Abstract:
The present invention is directed to an automatic injection device containing a pre-loaded charge of medicament for automatically self-administering the medicament upon actuation thereof. The automatic injection device includes a housing assembly having an interior chamber, an activation assembly and a needle assembly for dispensing a dissolved medicament to a user. A dry compartment for storing a predetermined dry charge of dry medicament is located within the interior chamber. A wet compartment for storing a predetermined amount of liquid injection solution is also located within the interior chamber. A separation assembly separates the dry compartment from the wet compartment. The separation assembly prevents transfer of the liquid injection solution from the wet compartment to the dry compartment prior to activation of the automatic injection device. One or more medicament support assemblies located within the dry compartment prevent the passage of undissolved medicament from the dry compartment.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims priority from U.S. Provisional Serial No. 60/238,448, filed Oct. 10, 2000, and is incorporated herein in its entirety by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to automatic injectors for delivering medicament to an injection site. In particular, the present invention is directed to an automatic injector assembly for quickly combining a liquid material with a dry material to form a liquid medicament for delivering the medicament to an injection site. In accordance with the present invention, the automatic injector assembly includes a dry medicament support structure that prevents blockage of the needle.  
         BACKGROUND OF THE INVENTION  
         [0003]    An automatic injector is a device for enabling an individual to self-administer a dosage of medicament into his or her flesh. The medicament is usually stored in liquid form. The advantage of automatic injectors is that they contain a measured dosage of a liquid medicament in a sealed sterile cartridge and can be utilized for delivering the medicament into the flesh during emergency situations. Another advantage of automatic injectors is that the self-administration of the medicament is accomplished without the user initially seeing the hypodermic needle through which the medicament is delivered and without having the user to manually force the needle into his or her own flesh.  
           [0004]    There are drawbacks associated with the storage of medicament in liquid form. Some medicaments are not stable in liquid form. Furthermore, some liquid medicaments typically have a shorter shelf life than their solid counterparts. Others have developed automatic injectors that store the medicament in solid form and a liquid injection solution. These injectors, disclosed for example in U.S. Reissue Pat. No. 35,986, entitled “Multiple Chamber Automatic Injector,” (the disclosure of which is incorporated herein specifically by reference), however, require the user of the injector to expedite dissolution of the solid component by manually shaking the liquid component and the solid component immediately prior to injection. This increases the time needed to administer a dose of medicament. Furthermore, the improper mixing of the medicament with the liquid injection solution may release an insufficient dose of medicament. There is a need for an automatic injector that stores medicament in solid form that does not require manual premixing by the user. Furthermore, rapid delivery of the medicament is needed for emergency medical situations (e.g. nerve gas and chemical agent poisoning).  
         OBJECTS OF THE INVENTION  
         [0005]    It is therefore an object of the present invention to provide an automatic injector device that stores medicament in a solid form for increased shelf life.  
           [0006]    It is another object of the present invention to provide an automatic injector device that automatically mixes a solid medicament with a liquid injection solution upon activation.  
           [0007]    It is another object of the present invention to provide an automatic injector device that provides at least one medicament support that prevents the passage of undissolved medicament to the needle assembly of the injector device.  
           [0008]    It is another object of the present invention to provide an automatic injector device that pressurizes the liquid injection solution upon activation of the injector device.  
           [0009]    Additional objects and advantages of the invention are set forth, in part, in the description which follows, and, in part, will be apparent to one of ordinary skill in the art from the description and/or practice of the invention.  
         SUMMARY OF THE INVENTION  
         [0010]    In response to the foregoing challenges, applicants have developed an innovative automatic injection device having both wet and dry storage compartments. The present invention is directed to an automatic injection device containing a pre-loaded charge of medicament for automatically self-administering the medicament upon actuation thereof. The operation of the automatic injector requires no shaking by the user. The automatic injection device includes a housing assembly having an interior chamber, an activation assembly and a needle assembly for dispensing a dissolved medicament to a user. A dry compartment for storing a predetermined dry charge of dry medicament is located within the interior chamber. A wet compartment for storing a predetermined amount of liquid injection solution is also located within the interior chamber. A separation assembly separates the dry compartment from the wet compartment. The separation assembly prevents transfer of the liquid injection solution from the wet compartment to the dry compartment prior to activation of the automatic injection device.  
           [0011]    The injection device may further include one or more medicament support assemblies located within the dry compartment. In accordance with the present invention, each medicament support assembly prevents the passage of undissolved medicament from the dry compartment. Preferably, each medicament support assembly includes a plurality of apertures formed therein, which are sized to prevent passage of the undissolved medicament. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The invention will be described in conjunction with the following drawing in which like reference numerals designate like elements and wherein:  
         [0013]    [0013]FIG. 1 is a cross-sectional side view of a wet/dry automatic injector assembly in accordance with a first embodiment of the present invention;  
         [0014]    [0014]FIG. 2 is a cross-sectional side view of a wet/dry automatic injector assembly in accordance with a second embodiment of the present invention;  
         [0015]    [0015]FIG. 3 is an overhead view of a medicament support for the wet/dry automatic injector assembly of the present invention;  
         [0016]    [0016]FIG. 4 is an overhead view of the medicament support of FIG. 3 illustrating the overlay of grooves on the medicament support to form an array of apertures;  
         [0017]    FIGS.  5 - 8  are various cross-sectional views illustrating various aperture configurations for the medicament support of FIGS. 3 and 4; and  
         [0018]    [0018]FIGS. 9 and 10 are cross-sectional views illustrating the shape and taper of various aperture configurations for the medicament support of FIGS. 3 and 4. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    The present invention is described in connection with a push button type auto injector, whereby the user removes an end cap assembly and presses a button to trigger the injection process. The present invention, however, is not limited to push button type automatic injectors; rather, it is contemplated that the present invention may be incorporated into a nose activated auto injector, as described for example in U.S. Pat. No. 5,658,259. The disclosures of which are hereby specifically incorporated herein by reference. It is contemplated that the present invention may be employed in a syringe.  
         [0020]    An automatic injector assembly  10  according to a first embodiment of the present invention is illustrated in FIG. 1. The automatic injector assembly  10  includes a generally hollow housing  110 . The housing  110  includes an injection insertion end  111  and an activation end  112 . An actuator assembly  120  extends from an opening  113  in the activation end  112  of the housing  110 . The actuator assembly  120  is slidably received within the housing  110 . A removable end cap assembly  130  is releasably secured to the actuator assembly  120 . When the end cap assembly  130  is secured to the actuator assembly  120 , a side portion  131  of the end cap assembly  130  is adapted to abut the housing  110  to prevent movement of the actuator assembly  120  and unintentional injection of the medicament.  
         [0021]    The actuator assembly  120  includes a push button actuator assembly  121  having a hollow interior. The end cap assembly  130  engages the push button actuator assembly  121 . A collet  122  is located within the hollow interior of the push button actuator assembly  121 . An inner tube  123  is also located within the hollow interior of the push button actuator assembly  121 . The inner tube  123  is adapted to contact the collet  122 , as shown in FIGS. 1 and 2. An opposite end of the inner tube  123  may include an engagement rib  1231  that is adapted to be received within a complementary recess  1211  within the push button actuator assembly  121 . A drive assembly  124  is positioned within a space formed between the collet  122  and the inner tube  123 . A pin  132  extends from the end cap assembly  130  and is received within the collet  122  to prevent or block the collet  122  from collapsing prior to activation.  
         [0022]    The user removes the end cap assembly  130 . The pin  132  no longer prevents movement of the collet  122 . Upon depression of the actuator assembly  121 , the drive assembly  124  provides the necessary force when activated to operate the injector to inject the user with a necessary dosage of medicament. It is contemplated that the drive assembly  124  may be a spring assembly, a compressed gas assembly or any other suitable energy storing device. When activated, the drive assembly  124  causes the collet  122  to move such that a needle assembly  140  extends from an opening in the injection end  111  of the housing  110 . Movement of the collet  122  also causes mixing of the dry medicament with the liquid injection solution, described in greater detail below.  
         [0023]    One end  1221  of the collet  122  extends into a wet container  150  located within the housing  110  for holding the liquid injection solution. The end  1221  of the collet  122  is adapted to contact a first plunger assembly  170  located within the wet container  150 . The first plunger assembly  170  is adapted to engage the side wall of the wet container  150  to prevent leakage of the contents (e.g. liquid injection solution) of the wet container  150  from the activation end  112  of the housing  110 . The first plunger assembly  170  is preferably formed from a material having low frictional properties such that the collet  122  and first plunger assembly  170  may easily slide within the wet container  150  when operated. Alternatively, the first plunger assembly  170  may be lubricated with silicon or other suitable non reactive lubricant. The movement of the collet  122  and the first plunger assembly  170  pressurizes the liquid located within the wet container  150 . A suitable medicament is located within a dry container  160 .  
         [0024]    A second plunger assembly  180  forms a barrier between the wet compartment  150  and the dry compartment  160 . The second plunger assembly  180  prevents mixing of the dry medicament and liquid injection solution prior to activation of the automatic injector assembly. The second plunger assembly  180  is adapted to engage the side wall of the wet container  150  to prevent passage of the contents (e.g. liquid injection solution) of the wet container  150  into the dry compartment  160  prior to activation of the automatic injection assembly. The second plunger assembly  180  is preferably formed from a material having low frictional properties such that the second plunger assembly  180  may easily slide when operated. Alternatively, the second plunger assembly  180  may be lubricated with silicon or other suitable non reactive lubricant. The movement of the second plunger assembly  180  opens the fluid passage between the wet compartment and the dry compartment  160 .  
         [0025]    During operation, the actuator assembly  120  releases the collet  122 , which applies pressure on the first plunger assembly  170 . The application of pressure on the first plunger assembly  170  by the collet and spring assembly  124  moves the first plunger assembly  170  in the direction of the needle assembly  140 . This pressurizes the liquid injection solution located within the wet compartment  150 . The increased pressure within the wet compartment  150  moves the second plunger assembly  180  towards the needle assembly  140 . This movement of the second plunger assembly  180  opens a fluid passageway  181  between the wet compartment  150  and the dry compartment  160 . There is no compression of the dry medicament. The fluid passageway  181  may include recesses formed in the sidewall of the wet compartment  150  and the dry compartment  160 , which open upon a predetermined movement of the second plunger assembly  180 . It is contemplated that the fluid passageway  181  may be formed by a reduced fit between the wet compartment  150  and the second plunger assembly  180 , a series of by-pass slots, changes in diameter in the compartments  150  and  160 , ribs on the container that distort the second plunger assembly or any other assembly that is capable of permitting that permit the flow of liquid injection solution around the second plunger assembly  180 .  
         [0026]    As the first plunger assembly  170  moves in the direction of the needle assembly  140 , the liquid injection solution is transferred from the wet compartment  150  to the dry compartment where it mixes with and dissolves the dry medicament. The mixture of dissolved dry medicament and the liquid injection solution is then transferred to the needle assembly  140  where it is injected into the user through needle  141 . To prevent the passage of undissolved dry medicament to the needle assembly  140 , a medicament support  190  is provided adjacent the end of the dry compartment  160  adjacent the needle assembly  140 . The support  190  prevents blockage of the needle assembly  141  with dry medicament. The support  190  prevents the dry medicament from entering the area surrounding the needle assembly  140  while permitting passage of the mixture of dissolved medicament and liquid injection solution. The support  190  will be described in greater detail below. It is contemplated that multiple supports  190  may be located within the dry compartent  160 . The provision of the supports  190  improves the laminar flow of the liquid injection solution through the dry medicament.  
         [0027]    A diaphragm assembly  200  may also be provided adjacent the medicament support  190 . The diaphragm assembly  200  prevents the passage of the liquid injection solution to the needle assembly  140  prior to activation of the actuator assembly  120 . The diaphragm assembly  200  does not rupture until sufficient pressure builds up whereby either the butt end of the needle assembly  140  or pressure build up rupture the diaphragm.  
         [0028]    An automatic injector assembly  20  according to a second embodiment of the present invention is illustrated in FIG. 1. The automatic injector assembly  20  includes a generally hollow housing  210 . The housing  210  includes an injection insertion end located at nose cone assembly  211  and an activation end  212 . Like the embodiment described above, an actuator assembly  120  extends from an opening  213  in the activation end  212  of the housing  210 . The actuator assembly  120  is slidably received within the housing  110 . A removable end cap assembly  130  is releasably secured to the actuator assembly  120 . When the end cap assembly  130  is secured to the actuator assembly  120 , a side portion  131  of the end cap assembly  130  is adapted to abut the housing  110  to prevent movement of the actuator assembly  120  and unintentional injection of the medicament.  
         [0029]    The drive assembly  124  provides the necessary force when activated to operate the injector assembly  20  to inject the user with a necessary dosage of medicament. When activated, the drive assembly  124  causes the collet  122  to move such that a needle assembly  140  extends from an opening in the nose cone assembly  211  of the housing  210 .  
         [0030]    One end  1221  of the collet  122  extends into a wet container  150  located within the housing  210  for holding the liquid injection solution. The end  1221  of the collet  122  is adapted to contact a first plunger assembly  170  located within the wet container  150 . The first plunger assembly  170  is adapted to engage the side wall of the wet container  150  to prevent leakage of the contents (e.g. liquid injection solution) of the wet container  150  from the activation end  212  of the housing  210 .  
         [0031]    A second plunger assembly  280  forms a barrier between the wet compartment  150  and a dry compartment  160 . The second plunger assembly  280  is adapted to engage the side wall of the wet container  150  to prevent passage of the contents (e.g. liquid injection solution) of the wet container  150  into the dry compartment  160  prior to activation of the automatic injection assembly.  
         [0032]    The second plunger assembly  280  includes a central cavity  281 . One end of the cavity  281  is open into the wet container  150 . An opposite end of the cavity is covered with a membrane assembly  282 . The membrane assembly  282  provides a barrier between the wet compartment  150  and the dry compartment  160 . Upon rupture of the membrane assembly  282 , the liquid injection solution travels from the wet compartment  150  through the cavity  281  into the dry compartment  160 . It is contemplated that the membrane assembly  282  may rupture either by a build up of pressure within the wet compartment  150  due to the movement of the first plunger assembly  170  or by contacting a projection or spike on medicament support, described below.  
         [0033]    The dry medicament located within the dry compartment  160  may be located between a pair of medicament supports  190 . The supports  190  prevent the passage of undissolved dry medicament to the needle assembly  140  and the wet compartment  150 . The supports  190  are described in greater detail below.  
         [0034]    During operation, the spring assembly  124  releases the collet  122 , which applies pressure on the first plunger assembly  170 . The application of pressure on the first plunger assembly  170  moves the first plunger assembly  170  in the direction of the needle assembly  140 . This pressurizes the liquid injection solution located within the wet compartment  150 . The increased pressure within the wet compartment  150  moves the second plunger assembly  280  towards the needle assembly  140 . The membrane  282  is ruptured when it contacts a projection  195  on one of the supports  190 , as shown in FIG. 2. The liquid injection solution then flows through the cavity  281  to the dry compartment  160 . The movement of the second plunger assembly  280  may also open at least one by-pass passageway  283  in the sidewall of the housing  210 . The liquid injection solution mixes and dissolves with the dry medicament in the dry compartment  160 . The mixture passes through the support  190  adjacent the needle assembly  140 .  
         [0035]    The structure of the supports  190  will now be described in connection with FIGS.  3 - 8 . Each support  190  is preferably formed from a single plate. The plate includes a plurality of openings or grooves  191  and  192  formed therein, as shown in FIGS. 3 and 4. The grooves  191  and  192  are formed on opposite sides of the plate. The intersection of the grooves  191  and  192  form apertures  193 . Each aperture  193  extends through the support  190  such that the liquid injection solution and the dissolved medicament may pass there through. The grooves  191  and  192 , as shown, have an arcuate shape. The present invention, however, is not limited to this configuration; rather, it is contemplated that any shaped groove may employed provided the grooves on one plate selectively overlap with the grooves on the other plate to form the above-described openings. The supports  190  may are provided with one or more tabs  194  extending from the perimeter of the plates. The optional tabs  194  are adapted to be received within complementary grooves, not shown, formed on the interior wall of the dry compartment  160  to maintain the lateral orientation of the supports  190  within the compartment  160 . It is contemplated that the supports  190  may be formed from plastic, metal or any other suitable material provided the material does not react with the dry medicament during storage. The grooves  191  and  192  may be formed by machining, photo-etching, molding or any other suitable means. Additionally, it is contemplated that the apertures  193  may be formed without the use of the grooves  191  and  192 ; rather, the apertures  193  may be formed by machining, photo-etching, molding or any other suitable means.  
         [0036]    The dimensions and cross-sectional shape of the apertures  193  may vary. It is preferable that the apertures  193  be sized and shaped to prevent the passage of dry medicament there through. The apertures  193  in the medicament support  190  may be of such a shape so that the dry medicament fills and blocks the aperture to prevent the passage of the dry medicament prior to being dissolved by the liquid injection solution. The dry medicament enters the aperture and becomes compacted in the aperture due to the restriction in the cross-sectional area of the aperture, which clogs and closes the aperture until it is opened by the liquid injection solution. The apertures need not have a particular cross sectional shape. The apertures may be circular or square, as shown, for example, in FIGS. 9 and 10. The apertures may have a gradual taper, as shown in FIG. 6, a taper that varies, as shown in FIG. 7 or an offset taper, as shown in FIG. 8. Any configuration is contemplated so long as the dry medicament is prevented from passing through the support. Numerous shapes and configurations are contemplated, as shown for example, in FIGS.  5 - 8 . In FIG. 5, the aperture  193  is sized to prevent the passage of undissolved medicament. The apertures  193  in FIGS.  6 - 8  are sized and shaped to trap the undissolved medicament. The supports  190  may also include a central aperture  196 . Although the supports  190 , as described herein, are formed from a single plate, it is contemplated that the supports can be formed a pair of plates  191  and  192 .  
         [0037]    It will be apparent to those skilled in the art that various modifications and variations may be made without departing from the scope of the present invention. For example, it is contemplated that a cover assembly, described for example in U.S. Pat. No. 5,295,965 (the disclosure of which is specifically incorporated herein by reference) may be secured to the injection end of the housing  110  after deployment of the medicament. Furthermore, the automatic injector may further include a nipple plunger assembly, as described for example in U.S. Pat. No. 5,465,727 (the disclosure of which is specifically incorporated herein by reference). Thus, it is intended that the present invention covers the modifications and variations of the invention, provided they come within the scope of the appended claims and their equivalents.