Abstract:
A pen needle according to the invention comprises a needle hub having a recess for a pen injector and vial. When the pen injector is loaded into the hub, the needle cannula mounted in the hub pierces the septum of the vial. A non-patient end (non-injection end) shield positioned in the hub member engages the pen injector and travels with the pen injector when the pen injector is removed, to shield the non-patient of the needle. The shield is locked into place securing the person administering the injection from accidental injury from the non-patient end of the needle.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention is directed to a passive safety shield which may be associated with an injection pen needle to shield the non-injection end of the needle. 
   2. Description of the Related Art 
   Accidental needlestick injuries from contaminated needles expose healthcare workers to the risk of infection from blood-borne pathogens, including the viruses that cause hepatitis B and C, and HIV. According to the Centers for Disease Control and Prevention, healthcare workers in the United States experience an estimated 600,000 exposures to blood each year, with RNs being subject to an overwhelming majority of these incidents. 
   While the injection device of choice in the U.S. remains the syringe, the demand for pen needles is growing rapidly. The use of self-injection pen needle devices is increasing due to the relative convenience, portability, and ease of use of these devices as compared to single use syringes. Pen needles are also becoming more commonplace in the hospital/clinical setting, as certain drugs, such as human growth hormone and osteoporosis medications, are available only in pen needle format. 
   Healthcare workers have sustained needlestick injuries while removing and disposing of needle hubs from pen needle devices after administering an injection to patients. The needles are typically removed after each injection to minimize contamination of the medication in the cartridge and to prevent needle re-use. Removal of the needle generally requires the re-shielding of the needle using the outer protective shield in which it was supplied and it is especially during the re-shielding step where injuries can occur. Needlestick injuries also occur during the removal of pen needles that have not been re-shielded. 
   U.S. Pat. No. 6,986,760 B2, assigned to the assignee of the present application, the disclosure of which is herein incorporated by reference in its entirety, teaches a pen needle and safety shield system wherein a safety shield, which normally encloses the needle cannula prior to use, permits retraction of the safety shield during injection and automatically extends and locks the shield in the extended enclosed position following use. The pen needle also prevents retraction of the shield during assembly of the shield and needle cannula and hub assembly on the pen injector. 
   However, this prior art does not disclose a pen needle having a non-injection end passive safety shield. Thus the invention disclosed herein, which may be incorporated into prior art safety shielded pen needles, represents an advance in the art, in that novel means are provided to guard against accidental needlestick from the non-injection end of a needle in a pen needle. 
   SUMMARY OF THE INVENTION 
   A non-injection end passive safety shield for an injection pen needle according to the present invention includes a needle hub having a needle mounted thereon, the needle having an injection end and a non-injection end, and the hub having a recess surrounding the non-injection end of the needle to receive a pen injector. A shield member situated on the non-injection end of the hub has an aperture to permit passage of the needle where it passes into the pen injector (and into a vial of insulin carried in the pen injector, for example). The shield member includes an element for engaging the shield member to the pen injector when the pen injector is received by the hub member, so that the shield member moves with the pen injector when the pen injector is removed from the hub to shield the non-injection end of the needle. 
   Alternatively (or in combination with the engaging element), a biasing element (such as a spring) biases the shield toward the pen injector to insure that the shield covers the non-injection end of the needle when the pen injector is removed from the hub. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  depicts a cross-sectional detail of the passive safety shield according to an embodiment of the invention, with the shield member situated within the hub prior to use of the pen needle. 
       FIG. 2  depicts a cross-sectional detail of the device after the pen injector has been inserted into the hub member, so that the non-injection end of the needle cannula is inserted into a vial carried in the pen injector. 
       FIG. 3  depicts a cross-sectional detail of the device after an injection has been administered, and the pen injector has been withdrawn and the shield member deployed, so that the shield member shrouds the non-injection end of the needle. 
       FIG. 4  is a perspective view of the shield member showing elements for engaging the pen injector. 
       FIG. 5  depicts a cross-sectional view of another embodiment of the device, with the pen injector installed on the hub. 
       FIG. 6  shows another cross-sectional view of still another embodiment of the device, with a biasing element biasing the shield member in the direction of the pen injector. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The safety shield system according to the invention is “passive” because shielding of the non-injection end is automatic upon removing the pen-injector. User-implemented steps are not required to shield the non-injection end of the needle. The terms “injection end” and “non-injection end” refer to directions on the device. The injection end refers to a direction toward the end of the device that is normally pressed against a patient&#39;s body during an injection (the distal end), while the non-injection end refers to the opposite direction, toward the proximal end, whether the patient injects himself or herself, whether someone else administers the injection, and whether or not an injection is actually accomplished. 
   As used herein, the non-injection end shield “covers” or “shrouds” the needle when the tip of the needle does not extend beyond the end wall of the shield, notwithstanding that the tip of the needle may be quite close to the aperture in the shield, and exposed to view. 
   As shown in  FIG. 2 , an injection pen needle  100  generally includes a tubular body referred to herein as pen injector  60  including a vial  90  for holding a fluid, such as insulin, anti-histamines, etc., which may be accessed by the needle  110 . In general, except where the context requires otherwise, reference to the pen injector refers to both the outer casework of the injector and the vial within it, or medication may be provided in the pen injector directly, without a vial, without departing from the scope of the invention. A needle hub  70 , on which the needle is mounted, receives the pen injector in a cup-shaped recess  80  on the non-injection side of the hub. The hub  70  and pen injector  60  may be threaded to engage one another, or another suitable mating connection may be used. The needle cannula  110  extends into an end portion of the hub  70  and includes a non-injection end extending into the body portion of the pen injector, to pierce the closure of the vial  90 . The opposed injection end of the needle is for injection, typically into the patient. 
     FIG. 1  shows a first embodiment, in which the shield member  10  is situated on the base of the pen needle hub  70  prior to fitting the pen injector. In this case, the needle  110  is not shrouded by the shield  10  when the pen injector is inserted. The shield may have threads  12  engaging with threads  14  on the hub and a small interference element (not shown) or frictional force may be used to prevent the shield moving during distribution and/or prior to use. It will be understood that any force required to retain the shield in this position should be less than the force required to retract the shield into the hub when the pen injector is removed so that the shield moves with the pen injector, as intended. 
   Alternatively, in an embodiment not shown in the figures, the shield  10  may sit so that it covers or protrudes from recess  80  in the hub  70  covering the non-injection end of the needle before the pen injector is inserted. The pen injector  60  may be engaged with the shield  10 , such as with one or more mating tabs and recesses, and then both the shield  10  and the pen injector  60  may be installed into the recess  80 , such as by pushing and/or screwing. Prior to engaging the pen injector in the hub, a retaining element may be used to retain the shield in a position covering the non-injection end of the needle. For example, as shown in  FIG. 3 , a raised portion  120  adjacent the thread may be used to prevent movement of the shield on the thread until the user installs the pen injector. Alternatively, the shield may be held in position by a frictional fit, which is overcome when the pen injector is installed. 
   Aperture  140  on the shield member  10  permits passage of the needle  110 . A raised feature, such as ridge  150  around the aperture  140 , may optionally be used to provide additional height to shroud the non-injection end of the needle prior to the user installing the pen injector or after the pen injector has been removed. The raised ridge  150  may be accommodated in a free space immediately above the vial septum area found in prior art pen injector devices. As the rest of the shield  10  may have reduced height compared with the ridge  150 , it is easier to accommodate the shield member into the hub of such prior art devices with less modification. Specifically, less height is required in the hub to accommodate the shield. 
     FIG. 2  shows the shield member  10  in the pen needle hub, with the pen injector tip fully engaged with the hub. The non-injection end of the needle  110  pierces septum  50 . In this position, the shield member  10  engages the pen injector  60 , so that when the pen is removed, the shield rotates with it and it is drawn into the free space in the hub. 
     FIG. 3  shows the shield member  10  in its protecting position, where the non-injection end surface provides an effective barrier to accessing the non-injection end of the needle tip. A lockout member (not shown) adjacent the thread on the shield may be utilized to prevent the shield member  10  from retreating into the hub, once the pen injector has been removed. Alternatively, a protuberance on the thread could create an interference such that shield  10  does not move down the threads in the hub. Another lockout element could be provided, as known in the art, to prevent the shield from retreating into the hub. 
     FIG. 4  shows a perspective view of the shield member  10  having a ring of teeth  130  which engage with the septum of the vial in the pen injector. The teeth  130  drive the shield in the threads in the hub and act as an engaging element to engage the shield  10  with the pen injector  60 , or with the septum of the vial inside the pen injector. As an alternative engaging element, one or more adhesive or grippy polymer elements arranged around the surface of the shield member may also be used. When the pen injector is fully screwed (or otherwise securely inserted) into the hub, the engaging element temporarily attaches the shield to the pen injector so that when the pen injector is unscrewed (or otherwise removed) from the hub after an injection has been administered, the shield is rotated (or otherwise moved in tandem) with the pen injector and retracted with it to cover the non-injection end of the needle. 
     FIG. 5  shows the pen injector  60  fully screwed home. In this state, the teeth  130  on the shield member are engaged with the pen injector&#39;s septum, such that as the pen is unscrewed, the rotating of the pen injector causes the shield to rotate with it and so that it can be driven up the thread in the pen needle&#39;s hub. 
     FIG. 6  also depicts the pen injector fully screwed home, and further depicts a biasing member  160  biasing the shield member toward the pen injector in the hub, so that the shield member securely engages the pen injector when the pen injector is withdrawn after an injection has been administered. In  FIG. 6 , biasing member  160  is shown as being integral with the shield member  10 , biasing the shield toward the pen injector and pressing against the inside surface of the injection end of the hub. That is, the shield and biasing member constitute one piece. Such an integral member may conveniently be made from plastic or metal. Alternatively, a separate spring element may be used to bias the shield in toward the non-injection end of the device. 
   In an alternative embodiment, the spring alone may be used to bias the shield to cover the non-injection end of the needle when the pen injector is removed. 
   By shielding the non-injection end of a pen needle device, the safety shield according to the invention provides a clear benefit to healthcare professionals in the hospital or clinic setting. The shield may have additional advantages of hiding the needle from view, which is an advantage for patients who are particularly needle-averse. In the non-clinical setting, safe disposal of the needle hub is facilitated according to the invention, as the needle is essentially enclosed once an injection is administered. A particular advantage of the safety shield is its simplicity of use, requiring little or no implementation from the user. Because the shield is built into the hub, there is no cap or other separate cover that can be separated from the device and lost. 
   A pen needle according to the invention may utilize a range of needle lengths and gauges. In preferred embodiments, the pen needle is small, to minimize patient discomfort, effect a successful injection, and enhance portability and ease of use. Thus, it is contemplated that the shield could effectively be used with 29, 30 and 31 gauge needles having injection lengths of 5 mm, 8 mm and 12 mm, although these examples are not limiting. Visible coding schemes may be added to indicate the type of injection to be administered, the size and gauge of needle, to indicate engagement of the pen injector, that the shield has moved or locked out, etc. The pen needle will, in most cases, be packaged in an outer shield with a foil sterility barrier, as commonly practiced in the art. Alternatively, other packaging to ensure sterility may be provided. These and other improvements and modifications may be made without departing from the scope of the invention, which is defined in the appended claims.