13    may incorporate features described with reference to the injector device  20  shown in  FIGS.  2  to  6    even though they are not explicitly described in the same embodiment. The embodiments have only been described separately in order to provide clarity in relation to each mechanism and the features shown in  FIGS.  2  to  6    and the features shown in  FIGS.  7  to  13    could be incorporated into the same injector device. 
     The terms “drug” or “medicament” are used herein to describe one or more pharmaceutically active compounds. As described below, a drug or medicament can include at least one small or large molecule, or combinations thereof, in various types of formulations, for the treatment of one or more diseases. Exemplary pharmaceutically active compounds may include small molecules; polypeptides, peptides and proteins (e.g., hormones, growth factors, antibodies, antibody fragments, and enzymes); carbohydrates and polysaccharides; and nucleic acids, double or single stranded DNA (including naked and cDNA), RNA, antisense nucleic acids such as antisense DNA and RNA, small interfering RNA (siRNA), ribozymes, genes, and oligonucleotides. Nucleic acids may be incorporated into molecular delivery systems such as vectors, plasmids, or liposomes. Mixtures of one or more of these drugs are also contemplated. 
     The term “drug delivery device” shall encompass any type of device or system configured to dispense a drug into a human or animal body. Without limitation, a drug delivery device may be an injector device (e.g., syringe, pen injector, auto injector, large-volume device, pump, perfusion system, or other device configured for intraocular, subcutaneous, intramuscular, or intravascular delivery), skin patch (e.g., osmotic, chemical, micro-needle), inhaler (e.g., nasal or pulmonary), implantable (e.g., coated stent, capsule), or feeding systems for the gastro-intestinal tract. The presently described drugs may be particularly useful with injector devices that include a needle, e.g., a small gauge needle. 
     The drug or medicament may be contained in a primary package or “drug container” adapted for use with a drug delivery device. The drug container may be, e.g., a cartridge, syringe, reservoir, or other vessel configured to provide a suitable chamber for storage (e.g., short- or long-term storage) of one or more pharmaceutically active compounds. For example, in some instances, the chamber may be designed to store a drug for at least one day (e.g., 1 to at least 30 days). In some instances, the chamber may be designed to store a drug for about 1 month to about 2 years. Storage may occur at room temperature (e.g., about 20° C.), or refrigerated temperatures (e.g., from about −4° C. to about 4° C.). In some instances, the drug container may be or may include a dual-chamber cartridge configured to store two or more components of a drug formulation (e.g., a drug and a diluent, or two different types of drugs) separately, one in each chamber. In such instances, the two chambers of the dual-chamber cartridge may be configured to allow mixing between the two or more components of the drug or medicament prior to and/or during dispensing into the human or animal body. For example, the two chambers may be configured such that they are in fluid communication with each other (e.g., by way of a conduit between the two chambers) and allow mixing of the two components when desired by a user prior to dispensing. Alternatively or in addition, the two chambers may be configured to allow mixing as the components are being dispensed into the human or animal body. 
     The drug delivery devices and drugs described herein can be used for the treatment and/or prophylaxis of many different types of disorders. Exemplary disorders include, e.g., diabetes mellitus or complications associated with diabetes mellitus such as diabetic retinopathy, thromboembolism disorders such as deep vein or pulmonary thromboembolism. Further exemplary disorders are acute coronary syndrome (ACS), angina, myocardial infarction, cancer, macular degeneration, inflammation, hay fever, atherosclerosis and/or rheumatoid arthritis. 
     Exemplary drugs for the treatment and/or prophylaxis of diabetes mellitus or complications associated with diabetes mellitus include an insulin, e.g., human insulin, or a human insulin analogue or derivative, a glucagon-like peptide (GLP-1), GLP-1 analogues or GLP-1 receptor agonists, or an analogue or derivative thereof, a dipeptidyl peptidase-4 (DPP4) inhibitor, or a pharmaceutically acceptable salt or solvate thereof, or any mixture thereof. As used herein, the term “derivative” refers to any substance which is sufficiently structurally similar to the original substance so as to have substantially similar functionality or activity (e.g., therapeutic effectiveness). 
     Exemplary insulin analogues are Gly(A21), Arg(B31), Arg(B32) human insulin (insulin glargine); Lys(B3), Glu(B29) human insulin; Lys(B28), Pro(B29) human insulin; Asp(B28) human insulin; human insulin, wherein proline in position B28 is replaced by Asp, Lys, Leu, Val or Ala and wherein in position B29 Lys may be replaced by Pro; Ala(B26) human insulin; Des(B28-B30) human insulin; Des(B27) human insulin and Des(B30) human insulin. 
     Exemplary insulin derivatives are, for example, B29-N-myristoyl-des(B30) human insulin; B29-N-palmitoyl-des(B30) human insulin; B29-N-myristoyl human insulin; B29-N-palmitoyl human insulin; B28-N-myristoyl LysB28ProB29 human insulin; B28-N-palmitoyl-LysB28ProB29 human insulin; B30-N-myristoyl-ThrB29LysB30 human insulin; B30-N-palmitoyl-ThrB29LysB30 human insulin; B29-N-(N-palmitoyl-gamma-glutamyl)-des(B30) human insulin; B29-N-(N-lithocholyl-gamma-glutamyl)-des(B30) human insulin; B29-N-(ω-carboxyheptadecanoyl)-des(B30) human insulin and B29-N-(ω-carboxyhepta-idecanoyl) human insulin. Exemplary GLP-1, GLP-1 analogues and GLP-1 receptor agonists are, for example: Lixisenatide/AVE0010/ZP10/Lyxumia, Exenatide/Exendin-4/Byetta/Bydureon/ITCA 650/AC-2993 (a 39 amino acid peptide which is produced by the salivary glands of the Gila monster), Liraglutide/Victoza, Semaglutide, Taspoglutide, Syncria/Albiglutide, Dulaglutide, rExendin-4, CJC-1134-PC, PB-1023, TTP-054, Langlenatide/HM-11260C, CM-3, GLP-1 Eligen, ORMD-0901, NN-9924, NN-9926, NN-9927, Nodexen, Viador-GLP-1, CVX-096, ZYOG-1, ZYD-1, GSK-2374697, DA-3091, MAR-701, MAR709, ZP-2929, ZP-3022, TT-401, BHM-034. MOD-6030, CAM-2036, DA-15864, ARI-2651, ARI-2255, Exenatide-XTEN and Glucagon-Xten. 
     An exemplary oligonucleotide is, for example: mipomersen/Kynamro, a cholesterol-reducing antisense therapeutic for the treatment of familial hypercholesterolemia. 
     Exemplary DPP4 inhibitors are Vildagliptin, Sitagliptin, Denagliptin, Saxagliptin, Berberine. 
     Exemplary hormones include hypophysis hormones or hypothalamus hormones or regulatory active peptides and their antagonists, such as Gonadotropine (Follitropin, Lutropin, Choriongonadotropin, Menotropin), Somatropine (Somatropin), Desmopressin, Terlipressin, Gonadorelin, Triptorelin, Leuprorelin, Buserelin, Nafarelin, and Goserelin. 
     Exemplary polysaccharides include a glucosaminoglycane, a hyaluronic acid, a heparin, a low molecular weight heparin or an ultra-low molecular weight heparin or a derivative thereof, or a sulphated polysaccharide, e.g. a poly-sulphated form of the above-mentioned polysaccharides, and/or a pharmaceutically acceptable salt thereof. An example of a pharmaceutically acceptable salt of a poly-sulphated low molecular weight heparin is enoxaparin sodium. An example of a hyaluronic acid derivative is Hylan G-F 20/Synvisc, a sodium hyaluronate. 
     The term “antibody”, as used herein, refers to an immunoglobulin molecule or an antigen-binding portion thereof. Examples of antigen-binding portions of immunoglobulin molecules include F(ab) and F(ab′)2 fragments, which retain the ability to bind antigen. The antibody can be polyclonal, monoclonal, recombinant, chimeric, de-immunized or humanized, fully human, non-human, (e.g., murine), or single chain antibody. In some embodiments, the antibody has effector function and can fix complement. In some embodiments, the antibody has reduced or no ability to bind an Fc receptor. For example, the antibody can be an isotype or subtype, an antibody fragment or mutant, which does not support binding to an Fc receptor, e.g., it has a mutagenized or deleted Fc receptor binding region. 
     The terms “fragment” or “antibody fragment” refer to a polypeptide derived from an antibody polypeptide molecule (e.g., an antibody heavy and/or light chain polypeptide) that does not comprise a full-length antibody polypeptide, but that still comprises at least a portion of a full-length antibody polypeptide that is capable of binding to an antigen. Antibody fragments can comprise a cleaved portion of a full length antibody polypeptide, although the term is not limited to such cleaved fragments. Antibody fragments that are useful in the present invention include, for example, Fab fragments, F(ab′)2 fragments, scFv (single-chain Fv) fragments, linear antibodies, monospecific or multispecific antibody fragments such as bispecific, trispecific, and multispecific antibodies (e.g., diabodies, triabodies, tetrabodies), minibodies, chelating recombinant antibodies, tribodies or bibodies, intrabodies, nanobodies, small modular immunopharmaceuticals (SMIP), binding-domain immunoglobulin fusion proteins, camelized antibodies, and VHH containing antibodies. Additional examples of antigen-binding antibody fragments are known in the art. 
     The terms “Complementarity-determining region” or “CDR” refer to short polypeptide sequences within the variable region of both heavy and light chain polypeptides that are primarily responsible for mediating specific antigen recognition. The term “framework region” refers to amino acid sequences within the variable region of both heavy and light chain polypeptides that are not CDR sequences, and are primarily responsible for maintaining correct positioning of the CDR sequences to permit antigen binding. Although the framework regions themselves typically do not directly participate in antigen binding, as is known in the art, certain residues within the framework regions of certain antibodies can directly participate in antigen binding or can affect the ability of one or more amino acids in CDRs to interact with antigen. 
     Exemplary antibodies are anti PCSK-9 mAb (e.g., Alirocumab), anti IL-6 mAb (e.g., Sarilumab), and anti IL-4 mAb (e.g., Dupilumab). 
     The compounds described herein may be used in pharmaceutical formulations comprising (a) the compound(s) or pharmaceutically acceptable salts thereof, and (b) a pharmaceutically acceptable carrier. The compounds may also be used in pharmaceutical formulations that include one or more other active pharmaceutical ingredients or in pharmaceutical formulations in which the present compound or a pharmaceutically acceptable salt thereof is the only active ingredient. Accordingly, the pharmaceutical formulations of the present disclosure encompass any formulation made by admixing a compound described herein and a pharmaceutically acceptable carrier. 
     Pharmaceutically acceptable salts of any drug described herein are also contemplated for use in drug delivery devices. Pharmaceutically acceptable salts are for example acid addition salts and basic salts. Acid addition salts are e.g. HCl or HBr salts. Basic salts are e.g. salts having a cation selected from an alkali or alkaline earth metal, e.g. Na+, or K+, or Ca2+, or an ammonium ion N+(R 1 )(R 2 )(R 3 )(R 4 ), wherein R 1  to R 4  independently of each other mean: hydrogen, an optionally substituted C1 C6-alkyl group, an optionally substituted C2-C6-alkenyl group, an optionally substituted C6-C10-aryl group, or an optionally substituted C6-C10-heteroaryl group. Further examples of pharmaceutically acceptable salts are known to those of skill in the arts. 
     Pharmaceutically acceptable solvates are for example hydrates or alkanolates such as methanolates or ethanolates. 
     Those of skill in the art will understand that modifications (additions and/or removals) of various components of the substances, formulations, apparatuses, methods, systems and embodiments described herein may be made without departing from the full scope and spirit of the present invention, which encompass such modifications and any and all equivalents thereof. 
     This specification includes the following clauses: 
     1. An injector device comprising: 
     an elongate housing having a proximal end and a distal end, and configured to receive a container of medicament; 
     a plunger rod moveable longitudinally within the housing between a primed position and a completed position, the plunger rod being configured to be engageable with a container of medicament when received in the housing; 
     wherein the housing comprises an indicator located in a proximal region of the housing; 
     the indicator being configured to provide a user with information associated with the progress of the injection process dependent upon the longitudinal position of the plunger rod. 
     2. The injector device according to clause 1, wherein the indicator comprises a display window located in a side wall of the housing, and 
     a proximally extending projection extending from the plunger rod, wherein the projection is coupled to the proximal end of the plunger rod, the projection being visible through the display window in at least the primed position. 
     3. The injector device according to clause 2, wherein the indicator further comprises an indication element, the projection being located between the display window and the indication element to obscure a user&#39;s view of the indication element in at least the primed position. 
     4. The injector device according to clause 3, wherein the projection is axially coupled to the plunger rod and configured to move between a first indicating position and a second indicating position when the plunger rod is moved from the primed position to the completed position and wherein movement of the projection towards the second indicating position makes a greater portion of the indication element visible through the display window. 
     5. The injector device according to clause 4, wherein when the projection is in the first indication position, a proximal end of the projection is located at a proximal end of the display window. 
     6. The injector device according to clause 5, wherein when the projection is in the first indicating position, only the projection is visible through the display window. 
     7. The injector device according to any one of clauses 4 to 6, wherein when the projection is in the second indicating position, a proximal end of the projection is located at a distal end of the display window. 
     8. The injector device according to clause 7, wherein when the projection is in the second indicating position, only the indication element is visible in the display window. 
     9. The injector device according to any one of clause 2 to clause 8, wherein the projection is rotationally decoupled from the plunger rod such that the projection remains aligned with the display window throughout the injection process. 
     10. The injector device according to clause 9, wherein an inner surface of the housing comprises a guide mechanism configured to restrict rotational motion of the projection about the longitudinal axis of the plunger rod. 
     11. The injector device according to any one of clauses 2 to 10, wherein the housing further comprises a second indicator comprising a second display window in the distal region of the housing, a container of medicament being visible through the second display window when the plunger rod is in its primed position and when the container of medicament is received in the housing, and wherein when the plunger rod is moved longitudinally into the completed position the distal end of the plunger rod is located at the distal end of the second display window. 
     12. The injector device according to clause 11, wherein the plunger rod and the indication element comprise the same indicia and the projection comprises a different indicia to the plunger rod and indication element. 
     13. The injector device according to any one of the preceding clauses, further comprising an external sleeve configured to extend around the housing, the external sleeve being moveable longitudinally from a first position at the proximal end of the housing in which the external sleeve covers the indicator to a second position at the distal end of the housing in which the external sleeve exposes the indicator. 
     14. An injector device according to any one of the preceding clauses, further comprising a container of medicament received within the housing between the plunger rod and the distal end of the injector device. 
     15. A method of using an injector device according to clause 1, the method comprising: 
     actuating the injector device such that a plunger rod is moved longitudinally within the housing from a primed position to a completed position; and 
     providing information associated with the longitudinal position of the plunger rod with an indicator.