Patent Publication Number: US-6213983-B1

Title: Injection device

Description:
This application is a continuation of Ser. No. 08/777,634 filed Dec. 31, 1996 now U.S. Pat. No. 5,776,107. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to a device for the parenteral administration through a needle of liquid or semi-solid drug compositions wherein the needle is protected before and after the injection. 
     The parenteral introduction of pharmaceutically active compounds is preferred over oral dosage for many indications, e.g., where the drug to be administered would partially or totally degrade in the gastrointestinal tract, or where there is need for a rapid biological response. The need for extemporaneous preparation of such parenteral compositions is eliminated, or simplified, by the use of pre-filled administration devices in which the liquid to be injected is pre-loaded into the device (e.g., a pre-loaded syringe). Such pre-loaded devices, however, have a number of drawbacks, including the inability to preserve the asepsis or sterility of the needle, as well as the general danger of using an exposed needle. To eliminate these drawbacks, it is necessary to avoid the direct exposure of the needle with the environment both prior to and following injection. 
     SUMMARY OF THE INVENTION 
     The invention features a comparatively inexpensive injection device with a needle for parenteral injection of liquid or semi-solid drug compositions into a subject, e.g., a mammal such as a human, wherein the needle is protected both before and after the injection. 
     In general, the invention features an injection device including a housing, the housing having proximal and distal ends and designed to contain a liquid or semi-solid drug composition; a hollow needle, the needle affixed to the distal end of the housing and extending longitudinally within the housing; a plunger, the plunger arranged to slide within the proximal end of the housing; and a hollow sleeve, the hollow sleeve arranged to cover the needle prior to injection and arranged to retract into the housing during injection; wherein the device is designed such that when the sleeve is pressed against the subject, the sleeve retracts into the housing thereby allowing the needle to penetrate the subject, and when the plunger is forced further into the housing, the drug composition is forced from the housing through the needle and into the subject. 
     In one embodiment, the device is further designed such that when the drug composition is forced from the housing, the plunger forces the sleeve out of the housing to cover the needle. In a further embodiment, the housing contains the liquid or semi-solid drug composition. 
     In another embodiment, the device further comprises a septum plunger, the septum plunger slidably arranged within the housing between the plunger and the distal end of the housing. In a further embodiment, the device is further designed such that when the drug composition is forced from the housing, the plunger forces the septum plunger into the sleeve, and the septum plunger forces the sleeve out of the housing to cover the needle. In still a further embodiment, the housing contains the liquid or semi-solid drug composition between the plunger and the septum plunger. 
     In still another embodiment, the housing contains a liquid and a dry drug composition, where the device is designed to combine the liquid and the dry drug composition prior to injection. 
     The device can further include a releasable lock to inhibit the movement of the plunger into the housing. The device can also include a removable cap which covers the sleeve. The proximal end of the housing may have a flange and the plunger may also have a flange. 
     Unless otherwise defined, 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 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 described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. 
    
    
     Other features and advantages of the invention will be apparent from the following detailed description, and from the claims. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial cross-sectional view of an injection device prior to use. 
     FIG. 2 is a partial cross-sectional view of the injection device of FIG. 1 during use. 
     FIG. 3 is a partial cross-sectional view of the device with the needle injected into a subject. 
     FIG. 4 is a partial cross-sectional view of the injection device being withdrawn from the subject with a drug composition remaining in the subject. 
     FIG. 5 is a partial cross-sectional view of the injection device following complete withdrawal of the needle from the subject. 
     FIG. 6 is a cross-section of the injection device through line  6 — 6  in FIG.  1 . 
     FIG. 7 is a view of the sleeve of the injection device. 
    
    
     DETAILED DESCRIPTION 
     It is believed that one skilled in the art can, based on the description herein, utilize the present invention to its fullest extent. The following specific embodiments are, therefore, to be construed as merely illustrative, and not limiting. 
     FIG. 1 shows injection device  1  including housing  10 , having a proximal end and a distal end  14   a ,  14   b . The distal end of housing  10  has two holes  40   a  and  40   b  partially separating the two parts  14   a  and  14   b  of the distal end (as best seen in FIG.  6 ). Needle  12  is attached to part  14   a  of the distal end. The housing  10  can be made from a rigid material such as glass, plastic, or metal. The needle  12  is hollow and double-ended, wherein its distal end, remaining outside housing  10 , has a point capable of piercing the skin of a subject, and its proximal end, remaining within housing  10 , is capable of piercing septum plunger  16 . On the proximal end of housing  10  is a flange  28  to assist in removal of device  1  from the subject following injection. 
     An sleeve  22  surrounds needle  12  so that needle  12  is not fully exposed to the environment until used. Sleeve  22  has longitudinal slots  45   a  and  45   b  along its length (see FIG. 7; slot  45   b  is on the back of the sleeve and is thus not shown). The two parts  14   a  and  14   b  of the distal end are joined by radially extending connecting members  42   a  and  42   b  (see FIG.  6 ). Connecting members  42   a  and  42   b , respectively, slide through slots  45   a  and  45   b  in sleeve  22 , while sleeve  22  slides through holes  40   a  and  40   b  in housing  10 . Sleeve  22  can be made of suitably rigid material, such as metal, glass, or plastic. Seal  24  covers the opening  23  of sleeve  22  to maintain the sterility of needle  12  and prevent sleeve  22  from unintentionally retracting into housing  10  through holes  40   a  and  40   b  prior to injection. 
     Seal  24  can be made of a thin material, such as plastic or wax, which is easily penetrated by needle  12  during injection. A similar seal can also cover slots  45   a  and  45   b  in sleeve  22 , to further protect the sterility of needle  12 . 
     Septum plunger  16 , contained within housing  10 , includes a bore  26 , in which needle  12  rests prior to subsequently piercing septum plunger  16 . A liquid or semi-solid composition  20  is isolated in housing  10  between the septum plunger  16  and the plunger tip  30 , attached to plunger  29 . Septum plunger  16  and plunger tip  30  may be made of non-rigid, solid material such as rubber, which allows septum plunger  16  and plunger tip  30  to slide within housing  10  but still maintain sufficient friction with the inner sides of housing  10  to seal composition  20  within housing  10 . 
     The proximal end of plunger  29  has a thumb flange  18  to assist in the depression of plunger  29  into housing  10 , and the distal end of plunger  29  has a longitudinal bore  27  to receive needle  12  following injection of composition  20  out and through needle  12 . Plunger  29  can be made from a rigid material, such as metal or plastic. A removable lock  25  may be placed between flange  18  and flange  28  to inhibit the further depression of plunger  29  into housing  10  after activation of device  1 , i.e., after the housing  10  is filled with a drug composition and the proximal end of the needle is pierced through septum plunger  16 . A removable cap  21  can also be used to protect both needle  12  and sleeve  22  prior to use. Both cap  21  and lock  25  can be made from suitable rigid material such as plastic, metal, or rubber. 
     FIG. 2 shows device  1  wherein plunger  29  has been pressed into housing  10  to activate device  1  as follows. When plunger  29  is depressed, plunger tip  30 , composition  20 , and septum plunger  16  are displaced toward the distal end of housing  10 . Septum plunger  16  is pierced at bore  26  by needle  12 . As a result, the proximal end of needle  12  is exposed to composition  20 . Device  1  is now in an activated state. Lock  25 , by contacting both flange  18  and flange  28 , inhibits the further displacement of composition  20  from housing  10  through needle  12  following activation of device  1 , i.e., composition  20  is allowed to fill needle  10 , but lock  25  inhibits significant release of composition  20  through needle  10 . 
     FIG. 3 shows device  1  wherein needle  12  has penetrated skin  32  of the subject being treated. As device  1  is pressed against skin  32 , sleeve  22  is retracted into housing  10 , through holes  40   a  and  40   b , by the force of pressure against skin  32 . Needle  12  passes through sleeve  22  at opening  23 . As shown, needle  12  has penetrated through skin  32  into the subcutaneous layer  34 . 
     FIG. 4 shows device  1  wherein lock  25  has been removed and plunger  29  has been depressed which moves plunger tip  30  toward septum plunger  16 , thereby injecting composition  20  into subcutaneous layer  34  through needle  12 . Once composition  20  has been injected and plunger tip  30  rests against septum plunger  16 , housing  10  is moved away from skin  32  by exerting pressure against the lower part of the flange  28  while simultaneously exerting opposing pressure on flange  18  of plunger  29 . This relative movement of the plunger  29  and housing  10  causes plunger tip  30  to force septum plunger  16  against sleeve  22  as both plunger tip  30  and septum plunger  16  slide toward parts  14   a  and  14   b  of the distal end of housing  10 , which in turn forces sleeve  22  out of housing  10  through holes  40   a  and  40   b . As plunger tip  30  and septum plunger  16  are moved toward distal end of housing  10 , needle  12  penetrates septum plunger  16 , plunger tip  30 , and enters bore  27  in plunger  29 . 
     FIG. 5 shows needle  12  fully withdrawn from skin  32  and sleeve  22  fully covering needle  12 . Composition  20  remains in the subcutaneous layer of the patient. As can also be seen in FIG. 5, the proximal end of needle  12  has been pushed through septum plunger  16  and plunger tip  30  and remains in bore  27  of plunger  29 . 
     FIG. 6 is a cross-sectional view of FIG. 1 at  6 — 6 . FIG. 6 shows holes  40   a  and  40   b  in housing  10 . Radially extending connecting members  42   a  and  42   b  extend through slots  45   a  and  45   b , respectively, to connect parts  14   a  and  14   b  of the distal end. Needle  12  is fixed to central part  14   a  of the distal end, and sleeve  22  can slide through holes  40   a  and  40   b . FIG. 7 shows an isolated sleeve  22  having slots  45   a  and  45   b  ( 45   b  is not shown but positioned directly opposite to slot  45   a  on the other side of sleeve  22 ) and opening  23 . Radially extending connecting members  42   a  and  42   b , respectively, slide through slots  45   a  and  45   b.    
     Composition  20  is a liquid or a viscous semi-solid composition containing a drug. The drug of composition  20  can be any drug capable of being parenterally administered as a liquid or a semi-solid. For example, the drug can be a vaccine, a peptide, a protein, or a small chemical entity. Examples of suitable drugs include insulin and heparin. For drugs which are not stable in liquids over an extended period of time, the liquid and the dry drug can be stored in separate chambers within housing  10 . The device can be designed such that the liquid and the dry drug are combined together just prior to injection. 
     For example, the chamber created between septum plunger  16  and plunger tip  30  (e.g., in FIG. 1) in housing  10  can be separated into two separate parts by a fixed wall or film that can be punctured, e.g., by pressure of the plunger  29  on the plunger tip  30 , or a puncturing means. Alternatively, the two parts of the chamber can be separated by a moving wall or septum. In this case, the top or proximal part of the chamber above the moving septum contains the liquid portion of the composition, and the distal part of the chamber contains the solid, e.g., powder, portion of the composition. When plunger  29  is pushed down, it applies pressure to the plunger tip  30 , which applies pressure to the liquid portion of the composition. This, in turn, applies pressure on the moving septum, causing it to move in a distal direction. The housing is designed with a liquid bypass (e.g., a bulge or passage in the housing wall) in a location that initially prevents passage of liquid from one part of the chamber to the other, but when the moving septum reaches a specific location, the bypass allows the liquid to pass from the top part of the chamber into the lower or proximal part of the chamber on the other side of the moving septum. 
     To maintain sterility, the device of the invention can be stored in a conventional blister pack prior to use. 
     OTHER EMBODIMENTS 
     It is to be understood that while the invention has been described in conjunction with the detailed description thereof, that the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the claims.