Patent Publication Number: US-2022215779-A1

Title: Drive mechanism for a medicament delivery training device

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to medicament delivery devices. In particular, it relates to drive mechanism for a medicament delivery training device and to a medicament delivery training device comprising such a drive mechanism. 
     BACKGROUND 
     Medicament delivery devices such as auto-injectors nowadays provide possibilities for the users themselves to handle medicament delivery in an easy, safe and reliable manner. 
     Before a user commences a drug administration programme by means of an auto-injector, it may be valuable for the user to undergo training to learn how to administer a drug properly by means of a specific auto-injector. A training device may be used for this purpose. It is known to provide a feedback mechanism for indicating to the user when the appropriate volume of medicament has been injected by the auto-injector. There are feedback mechanism that indicate the user when the injector can be removed from an injection site. 
     WO2018/082887 discloses a feedback mechanism for an injection device configured to deliver a medicament to a user. The feedback mechanism comprises a piston and a fluid chamber. The piston is adapted to move into the fluid chamber during use of the injection device. The feedback mechanism also has a damper arranged to damp movement of the piston. An indicator is arranged to provide feedback to the user after the piston has moved a pre-determined distance into the fluid chamber. 
     To conduct an exact imitation of the auto-injector functions, it is desired that the trainer is also able to produce signals for indicating the different steps in the injecting process for the user as the real auto-injectors. This will improve a training efficiency. Such feedback mechanisms can be different, produce different audio, tactical and visual signals and indicate a beginning or an end of the imitated injection process. 
     Furthermore, it is advantageous if the trainer device could be used a number of times for a training purpose. Therefore, it requires a possibility to be reset after a training operation for a multiple usage. 
     SUMMARY 
     An object of the present disclosure is to provide a drive mechanism for a medicament delivery training device which solves or at least mitigates problems of the prior art. 
     There is hence according to a first aspect of the present disclosure provided a drive mechanism for a medicament delivery training device, the delivery mechanism comprising: a plunger rod having a proximal end and a distal end, a stopper provided on the proximal end of the plunger rod, and a container having an inner chamber, a proximal container end, and an open distal container end leading into the inner chamber, wherein the inner chamber has a distal portion and a proximal portion, wherein in an initial state of the delivery mechanism the plunger rod is axially fixedly arranged in a first position in which the stopper is arranged distally relative to the proximal portion, the plunger rod being biased towards the proximal container end, and wherein the plunger rod is configured to be released from the first position, causing the plunger rod to move towards the proximal container end and the stopper to impact with a stopper contact surface, resulting in an initial signal, and to subsequently move into the proximal portion. 
     A medicament delivery training device, for which the drive mechanism is designed for, may thereby simulate medicament administration of a real medicament delivery device. In particular, a user is due to the initial signal able to learn and understand when the medicament administration process is commenced during medicament administration. 
     The initial signal may be an initial sound such as an initial click. 
     According to one embodiment the stopper has an outer stopper diameter, the distal portion has a distal portion inner diameter and the proximal portion has a proximal portion inner diameter which is smaller than the distal portion inner diameter and the outer stopper diameter, the distal portion transitioning to the proximal portion via the stopper contact surface. The stopper hence impacts with the stopper contact surface because the outer stopper diameter is larger than the proximal portion inner diameter. 
     One embodiment comprises a holding structure provided with a radially flexible arm, wherein the plunger rod is provided with a radial recess configured to engage with the radially flexible arm to maintain the plunger rod axially fixed in the distal portion. 
     One embodiment comprises an actuator sleeve configured to receive the holding structure, the actuator sleeve being configured to move between a proximal position and a distal position, wherein in the proximal position the actuator sleeve is configured to urge the radially flexible arm radially inwards to engage with the radial recess. 
     According to one embodiment when the actuator sleeve is in the distal position the actuator sleeve is configured to enable the radially flexible arm to move radially outwards to disengage from the radial recess, thereby releasing the plunger rod from the first position. 
     According to one embodiment the actuator sleeve is biased towards the proximal position. 
     One embodiment comprises a delivery member cover configured to move linearly relative to the container, between an initial position and an activating position, wherein the delivery member cover is configured to move the actuator sleeve from the proximal position to the distal position when moved from the initial position to the activating position. 
     One embodiment comprises a housing configured to receive the container, wherein the housing has an inner stop structure configured to stop proximal movement of the plunger rod in the inner chamber, causing the stopper to impact with the stop structure, resulting in a subsequent signal. 
     The subsequent signal may be a subsequent audible sound such as a click. 
     A user may thereby be able to learn and understand when a medicament administration process has been finalised. 
     According to one embodiment the stop structure comprises a plurality of radially inwards extending protrusions. 
     According to one embodiment the container is provided with a proximal engagement structure configured to engage with the housing. 
     According to one embodiment the radially inwards extending protrusions and the proximal engagement structure are arranged to form a central proximal opening into the container. 
     According to one embodiment the stopper is made of a resilient material. 
     According to one embodiment the proximal portion inner diameter is dimensioned to cause friction between the stopper and the inner surface of the proximal portion to control a driving speed of the plunger rod. 
     There is according to a second aspect of the present disclosure provided a medicament delivery training device comprising a delivery mechanism according to the first aspect. 
     According to one embodiment the drive mechanism is configured to be actuated mechanically or electrically. 
     Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the element, apparatus, component, means, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, etc.”, unless explicitly stated otherwise. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The specific embodiments of the inventive concept will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  depicts a perspective view of an example of a medicament delivery training device; 
         FIG. 2  is an exploded view of the medicament delivery training device in  FIG. 1 ; 
         FIG. 3  is a perspective view of a housing of the medicament delivery training device; 
         FIG. 4  is a perspective view of a housing of the medicament delivery training device when the container is fitted in the housing; 
         FIG. 5  is a longitudinal sectional view of a container of a medicament delivery training device; 
         FIG. 6  shows a perspective view of a plunger rod, an actuator sleeve and a holding structure; 
         FIG. 7  shows a perspective view of a cap with a resetting structure; 
         FIG. 8  is a longitudinal section of the medicament delivery training device in  FIG. 1  in an initial state; 
         FIG. 9  is a longitudinal section of the medicament delivery training device with the cap removed; 
         FIG. 10  is a longitudinal section of the medicament delivery training device when the medicament delivery training device is being activated; 
         FIG. 11  is a longitudinal section of the medicament delivery training device when the plunger rod has been released; 
         FIG. 12  is a longitudinal section of the medicament delivery training device just before the plunger rod has moved maximally in the proximal direction; 
         FIG. 13  is a longitudinal section of the medicament delivery training device when the plunger rod has reached its most proximal position; 
         FIG. 14  is a longitudinal section of the medicament delivery training device when the delivery member cover has been released; 
         FIG. 15  is a longitudinal section of the medicament delivery training device when it is being reset; and 
         FIG. 16  is a longitudinal section of the medicament delivery training device when the medicament delivery training device has been reset. 
     
    
    
     DETAILED DESCRIPTION 
     The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplifying embodiments are shown. The inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. 
     In the present disclosure, when the term “distal” is used, this refers to the direction pointing away from the dose delivery site. When the term “distal part/end” is used, this refers to the part/end of the medicament delivery training device, or the parts/ends of the members thereof, which under use of the medicament delivery training device is/are located furthest away from the dose delivery site. Correspondingly, when the term “proximal” is used, this refers to the direction pointing to the dose delivery site. When the term “proximal part/end” is used, this refers to the part/end of the medicament delivery training device, or the parts/ends of the members thereof, which under use of the medicament delivery training device is/are located closest to the dose delivery site. 
     Further, the term “longitudinal”, with or without “axis”, refers to a direction or an axis through the device or components thereof in the direction of the longest extension of the device and/or component. 
     Similarly, the terms “radial”, “transversal” or “orthogonal” refers to a direction generally perpendicular to the longitudinal direction which is the axis direction and e.g. “radially or orthogonally outward” will refer to a direction pointing away for the longitudinal axis. 
       FIG. 1  depicts an example of a medicament delivery training device  1 . The medicament delivery training device  1  is a dummy device to be used for learning how a corresponding real medicament delivery device is to be handled and operated. 
     The medicament delivery training device  1  has a proximal end  1   a  and a distal end  1   b.  The medicament delivery training device  1  comprises a housing  3  and a cap  5 . The cap  5  is configured to be removably attached to the housing  3 . The cap  5  forms the proximal end  1   a  of the medicament delivery training device  1  when attached to the housing  3 . 
       FIG. 2  shows an exploded view of the medicament delivery training device  1 . The exemplified medicament delivery training device  1  comprises a resetting structure  5   a.  The resetting structure  5   a  has an elongated shape. The resetting structure  5   a  may comprise a rod. The resetting structure  5   a  is configured to be attached to the cap  5 . The cap  5  has a distal opening  5   b  configured to receive the resetting structure  5   a.  The resetting structure  5   a  extends in the distal direction from the cap  5  when fitted in the cap  5 , along a central axis of the cap  5 . 
     The medicament delivery training device  1  comprises a delivery member cover  7 , and a first resilient member  9  configured to bias the delivery member cover  7  in the proximal direction. The exemplified first resilient member  9  may be a spring. The delivery member cover  7  is configured to be received by the housing  3 . The delivery member cover  7  is configured to be moved linearly relative to the housing  3 , between an initial position and an activation position. The delivery member cover  7  extends more in the proximal direction from the housing  3  in the initial position than in the activation position. Hereto, the initial position is an extended position and the activation position is a retracted position relative to the housing  3 . The first resilient member  9  is configured to bias the delivery member cover  7  towards the initial position, i.e. the extended position. 
     The medicament delivery training device  1  comprises a container  11 . The container  11  is a syringe dummy. Since it is the syringe dummy, the exemplified container  11  does not comprise any needle or canula. The container  11  has an inner chamber  11   a.  The inner chamber  11   a  extends through the container  11 . The container  11  has an open distal container end  11   b.  The container  11  has an open proximal container end  11   c.  The inner chamber  11   a  extends between the open distal container end  11   b  and the open proximal container end  11   c.    
     The medicament delivery training device  1  comprises a plunger rod  13 . The plunger rod  13  is provided with a stopper  15 . The stopper  15  is provided on a proximal end of the plunger rod  13 . The stopper  15  may be made of an elastic, resilient or flexible material. 
     The plunger rod  13  may have a proximal end face or cap/cover which may form part of the stopper  15  or which may extend in the proximal direction from the stopper  15 . The proximal end face of the plunger rod  13  may be made of a rigid material such as a plastic material or a metal. In examples in which the plunger rod has a proximal end face, the proximal end face and the elastic stopper body together form the stopper as defined herein. 
     The plunger rod  13 , the stopper  15  and the container  11  forms part of a drive mechanism of the medicament delivery training device  1 . 
     The container  11  is configured to receive the plunger rod  13 . The plunger rod  13  is configured to extend in the proximal direction into the inner chamber  11   a  through the open distal container end  11   b.    
     The exemplified plunger rod  13  comprises a recess  13   a.  The recess  13   a  is a radial recess. In the example shown in  FIG. 2 , the recess  13   a  extends a full turn in the circumferential direction. The plunger rod  13  could alternatively comprise a plurality of physically separate recesses distributed in the circumferential direction. The recess  13   a  may have an inclined distal transition surface, relative to the central axis of the plunger rod  13 , where the recess  13   a  transitions to the outer surface of the plunger rod  13 . 
     The medicament delivery training device  1  comprises a second resilient member  17  configured to bias the plunger rod  13  in the proximal direction. The second resilient member  17  may be a spring. The second resilient member  17  is configured to be received by the plunger rod  13 . The plunger rod  13  may hence be hollow. 
     The medicament delivery training device  1  comprises a holding structure  21 . The holding structure  21  is configured to be received by the housing  3 . The holding structure  21  is configured to be fixedly arranged in the housing  3 . The holding structure  21  is axially fixed relative to the housing  3 . The holding structure  21  is arranged in a distal portion of the housing  3 . The holding structure  21  is an elongated structure. The holding structure  21  is hollow. The holding structure  21  is configured to receive a distal end portion  13   b  of the plunger rod  13 . 
     The holding structure  21  comprises a plurality of radially flexible arms  21   a.  The radially flexible arms  21   a  extend in the proximal direction. The radially flexible arms  21   a  form a proximal end of the holding structure  21 . Each radially flexible arm  21   a  is configured to engage with the recess  13   a  of the plunger rod  13 . Each radially flexible arm  21   a  comprises a radially inwards extending protrusion configured to engage with the recess  13   a.    
     The medicament delivery training device  1  comprises an actuator sleeve  19 . The actuator sleeve  19  is configured to be arranged around a proximal portion of the holding structure  21 . The actuator sleeve  19  is configured to be moved linearly relative to the holding structure  21  between a proximal position and a distal position. The delivery member cover  7  is configured to move the actuator sleeve  19  from the proximal position to the distal position. When the delivery member cover  7  is in the initial position, the actuator sleeve  19  is arranged in the proximal position. When the delivery member cover  7  is moved in the distal direction towards the activation position, the actuation sleeve  19  is moved towards the distal position. The actuator sleeve  19  has a proximal flange  19   a.  The delivery member cover  7  has distally extending legs configured to bear against/engage with the proximal flange  19   a  when the delivery member cover  7  is moved towards the activation position. The actuation sleeve  19  is thereby moved towards the distal position as the delivery member cover  7  is moved in the distal direction. 
     The actuator sleeve  19  is configured to be arranged around the radially flexible arms  21   a  and urge the radially flexible arms  21   a  to engage with the recess  13   a  of the plunger rod  13  when the actuator sleeve  19  is in the proximal position. 
     The medicament delivery training device  1  comprises a third resilient member  23 . The third resilient member  23  may be a spring. The third resilient member  23  is configured to bias the actuator sleeve  19  in the proximal direction towards the proximal position. The holding member  21  has a distal flange surface  21   b.  The third resilient member  23  is configured to be arranged between the distal end of the proximal flange  19   a  of the actuator sleeve  19  and the distal flange surface  21   b.  The third resilient member  23  thereby biases the actuator sleeve  19  in the proximal direction towards the proximal position. 
       FIG. 3  shows a perspective view of the housing  3 . The housing  3  has an inner stop structure  3   a.  The stop structure  3   a  comprises a plurality of radially inwards extending protrusions  3   b.  The radially inwards extending protrusions  3   b  form a central proximal opening  3   c  between them. The radially inwards extending protrusions  3   b  do hence not meet as they extend towards the central axis of the housing  3 . The central proximal opening  3   c  is dimensioned such that the resetting structure  5   a  may be received through the central proximal opening  3   c  when the cap  5  with the resetting structure  5   a  is attached to the housing  3  and hence the resetting structure  5   a  is inserted into the housing  3 . The central proximal opening  3   c  is dimensioned such that the stopper  15  is not able to move through the central proximal opening  3   c  when the plunger rod  13  is moved in the proximal direction, as will be explained in what follows. Hereto, the stopper  15  has an outer stopper diameter which is larger than the central proximal opening  3   c.    
       FIG. 4  shows a perspective view of the housing  3  when the container  11  is arranged in the housing  3 . The container  11  is provided with a proximal engagement structure  11   d  configured to engage with the housing  3 . The proximal engagement structure  11   d  comprises a plurality of radially outwards extending flexible snap structures  11   e.  According to the present example, the housing  3  has a radially inwards extending structure  3   d  between each adjacent pair of radially inwards extending protrusion  3   b.  The radially inwards extending structures  3   d  have a shorter radially inwards extension than the radially inwards extending protrusions  3   b.  Each of the plurality of radially outwards extending flexible snap structures  11   e  is configured to engage with a respective radially inwards extending structure  3   d.  The container  11  is thereby attached to the housing  3 . 
       FIG. 5  shows a longitudinal sectional view of the container  11 . The container  11  has a proximal container end  11   f  and a distal container end  11   g.  The inner chamber or channel  11   a  which extends between the proximal container end  11   f  and the distal container end  11   g  has a proximal portion  11   h  and a distal portion  11   i.  The proximal portion has a proximal portion inner diameter d 1  and the distal portion  11   i  has a distal portion inner diameter d 2 . The proximal portion inner diameter d 1  is smaller than the distal portion inner diameter d 2 . 
     The open distal container end  11   b  opens into the distal portion  11   i.  The distal portion  11   i  transitions to the proximal portion  11   h  via a stopper contact surface  11   j.  The stopper contact surface  11   j  may for example be inclined relative to the central longitudinal axis of the container  11 , as shown in  FIG. 5 , or it may be orthogonal to the central longitudinal axis. In the former case, the stopper contact surface  11   j  provides a gradual decrease of the inner diameter of the container  11  in the proximal direction. In the latter case, the stopper contact surface forms a step between the distal portion  11   i  and the proximal portion  11   h.    
     The outer stopper diameter may for example be defined by the largest outer dimension or diameter of the stopper  15 . The proximal portion inner diameter d 1  is smaller than the outer stopper diameter. The proximal portion inner diameter d 1  is dimensioned to provide friction onto the stopper  15  to control the driving speed of the plunger rod  13 . The driving speed should preferably simulate the driving speed of the plunger rod of the corresponding real medicament delivery device which the medicament delivery training device  1  is designed to simulate. 
       FIG. 6  shows a perspective view of the plunger rod  13 , the actuator sleeve  19  and the holding structure  21 . 
       FIG. 7  is a perspective view of the cap  5  with the resetting structure  5   a  attached to the cap  5 . In a typical example, the resetting structure  5   a  is fixedly attached to the cap  5  such that when the cap  5  is removed from the housing  3 , the resetting structure  5   a  is also removed from the housing  3  together with the cap  5 . 
       FIG. 8  shows a longitudinal section of the medicament delivery training device  1  in an initial state thereof. The initial state is the state of the medicament delivery training device  1  before it has been activated. In the initial state, the cap  5  is attached to the housing  3 . The resetting structure  5   a  extends into the container  11  through the central proximal opening  3   c  of the housing  3 . The drive mechanism is also in an initial state when the medicament delivery training device  1  is in the initial state. 
     The actuator sleeve  19  is arranged in the proximal position as it is biased by the third resilient member  23  in the proximal direction and the delivery member cover  7  is in the initial position in which it does not apply any, or at least negligible force in the distal direction onto the actuator sleeve  19 . The radially flexible arms  21   a  are hence urged radially inwards by the actuator sleeve  19  which is arranged around the radially flexible arms  21   a.  The radially flexible arms  21   a  thereby engage with the recess  13   a.  The plunger rod  13  is therefore maintained in a first position in which it extends through the open distal container end  11   b  and the stopper  15  is arranged fixed in the distal portion  11   i  of the container  11 . The proximal end of the stopper  15  is typically arranged at a distance from the stopper contact surface  11   j.    
     When a user is to perform training with the medicament delivery training device  1 , the cap  5  is first to be removed from the housing  3 . This is shown in  FIG. 9 . As the cap  5  is removed, so is the resetting structure  5   a.  The delivery member cover  7  is in the initial position, i.e. in the extended position relative to the housing  3 . The plunger rod  13  is still fixed in the first position as in the initial state depicted in  FIG. 8 . 
     In  FIG. 10 , the delivery member cover  7  has been moved into the housing  3  to the activation position as shown by arrow A. This may for example be achieved by a user pressing the medicament delivery training device  1  towards an intended site of injection. The delivery member cover  7  has pushed the actuation sleeve  19  in the distal direction towards the distal position, as shown by arrow B. The actuation sleeve  19  is hence moved distally from the radially flexible arms  21   a.  Since the plunger rod  13  is biased in the proximal direction and urged towards the proximal container end  11   c,  the radially flexible arms  21   a  are now moved out from the recess  13   a.  The plunger rod  13  is hence released and moved in the proximal direction further into the container  11 . 
       FIG. 11  shows the medicament delivery training device  1  when the plunger rod  13  has been released from its engagement with the holding structure  21 . The stopper  15  has moved from the distal portion  11   i  into the proximal portion  11   h  of the inner chamber  11   a  via the stopper contact surface  11   j,  as shown by arrow C. As the stopper  15  is moved from the distal portion  11   i  into the proximal portion  11   h,  the stopper impacts with the stopper contact surface  11   j,  since the outer stopper diameter is larger than the proximal portion inner diameter d 1 . This impact results in an initial signal. The initial signal may be an audible sound such as a click. A user will thereby become aware that simulated medicament administration has commenced. 
     In  FIG. 12  the plunger rod  13  has been further moved in the proximal direction inside the container  11  as shown by arrow D. 
     In  FIG. 13 , the stopper  15  has impacted with the housing  3 , in particular with the inner stop structure  3   a  with the plurality of radially inwards extending protrusions  3   b.  A subsequent signal is generated by this impact. The subsequent signal may for example be an audible sound such as a click. A user of the medicament delivery training device  1  will thereby understand that the simulated medicament injection has been finalised. 
     In  FIG. 14  the medicament delivery training device  1  has been removed from the injection site by the user. The delivery member cover  7  is hence moved back to the initial position due to its proximal biasing, as shown by arrow E. As a result, the actuation sleeve  19  is moved back to the proximal position from the distal position. 
     In this used state of the medicament delivery training device  1 , the medicament delivery training device  1  may be reset manually for further training. The plunger rod  13  may in particular be reset to the first position. 
     This resetting may be performed by manually inserting the resetting structure  5   a.  In particular, the resetting may be performed manually by a user placing the cap  5  back onto the housing  3 . 
       FIG. 15  shows a resetting operation of the medicament delivery training device  1 . The cap  5  is being placed back onto the housing  3  as shown by arrow F. The resetting structure  5   a  thereby first penetrates the central proximal opening  3   c  formed between the radially inwards extending protrusions  3   b  and subsequently the open proximal container end  11   c  of the container  11 . The resetting structure  5   a  has a distal end tip  5   c  which pushes the plunger rod  13  in the distal direction towards the first position, as shown by arrow G. The resetting structure  5   a  has a length which enables it to reset the plunger rod  13  in the first position when the cap  5  is attached to the housing  3 . Hence, as the resetting structure  5   a  is moved further into the container  11  the recess  13   a  of the plunger rod  13  will become aligned with the radially flexible arms  21   a,  which at this time are urged radially inwards by the actuator sleeve  19  arranged in the proximal position and hence around the radially flexible arms  21   a.  The radially flexible arms  21   a  will therefore engage with the recess  13   a  and the plunger rod  13  once again becomes fixedly arranged in the first position with the stopper  15  arranged in the distal portion  11   i  of the container  11 . This is shown in  FIG. 15 , where the medicament delivery training device  1  has once again obtained its initial state in which it is ready to be used for further training. 
     The inventive concept has mainly been described above with reference to a few examples. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended claims.