Abstract:
A dose setting mechanism for a medicament delivery device is presented having a pinion mounted to a locking member where the axis of rotation of the pinion is offset and parallel to the longitudinal axis of the housing containing the dose setting components. Primary and secondary dose members are engaged with the pinion to indicate a set dose of medicament.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 14/449,671, filed Aug. 1, 2014, which is a continuation of U.S. patent application Ser. No. 13/896,639, filed May 17, 2013, now U.S. Pat. No. 8,827,962, which is a continuation of U.S. patent application Ser. No. 13/203,040, filed Jan. 31, 2012, now U.S. Pat. No. 8,491,536, which is a U.S. National Phase Application pursuant to 35 U.S.C. §371 of International Application No. PCT/US2010/060022 filed Dec. 13, 2010, which claims priority to Swedish Patent Application No. 0950958-9 filed on Dec. 15, 2009. The entire disclosure contents of these applications are herewith incorporated by reference into the present application. 
    
    
     TECHNICAL AREA 
     The present invention relates to a medicament delivery device comprising a dose setting function. 
     BACKGROUND 
     Medicament delivery devices such as injectors are sometimes provided with functions where a specific dose can be set by the user, which dose may be varied within a range. 
     Quite often this dose setting function is performed by turning a knob or wheel at the distal end of the device whereby it is moved in the distal direction. When performing a subsequent injection, the knob is pushed linearly in the proximal direction. One such injector is disclosed in the document U.S. Pat. No. 6,221,053 in which the distal dose knob of the injector is threaded out of a rod barrel tube as a dose is set. Thus the distance the knob is moved in the distal direction is directly related to the dose quantity to be delivered. 
     One drawback with that type of solution is that if larger doses are to be delivered the dose knob has to be moved quite a long distance in the distal direction, which means that it might be difficult for a user to push the dose knob in the proximal direction during injection. 
     SUMMARY 
     The aim of the present invention is to remedy the drawbacks of the state of the art medicament delivery devices and to provide a device by which it is possible to set a desired or required dose in a simple and intuitive way. 
     This aim is obtained by a medicament delivery device according to the features of the independent patent claim. Preferable embodiments of the invention are subject of the dependent patent claims. 
     According to a main aspect of the invention it is characterised by a medicament delivery device comprising a housing having opposite distal and proximal ends; a medicament container holder releasably connected to said housing; a medicament container arranged inside said medicament container holder; a threaded plunger rod arranged to pass through a first inner wall of the housing and arranged to act on a stopper in the medicament container; a lead screw member coaxially connected to the threaded plunger rod by co-acting first slidably-and-rotatably-locked means; wherein said device further comprises a nut coaxially connected to the threaded plunger rod by a treaded engagement between them, connected to the lead screw member by co-acting non-slidable-and-rotatable means, and connected to the housing by co-acting second slidably-and-rotatably-locked means; a primary dose member coaxially rotatable on the lead screw member when the device is in a non-activated state and connected to the lead screw member by co-acting third slidably-and-rotatably-locked means when the device is in an activated state; a locking member fixedly connected to the housing and releasably connected to the lead screw member by co-acting locking means; a first spring force means arranged between the first inner wall of the housing and the nut, wherein the first spring force means is in a pre-tensioned state when said locking means are engaged and the device is in the non-activated state; a secondary dose member rotatably connected to said primary dose member via a pinion gear; dose setting means connected to the primary dose member by co-acting fourth slidably-and-rotatably-locked means, such that when the device is to be set from the non-activated state to the activated state, the dose setting means are manually manipulated in a pre-determined direction, whereby the locking means are released and the lead screw member is distally moved a pre-determined distance by the first spring force means independent of the size of a dose to be set. 
     According to a further aspect of the invention, said primary and said secondary dose members are provided with indicia. 
     According to another aspect of the invention, the locking means comprises a proximally pointing and radial flexible lever arranged on the locking member, an annular ledge on the circumferential surface of the lead crew member, and the circumferential inner surface of the secondary dose member; such that when the first spring force means is in a pre-tensioned state, the circumferential inner surface of the secondary dose member forces the flexible lever radial inwardly in contact with the ledge; and when the dose setting means are manually manipulated, the secondary dose member is rotated to a position wherein the flexible lever is radial outwardly flexed into a longitudinal groove on the inner circumferential surface of the secondary dose member. 
     According to yet a further aspect of the invention, the locking member comprises on its distal circumferential surface a distally pointing stop member, and wherein the secondary dose member comprises on its proximal circumferential surface a first and a second proximally pointing stop members arranged to interact with the stop member of the locking member. 
     According to yet another aspect of the invention, the non-slidable-and-rotatable means comprises ratchet arms and radial inwardly directed arms on the nut, grooves on the outer circumference of wheels on the proximal end of the lead screw member, and an annular groove between the wheels, wherein the ratchet arms cooperate with the grooves for giving an audible signal when the lead screw member is rotated; and wherein the radial inwardly directed arms cooperate with the annular groove such that the lead screw member and the nut are slidably locked and rotatable in relation to each other. 
     According to a further aspect of the invention, the first slidably-and-rotatably-locked means comprises radial inwardly directed ledges on the inner surface of the proximal end of the lead screw member, and longitudinally extending grooves on the plunger rod, wherein the grooves cooperate with the radial inwardly directed ledges such that the lead screw member and the plunger rod are rotationally locked and slidable in relation to each other. 
     According to another aspect of the invention, the second slidably-and-rotatably-locked means comprises grooves on the outer circumferential side surface of the nut, and longitudinal ribs on the inner surface of the housing, wherein the grooves cooperate with the longitudinal ribs such that the nut and the housing are rotationally locked and slidable in relation to each other. 
     According to yet a further aspect of the invention, the third slidably-and-rotatably-locked means comprises splines on the outer circumferential surface of the lead screw member, and corresponding splines arranged on the inner circumferential surface of the primary dose member, wherein the splines cooperate with corresponding splines such that the lead screw member and the primary dose member are rotationally locked and slidable in relation to each other. 
     According to yet another aspect of the invention, the dose setting means comprises a clutch plate provided with a first annular ratchet, a dose setting knob provided with a second annular ratchet, and a second spring force means arranged between a second inner wall of the housing and a proximal surface of the clutch plate, such that clutch plate is distally urged and the first and the second ratchet are abutting each other, and which dose setting knob protrudes through the distal end of the housing. 
     According to a further aspect of the invention, the fourth slidably-and-rotatably-locked means comprises longitudinally extending grooves on the outer circumferential surface of the primary dose member, and radial inwardly directed protrusions on the inner surface of the clutch plate, wherein the longitudinally extending grooves cooperate with radial inwardly directed protrusions such that the primary dose member and the clutch plate are rotationally locked and slidable in relation to each other. 
     According to another aspect of the invention, the plunger rod is arranged to be proximally moved a distance corresponding to a set dose to be delivered by manually manipulating the dose setting knob when the device is in the activated state. 
     There are a number of advantages with the present invention. Because the lead screw, e.g. the manually operating delivery means, protrudes outside the housing with the same length independent of the set dose quantity the manual dose delivery operation is the same independent of set dose, i.e. the lead screw member has always the same position when a dose has been set. 
     Compared to the state of the art medicament delivery devices, this solution is a great advantage for the user or patient who suffers of dexterity problems. Also when not in use, the lead screw member is inside the medicament delivery device and locked. The unlocking of the lead screw member is performed when said dose setting knob is turned to an initial position, preferably a zero-dose position. 
     These and other features and advantages will become apparent from the detailed description and from the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       In the detailed description reference will be made to the accompanying drawings in which 
         FIGS. 1 a,b    are a cross-sectional view of a medicament delivery device according to the present invention; 
         FIG. 2  is an exploded view of the medicament delivery device of  FIGS. 1   a,b;    
         FIG. 3  is a detailed view of a dose-setting mechanism comprised in the present invention; 
         FIG. 4  is a further detailed view of the dose-setting mechanism comprised in the present invention; and 
         FIG. 5  is yet a further detailed view of the dose-setting mechanism comprised in the present invention; and 
         FIGS. 6, 7   a ,  7   b ,  8   a , and  8   b  are cross-sectional view of different functional positions. 
     
    
    
     DETAILED DESCRIPTION 
     In the present application, when the term “distal part/end” is used, this refers to the part/end of the injection device, or the parts/ends of the members thereof, which under use of the injection device is located the furthest away from the medicament injection site of the patient. Correspondingly, when the term “proximal part/end” is used, this refers to the part/end of the injection device, or the parts/ends of the members thereof, which under use of the injection device is located closest to the medicament injection site of the patient. 
     The medicament delivery device  10  according to the drawings comprises a generally elongated housing  12  having opposite distal and proximal ends. The elongated housing being e.g. divided in a proximal  12   a  and a distal part  12   b . The proximal end of the housing is arranged with fastening means such as e.g. threads  14  on its inner surface, which fastening means cooperate with corresponding fastening means such as outwardly threads  16  on a distal end of a medicament container holder  18 , providing a releasable connection. Inside the medicament container holder a medicament container  20  can be placed. The proximal end of the medicament container holder  18  is arranged with a threaded neck  22  for connection of a medicament delivery member such as an injection needle  24 , a mouthpiece, a nozzle or the like,  FIG. 2 . 
     When received by a user, the medicament delivery device  10  is provided with a releasably attachable protective cap  26 . At the distal end of the medicament container holder a sleeve-shaped container support  28  is inserted for holding and supporting the medicament container  20  when inserted,  FIG. 2 . At the proximal end of the housing a first inner wall  30  is arranged, which wall is provided with a central passage  32 ,  FIG. 1 b   . The central passage is arranged with a distally directed tubular flange  34 ,  FIG. 1 a   . A threaded plunger rod  36  extends in the longitudinal direction through the central passage  32  with a proximal end adjacent a stopper  38  inside said medicament container  20 ,  FIG. 1 a   . The proximal end of the plunger rod  36  is further arranged with a plunger rod tip  40 ,  FIG. 2 . 
     The device further comprises a lead screw member  58  coaxially connected to the threaded plunger rod by co-acting first slidably-and-rotatably-locked means; and a nut  44  coaxially connected to the threaded plunger rod by a treaded engagement between them. The nut also being connected to the lead screw member by co-acting non-slidable-and-rotatable means, and to the housing by co-acting second slidably-and-rotatably-locked means. 
     The first slidably-and-rotatably-locked means comprises radial inwardly directed ledges  57  on the inner surface of the proximal end of the lead screw member, and longitudinally extending grooves  42  on the plunger rod,  FIG. 2 , wherein the grooves cooperate with the radial inwardly directed ledges  57  such that the lead screw member and the plunger rod are rotationally locked and slidable in relation to each other. 
     The non-slidable-and-rotatable means comprises ratchet arms  50  and radial inwardly directed arms  51  on the nut  44 , grooves  56  on the outer circumference of wheels  54  on the proximal end of the lead screw member, and an annular groove  53  between the wheels  54 , wherein the ratchet arms  50  cooperate with the grooves  56  for giving an audible signal when the lead screw member is rotated; and wherein the radial inwardly directed arms  51  cooperate with the annular groove  53  such that the lead screw member and the nut are slidably locked and rotatable in relation to each other,  FIG. 3 . 
     The second slidably-and-rotatably-locked means comprises grooves  52  on the outer circumferential side surface of the nut  44 ,  FIG. 3 , and longitudinal ribs on the inner surface of the housing (not shown), wherein the grooves cooperate with the longitudinal ribs such that the nut and the housing are rotationally locked and slidable in relation to each other. 
     The nut  44  comprises a threaded central passage  46  which cooperates with the threads of the plunger rod,  FIG. 2 , thereby forming the threaded engagement between them. 
     The device also comprises a primary dose member  66  coaxially rotatable on the lead screw member when the device is in a non-activated state and connected to the lead screw member by co-acting third slidably-and-rotatably-locked means when the device is in an activated state. The third slidably-and-rotatably-locked means comprises splines  60  on the outer circumferential surface of the lead screw member; and corresponding splines  64  arranged on the inner circumferential surface of the primary dose member, wherein the splines  60  cooperate with corresponding splines  64  such that the lead screw member and the primary dose member are rotationally locked and slidable in relation to each other,  FIGS. 2 and 3 . 
     The device further comprises:—a locking member  96  fixedly connected to the housing and releasably connected to the lead screw member by co-acting locking means;—a first spring force means  48  arranged between the first inner wall  30  of the housing and the nut, wherein the first spring force means is in a pre-tensioned state when said locking means are engaged and the device is in the non-activated state; and—a secondary dose member  90  rotatably connected to said primary dose member  66  via a pinion gear  94 ,  FIG. 3 . 
     The device also comprises dose setting means connected to the primary dose member by co-acting fourth slidably-and-rotatably-locked means, such that when the device is to be set from the non-activated state to the activated state, the dose setting means are manually manipulated in a pre-determined direction, whereby the locking means are released and the lead screw member is distally moved a pre-determined distance by the first spring force means independent of the size of a dose to be set. 
     The dose setting means comprises a clutch plate  74  provided with a first annular ratchet  76 , a dose setting knob  84  provided with a second annular ratchet  82 , and a second spring force means  78  arranged between a second annular inner wall  80  of the housing and a proximal surface of the clutch plate, such that clutch plate is distally urged and the first and the second ratchet are abutting each other, and which dose setting knob protrudes through the distal end of the housing,  FIGS. 1 a    and  4 . The fourth slidably-and-rotatably-locked means comprises longitudinally extending grooves  70  on the outer circumferential surface of the primary dose member  66 , and radial inwardly directed protrusions  72  on the inner surface of the clutch plate  74 , wherein the longitudinally extending grooves  70  cooperate with radial inwardly directed protrusions  72  such that the primary dose member and the clutch plate are rotationally locked and slidable in relation to each other,  FIGS. 2 and 3 . The distal end of the lead screw member  58  protrudes through the dose setting knob  84 , and is at its distal end arranged with a dose injection button  86 ,  FIGS. 2 and 7   b . Outside the dose injection button  86  a spin ring  88  is rotatably arranged,  FIG. 2 . 
     The locking means comprises:—a proximally pointing and radial flexible lever  102  arranged on the locking member,—an annular ledge  62  on the circumferential surface of the lead crew member, and—the circumferential inner surface of the secondary dose member,  FIG. 2 . The secondary dose member  90  is also arranged with teeth  92  arranged around its circumference, which teeth cooperate with teeth on the pinion gear  94 , which is journalled in the housing as well as the locking member  96  via a locking lever bracket,  FIG. 3 . Further the primary dose member  66  is arranged with a gear segment  98 , which also cooperate with the pinion gear  94 ,  FIG. 3 . A certain part of the lead screw member  58  is arranged with the splines  60  on its outer circumferential surface,  FIG. 2 ; which splines have a lesser diameter than the proximal part of the lead screw member, thereby creating the annular ledge  62 ,  FIG. 2 . The locking member  96  also comprises on its distal circumferential surface a distally pointing stop member  95 , and the secondary dose member  90  comprises on its proximal circumferential surface a first  91  and a second  93  proximally pointing stop member arranged to interact with the stop member of the locking member,  FIG. 4 . 
     The proximal part of the primary dose member  66  and the secondary dose member  90  are arranged with a circumferential band containing numbers or indicia  68  which are used to indicate dose size through a dose window on the housing, as will be explained below,  FIG. 3 . 
     The device is intended to function as follows. When delivered to the user, the device is in the non-activated state wherein a medicament container  20  has been inserted in the medicament container holder  18  in the proximal end of the device,  FIG. 1 , the first spring force means is in a pre-tensioned state and said locking means are engaged, wherein the circumferential inner surface of the secondary dose member  90  forces the flexible lever  102  radial inwardly in contact with the ledge  62 . 
     When the device is to be used the protective cap  26  is removed and the dose setting means are manually manipulated for setting the device from the non-activated state to the activated state by rotating the dose setting knob  84  counter clockwise until activating indicia as e.g. two zeros are visible through the window of the housing. The rotation of the dose setting knob  84  causes the clutch plate  74  and thereby the primary dose member  66  to rotate due to the engagement between the co-acting fourth slidably-and-rotatably-locked means, and due to the connection between the first  76  and the second  82  ratchets. However, the lead screw member is not rotated since the third slidably-and-rotatably-locked means  60 ,  64  are not in engagement, i.e. the splines  60  on the outer circumferential surface of the lead screw member and the corresponding splines  64  arranged on the inner circumferential surface of the primary dose member  66  are not in engagement. The secondary dose member  90  also rotates due to the connection between the gear segment  98  of the primary dose member  66  and the teeth  92  of the secondary dose member  90  through the pinion gear  94 . The rotation of the secondary dose member  90  is stopped when its second proximally pointing stop member  93  abuts the distally pointing stop member  95 . This causes a longitudinal groove on the inner circumferential surface (not shown) of the secondary stop member to be aligned with the flexible lever  102  whereby the flexible lever is radial outwardly flexed into the groove and thereby moved out of contact with the ledge  62  of the lead screw member  58 . This causes the lead screw member  58  to move a pre-determined distance in the distal direction due to the force of the spring  48  acting on the nut  44 , which in turn is attached to the lead screw member  58 . The splines  60  on the outer circumferential surface of the lead screw member and the corresponding splines  64  arranged on the inner circumferential surface of the primary dose member are then engaged to each other. Because of the movement of the nut  44 , the plunger rod  36  is also moved. The distal end of the lead screw member  58  and its dose injection button  86  now protrude distally out of the housing said predetermined distance and independent of the size of the dose to be set. 
     The device is now in the activated state and ready for setting a required dose of medicament,  FIGS. 7 a    and  7   b.    
     When setting a dose, the plunger rod is arranged to be proximally moved a distance corresponding to a set dose to be delivered by manually manipulating the dose setting knob. The dose setting knob  84  is rotated in the clockwise direction which also rotates the primary dose member  66  clockwise indicating the dose that is being dialed. At the same time the primary dose member  66  rotates the lead screw member  58  clockwise due to the engagement between the co-acting third slidably-and-rotatably-locked means  60 ,  64 ; and the lead screw rotates the plunger rod due to the engagement between the co-acting first slidably-and-rotatably-locked means, driving the plunger rod  36  through the nut  44  because of the threaded engagement between them, thereby moving the plunger rod  36  proximally. The secondary dose member  90  also rotates due to the connection between the gear segment  98  of the primary dose member  66  and the teeth  92  of the secondary dose member  90  through the pinion gear  94 . The rotation of the secondary dose member  90  is stopped when its first proximally pointing stop member  91  abuts the distally pointing stop member  95 , which indicates the maximum dose the device can deliver e.g. two indicia as e.g. a seven and a zero are visible through the dose window. In any case, the set dose is visible through the dose window of the housing. At this point the device is ready for an injection. 
     Moreover, if the user attempts to dial past the maximum dose the device can deliver or if the user attempts to dial pass the activating indicia, the connection between the first annular ratchet  76  and the second annular ratchet will function as a clutch. 
     When the dose is set, a medicament delivery member  24  is attached to the proximal end of the device, such as e.g. an injection needle. It is however to be understood that other types of medicament delivery members may be used in order to deliver a dose of medicament. The medicament delivery member is then placed at the delivery site and the user presses the dose injection button  86  in the proximal direction the predetermined distance that the distal end of the lead screw member  58  and its dose injection button  86  protrudes distally out of the housing and which said predetermined distance is independent of the size of the dose to be delivered. This causes the lead screw member  58  to move in the proximal direction as well as the nut  44  and the plunger rod  36 . This proximal movement of the plunger rod  36  causes it to act on the stopper  38  of the medicament container  20  whereby a dose of medicament is expelled through the medicament delivery member  24 . When the lead screw member  58  has reached a certain distance inside the housing, the flexible lever  102  of the locking member is again moved in contact with the ledge  62  of the lead screw member  58 ,  FIG. 8 . The medicament delivery member may now be removed and discarded. 
     When a subsequent dose is to be performed, the above described procedure is performed and can be repeated until the medicament container is emptied. 
     It is to be understood that the embodiment described above and shown in the drawings is to be regarded only as a non-limiting example of the invention and that it may be modified in many ways within the scope of the patent claims.