Abstract:
A dispensing device, such as a needle free injector, comprising a spring which provides an energy store, and a dispensing member movable to effect dispensing under the force of the spring, a latch having a first, safe position which disables triggering of the device, a second, ready to trigger position in which it restrains movement of the dispensing member but enables triggering, and a third, triggered position in which it permits such movement. A trigger is operable by the user for moving the latch from the second position to the third position. A safety mechanism, preferably in the form of an appropriately shaped slot in the dispensing member, is effective before triggering the device to prevent movement of the latch to the third position. An attachment is provided for moving the latch from the first, safe position to the second, ready to trigger position to enable triggering of the device. cap is provided to maintain the sterility and stability of the contained medicament, and the device is configured such that it is impossible to place it in the ready to trigger state prior to removal of the cap.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Needle-free -injectors are used as an alternative to needle-type hypodermic injectors for delivering liquid drugs and other substances through the skin and into the underlying tissue. The drug is dispensed by a piston from a drug capsule at pressures high enough to pierce the skin. 
         [0002]    Typically, the drug capsule will comprise a hollow cylindrical chamber narrowing to a discharge orifice at one end, with the piston slidingly and sealingly located at the other. The piston is driven towards the orifice to dispense the drug by a dispensing member. Typically devices are powered by a variety of means, such as a spring (the spring force being supplied by a resilient element or a pressurised gas) or pyrotechnic charge. Examples of such devices are described in U.S. Pat. Nos. 5,891,086 and 5,480,381 
         [0003]    For spring powered needle-free injectors, the spring constantly exerts a force on the dispensing member prior to use and a restraining means is required to prevent the dispensing member from moving under the force of the spring. The needle-free injector is triggered by moving the injector into a condition in which the restraining means no longer has a restraining effect, thus permitting the dispensing member to move. 
         [0004]    It is often desirable for the triggering of the delivery of the medication to involve a very modest force, for example by the patient pressing a button or pressing the injector against the injection site. However, this low force can cause premature triggering, such as when the device is dropped, or when the cap over the injection orifice that maintains formulation stability and sterility on storage is removed. 
         [0005]    A problem exists during the assembly of such devices—producing a device which is easy to operate, may result in a device which is also easy to accidentally trigger during manufacture and assembly. This is both wasteful and can be a safety hazard to the personnel involved. 
         [0006]    WO 97/37705 addressed this issue by providing a device for dispensing a material or article, which comprises a spring, which provides an energy store, a dispensing member movable to effect dispensing under the force of the spring, latch means having a first position which prevents triggering of the device, a second position in which it restrains movement of the dispensing member but enables triggering, and a third position in which it permits such movement, trigger means operable by the user for moving the latch means from said second position to said third position, the first position being a safety mechanism effective before the device has been completely assembled to prevent movement of the latch means to the third position 
         [0007]    For the embodiments of the inventions disclosed in WO 97/37705, the safety mechanism is disengaged at the end of the assembly process, using a tool inserted into the device to move the latch from the first position to the second position. with the latch being restrained from moving to the third position by an outer-ring. The triggering means, which functions by moving the latch so that it is no longer restrained by the outer-ring, is then restricted from operating by a tear-off band, which physically stops the movement of the latch with respect to the outer ring, the band being removed prior to triggering the device. 
         [0008]    As an alternative to the above, it may be advantageous to store the devices in the first position, with the original safety mechanism engaged. The devices are stored for up to three years before use and from both a general safety and device performance perspective there are advantages to keeping the safety mechanism engaged. Then following storage, just prior to triggering, an attachment to the device is used to disengage the safety mechanism. 
         [0009]    In addition, the orifice must be kept sealed during storage to ensure stability and sterility of the drug product. The removal of the orifice seal is preferably combined with the disengagement of the safety mechanism, to ensure the system is easy to use, and to ensure that the orifice seal is removed prior to the disengagement of the safety mechanism, so that it is not possible that the act of removing the orifice seal triggers the delivery of the drug. 
       SUMMARY OF THE INVENTION 
       [0010]    According to the present invention, there is provided a device for readying a needle free injector for delivery. The injector comprises a energy store, such as a pyrotechnic charge, a mechanical spring, or preferably a pressurized gas spring, and a dispensing member movable, to effect dispensing, under the force of the spring. The invention provides a cap comprising a seal covering the injection orifice to ensure stability and sterility of the contents, and a mechanism for removing said cap. The invention also provides a mechanism for changing the state of the device from a safe state to a ready to deliver state. The safe state is characterized by an inability to accidentally deliver the contents, when for example, the device is dropped, the cap is removed, or the device is otherwise affected. The invention also provides for a linkage between the two mechanisms, such that they must be completed in the correct order, ie the cap is removed while the device is in the safe state. 
         [0011]    It is preferred that the act of removing the cap and placing the device in the ready to deliver state be accomplished in a single motion, for example by (but not limited to) having a lever, the end of which is attached to the cap, and the base of the lever actuating the safety mechanism. However, it could also be accomplished in two motions, for example wherein the removal of the cap exposes a safety mechanism which is subsequently activated by the user, or alternatively wherein the cap is removed, exposing the end of the lever to allow the lever to be pivoted, placing the device in the ready to deliver state. 
         [0012]    In one embodiment, the removal of the cap and the placing of the device into the ready state exposes a button, said button being pushed by the user to deliver the contents. However, it is preferred that the act of pressing the delivery orifice against the delivery site is what triggers the device to deliver. 
         [0013]    An advantage of the invention is that the cap keeps the contents sterile until the delivery 
         [0014]    It is another advantage of the invention that the cap maintains the stability of the contents, especially to evaporation. 
         [0015]    It is another advantage that the device keeps the injector in the safe state until it is ready to deliver. 
         [0016]    It is another advantage that the device ensures that the injector is in the safe state until after the cap is removed, to ensure that the act of removing the cap does not lead to accidental delivery, by for example, accidentally pressing on a trigger button or accidentally pressing the end of the injector in a way that mimics pressing the injector into the skin, causing premature delivery. 
         [0017]    These and other advantages will be readily apparent to those skilled in the art. 
         [0018]    In the preferred embodiment, the invention provides a latch means having a first position wherein the device is safe, and cannot trigger until the latch is forcibly moved. The latch also has a second position, which it restrains movement of the dispensing member, a third position which releases the device to cause delivery, and a trigger means operable by the user for causing the latch means to move from said second position to said third position. Moreover, there is provided a second safety mechanism which engages and disables the trigger until after the cap has been removed and as the device is placed into the ready to trigger state. The invention is linked such that it cannot be activated to move the latch from the first to the second position or disengage the second safety mechanism until the cap providing a sterile barrier to the formulation within drug capsule has been removed. 
         [0019]    These and other objects, advantages, and features of the invention will become apparent to those persons skilled in the art upon reading the details of the embodiments as more fully described below. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0020]    The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following figures: 
           [0021]    A number of different embodiments of the invention are described in the following section making reference to the accompanying drawings, in which: 
           [0022]      FIG. 1  presents a longitudinal cross-section through the preferred embodiment of the invention; 
           [0023]      FIGS. 2   a, b  and  c  show the latch  6  and dispensing member  2  part of the injector from  FIG. 1  in the three stages ending in triggering. In (a) the latch  6  is in the first, or safe position. In (b) the latch  6  is in the second position, the non-safety, ready to trigger position. In (c), the latch  6  is in the third position, following triggering; 
           [0024]      FIG. 3  illustrates a needle free injector with one embodiment of the attachment for disengaging the safety mechanism; 
           [0025]      FIGS. 4   a  and  b  show the latch  6 , dispensing member  2  and collar  33  components of  FIG. 3  with the latch  6  in the first, safe position (a) and the second, ready to trigger position (b) respectively; 
           [0026]      FIGS. 5   a  and  b  present end on views of the device in  FIG. 3  showing a second safety mechanism comprising block sections, with the (a) the block sections  38  engaged and (b) the block sections  38  disengaged; 
           [0027]      FIGS. 6   a, b  and  c  illustrate another embodiment of the attachment for disengaging the safety mechanism (a) with the outer cap  31  in place, (b) with the outer cap  31  inverted to cover the seal carrier  20  and (c) with the seal carrier  20  snapped off by applying pressure to the outer cap  3   1 . 
           [0028]      FIGS. 7   a, b  and  c  present the third embodiment of the attachment for disengaging the safety mechanism (a) with the outer cap  31  in place, (b) with the outer cap  31  removed, removing the seal carrier  20  and (c) on rotating the ring section  39 ; and 
           [0029]      FIGS. 8   a  and  b  present a cross-sectional view of the injector in  FIG. 7  showing a) the safe position and (b) the ready to trigger position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Before the present device and method are described, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims. 
         [0031]    Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention. 
         [0032]    Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described. AR publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. 
         [0033]    It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a storage means” includes a plurality of such storage means and reference to “the spring” includes reference to one or more springs and equivalents thereof known to those skilled in the art, and so forth. 
         [0034]    The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed. 
         [0035]    The embodiments of the invention disclosed are based on Aradigm&#39;s (formerly Weston Medical&#39;s) Intraject needle-free injector, described in WO 95/03844.  FIG. 1  presents a longitudinal section through the Intraject needle-free injector prior to integration with the device of the present invention. In  FIG. 1 , the injection force is provided by a compressed gas spring, which comprises a cylinder  1  enclosed at one end containing a gas, typically nitrogen, typically at a pressure between 150 and 300 bar. Contained within the cylinder is a dispensing member  2 . 
         [0036]    The end of the dispensing member has a frusto-conical, truncated cone—portion  3  and a flange  4 . There is a double o-ring seal  5  situated between the truncated cone section  3  and the flange  4 . 
         [0037]    Prior to triggering the device, the dispensing member  2  is held in the position illustrated in  FIG. 1  by a latch  6  which sits in a groove in the dispensing member. The upper surface of the groove forms a cam surface  7 . Consequently, there is force urging the latch to move to the left. In the configuration shown in  FIG. 1 , the latch is restricted from moving by the outer ring  8 . 
         [0038]    At the lower end of the cylinder  1 , there is an outwardly directed flange  9 . The cylinder is held in place by crimping the flange  9  to another outwardly directed flange  10  on the upper end on a coupling  11 . The sleeve  8  consists of an upper sleeve portion  12  within which the cylinder is situated, and a lower sleeve portion  13 . The lower sleeve portion  13  is connected to the coupling  11  by inter-engaging screw threads  14  formed on the inner and outer walls of the lower sleeve portion  13  and the coupling respectively  11 . 
         [0039]    The injector has a cartridge  15  which contains the medicament. In the cartridge there is a piston  16 , slidingly and sealingly located therein. The piston  16  may comprise a cylindrical portion containing two larger diameter ribs, and a frusto-conical portion. The piston  16  is in contact with the medicament  17  and at the other end of the cartridge  15  there is a discharge orifice  18 . Adjacent to the orifice  18  there is an interface seal  19  contained within a seal carrier  20 . The interface seal  19  is required for filling the needle-free device as described in PCT/GB9700889. A stopper  20   a  seals the medicament into the capsule. Seal  19 , seal carrier  20 , and stopper  20   a,  comprise the cap that must be removed prior to delivery. 
         [0040]    To place the device in the ready to deliver state, the cap must be snapped off at the frangible joint  21 . This removes the seal  19  and exposes the orifice  18 . The trigger blocking mechanism  22 , which prevents the medication cartridge from moving back toward the upper sleeve portion  22 , thereby preventing delivery, is removed. Finally, latch  6  must be moved from the first (safe) position, to the second (ready to deliver) position, 
         [0041]    The latch  6  is incorporated into a groove in the dispensing member  2 —not only does the groove have a cam surface  7  but also a locking surface  27  which is perpendicular to the dispensing member axis and is located radially inward of the cam surface  7 . Additionally, to access the latch  6  there is an opening  28  in the upper sleeve  12 , which prior to triggering is aligned with the latch  6 . 
         [0042]      FIGS. 2   a, b  and  c  illustrate the operation of the safety mechanism. When the latch and dispensing member are initially assembled, the latch occupies the first (safe) position, as shown in  FIG. 2   a. In this position, the dispensing member-engaging latch portion  29  is acted on by the locking surface  27 . Frictional force ensures that the latch is held rigid by the locking surface-typically the dispensing member exerts a force of at least 100N. 
         [0043]    The latch is placed in the second (ready to deliver) position using a pin which fits through opening  28  to push the latch in the direction of the arrow P into the position shown in  FIG. 2   b,  (and in  FIG. 1 ). In this position the dispensing member engaging latch portion  29  is in contact with the radially inner end of the cam surface  7 . 
         [0044]    To cause delivery, the orifice  18  is then placed against the skin of the patient. Practically, this involves holding the device by the upper sleeve  12  portion. The upper sleeve  12  is then moved downwards with respect to the lower sleeve  13 , bringing aperture  25  in the wall of the upper sleeve portion  8  into alignment with the latch  6 . The latch then moves to the left into the aperture  25 , under the force exerted on it by the cam surface  7  formed in the dispensing member  3  into the position shown in  FIG. 2   c.  The injector then delivers. 
         [0045]    It is advantageous to have a mechanism that places the device in the ready to deliver state in a simple motion or motions.  FIG. 3  illustrates one embodiment of the combined needle-free injector plus means for disengaging the safety mechanism  30 . In this Figure, the means for disengaging the safety mechanism consists of a cap  31  enclosing, and holding rigidly, the seal carrier  20 , a lever  32  and a collar  33 . The lever  32  and collar  33  are presented in more detail in  FIGS. 4   a  and  4   b.  The lever contains a lip  34  at the far end, over which the cap  31  is positioned. This ensures that the lever  32  cannot be moved before the outer cap  31  is removed, which in turn ensures that the user cannot move the latch or disengage the safety mechanism until the cap has been removed. The lever  32  is pivoted around the pivot axis  35 , with the pivoted surface in contact with injector being a cam surface  36 . The force required to pivot lever  32  is in the range from about 2N to about 30N. The collar  33  contains a pin  37  which extends into the device through the opening  28  in the upper sleeve  12  to impinge on the far side of the latch  6 , see  FIG. 4   a.  The force required to move the latch is in the range from about 20N to about 120N. To stop the upper sleeve section  12  moving with respect to the lower sleeve section  13 , there are block sections  38  between the upper and lower sleeves, which form part of the collar  33 . The relative position of the block sections  38  with respect to the lever  32  is more clearly presented in the end- on view of the device shown in  FIG. 5   a.    
         [0046]    To deliver the device contents, the cap  31  is removed, exposing the injection orifice  18 . With the outer cap  31  removed, the lip  34  is exposed, enabling the lever  32  to rotate about the pivot axis  35 . Only when the outer cap  31  is removed can the lever  32  be rotated. As the lever  32  rotates, the cam surface  36  forces the collar  33  to move in the direction Q in  FIGS. 3 ,  4   a  and  5   b  pushing the pin  37  against the latch  6 . When the lever  32  has rotated through a complete cycle, approximately 180° as shown in  FIG. 4   b,  the latch  6  moves to the second position, as shown in  FIG. 2   b.  The blocks  38  no longer restrict the movement of the upper sleeve  12  with respect to the lower sleeve  13  and the device can trigger as described above. The relative movement of the block  38  with respect to the sleeve section  12  and  13  is seen in the end on view presented in  FIG. 5b . By integrating the cap  31  to the lever  32  with a flexible joint at the tip  34 , the mechanism can also be configured to ensure that the user removes the stopper and sets the safety in a single action. 
         [0047]    It will be obvious to one skilled in the art that rather than using the blocks  38 , the movement of the lever  32  could expose a trigger button, said trigger button subsequently being pressed by the subject to deliver the medication. 
         [0048]    Another embodiment of the invention is shown in  FIGS. 6   a, b  and  c.  In  FIG. 6   a  the as-received device is presented. To operate the device the outer cap  31  is removed, leaving the seal carrier  20  intact. The outer cap  31  is then inverted and placed back over the seal carrier  20 , as shown in  FIG. 6   b.  Pressure is then applied to the outer cap  31  to break the frangible seal between the seal carrier and the lower sleeve, as shown in  FIG. 6   c.  The device is then placed in the ready to deliver state by rotating the lever  32  as described above and presented in  FIGS. 4   a  and  b.    
         [0049]    A third embodiment of the invention is shown in  FIGS. 7   a, b  and  c.  This version of the attachment for disengaging the safety mechanism consists of an outer cap  31  covering and holding rigid the seal carrier  20 —not shown in  FIG. 7   a -, a collar section  39  and a barrel section  40 . The needle-free device fits within the barrel section  40  upper sleeve portion  12  first, so that the longitudinal axis of the device is aligned with the longitudinal axis of the barrel section  40 . The needle-free device is held rigidly within the barrel section  40 . The collar section  39  fits over and is attached to the barrel  40 , so that the collar section  39  is free to rotate about the axis of the device in a clockwise direction when the outer cap  31  has been removed. The outer cap  31  contains a locking mechanism  41  which locks the collar  39  rigid when the cap  31  is in place. To trigger the device the outer cap  31  is removed, which in turn removes the seal carrier  20 , exposing the injection orifice  8 . The collar section  39  is now free to rotate clockwise about the axis of the needle free device. Because the cap  31  is locked into the collar section  39 , this ensures that the user cannot move the latch or disengage the safety mechanism until the cap has been removed so forcing the user to prepare the device in the correct order. There is a lip  42  on the collar section  39 , which is aligned so that the lip fits under the lip of the tear-off band  22 . As the collar section rotates clockwise the tear-off band  22  is torn off, so that after a complete revolution, 360°, the tear-off band  22  is completely removed. Simultaneously the safety mechanism is disengaged. This is illustrated by the cross-sections through the collar section shown in  FIGS. 8   a  and  b.  In  FIG. 8   a  the safety mechanism is engaged—that is the latch is in the safe position shown in  FIG. 2   a.  On the inside of the collar section there is a pin  37  which extends into the device through the opening  28  in the upper sleeve  12  to impinge on the far side of the latch  6 . The pin is in contact with the inner surface of the collar section. The inner surface of the ring section is a cam surface  43 , so that as the collar rotates the action of the cam surface pushes the pin against the latch moving the latch from the safe position to the first position as shown in  FIG. 8   b.  With the tear-off band  22  removed, the device can deliver as outlined above. 
         [0050]    The preceding merely illustrates the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. The scope of the present invention, therefore, is not intended to be limited to the exemplary embodiments shown and described herein. Rather, the scope and spirit of present invention is embodied by the appended claims.