Abstract:
A device and method for making an injection with a short needle, which includes a needle cannula and a limiter surrounding the needle cannula and includes a skin engaging surface on the limiter. The limiter is moveable from a first position in which an elongate portion of the needle cannula is exposed for access to a medication vial, to a locked second position in which the limiter is not movable from the second position to the first position. In the second position, the needle tip extends beyond the skin engaging surface a distance which is ordinarily unable to access the vial.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 12/361,788 filed on Jan. 29, 2009, which is a continuation of U.S. patent application Ser. No. 11/774,640 filed on Jul. 9, 2007, now U.S. Pat. No. 7,497,841 which is a continuation of U.S. patent application Ser. No. 11/463,677 filed on Aug. 10, 2006, now U.S. Pat. No. 7,250,036, which is a continuation of U.S. patent application Ser. No. 10/798,594 filed on Mar. 11, 2004, now U.S. Pat. No. 7,108,679. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a delivery device for injecting drugs, vaccines, and the like into the intradermal region of the skin. 
     2. Description of Related Art 
     There are several injection techniques and devices known in the art. Based on the drug substance being injected, one technique and device may provide for a more efficacious delivery and uptake of the particular drug substance. One technique and device delivers a drug substance intramuscularly using a hypodermic needle that penetrates through a patient&#39;s skin and into muscle tissue. 
     Another technique and device delivers a drug substance into the subcutaneous region of the skin. It is possible that the same device may be used to delivery an intramuscular and a subcutaneous injection, with the health care provider controlling the depth of the injection. 
     Techniques and devices are also known for administering an injection into the intradermal (intradermal) region of the skin. One technique, commonly referred to as the Mantoux technique, uses a “standard” syringe, i.e., a syringe typically used to administer intramuscular or subcutaneous injections. The health care provider administering the injection follows a specific procedure that requires a somewhat precise orientation of the syringe with regard to the patient&#39;s skin as the injection is administered. The health care provider must also attempt to precisely control the penetration depth of the needle into the patient&#39;s skin to ensure that it does not penetrate beyond the intradermal region. Such a technique is complicated, difficult to administer, and often may only be administered by an experienced health care professional. 
     Devices have been proposed for providing intradermal injections which include shortened fine gauge needles compared to conventional needle sizes. The smaller needles are not intended to penetrate beyond the dermis layer of the skin. Such devices are shown in U.S. Pat. No. 5,527,288 to Gross et al., U.S. Pat. No. 4,886,499 to Cirelli et al., and U.S. Pat. No. 5,328,483 to Jacoby. The proposed devices, however are not without shortcomings and drawbacks. 
     For example, the devices shown in U.S. Pat. Nos. 5,527,288 and 4,886,499 are highly specialized injectors. The designs for these injectors include relatively complex arrangements of components that cannot be economically manufactured on a mass production scale. Therefore, such devices have limited applicability and use. 
     For many drug substances, it may be desirable to fill the delivery device at the point of, and immediately prior to use. In this situation, the delivery device is normally filled from a multi-dose vial. A multi-dose vial may be more economical and it enables the user to fill the delivery device with the specific dose required. The multi-dose vial may be pre-filled with a liquid substance or with a dry substance. For example, it is now conventional to reduce certain drugs to a dry or powdered form to increase the shelf life of drugs and reduce inventory space. Multi-dose vials are typically sealed with an elastomeric stopper or septum. A needle on the delivery device may be used to pierce the stopper or septum and draw the drug substance from the vial into the delivery device, typically a syringe. The drug substance may then be administered using the delivery device, which is discarded after use, and the unit-dose vial may be stored for further use. 
     As advances in understanding the delivery of drug proceeds, the use of intradermal delivery systems is expected to increase. Use of a “standard” length needle to deliver a drug substance intradermally has its shortcomings, come of which are identified above. It is not possible to use a delivery device having a needle length suited for intradermal injection to aspirate a syringe with drug substance from a multi-use vial. Thus, there are shortcomings in the prior art that prevent administering an intradermal injection using a “standard” length needle and a multi-use vial. It would be advantageous to have a drug delivery device capable of accessing substances stored in multi-dose vials and delivering such substances into the intradermal region of the skin without encountering the shortcomings described above. 
       FIG. 1  shows an intradermal injection device  101  comprising a syringe  114  having a syringe body  116  that defines a reservoir  118  within which a drug substance may be held, a plunger  120  disposed in the syringe body  116  and having a flange  122  at a distal end thereof and a stopper  124  at the opposed proximal end thereof, and a needle assembly  102  secured to a distal end of the syringe body  116 . An exemplary needle assembly  102  of the type depicted in  FIG. 1  is disclosed in U.S. Pat. No. 6,494,865 to Alchas, the entire contents of which is incorporated by reference herein. The needle assembly  102  is specifically designed for making intradermal injections. The needle assembly  102  may carry a needle cannula  104  having a needle tip  106  at a distal end thereof. Alternatively, the needle cannula  104  may be secured directly to the syringe body  116 . The needle assembly  102  also includes a penetration limiter  108  having a hub portion  109  that may be secured to the syringe body  116 , and a limiter portion  111  that defines a generally flat skin engaging surface  110  at a distal end of the limiter  108 . The limiter  108 , which generally surrounds the proximal end of the needle  104 , permits a certain predetermined length of the needle cannula  104 , including the needle tip  106 , to protrude beyond the skin engaging surface  110  so that the distance between the needle tip  106  and skin engaging surface  110  limits penetration of the needle tip  106  into the intradermal space of the patient&#39;s skin. Preferably, the needle tip  106  of the needle cannula  104  extends beyond the skin engaging surface  110  a distance ranging from approximately 0.5 mm to 3 mm. The needle cannula  104  and skin engaging surface  110  are also arranged with respect to each other in a generally perpendicular relationship that serves to ensure a generally perpendicular relationship between the needle cannula  104  and the patient&#39;s skin; such an angular relationship being preferred when making intradermal injections. The skin engaging surface  110  engages the surface of the skin of a patient and limits the penetration depth of the needle tip  106  into the patient&#39;s skin. The needle assembly  102  is secured to the syringe  114  via the hub portion  109 , which may be fixedly secured to the syringe body  116 , or the hub portion  109  may be secured by a Luer fit or equivalent attachment method. 
     Referring now to  FIG. 2 , a conventional syringe  114  being filled from a multi-use vial  126  is shown. The vial  126  includes an open end, a rim surrounding the open end and a reduced diameter neck portion adjacent the rim. The vial  124  is typically sealed with an elastomeric septum  128  which includes a portion inserted into the neck of the vial  126  and a planar rim portion which overlies the vial rim. The septum  128  is normally secured to the vial rim with an aluminum collar  130 . In  FIG. 2 , a conventional syringe  114  is being used to access a drug substance contained within the vial  126 . The needle  104  in this case is sufficiently long to penetrate the septum  128  to access the drug substance contained in the vial  126 . 
     As may be appreciated from  FIGS. 1 and 2 , it is not possible, using a device having a stationary limiter, to fill a reservoir from a conventional vial. The distance d is too short to adequately penetrate the depth of the septum and access the substance contained in the vial. The present invention allows for access to a substance contained in a conventional vial by an intradermal needle device or assembly. As a result, there is no need to pre-fill an intradermal device of the present invention prior to use. Thus, standard methods for preserving the therapeutic and/or diagnostic substances, such as maintaining them in liquid or powder form in conventional vials for future use, may be used with the intradermal devices of the present invention. Furthermore, using the intradermal devices of the present invention, it is possible to use conventional, inexpensive delivery devices such as plastic syringes, in conjunction with the intradermal devices, which are often not appropriate for use as pre-filled devices. 
     In light of the above, there is a present need for a drug delivery device intradermal that enables a user to fill the intradermal device with a drug substance at the time of use by aspiration from a multi-dose vial, and to administer an injection into the intradermal region of the skin easily and repeatedly and without relying on the experience of the health care professional administering the injection. 
     SUMMARY OF THE INVENTION 
     The present invention provides a drug delivery device that overcomes the above-described shortcomings of the prior art. In an embodiment of the present invention, intradermal the drug delivery device, also referred to herein as an intradermal injection device, comprises a syringe having a needle cannula and a limiter that is movable with respect to the forward tip of the needle cannula between a first position in which a length of the needle cannula is exposed that is sufficient to enable aspiration of a drug substance from a multi-dose vial into the syringe, and a second position in which a length of the needle cannula is exposed that is preferably approximately equal to or less than 3 mm, when measured from the forward tip of the needle cannula to a top surface of the limiter. 
     As used herein, the term “proximal” and derivatives thereof, shall mean the end of an item or direction away from a patient during use of the subject invention. The term “distal”, and derivatives thereof, shall mean the end of an item or direction towards a patient during use of the subject invention. As used herein, the term “drug substance” and derivatives thereof, shall mean any substance that is intended for injection into a patient, including, by way of non-limiting example, drugs, vaccines, therapeutics, and the like. It will be obvious to a person of skill in the art, and from the disclosure provided herein, that the subject invention is not limited or otherwise defined by the type or class of substance administered using the inventive injection device. 
     An intradermal injection device constructed in accordance with embodiments of the present invention includes a syringe defining a reservoir in which a drug substance may be held, a needle cannula having a proximal end provided at a distal end of the syringe and in fluid communication with the reservoir and a distal needle tip. The inventive injection device also includes a movable limiter having a skin engaging surface with an aperture defined therethrough and through which the needle cannula may pass. The limiter is selectively moveable from a first refracted position in which an elongate portion (d 1 ) of the needle cannula is exposed and extends through the aperture and beyond the skin engaging surface, and a locked second extended position in which the limiter may not be moved from the second position back to the first position and in which the portion of the needle cannula exposed and extending through the aperture and beyond the skin engaging is limited to about 3 mm or less. 
     The present invention is also directed to a needle assembly for use in connection with a syringe for administering an intradermal injection. The inventive needle assembly may be coupled to a syringe and include a needle cannula having a proximal end provided at a distal end of the syringe and in fluid communication with the reservoir and a distal needle tip. The inventive needle assembly also includes a movable limiter having a skin engaging surface with an aperture defined therethrough and through which the needle cannula may pass. The limiter is selectively moveable from a first retracted position in which an elongate portion (d 1 ) of the needle cannula is exposed and extends through the aperture and beyond the skin engaging surface, and a lockable second extended position in which the limiter may not be moved back to the first position and in which the portion of the needle cannula exposed and extending through the aperture and beyond the skin engaging is limited to about 3 mm or less. The needle assembly may be coupled to the syringe using a luer-type connector, via a friction fit, using adhesive, or other now know or hereafter developed techniques for securing a needle cannula to a syringe. 
     Additionally, a method of intradermally injecting a mammal with a substance is provided including the steps of pressing a needle assembly of the invention in an orientation substantially perpendicular to the patient&#39;s skin such that the skin engaging surface of the limiter encounters the skin and prevents penetration of the needle cannula deeper than about 3 mm; maintaining the skin engaging surface on the skin and the orientation of the needle assembly; and injecting the substance under conditions and for a time sufficient to deliver the substance into the dermis layer of the skin. 
     The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiments. While this invention is satisfied by embodiments in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as exemplary of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be measured by the appended claims and their equivalents. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a partial cross-sectional view of an intradermal injection device having a non-movable penetration limiter; intradermal 
         FIG. 2  shows a perspective view of a conventional syringe being filled from a multi-dose vial; 
         FIG. 3  shows an intradermal injection device having a needle assemble with a movable penetration limiter in the refracted position and constructed in accordance with an embodiment of the present invention; 
         FIG. 4A  shows a partial cross-sectional view of a needle assembly having a movable penetration limiter located in a retracted position and constructed in accordance with an embodiment of the present invention; and 
         FIG. 4B  shows the needle assembly of  FIG. 4A  with the movable penetration limiter in an extended position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring next to the drawings in detail, in which like characters refer to like parts throughout the several views,  FIGS. 3 ,  4 A and  4 B depict an intradermal injection device  2  and needle assembly  4 , each constructed in accordance with embodiments of the present invention. The inventive injection device  1  includes a syringe  114  having a cylindrical body  116  that defines a reservoir  118  within which a drug substance may be contained and from which such substance may be expelled. A plunger  20  having a stopper  24  secured thereto is selectively movable within the reservoir  118 , where movement in the proximal to distal direction will cause the drug substance to be expelled from the reservoir  118  through the needle cannula  4 . 
     The inventive injection device  1  also includes a needle assembly  2  at the distal end of the body  116 . The needle assembly  2  includes a needle cannula  4  supported by an inner support member  36  which is located at the distal end of the body  116 . In the embodiment depicted in  FIG. 3 , inner support member  36  of the needle assembly  2  is secured to a hub  12  defined at that distal end of the body  116  in a manner known to those skilled in the art. For example, inner support member  36  may be secured using a friction fit, snap fit, suitable adhesive, luer connection, or other now known or hereafter developed means of securing a needle assembly to a syringe body. Alternatively, the needle cannula  4  may be secured directly to the body  116  via the hub  12  or other suitable structure that provides sufficient stability of connection between the needle cannula  4  and body  116  and that permits fluid communication between the reservoir  118  and needle cannula  4 . 
     The needle assembly  2  further includes a limiter  32  comprised of an outer sheath  34  and the inner support member  36 . In the embodiment depicted in  FIG. 3 , the inner support member  36  performs the function of a conventional hub. It is also possible to separately form a hub and an inner support member. However, for ease in construction, it is preferred that the hub and inner support member be formed unitarily. The outer sheath  34  has a generally flat skin engaging surface  10  defined at its distal end. The skin engaging surface  10  is preferably generally planar and continuous and provides for stable placement of the inventive injection device  1  against a patient&#39;s skin. The skin engaging surface  10  may, however, have alternate configurations. An aperture  38  is defined through the skin engaging surface  10  that is sized and shaped to permit the needle cannula  4  to pass freely therethrough when the outer sheath  34  is moved from the first position to the second position, as discussed in more detail below and elsewhere herein. 
     The outer sheath  34  is a generally tubular member that is selectively movable between a first refracted position, depicted in  FIG. 4A , in which the a first predetermined length of the needle cannula  4  is exposed, and a locked second extended position, depicted in  FIG. 4B , in which the limiter may not be moved back to the first position and in which a second predetermined length of the needle cannula  4  is exposed; the second predetermined length being shorter than the first predetermined length. When the sheath  34  is in the retracted position, as shown in  FIG. 4A , the needle cannula  4  extends through the aperture  38  and the needle tip  6  is located a predetermined distance d 1  beyond the skin engaging surface  10 ; the predetermined distance preferably being in excess of about 5 mm. Preferably, d 1  is in the range of about 8 mm to about 15 mm, more preferably, d 1  is in the range of about 10 mm to about 13 mm. The length d 1  is sufficient to permit a user to insert the needle tip  6  into a conventional multi-use vial to withdraw a drug substance stored therein. 
     The outer sheath  34  is preferably in the first position depicted in  FIG. 4A  when it is desired to aspirate the syringe  14  with a drug substance from a multi-use vial. Once the desired dose is drawn into the reservoir  18  (by causing the plunger  120  and stopper  124  to move in a distal to proximal direction), the outer sheath  34  may be moved from the first position to the locked second position, depicted in  FIG. 4B . 
     The sheath  34  is selectively movable on and along the support member  36  from a refracted position as illustrated in  FIG. 4A , in which an elongate portion d 1  of the needle cannula  4 , including the needle tip  6 , is exposed through the aperture  38  and extends beyond the skin engaging surface  10 , to a locked extended position as illustrated in  FIG. 4B , in which a shorter portion d 2  of the needle cannula  4 , including the needle tip  6 , is exposed through the aperture  38  and extends beyond the skin engaging surface  10 . 
     The inner support member  36  resides at least partially within the sheath  34  and is shown carrying the needle cannula  4  and being attached at a distal end of the syringe body  116 . However, it is to be understood that other configurations are possible. For example, it is possible for the needle cannula  4  to be carried directly by the syringe body  116 , either being secured directly to the syringe body  116  or being removably securable thereto. Additionally, the support member  36  may be formed unitarily with the syringe body  116  such that elements defined on the support member  36  as described below, will be formed on the syringe body  116 . Each of these configurations is envisioned as within the scope of the invention, as are other configurations which will be apparent to those having ordinary skill in the art from the disclosure provided herein. 
     As discussed in further detail below, an inner surface  40  of the outer sheath  34  and an outer surface  42  of the inner support member  36  have cooperating parts which releasably secure the outer sheath  34  in the refracted position, and which lockingly secure the outer sheath  34  in the extended position. 
     Referring again to  FIG. 4A , the outer sheath  34  may be releasably held in the retracted position by an inwardly directed projection  44  provided toward a proximal end of the sheath  34  and a corresponding recess  46  defined in the outer surface  42  of the support member  36  and bound by a retaining projection  48  and a proximal stop  50 . The recess  46  is adapted to accept the projection  44  when the sheath  34  is in the refracted position. Movement of the sheath  34  in the proximal direction from the retracted position depicted in  FIG. 4A  is obstructed by interference between the projection  44  and proximal stop  50 . Movement of the sheath  34  in the distal direction from the refracted position depicted in  FIG. 4A  is possible by applying sufficient force so that the projection  44  overcomes the retaining projection  48 . 
     Upon application of a manual distal force to the sheath  34 , the inwardly directed projection  44  moves out of the retaining recess  46  and moves distally beyond the retaining projection  48 . The inwardly directed projection  44  then moves relatively along a cylindrical guide portion  52  of the support member  36 . 
     Referring next to  FIG. 4B , sheath  34  may be lockingly held in the extended position by complementary features defined on the sheath  34  and support member  36 . A ramp  54 , indent  56  and distal stop  58  are provided toward a distal end of the support member  36 . The ramp  54  is wedge-shaped and is wider at its distal end than at its proximal end. The indent  56  is sized and shaped so as to accommodate the inwardly directed projection  44 . The distal stop  58  prevents the inwardly directing projection  44  from moving distally beyond the indent  56 , i.e., prevents the sheath  34  from being removed from the support member  36 . 
     Once the sheath  34  is moved along the cylindrical guide portion  52 , the inwardly directed projection  44  of the sheath  34  slides up and over the ramp  54  into the indent  56 . When the sheath  34  is positioned as shown in  FIG. 4B , with the inwardly directed projection  44  abutting the ramp  54 , the needle tip  6  extends beyond the skin engaging surface  10  a distance ranging from approximately 0.5 to 3 mm. Preferably, the length the needle tip  6  extends beyond the skin engaging surface is sufficient to limit penetration of the needle cannula into the dermis, to a depth of 3 mm or less. More preferably, the length ranges from about 1 mm to about 2 mm. 
     Once the sheath  34  is in the extended position, the inventive intradermal device  1  is ready for use in administering an intradermal injection. Under normal conditions of use, pressure on the skin engaging surface  10  during an intradermal injection will move the inwardly directed projection  44  proximally in the indent  56  until a proximal edge  60  of the inwardly directed projection  44  abuts a distal edge  62  of the ramp  54 . 
     The sheath  34 , although preferably rigid, possesses sufficient elasticity to permit sufficient expansion to slide over the retaining projection  48  and/or the ramp  54  without damage to the sheath  34 . Alternatively, or additionally, the support member  36  will possess sufficient flexibility to yield sufficiently to allow a substantially rigid sheath  34  to move beyond the retaining projection  48  and/or the ramp  54 . However, the flexibility of the sheath  34  and/or support member  36  will not permit proximal movement of the sheath  34  from the extended position to the refracted position when exposed to forces normally associated with the use of injection devices. 
     In a further aspect of the invention, the inwardly directed projection  44  and the ramp  54  are configured so that when the sheath  34  is moved distally from the refracted position into the extended position, the inwardly directed projection  44  will snap past the end of the ramp  54 , making an audible sound to provide an audible indication that the sheath  34  is in the extended position. 
     In a preferred embodiment of the present invention, all components of the intradermal device  2  will be made from moldable plastic materials such as, for example, polymeric plastics such as polypropylene, polycarbonate, and the like (except for the needle cannula  4  which is preferably made from steel). This construction allows for the syringe body  16  and the inner sheath  34  to be unitarily formed from a single moldable plastic. This is especially helpful in ease of assembly as well as reducing costs of manufacture. 
     The needle assembly  2  of the present invention may be supplied as an add-on to conventional drug delivery devices, i.e., glass or plastic syringes. In that case, the needle assembly  2  may be attached to a conventional drug delivery device, such as a syringe at the point of use. Alternatively, the needle assembly  2  may be provided with a syringe  14 , thus comprising an intradermal device  1  in accordance with embodiments of the present invention. Generally, the intradermal device  1  will be provided with a protective packaging to maintain the integrity of the unit and/or sterility thereof. The intradermal device  1  may further be provided with a protective cap to cover the needle tip prior to use thereof. 
     In use, a health care professional administering the intradermal injection will unwrap the protective packaging from the needle assembly  2  (if provided as a separate component) or injection device  1 . If necessary, the injection device  1  can be filled with the drug substance at this time, using methods that are conventional and known in the art. The health care professional will then manually slide the sheath  34  of the limiter  32  from the refracted position (see, e.g.,  FIG. 4A ) to the extended position (see, e.g.,  FIG. 4B ) in preparation for administration of the intradermal injection. Administration will typically involve pressing the skin engaging surface  10  of the limiter  32  substantially perpendicular to a surface of the patient&#39;s skin. The health care professional will maintain this orientation so as to maintain the needle in a position substantially perpendicular with the skin surface. The drug substance will then be injected using the plunger or other device conventionally used to deliver a drug substance. The injection will continue for a period of time determined by one having skill in the art based on the particular substance being administered as well as the dosage volume. Upon completion of the injection, the health care professional withdraws the needle cannula  4  from the patient&#39;s skin and disposed of the used injection device  1  in a suitable container. 
     Although the subject invention is well-suited for filling at point-of-use, it can be pre-filled. Optionally, for a prefilled device, a protective cap (not shown) may be provided for covering the needle before use, with the cap being positioned over the needle tip  6  and skin engaging surface  10 . Preferably, the cap is formed from an elastomeric material or thermoplastic elastomer that allows for the forward tip  6  to penetrate the cap and thus be sealed thereby  34 . Accordingly, the cap, by sealing the needle cannula  4 , seals the reservoir and prevents the substance therein from leaking into the needle cannula  4  prior to administration of the intradermal injection. Such a cap also provides a certain degree of sterility for the needle tip  6  and maintains its sharpness. 
     Additionally, a shield member may also be provided for covering the needle tip  6  after use of the inventive injection device  1 . Such a shield may be provided as part of the outer sheath  34 , or as a component separate therefrom. Alternatively, the shield may be provided by the sheath  34  and support member  36 , such as, for example, by providing additional complementary and interacting features on each part. Such features permitting further movement of the sheath  34  from the extended position to a shielding position in which the needle tip  6  is completely enclosed within the sheath  34 , and the sheath  34  is lockingly secured to the support member  36  in the shielding position. in another alternative embodiment, a needle shield may be hingedly attached to a part of the needle assembly  2  or syringe  14 . Other equivalent structures may also be used for this purpose. 
     While the invention has been described in relation to the preferred embodiments with several examples, it will be understood by those skilled in the art that various changes may be made without deviating from the spirit and scope of the invention as defined in the appended claims.