Abstract:
One form of the present invention provides a needle-free injection system including the following components: a cartridge for holding liquid drug prior to injection, the cartridge having a rear end and a front end; a plug mounted to the front end of the cartridge, the plug including a channel; a displaceable valve positioned within the channel prior to injection; and a nozzle portion for receiving liquid drug from the glass cartridge for injection, the nozzle portion including an injection orifice and a drug chamber having a valve seat designed to receive the valve to facilitate injection of liquid drug through the injection orifice.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application is a continuation in part of my prior application entitled Disposable Needle-Free Injection Apparatus and Method, filed Mar. 5, 2001, and given Ser. No. 09/799,787. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates generally to needle-free or needle-less injection systems and more specifically to such a system that is particularly well suited for being used a single time and then being disposed.  
         RELATED TECHNOLOGY  
         [0003]    Needle-free systems have been in use for many years. Some such systems have used a pressurized gas to power a hypodermic jet injection. The related technology includes a number of teachings for gas-powered injection devices, including: U.S. Pat. No. 4,596,556 to Morrow, et al.; U.S. Pat. No. 4,913,699 to Parsons; U.S. Pat. No. 5730,723 to Castellano, et al.; and WIPO publication WO 97/3705 naming Weston and Thomlea as inventors.  
           [0004]    It is also known in this art to provide a needle-free injection system having two plungers that are initially spaced adjacent either end of a glass drug storage sleeve, with liquid drug being disposed between the plungers within the sleeve. Such a system also includes a plastic drug storage chamber disposed coaxially with and forwardly of the glass drug storage sleeve. The forward end of the plastic drug chamber terminates in an injection orifice. The plastic drug chamber includes an enlarged portion that permits drug to flow past the forward plunger when that plunger is aligned with the enlarged portion.  
           [0005]    In this prior system, axial force is exerted on the rear plunger immediately prior to injection. Because liquid drug is disposed in the space between the plungers, the plungers move in unison in a forward direction until the forward plunger is aligned with the enlarged portion. At that point, the continued forward travel of the rearward plunder forces liquid drug around the forward plunger until all of the drug is disposed in the plastic drug chamber forward of both plungers, which are now in abutment. The unit thus is ready for actuation. When this prior unit was actuated, the plungers both exerted a forward axial force, causing liquid drug to be directed out of the injection orifice and into the patient.  
           [0006]    The invention described in my earlier application, referenced above, is similar to the present invention except that the prior invention, which is not prior art, included more parts and therefore would likely be more expensive to fabricate.  
           [0007]    This may be more than a theoretical drawback, given that in many applications the user may need to purchase units in quantity because each unit is normally designed to be used only one time prior to disposal.  
         SUMMARY OF THE INVENTION  
         [0008]    One form of the present invention provides a needle-free injection system including the following components: a cartridge for holding liquid drug prior to injection, the cartridge having a rear end and a front end; a plug mounted to the front end of the cartridge, the plug including a channel; a displaceable valve positioned within the channel prior to injection; and a nozzle portion for receiving liquid drug from the glass cartridge for injection, the nozzle portion including an injection orifice and a drug chamber having a valve seat designed to receive the valve to facilitate injection of liquid drug through the injection orifice.  
           [0009]    Another aspect of the invention provides a needle free injector with the following components: a housing for holding various injector components; a gas cartridge mounted in the housing for providing a source of pressurized gas; a mechanism for piercing the gas cartridge upon demand, the mechanism being mounted in the housing such that it is moveable with respect to the gas cartridge; a drug cartridge mounted in the housing for storing liquid drug prior to injection; the drug cartridge having a plunger initially positioned at a rearward portion thereof; an injection orifice defined in a front end of the housing and having a fluid inter connection with the drug cartridge; a gas piston for converting gas pressure from the gas cartridge into a forward force exerted on the plunger; and a seal system mounted in the housing for preventing pressurized gas leaving the pierced gas cartridge from reaching the gas piston prior to injection.  
           [0010]    A third aspect of the invention provides a method for filling a cartridge with liquid drug for use in a needle-free injection device. The method includes the following steps: providing a plug with a front and a rear and having a rearwardly extending portion and a central channel; positioning a valve in the central channel at a point set back from the front of the plug; providing a cylindrical glass drug cartridge having a front and a rear; positioning a plunger in the rear end of the cartridge; filling the cartridge with liquid drug; and inserting the plug with the valve disposed therein in the front end of the cartridge, and simultaneously having the rearwardly extending portion displace some of the liquid drug in the cartridge so that the liquid drug enters the channel, displacing the valve forwardly within the channel. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is an isometric view of a first embodiment of the present invention, showing the unit after it has been fired;  
         [0012]    [0012]FIG. 2 is a side elevation sectional view of the first embodiment;  
         [0013]    [0013]FIG. 2A is a fragmentary side elevation sectional view of the front end of the nozzle portion of a second embodiment of the present invention designed for intradermal injections;  
         [0014]    [0014]FIG. 2B is an end elevation sectional view taken along line  2 B -  2 B of FIG. 2, showing the bypass conduits in the plastic drug chamber;  
         [0015]    [0015]FIG. 3 is a side elevation sectional view corresponding to FIG. 2 except that the view is fragmentary and enlarged, showing the preferred gas flow channels and piercing pin position prior to piercing the gas cartridge;  
         [0016]    [0016]FIG. 4 is a side elevation sectional view corresponding to FIG. 2 except that the first embodiment is shown to be in its primed condition, but prior to the gas cartridge being pierced;  
         [0017]    [0017]FIG. 5 is a side elevation sectional view corresponding to FIGS. 2, 3 and  4  except that the first embodiment is shown to be in its primed and ready condition, after the gas cartridge has been pierced;  
         [0018]    [0018]FIG. 6 is a side elevation sectional view corresponding to FIGS. 2, 3,  4  and  5  except that the first embodiment is shown immediately after injection;  
         [0019]    [0019]FIG. 7 is a side elevation sectional view corresponding to FIG. 6 except that the view is fragmentary and enlarged, showing the preferred mechanism for controlling the flow of gas under pressure from the gas cartridge to the forward portion of the injector, showing gas pressure being conveyed to the forward portion of the injector;  
         [0020]    [0020]FIG. 8 is an exploded view of the first embodiment of the present invention;  
         [0021]    [0021]FIG. 9 is an enlarged, side elevation sectional view of a plastic plug disposed in the forward portion of the first embodiment of the present invention, showing how the plug fits into the forward end of a glass cartridge (which is shown in phantom);  
         [0022]    [0022]FIG. 10 is an enlarged, side elevation sectional view of the first embodiment showing how the plastic plug and glass cartridge fit into the forward or nozzle portion of the injector;  
         [0023]    [0023]FIG. 11 is an enlarged, side elevation sectional view corresponding to FIG. 10 except that an alternate embodiment of the nozzle portion is shown;  
         [0024]    FIGS.  12 - 16  are a series of schematic views showing how the glass cartridge may be filled with liquid drug prior to assemble of the injector; more specifically,  
         [0025]    [0025]FIG. 12 is a side elevation view showing a ball valve being initially positioned in the rearward end of the plastic plug;  
         [0026]    [0026]FIG. 13 is a side elevation view showing a drug plunger being positioned in the rearward end of the glass cartridge;  
         [0027]    [0027]FIG. 14 is a side elevation view showing a liquid drug filling tube having filled the cartridge with liquid drug;  
         [0028]    [0028]FIG. 15 is a side elevation view showing the plastic plug being pressed into position in the forward end of the glass cartridge which is filled with liquid drug, and depicting how the ball valve is displaced forwardly in the plastic plug during this process; and  
         [0029]    [0029]FIG. 16 is a side elevation view showing the glass cartridge filled with liquid drug and with the drug plunger and plastic plug in place, being installed into the nozzle portion of the injector. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0030]    The objects of the invention are best achieved when the invention takes the form of the embodiment depicted in the figures. FIGS.  1 - 10  depict a first embodiment of the apparatus that is designated generally with the numeral  10 . FIGS.  1 - 8  depict three basic components of the preferred embodiment  10 —a nozzle portion  12 , a body portion  14  and a trigger portion  16 . Nozzle portions  12 , body portion  14  and trigger portion  16  combine to form a housing for apparatus  10 . These portions will be individually discussed as this description continues.  
         [0031]    Reference should first be made to FIGS. 2 and 3, which depict apparatus  10  as it is packaged, shipped and received by the customer. The customer in this case may be a clinic, a physician or even a patient. Nozzle portion  12  includes outwardly facing threads  22  that are received in body portion  14 , as will be explained in a moment. The nozzle portion  12  also includes strengthening ribs  20 .  
         [0032]    Body portion  14  includes a forwardly-positioned body  24  and a series of interior threads  40  in the forward portion thereof, designed to receive nozzle portion threads  22 . Exterior threads  41  are provided on the body rearwardly of the interior threads to facilitate the body being mounted to trigger portion  16 , as will be explained below. Body portion  14  also includes a rearward portion of reduced outer diameter, referred to herein as a gas pressure conduit  72 .  
         [0033]    Trigger portion  16  extends over body portion  14  and includes interior threads  42  designed to engage body portion threads  41  when apparatus  10  is assembled. Trigger portion  16  also includes strengthening ribs  53  and a pair of undercut portions  46  designed to receive a pair of trigger members  52 . A pair of trigger slots  47  permit engagement portions of trigger members  52  to extend therethrough to engage interior components of apparatus  10 . The configuration of trigger member engagement portions and the interior components will be described below.  
         [0034]    Beginning now at the forward end of apparatus  10 , and referring primarily to FIG. 2, the various parts will now be described in more detail. The forward end of nozzle section  12  terminates in an injection orifice  54 . The injection orifice provides the means by which liquid drug exits apparatus  10  in a defined, high pressure stream directed into the patient.  
         [0035]    A liquid drug chamber is depicted generally at  56 , and includes a plastic drug chamber  58  defined by the inwardly facing wall of nozzle portion  12 , and a drug storage chamber  57  defined by a glass cartridge  60 . Glass cartridge  60  retains the liquid drug during storage and shipment, prior to the point that apparatus  10  is converted to its primed mode. As shown best in FIG. 2B, defined in the walls of plastic drug chamber  58  at the forward end thereof, are three drug bypass conduits  64 , evenly spaced around the periphery at 120° increments. While three drug bypass conduits are shown, any number of conduits can be utilized. However many conduits are included, they should be symmetrically positioned around the periphery of plastic drug chamber  58 .  
         [0036]    Bypass conduits  64  include axially-extending portions that extend along the length of plastic drug chamber  58 . These portions are shown in section in FIG. 2B. Bypass conduits  64  also include generally radially-extending portions, which follow the narrowing of the plastic drug chamber. FIGS. 4, 5 and  6  all show a plastic ball valve  62  in its forward position within plastic drug chamber  58 . The portions of the inward facing nozzle wall extending between bypass conduits  64  can be seen to support ball valve  62  from the sides and from the front (see also FIGS. 2, 4,  5  and  6 ).  
         [0037]    Positioned immediately to the rear of the plastic drug chamber is a plastic plug  59 . The plastic plug is normally fabricated of Teflon, and is used to step down the diameter of glass cartridge  60 . Plastic plug  59  fits tightly into the forward end of glass cartridge  60  and also fits tightly into the forward end of the nozzle portion  12 . The fit between plastic plug  59  and glass cartridge  60  is shown best in FIG. 9, and the fit of the plastic plug into the forward end of the nozzle portion  12  is shown best in FIG. 10. Plastic plug  59  includes a body  61  that exerts a rearward force on the cartridge, a rearwardly extending flared portion  63  that exerts an outward force on the interior walls of the cartridge, and a plug channel  65  that extends through the center of the plug. The diameter of plug channel  65  is slightly smaller than that of ball valve  62  so that the ball valve stays in place in the channel unless pressure acts on it to displace it in a forward direction. Ball valve  62  is typically fabricated of Teflon, although it may be formed of butyl rubber or a similar material.  
         [0038]    [0038]FIG. 11 shows a ball valve  62  that is identical to ball valve  62  of the other figures but the depicted nozzle portion  112  is of slightly different design.  
         [0039]    Referring again to FIGS.  1 - 10 , glass cartridge  60  is shown to be of cylindrical configuration. This is preferable to a narrowed bottle-like configuration of some prior designs because it is easier and therefore less expensive to fabricate. The drawback with some prior systems that included cylindrical designs is that the plastic drug chamber of those prior systems ends up being much wider in crosssection than is needed. In fact, the wider cross-section is a drawback in that a larger area needs to be filled with liquid drug before injection can take place. The use of a plastic plug  59  combines the inexpensive fabrication advantages of a cylindrical glass cartridge and the small plastic drug chamber advantages of a bottle-shaped glass cartridge.  
         [0040]    As mentioned previously, liquid drug chamber  56  includes a plastic drug chamber  58  and a glass drug storage chamber  57 . The forward end of glass drug storage chamber  57  is defined by plastic plug  59  and ball valve  62 . The rearward end of glass drug storage chamber  57  is defined by a drug plunger  66 . Drug plunger  66  is fabricated of a relatively impermeable elastomer material, such as butyl rubber, which is also inert so that there is no chemical or biological reaction to the drug. Drug plunger  66  fits tightly into the glass cartridge so that the drug plunger maintains its position with respect to glass cartridge  60  unless it is forced in a forward directly by a gas piston  70 , disposed immediately rearwardly thereof. Gas piston  70  is positioned along the longitudinal center line of apparatus  10  in directly alignment with drug plunger  66  and ball valve  62 . Gas piston  70  extends rearwardly or to the left in the figures, and includes a rearwardly extending cupped portion  78  facing rearwardly in a concave figuration. Cupped portion  78  of gas piston  70  fits tightly against an inner diameter  80  of body portion  14 . If fluid pressure is exerted in a rightward or forward direction, cupped portion  78  pushes even more forcefully against inner diameter  80  so that leakage past the cup portion is prevented. Configuration of gas piston  70  therefore facilitates a conversion of fluid pressure exerted from the rear of the gas piston to a forward force exerted on drug plunger  66 . This facilitates injection of liquid drug into a patient as will be understood as this discussion continues.  
         [0041]    As described earlier, body portion  14  is one of the three basic components of apparatus  10 . FIG. 2 shows nozzle threads  22  only partially engaged in body threads  40 , this condition is maintained when apparatus  10  is in its storage or shipping condition. When nozzle portion  12  is threaded entirely into body portion  14 , as shown in FIG. 4, space  120  is reduced in size as nozzle portion  12  butts up against an abutment member  79 . Abutment member  79  includes threads  81  which thread into body interior threads  40 . When nozzle portion  12  is in abutment with abutment member  79  as shown in FIG. 4, an abutment member flange  83  comes into abutment with the rearward end of glass cartridge  60 . This holds glass cartridge  80  in position during the injection process.  
         [0042]    Referring again to gas pressure conduit  72  at the rearward end of body portion  14 , it can be seen that an axially extending gas pressure channel extends through the center of the gas pressure conduit. This gas pressure channel is divided into two axially spaced channels  76  and  77 . A plurality of radially-extending gas pressure channels  103  are positioned at the rearward end of the forward gas pressure channel  76 . In the depicted embodiment, four angularly spaced, radially-extending gas pressure channels  103  are included, but it may be desirable in certain applications to have more or fewer such channels. For example, in certain applications it may be possible to have only one such channel. On some applications, where there are multiple channels, they may be referred to as radial gas conduits. Four radially-extending gas pressure channels  104  are also included in the forward end of the rearward gas pressure channel  77 , although, again, more or fewer such channels may be provided.  
         [0043]    A piercing pin receiving seat  98  is positioned at the rearward end of the rearward gas pressure channel  77  and this seat is designed to hold a hollow piercing pin  100 . The piercing pin will sometimes be called a piercing mechanism. Piercing pin  100  is in position adjacent the front end of a gas cartridge  102 . Gas pressure cartridge  102  typically includes Nitrogen (N 2 ) gas to provide gas pressure for the injection process. An O ring  105  is provided adjacent to the forward end of gas cartridge  102 , and a cap  106  is positioned to hold O ring  105  in place.  
         [0044]    The third of the three major components of apparatus  10  is trigger portion  16 . It includes a long extension member  51 , which extends forwardly to nozzle portion  12 . Extension member  51  includes a plurality of axially extending ribs  53  designed to strengthen apparatus  10  and provide a gripping surface for the user.  
         [0045]    As mention previously, a pair of trigger members  52  are positioned in undercut portions  46  of trigger portion  16 . Also included are trigger slots  47  into which engagement portions of the trigger members extend. The engagement portions of trigger members  52  include a forward engagement member  48  and a rearward engagement member  49 . Forward engagement member  48  engages a sliding bushing  92  which is pushed forwardly by forward engagement member  48  as each trigger member  52  is slid to its forward position depicted in FIG. 6. Rearward engagement member  49  engages a sealing bushing  94 . Sealing bushing  94  is best shown FIG. 3, and includes an annular gap  95  that extends all of the way around gas pressure conduit  72  at the midportion of sealing bushing  94 . The function of sealing bushing  94  is to either block or permit flow of gas pressure from forward and rearward radially-extending gas pressure channels  103  and  104  to control the firing of apparatus  10 . Thus, for example, with each of the trigger members  52  in its rearward most position as shown in FIGS. 2 and 3, sealing bushing  94  prevents gas under pressure from passing out of rearward radially-extending gas pressure channels  104 . When trigger members  52  are slid to their forward-most position, shown in FIG. 6, both the forward and the rearward radially-extending gas pressure channels  103  and  104  are uncovered by sealing bushing  94  and are exposed to annular gap  95 . As shown by the flow lines in FIG. 7, this permits gas under pressure to flow from rearward gas pressure channel  76 , out rearward radially-extending gas pressure channels  104 , forwardly through annular gap  95  and into forward radially-extending gas pressure channels  103  and forward gas pressure channel  77 . This permits gas to flow forwardly through forward gas pressure channel  77  to facilitate the injection process, as will be more fully explained below.  
       Filling the Preferred Embodiment with Liquid Drug  
       [0046]    FIGS.  12 - 16  schematically depict the operation in which glass cartridge  60  is filled with liquid drug. FIG. 12 shows the process by which ball valve  62  is inserted into plastic plug  59 . A ball positioning tool  108  having an extension member  110  is depicted. The ball is initially positioned at the forward (or upper as depicted) end of plug channel  65 , but is then pushed to its rearward-most position within the plug channel by extension member  110 .  
         [0047]    [0047]FIGS. 13 and 14 show the positioning of drug plunger  66  in glass cartridge  60 , using a drug plunger positioning tool  112  having an extension member  114 . The use of drug plunger positioning tool  112  positions the drug plunger at a point only slightly forward (or above as depicted) of the rearward (or bottom) end of glass cartridge  60 .  
         [0048]    Once drug plunger  66  has been properly positioned within glass cartridge  60 , the glass cartridge is filled with liquid drug as shown in FIG. 14 using a conventional filling tube  116 . Once glass cartridge  60  has been filled to the top with liquid drug, plastic plug  59  with ball valve  62  positioned therein is ready for mounting to the glass cartridge. This is shown in FIG. 15. During this process, drug plunger  66  must be held in position, either due to friction, or by keeping drug plunger positioning tool  112  in position as depicted. Plastic plug  59  is pressed onto the forward (or upper) end of glass cartridge  60  using a plug positioning tool  122 . As plastic plug  59  is pressed into glass cartridge  60 , liquid drug is displaced by flange portion  63  of the plastic plug. This displacement is accommodated by ball valve  62  which shifts from its rearward-most position depicted in FIG. 12, to its forward-most position depicted in FIG. 15.  
         [0049]    This system of mounting plastic plug  59  into glass cartridge  60  minimizes the amount of air which is introduced into the liquid drug and reduces the effort that must be made to precisely position the various components during the assembly process. This reduces the cost of assembly which is likely to be passed to the end user in lower costs as well.  
         [0050]    With the now-filled glass cartridge being stopped at both ends, glass cartridge  60  can be stored and held for use, or can be mounted into nozzle portion  12 , which is the preferred storage mode.  
         [0051]    FIGS.  16  shows the process by which the filled glass cartridge  60  is inserted into nozzle portion  12  of apparatus  10 . Because air within nozzle portion  12  will be permitted to pass out injection orifice  54  during this insertion process, ball valve  62  will not be displaced and air will not be introduced into the liquid drug within glass cartridge  60 .  
       Operation of the Preferred Embodiment  
       [0052]    At any time after the filled glass cartridge  60  has been installed into nozzle portion  12 , assembly of apparatus  10  may be completed. This is performed at the factory and is shown in its assembled condition in FIG. 2. The nozzle portion  12  is shown to be only partially threaded into body portion  14 , leaving a large space  120  between nozzle portion  12  and trigger portion  16 . Thus, nozzle threads  22  are shown to engage interior body threads  40 , but the two portions are not threaded all of the way into one another. In this storage condition, ball valve  62  is shown to be positioned as it was at the end of the filling process depicted in FIGS. 15 and 16. That is, it is within plug channel  65 , adjacent the forward end thereof. In this storage condition, trigger members  52  are in their rearward position, so sealing bushing  94  covers the rear radially-extending gas pressure channels  104 , as best shown in FIG. 3. In this storage configuration, piercing pin  100  is shown to be adjacent to the forward end of gas cartridge  102 , but the gas cartridge is not yet pierced and the apparatus is not yet primed.  
         [0053]    After apparatus  10  has been shipped to the end user, normally the patient, and the patient is ready for an injection, the patient threads nozzle portion  12  all of the way into body portion  14 . As seen in FIG. 4, this substantially reduces space  120  and causes ball valve  62  to shift forwardly into plastic drug chamber  58 , and liquid drug flows through bypass conduits  64  and around ball valve  62  to remove any air in the front of plastic drug chamber  58 . Liquid drug within glass cartridge  60  is pushed forwardly during the process of threading nozzle portion  12  all of the way into body portion  14  because drug plunger  66  is held stationary by gas piston  70  as the nozzle portion is threaded toward the body portion. Once nozzle portion  12  has been threaded all the way into body portion  14 , the rearward end of the nozzle portion comes into contact with abutment member  79 . A small amount of liquid drug may dribble out of injection orifice  54 , but this is necessary to ensure that all of the air has been removed from nozzle portion  12 . Apparatus  10  is now primed, but it is not yet ready for injection.  
         [0054]    To complete the preparation process, body portion  14  is threaded all of the way into trigger portion  16  as exterior threads  41  in body  24  are threaded into trigger interior threads  42 . This final threading process causes piercing pin  100  to pierce gas cartridge  102 . This primed and ready condition is shown in FIG. 5. However, injection is not yet effected, because trigger members  52  remain in their rearward position. In this condition, pressurized N 2  gas passes from gas cartridge  102 , through piercing pin  100  and into rearward axial gas pressure channel  77  and rearward radial gas pressure channels  104 . Pressure is blocked from reaching forward radial gas pressure channels  103  by sealing busing  94  which now covers forward radial gas pressure channels  103 .  
         [0055]    In order to effect injection, the patient simply positions the forward end of injection orifice  54  against the body part to be injected. With one hand, the patient can then shift trigger members  52  to the forward position depicted in FIG. 6. The forward engagement member pushes sliding bushing  92  forwardly or to the right as shown in the figures. Rearward engagement member  49  pushes sealing bushing  94  forwardly to the position shown in FIGS. 6 and 7. This permits gas to flow under pressure from gas cartridge  102  through piercing pin  100  and rearward gas pressure channel  77 , out rearward radially-extending gas pressure channels  104 , across annular gap  95  and back into forward radially-extending gas pressure channels  103  and then forwardly through forward gas pressure gas channel  76  all as shown in FIG. 7. Gas under pressure then enters the interior of body  24 , pushing cupped portion  78  of gas piston  70  forwardly or to the right in FIG. 6. This forward force forces cupped portion  78  outwardly, to provide an effective seal between the cup portion and inner diameter  80  of body  24 . Gas piston  70  is thus driven forwardly, pushing drug plunger  66  to the right, and causing liquid drug to flow around ball valve  62  via bypass conduits  64  and out injection orifice  54  and into the patient.  
         [0056]    This system thus provides an effective and simple injection which may be performed by the patient using a single hand. This is accomplished using far fewer parts than prior systems. Because this results in the apparatus relatively inexpensive, it is designed for single use and can be disposed after firing.  
         [0057]    Variations can be made to the depicted embodiment without departing from the scope of the invention, and the following claims are intended to cover such variations.