Abstract:
A syringe is provided with an assembly received on the distal end for adjusting the penetration depth. In embodiments, the assembly includes a collar attached to the syringe hub which moves with respect to the needle between axial positions depending on the desired needle penetration depth. The adjustable penetration depth syringe is useful in the context of self-administered drugs such as insulin, where a longer length needle is needed to fill a syringe from a vial, but a shorter penetration depth is preferred for administering a subcutaneous injection.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention is in the field of syringe technology. In particular, the invention is directed to a syringe having an adjustable penetration depth. The adjustable penetration depth syringe is particularly useful in the context of self-administered drugs such as insulin. 
         [0003]    2. Description of the Related Art 
         [0004]    Syringe needles preferably require a penetration depth of 6 mm to 8 mm to penetrate a vial closure. Shorter needles will not consistently penetrate the vial septum, or be able to inject air into the vial and withdraw medication. However, injection lengths shorter than 6 mm are preferred by patients and health care professionals for administering an injection. This is particularly true for injections to be delivered in the subcutaneous region, for medications such as insulin. Recent studies have also shown that the possibility of intramuscular (IM) injections increases with needle penetration depth. For administering injections in the subcutaneous region, the optimal needle length tends to be around 4 mm. Current insulin needles on the market are a fixed length, generally 6 mm, in order to properly penetrate the vial septum. These needles do not provide optimal penetration depth for injection into the subcutaneous space while minimizing risk of intramuscular injection. 
         [0005]    U.S. Pat. No. 7,651,512 depicts a propelled lancer which optionally has an adjustable tip portion that permits a user to select a desired depth of stylet penetration from a number of depth-penetration choices. However, the lancer is not a syringe, and the design does not expose a specified needle length for an injection; in fact the needle moves within the device. 
         [0006]    Thus, an object of the invention is to provide a syringe having an adjustable penetration depth which can be used both to fill the syringe from a vial at one penetration depth, and administer an injection at an optimal injection depth. 
         [0007]    Another object of the invention is to provide a syringe having an adjustable penetration depth to accommodate different injection sites and different medications. 
         [0008]    Yet another object of the invention is to provide an adjustable penetration depth device which also shields the syringe and places a protective cover over the needle cannula after use to minimize the risk of accidental needle sticks. 
         [0009]    Yet another object of the invention combines the above advantages of adjustable penetration depth with an interchangeable needle-hub assembly, so that different gauge needles may be installed on differently sized syringes. 
         [0010]    These and other objects of the invention are achieved with an adjustable collar received on the distal end of a syringe movable between fixed positions to adjust the penetration depth of the needle as described below. 
       SUMMARY OF THE INVENTION 
       [0011]    In one aspect, the invention is a syringe with adjustable penetration depth, comprising: a tubular syringe barrel; a plunger positioned within the syringe barrel; a hub bearing a needle and attached to the syringe barrel; and a movable collar having an open proximal end received over the hub. The collar has a distal end wall having an opening through which the needle protrudes and a sidewall extending proximally from the distal end wall. The sidewall has an interior surface engaging the hub or syringe barrel and a retaining feature engaging the hub or barrel, retaining the collar at a plurality of axial positions with respect to the needle. The collar travels with respect to the hub along a path defined by features on the interior surface of the sidewall engaging the hub or barrel, exposing a greater length of the needle as the collar travels toward the plunger, and is retained in a fixed position at each of said plurality of axial positions. 
         [0012]    In another aspect, the invention is a syringe with adjustable penetration depth, comprising a tubular syringe barrel, a plunger positioned within the syringe barrel and a hub bearing a needle attached to the syringe barrel. The hub is provided with a plurality of laterally extending protrusions defining slots at distinct axial positions on the hub. The syringe is provided with a movable collar having an open proximal end, a distal end wall having an opening through which the needle protrudes, and a sidewall extending from the distal end wall. A tab is provided on the interior surface of the sidewall adapted to be received in the slots between the laterally extending protrusions on the hub at distinct axial positions of the collar when the collar is rotated. 
         [0013]    In another aspect, a syringe according to the invention is provided with a tubular barrel, a plunger positioned within the barrel and a hub bearing a needle attached to the barrel. A tubular adapter is attached to the distal end of the barrel. A tubular sleeve received around the adapter engages the adapter at fixed positions, exposing a longer or shorter length of needle beyond an opening in the distal end of the sleeve. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a view of an adjustable penetration depth syringe according to an embodiment of the invention. 
           [0015]      FIG. 2  is a detail of the distal portion of the syringe of  FIG. 1  at a first penetration depth setting. 
           [0016]      FIG. 3  is a detail of the distal portion of the syringe of  FIG. 1  at a second penetration depth setting. 
           [0017]      FIG. 4  is a detail of the distal portion of the syringe of  FIG. 1  showing a collar covering and shielding the needle in a locked position. 
           [0018]      FIG. 5  is a schematic view of a collar design showing the operation of the collar on the hub. 
           [0019]      FIG. 6  is a cross sectional view of a collar design according to another embodiment of the invention. 
           [0020]      FIG. 7  is a side view of a syringe according to another embodiment of the invention having an adjustment assembly on the distal end of the syringe. 
           [0021]      FIG. 8  depicts the adapter component of the adjustment assembly. 
           [0022]      FIG. 9  depicts the sleeve component of the adjustment assembly. 
           [0023]      FIG. 10  depicts the assembled adjustment assembly. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    As used herein, “axial” means along or parallel to the longitudinal axis of the needle and “radial” is the perpendicular direction. “Rotation” refers to rotation about the longitudinal axis. “Interior” means radially inward, either toward or facing the needle, and outward means radially outward or away from the needle. The “distal” direction is the direction toward the injection site and the injection end of the needle, and the “proximal” direction is the opposite direction. 
         [0025]    As shown in the embodiment of  FIG. 1 , a syringe  10  according to this embodiment of the invention comprises barrel  14  having a plunger  12  therein. The plunger  12  is arranged within the syringe barrel  14  such that depressing the plunger  12  pushes a stopper through the medication compartment within the syringe barrel to pressurize the compartment and eject medication out of needle  13 . A hub  16  is attached to the barrel  14 , and a needle  13  is attached to the hub  16 . The needle may be molded with the hub, affixed to the hub with adhesive, by welding, using a mechanical lock or other permanent means to fix the needle. The hub-needle assembly is then preferably snap-fit to the syringe barrel and is typically delivered to the user pre-assembled. A rotating collar  20  fits over the hub  16  and is provided with an opening on the distal end thereof through which the needle  13  protrudes. The collar  20  can be adjusted to set the penetration depth of the needle as described below. 
         [0026]    At the setting depicted in  FIG. 2 , the collar is retained in its proximal-most position, so that the open proximal end of the collar  20  abuts the syringe body  14 . In this axial position, the maximum length of the needle is exposed. For example, the setting at this position may be 8 mm, and suitable for filling the syringe from a vial. Indicia  17  are provided on the hub so that the user can observe what setting is being used through a window  27  in the collar. 
         [0027]    The bayonet-style arrangement of the collar  20  on the hub is shown in  FIGS. 1-3 . In this embodiment, hub  16  is snap-fit onto syringe body  14  so that the hub is preassembled as part of the syringe and not removed during ordinary use. As shown in  FIG. 4 , the hub is provided with lateral protrusions  25  on the hub defining slots  29  at specified increments of, for example, 1 mm each. As shown in  FIG. 5 , collar  20  is provided with tab  65  formed on the interior side wall of the collar  20  which can be rotated in a first direction designated by the horizontal arrows in  FIG. 5  into the slots defined by lateral protrusions  25  at distinct axial positions of the collar with respect to the needle  13 . Axial movement of the collar is permitted along the direction indicated by the vertical arrow in  FIG. 5  when tab  65  is not engaged with any slot. For this purpose, an axially extending channel may also be provided on the radially inward surface of the collar or on the radially outward surface of the hub, engaging a corresponding member on the other of the collar or the hub, to permit smooth axial movement of the hub between different axial positions. To attain the position depicted in  FIG. 3 , for example, collar  20  is moved axially to a needle penetration depth of 4 mm, appropriate for an insulin injection. The user then rotates the collar  20  in the clockwise direction to set the collar at the desired penetration depth. In the embodiment shown, the window  27  in the collar sidewall permits the viewer to see the indicia on the hub which indicate the penetration depth of the needle at each setting. 
         [0028]    As further shown in  FIG. 4  and  FIG. 5 , at the distal most position of the collar  20 , a counterclockwise turn will receive tab  65  in slot  69  attaining the “locked out” position of  FIG. 4 . A depression in slot  69  may receive tab  65  to inhibit clockwise rotation that would remove the collar from the locked-out state and provide a tactile indication to the user that the locked out position has been reached. Similarly, bumps or depressions may be provided in the slots at the different axial positions of the collar, providing a tactile indication for the user that the desired penetration depth of the needle has been achieved. The covering position of the collar is depicted in  FIG. 4 . A visual indicator may be provided to indicate the locked after-use position. 
         [0029]    A spring (not shown) may be provided inside the collar between the distal end wall of the collar and the syringe body, biasing the collar in the distal direction, which may provide for smoother axial movement of the collar  20  on the hub  16 . An internally facing flange or detent (not shown) on the collar may be used to prevent the collar from sliding distally off the hub and may also engage a corresponding feature on the hub to provide a locking action to prevent proximal or rotational movement of the collar after use. The hub-needle assembly may be provided as interchangeable units and pre-assembled with different syringe bodies. In this way, different gauge needles may be installed on different volume syringe bodies, reducing subcomponent inventory. 
         [0030]    The cross sectional view of  FIG. 6  depicts the interior of a collar according to another general embodiment of the invention. In this embodiment, collar  50  comprises a distal end wall  15  and a sidewall  21  extending proximally from the end wall and terminating in an opening large enough to accommodate the hub and in some embodiments also accommodates the distal portion of the syringe body. The sidewall  21  has an opening  19  through which the needle  13  protrudes. Channel  24  on an interior surface of the sidewall is pitched at an angle with respect to the distal end wall  15  forming a circumferential channel like a thread. When the user rotates collar  50  with respect to the syringe body, a protrusion on the hub travels in the channel  24  reaching detent  22 . Preferably the hub comprises at least two protrusions on an interior surface thereof each engaging the channel. Thus, a second protrusion is received in detent  26 , fixing the axial position of the collar and preventing wobble. Detents  22  and  26  act to limit rotational movement of the collar. A plurality of detent pairs may be provided in channel  24  to allow for different axial positions as the collar  20  is rotated to move proximally and distally. Protrusions which engage the channel  24  can reside on the hub or on the distal end of the syringe body. Alternatively, protrusions are provided on the collar  20 , in which case a corresponding channel is provided on the hub or barrel. 
         [0031]      FIG. 6  depicts a partial travel path, in which the collar moves axially in the course of being rotated. Alternatively, or in addition, one or more axial channels may be provided so that the collar is moved axially without rotating for all or part of the travel path. For example, the collar may be designed with a linear channel with detents at each end. The user may rotate the collar to disengage the detent, slide the collar distally or proximally along the hub to adjust the needle penetration depth, and rotate the collar again to engage detents. Multiple channels may be provided to reduce wobble or loose feel and prevent needle contact. 
         [0032]    Another adjustable length syringe embodiment according to the invention is depicted in  FIGS. 7 through 9 , wherein telescoping adjustment assembly  74  is installed on the hub at the distal end of the syringe body  14  to permit adjustment of needle penetration depth. The side view of  FIG. 7  schematically depicts an integral barrel syringe, in which a needle bearing hub portion is injection molded, or otherwise formed integrally, with the syringe body. As would be apparent to one of ordinary skill in the art, the assembly  74  could also be installed on a snap fit hub, simply by varying the interface of the assembly  74  and the syringe body or hub. 
         [0033]    In the embodiment shown, the telescoping assembly  74  comprises a tubular adapter  76  attached to the distal end of the syringe barrel using an adhesive, shrink fitting, heat staking or other means. A tubular sleeve  78  is received around the adapter  76  and is engaged with the adapter at a plurality of fixed positions, exposing a different length of needle beyond the distal end of the sleeve at each one of the plurality of fixed positions. 
         [0034]    As shown in  FIGS. 8-10 , a channel  82  is provided on the outside of the adapter  76  which engages a tab  81  on an interior surface of the sleeve  78 . Alternatively, the channel may be provided on the sleeve  78  and the tab provided on the adapter. In the embodiment shown, the channel  82  has recesses at opposite ends which receive the tab  81  at different axial positions of the sleeve to retain the sleeve in position. Thus, the user can select a 4 mm, 6 mm or 8 mm penetration depth for the needle. The variations described above in connection with  FIG. 6 , using multiple tabs engaging detents associated with the channel, may be used to guide the sleeve travel with respect to the adapter and secure the sleeve in each of the plurality of axial positions. In addition to setting different penetration depths for the needle, the sleeve may be provided with an additional distal position, such that the distal end of the sleeve is located distally of the needle tip to minimize or prevent accidental needle stick prior to or after use. The distal end of sleeve  78  may form a skin-interfacing ring, so that the user knows that the appropriate injection depth has been reached. 
         [0035]    In embodiments, a cap  75  is provided over the needle in the state that the device is initially encountered by the user. The cap  75  is received on the distal end of the adapter  76 , between the adapter  76  and the sleeve  78 , forming a sterile enclosure. Prior to administering an injection, the user manually removes any external labeling and removes cap  75  exposing the maximum penetration depth of the needle, with the sleeve in its proximal-most position. The user may choose to use this length to fill the syringe from a vial and thereafter rotate the sleeve  78  to select another depth to administer an injection. As with the foregoing embodiments, the sleeve or adapter may be provided with indicia so that the user knows what penetration depth of the needle has been selected. 
         [0036]    In another variation, adapter  76  and sleeve  78  are provided with mating end stops. Instead of a circumferential groove in which the sleeve  78  moves axially and rotates at the same time, the sleeve is moved axially without rotation until the end stops on the adapter  76  and sleeve  78  are mated at the desired axial position of the sleeve. 
         [0037]    The plastic parts described herein, the hub, collar(s), adapter, sleeve, etc., are typically made of injection molded polypropylene using techniques known to those having skill in the art of manufacturing syringes and medication pens. However, the invention is not limited to any particular production method. The needle is typically a standard gauge surgical stainless steel part. The adjustable length syringes may be used for any type of medication deliverable by syringe, but it is particularly preferred that the needles are used for self-injectable medications, such as insulin. The foregoing description of the preferred embodiments is not to be deemed to limit the invention, which is defined by the following claims.