Abstract:
The subject invention provides a safety pen needle assembly which includes: a hub; a needle carrier; a needle fixed to the needle carrier; a shield; and, a first engageable locking arrangement for fixing the shield to the needle carrier. Upon a predetermined extent of distal movement of the shield relative to the hub, the first locking arrangement is engaged such that the shield becomes fixed to the needle carrier. Upon further distal movement of the shield relative to the hub beyond the predetermined extent of distal movement, the shield and the needle carrier move in concert together relative to the hub causing a proximal end of the needle to move distally relative to the hub to a retracted state. Advantageously, the subject invention provides a reliable, low-cost safety pen needle assembly which does not require a spring or other biasing element.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Patent Application No. 61/914,009, filed Dec. 10, 2013, the entire contents of which are incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     Safety pen needle assemblies are known in the prior art for shielding a used needle post-injection. Such assemblies may be generally classified as “passive” or “active”. A passive device is typically considered to be one where shielding may be achieved without requiring additional steps beyond that required to conduct an injection. In contrast, an active device is typically considered to be one where shielding requires one or more additional steps beyond that required to conduct an injection, such as, for example, triggering a spring-fired shield. 
     In addition, shielding is most commonly utilized with the distal, patient end of the needle. Shielding has been also provided for the proximal, non-patient end of the needle and has been provided on the same device for both the distal and proximal ends of the needle post-injection. U.S. Pat. No. 7,540,858 to DiBiasi and U.S. Published Patent Application No. 2011/0178473 A1 to Richards et al., both to the assignee herein, show passive dual end shielding safety pen needle assemblies where both the distal and proximal ends of the needle may be shielded passively post-injection. 
     SUMMARY OF THE INVENTION 
     The subject invention provides an active safety pen needle assembly which includes: a hub having features for mounting onto a medical injector; a needle carrier; a needle fixed to the needle carrier, the needle including proximal and distal ends, the distal end formed for insertion into a patient; a shield; and, a first engageable locking arrangement for fixing the shield to the needle carrier so that the shield and the needle carrier move in concert. In an initial state, the shield is moveable relative to the needle carrier. Upon a predetermined extent of distal movement of the shield relative to the hub, the first locking arrangement is engaged such that the shield becomes fixed to the needle carrier. Upon further distal movement of the shield relative to the hub beyond the predetermined extent of distal movement, the shield and the needle carrier move in concert together relative to the hub causing the proximal end of the needle to move distally relative to the hub to a retracted state. Advantageously, the subject invention provides a reliable, low-cost safety pen needle assembly which does not require a spring or other biasing element. 
     These and other features of the invention will be better understood through a study of the following detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a safety pen needle assembly formed in accordance with the subject invention accommodated in an outer casing; 
         FIG. 2  is a cross-sectional view taken along line  2 - 2  of  FIG. 1 ; 
         FIGS. 3-5  are various views of a hub useable with the subject invention; 
         FIGS. 6-8  are various views of a needle carrier useable with the subject invention; 
         FIGS. 9-11  are various views of a shield useable with the subject invention; and, 
         FIGS. 12-17  show a safety pen needle assembly formed in accordance with the subject invention in use. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the Figures, a safety pen needle assembly  10  is shown which generally includes a hub  12 , a needle carrier  14 , a needle  16 , and a shield  18 . The safety pen needle assembly  10  may be used with various medical injectors, but is particularly well-suited for use with medical pen injectors. 
     As used herein, the term “distal”, and derivatives thereof, refer to a direction generally towards a patient, while, the term “proximal”, and derivatives thereof, refer to a direction generally away from a patient. 
     The hub  12  is generally tubular and includes feature  20 , such as threads or a bayonet-lock feature, for mounting onto a medical injector. The feature  20  may be a surface formation or other mounting arrangement, such as a friction-fit (e.g., tapered (luer)) surface, snap-on features, and so forth. A stop  21  may be provided to define a final mounting position relative to an injector. 
     The needle carrier  14  is generally tubular and formed to telescopingly receive the hub  12 . The needle  16  is fixed to the needle carrier  14  with a distal end  22 , formed for insertion into a patient, located distally from the needle carrier  14 , and a proximal end  24  located proximally from the needle carrier  14 . The needle  16  may be of any known configuration capable of conveying fluid between the distal and proximal ends  22 ,  24 , e.g., being a cannula having a hollow lumen therein extending through the needle  16 . 
     The shield  18  includes a sidewall  26  formed to encircle the needle carrier  14 . The sidewall  26  includes proximal and distal ends  28 ,  30 . The proximal and distal ends  28 ,  30  surround proximal and distal openings  32 ,  34 , respectively, each configured to permit passage therethrough of the needle  16 . Optionally, a covering wall  36  may extend between the distal opening  34  and the sidewall  26 . The covering wall  36  may act to impede access to the distal end  22  of the needle  16 , particularly in a post-use state as discussed below. As will be appreciated by those skilled in the art, the covering wall  26  may not be necessary if, for example, the sidewall  26  is provided with sufficient length to impede such access. 
     A first locking arrangement  38  is provided for fixing the shield  18  to the needle carrier  14  so that the shield  18  and the needle carrier  14  may move together in concert. The first locking arrangement  38  may be of any configuration which is engageable with sufficient relative movement, e.g., axial movement, between the shield  18  and the needle carrier  14 . By way of non-limiting example, the needle shield  18  may be provided with a detent  40 , e.g., in the sidewall  26 , for snap engagement with a recess  42  formed in the needle carrier  14 . The shield  18  is formed with sufficient inherent memory to maintain snap engagement between the detent  40  and the recess  42 . It is preferred that the detent  40  be provided on a cantilevered arm  44 . Alternatively, the constituent material of the sidewall  26  may be utilized to provide the inherent memory. As will be appreciated by those skilled in the art, a plurality of the first locking arrangements  38  may be provided (e.g., a plurality of sets of detents  40 /recesses  42 ). 
     A ramped surface  46  is preferably provided adjacent to the recess  42  to allow the detent  40  to by-pass in one direction, over the ramped surface  46  in a rising direction. The ramped surface  46  defines a step  48  adjacent the recess  42  to inhibit movement of the detent  40  in the reverse direction. In addition, a channel  50  may be provided in the needle carrier  14  formed to accommodate sliding movement of the detent  40 . Preferably, the channel  50  is generally parallel to a longitudinal axis of the needle carrier  14  and longitudinally aligned with the recess  42 . 
     With reference to  FIG. 13 , for use, the safety pen needle assembly  10  is mounted onto a medical injector I, in particular with the feature  20  of the hub  12  cooperatively engaging a corresponding feature (e.g., threads) on the injector I. Once mounted, the injector I may be prepared for injection, for example by priming the needle  16 . As shown in  FIG. 2 , in an initial state, the shield  18  may be located to cover the distal end  22  of the needle  16 . Alternatively, the distal end  22  may be initially exposed so as to provide visual access to a user for priming and insertion into a patient. Once prepared, the needle  16  may be inserted into a patient. Depending on the initial position of the shield  18  relative to the hub  12 , the shield  18  may be forced proximally due to contact with the patient&#39;s skin. Interengagement of the shield  18  with portion(s) of the needle carrier  14  and/or interengagement of the shield  18  with the patient&#39;s skin shall limit proximal movement of the shield  18 . With the needle  16  being exposed, an injection may be administered. 
     Once the injection is completed, the needle  16  is removed from the patient, as shown in  FIG. 15 , with the distal end  22  of the needle  16  being exposed. As shown in  FIG. 16 , with the safety pen needle assembly  10  being maintained on the injector I, the shield  18  is urged distally relative to the hub  12  until the first locking arrangement  38  is engaged. Here, as shown in  FIG. 17 , the detent  40  may be seated in the recess  42 . Further distal advancement of the shield  18  relative to the hub  12  causes the shield  18  and the needle carrier  14  to move in concert. As shown between  FIGS. 16 and 17 , with the needle carrier  14  moving distally relative to the hub  12 , the proximal end  24  of the needle  16  is caused to be retracted relative to the hub  12 . The proximal end  24  of the needle  16  is retracted sufficiently relative to the hub  12  so as to restrict inadvertent access thereto by a user post-injection. For example, the proximal end  24  of the needle  16  may be retracted to be located 0.25″, or more, within the hub  12 . Thereafter, the safety pen needle assembly  10  may be removed from the injector I and disposed. 
     With the subject invention, the distal advancement of the shield  18  is provided manually by a user with the hub  12  being maintained on the injector I after injection. Continuous distal displacement of the shield  18 , with the hub  12  maintained on the injector I, results in sequential distal displacement of the shield  18  and the needle carrier  14 . This provides for active activation of shielding. It is preferred that the shield  18  cover the distal end  22  of the needle  16  with the shield  18  being fixed to the needle carrier  14  with engagement of the first locking arrangement  38 . With retraction of the proximal end  24  of the needle  16  and the covering of the distal end  22  of the needle  16  by the shield  18 , both ends of the needle  16  may be covered post-injection. 
     A second locking arrangement  52  may be provided for fixing the needle carrier  14  to the hub  12 , particularly with the proximal end  24  of the needle  16  being in the retracted state. The second locking arrangement  52  may be of any configuration which is engageable with sufficient relative movement, e.g., axial movement, between the needle carrier  14  and the hub  12 . By way of non-limiting example, the needle carrier  14  may be provided with a secondary detent  54  for snap engagement with a secondary recess  56  formed in the hub  12 . The needle carrier  14  is formed with sufficient inherent memory to maintain snap engagement between the secondary detent  54  and the secondary recess  56 . It is preferred that the secondary detent  56  be provided on a secondary cantilevered arm  58 . Alternatively, the constituent material of the needle carrier  14  may be utilized to provide the inherent memory. As will be appreciated by those skilled in the art, a plurality of the second locking arrangements  52  may be provided (e.g., a plurality of sets of secondary detents  54 /secondary recesses  56 ). 
     A secondary ramped surface  60  is preferably provided adjacent to the secondary recess  56  to allow the secondary detent  54  to by-pass in one direction, over the secondary ramped surface  60  in a rising direction. The secondary ramped surface  60  defines a secondary step  62  adjacent to the secondary recess  56  to inhibit movement of the secondary detent  54  in the reverse direction. A secondary channel  64  may be provided in the hub  12  formed to accommodate sliding movement of the secondary detent  54 . Preferably, the secondary channel  64  is generally parallel to a longitudinal axis of the hub  12  and longitudinally aligned with the secondary recess  56 . 
     During use, with sufficient distal movement of the needle carrier  14  relative to the hub  12 , the second locking arrangement  52  may be engaged whereby the needle carrier  14  becomes fixed to the hub  12 . This distal movement shall occur with the shield  18  fixed to the needle carrier  14 . The second locking arrangement  52  is preferably engaged with the proximal end  24  of the needle  16  being in the retracted state. 
     The secondary detent  54  may be also used to releaseably fix the needle carrier  14  to the hub  12 , for example, by being seated in an initial position in initial recess  66 . The initial recess  66  is preferably longitudinally aligned with the secondary channel  64 . In addition, it is preferred that angled surface  68  be located adjacent to the initial recess  66  configured to provide a rising surface in a distal direction to facilitate removal of the secondary detent  54  from the initial recess  66  upon a threshold amount of force being applied to urge the secondary detent  54  in a distal direction relative to the hub  12 . It is preferred that the angled surface  68  be provided with a greater angle of inclination than the secondary ramped surface  60  so that the angled surface  68  provides resistance against movement thereacross by the secondary detent  54 , such resistance being surmountable. The secondary detent  54  may act to maintain the needle carrier  14  in a fixed position relative to the hub  12  with the shield  18  being initially distally displaced prior to the first locking arrangement  38  being engaged. 
     It is preferred to maintain radial alignment of the needle carrier  14  with the hub  12 , particularly with the secondary detent  54  being seated in the secondary channel  64 . Torque may be applied to the safety pen needle assembly  10  during mounting onto the injector I (for example, with the feature  20  being threads). To limit possible relative rotation between the needle carrier  14  and the hub  12  as a result of the applied torque, an alignment groove  70  may be formed in the hub  12  with a corresponding alignment tooth  72  being formed on the needle carrier  14 . As shown in  FIG. 17 , the alignment tooth  72  is seated in the alignment groove  70  so as to inhibit rotational movement between the needle carrier  14  and the hub  12 , yet permit relative longitudinal movement therebetween. A plurality of sets of alignment grooves  70 /alignment teeth  72  may be provided. 
     In an initial state, as described above, the shield  18  is moveable relative to the needle carrier  14 . The shield  18  may be releasably fixed to the needle carrier  14  to define an initial position. For example, primary recess  74  may be provided in the needle carrier  14 , located proximally of the recess  42  along the channel  50 . The detent  40  may be seated in the primary recess  74  in an initial state of the safety pen needle assembly  10 , prior to use. As will be appreciated by those skilled in the art, the relative positioning of the primary recess  74  will define whether the distal end  22  of the needle  16  will be covered in an initial state. Thus, with reference to  FIG. 2 , it is preferred that the primary recess  74  be located so that the shield  18  in fact covers the distal end  22  in an initial state. 
     It is preferred that the channel  50  be provided with sufficient length in a proximal direction so as to permit movement of the detent  40  proximally, with the shield  18  being retracted during use, particularly to expose the needle  16  sufficiently to perform an injection. The primary recess  74  may be positioned between the ramped surface  46  and a primary ramped surface  76  configured to rise in a proximal direction away from the primary recess  74 . Further, a holding recess  78  may be provided along the channel  50  formed to accommodate the detent  40 , particularly with the shield  18  being in a position desired for injection. This allows for the shield  18  to be releasably fixed to the needle carrier  14  with a proper working length of the needle  16  being exposed for the injection. A holding ramped surface  80  may be provided adjacent to the holding recess  78 . As best shown in  FIG. 8 , the primary ramped surface  76  and the holding ramped surface  80  may be disposed adjacent to one another so that both rise to a common ridge  82 . With this arrangement, during use, the detent  40  of the shield  18  is initially seated in the initial recess  66  then advanced proximally to the holding recess  78  for the injection and then advanced distally into locking snap engagement with the recess  42  post-injection. 
     To limit inadvertent activation of the shielding prior to injection, a storage channel  84  may be defined in the needle carrier  14  disposed transversely to the channel  50 . A storage recess  86  may be provided along the storage channel  84  having adjacent thereto a storage ramped surface  88 . Prior to use, the detent  40  may be seated in the storage recess  86 , out of longitudinal alignment with the channel  50 . To prepare for use, with the hub  12  mounted onto the injector I, as shown in  FIG. 14 , the shield  18  may be rotated relative to the hub  12  to align the detent  40  in the channel  50 ; such alignment may result in the detent  40  being seated in the primary recess  74 . It is noted that the feature  20  may be threads which require rotating mounting of the safety pen needle assembly  10  onto the injector I. It is thus preferred that the storage channel  84  extend from the channel  50  in a direction coincident with the direction of rotation necessary to mount the safety pen needle assembly  10  onto the injector I. Thus, for example, if clockwise rotation is required of the hub  12  relative to the injector I, it is preferred that the storage channel  84  extend generally in a clockwise direction away from the channel  50  (with viewing rotation from the same point). In this manner, the detent  40  is maintained in the storage recess  86  during mounting. In addition, torque applied to the shield  18  for mounting the safety pen needle assembly  10  may be transmitted through the interengagement of the detent  40  and the needle carrier  14 , e.g., transmitted to the end of the storage channel  84 . 
     In addition, the safety pen needle assembly  10  may be initially packed into a casing  90  for storage and transportation, as shown in  FIGS. 1 and 2 . A peelable foil or other covering may be applied to the casing  90  to seal the safety pen needle assembly  10  therein. To prevent inadvertently causing relative longitudinal movement between the needle carrier  14  and the hub  12  upon removal of the safety pen needle assembly  10  from the casing  90 , one or more fins  92  may be provided on the secondary cantilevered arms  58 . The fins  92  are dimensioned so as to restrict outward radial movement of the secondary detent  54  while in the casing  90 . In this manner, the secondary detent  54  is caused to remain seated in the initial recess  66 . Cut-outs  94  may be provided in the needle shield  18  as needed to slide over the fins  92  during use, for example, as shown in  FIG. 15 . 
     As shown in  FIG. 17 , the safety pen needle assembly  10  may be inserted into the casing  90  after use, at least partially, for disposal. 
     It is preferred that all of the components described herein, with the exception of the needle  16 , be formed of a thermoplastic material. Each of the hub  12 , the needle carrier  14 , the shield  18  and the casing  90  may be separately and unitarily formed by molding, for example, injection molding. To facilitate assembly, one or more ramped assembly surfaces  96  may be provided on the needle carrier  14  to facilitate mounting of the shield  18  thereonto, particularly with the gradual passage of the detent  40  into the storage channel  84  with mounting the shield  18  during assembly onto the needle carrier  14 . Likewise, the ramped assembly surfaces  96  may be provided on the hub  12  to permit gradual passage of the alignment tooth  72  into the alignment groove  70  with mounting the needle carrier  14  during assembly onto the hub  12 .