U.S. patent application number 13/061028 was filed with the patent office on 2011-06-30 for medical needle assembly.
Invention is credited to Barry Peter Liversidge.
Application Number | 20110160676 13/061028 |
Document ID | / |
Family ID | 39865934 |
Filed Date | 2011-06-30 |
United States Patent
Application |
20110160676 |
Kind Code |
A1 |
Liversidge; Barry Peter |
June 30, 2011 |
Medical Needle Assembly
Abstract
A needle assembly for an injection pen (22) has a sleeve (21)
supporting internally a double-ended needle having an injection end
and a non-injection end (25). The end of the sleeve surrounding the
non-injection end (25) of the needle is divided into deformable
segments (28) and is internally threaded for interengagement with a
threaded boss (23) of the injection pen (22). A collar (29) is
mounted on the sleeve (21) for sliding movement between a first
position where the collar (29) overlies the segmented end and
maintains interengagement of the threads at that end with those of
the injection pen boss (23) and a second position where the
segments may expand radially to come free of the injection pen boss
(23). The needle may be mounted on a carrier (68) slidable with
respect to the sleeve (21), the carrier (68) being coupled to the
sleeve (21) for movement thereby.
Inventors: |
Liversidge; Barry Peter;
(Colchester, GB) |
Family ID: |
39865934 |
Appl. No.: |
13/061028 |
Filed: |
August 28, 2009 |
PCT Filed: |
August 28, 2009 |
PCT NO: |
PCT/GB09/51094 |
371 Date: |
February 25, 2011 |
Current U.S.
Class: |
604/198 ;
604/206 |
Current CPC
Class: |
A61M 5/347 20130101;
A61M 5/3205 20130101; A61M 5/3293 20130101; A61M 2005/3253
20130101; A61M 5/2466 20130101; A61M 5/3245 20130101; A61M 5/3243
20130101; A61M 2005/3254 20130101 |
Class at
Publication: |
604/198 ;
604/206 |
International
Class: |
A61M 5/31 20060101
A61M005/31; A61M 5/32 20060101 A61M005/32 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 29, 2008 |
GB |
0815748.9 |
Claims
1. A needle assembly for connection to an injection pen having a
boss with external threads for receiving the needle assembly,
comprising: a sleeve supporting internally a double-ended needle to
extend axially of the sleeve, said needle having an injection end
and a non-injection end and the sleeve having a radially deformable
end provided with at least one internal profile for radial
interengagement with the threads of the pen boss such that with
full radial inter-engagement the sleeve is securely connected to
the injection pen, the needle being orientated with the
non-injection end directed towards said deformable end so that on
connection of the sleeve to an injection pen, the non-injection end
of the needle penetrates a drug reservoir within the pen; a collar
mounted around the sleeve for sliding movement between a first
position adjacent the deformable end at which the collar maintains
full radial inter-engagement of the profile with the threads of the
boss and a second position where the collar is displaced from said
end so that radial deformation of said end allows radial
disengagement of the profile from the threads whereby the needle
assembly may be pulled axially from the boss.
2. A needle assembly as claimed in claim 1, wherein the internal
profile is defined by an internally-threaded portion at said end of
the sleeve corresponding to the external threads formed on the pen
boss.
3. A needle assembly as claimed in claim 2, wherein there is at
least one generally axially-extending slit in the wall of the
sleeve at said deformable end whereby the effective diameter of the
deformable end may increase by enlargement of the slit.
4. A needle assembly as claimed in claim 3, wherein there is a
plurality of generally axially-extending slits in the wall of the
sleeve at said deformable end thereby dividing said end into a
plurality of segments.
5. A needle assembly as claimed in claim 4, wherein each segment is
provided internally with a respective profile for interengagement
with the threads of the pen boss.
6. A needle assembly as claimed in claim 1, wherein the needle is
mounted on a needle hub and the needle hub is supported internally
within the sleeve.
7. A needle assembly as claimed in claim 6, wherein the needle hub
is mounted within the sleeve for axial sliding movement with
respect thereto.
8. A needle assembly as claimed in claim 1, wherein there is
provided a shield mounted on the sleeve for sliding movement
between an injection position where the injection end of the needle
is exposed and a shielding position where the injection end of the
needle is covered by the shield.
9. A needle assembly as claimed in claim 8, wherein there is
provided means interconnecting the needle hub and the shield.
10. A needle assembly as claimed in claim 9, wherein the
interconnecting means serves to slide the needle hub so that the
non-injection end of the needle moves deeper into the sleeve on
movement of the shield to its shielding position.
11. A needle assembly as claimed in claim 10, wherein the
interconnecting means is arranged to give lost motion between
movement of the shield and movement of the needle hub.
12. A needle assembly as claimed in claim 8, wherein means are
provided to lock the shield in its shielding position once moved to
that position, thereby to restrain movement of the shield back
towards its injection position.
13. A needle assembly as claimed in claim 8, wherein the shield is
integrated with the collar.
14. A needle assembly as claimed in claim 1, wherein the collar is
unitary with a forward section of the sleeve, the needle is
supported on a hub within the forward section of the sleeve and the
deformable end of the sleeve is slidably mounted with respect to
the forward section such that forward movement of the collar to
allow radial enlargement of the deformable end of the sleeve takes
the non-injection end of the needle deeper into the sleeve, with
respect to the forward end thereof.
15. A needle assembly as claimed in claim 14, wherein means are
provided to lock the deformable end of the sleeve with respect to
the forward section thereof when the collar has been moved fully
forwardly.
16. A needle assembly for connection to an injection pen having a
boss with external threads for receiving the needle assembly,
comprising: a sleeve having internal threads at one end for
threaded engagement with the external threads of an injection pen
boss, the sleeve defining at least one guide extending along the
length thereof; a needle carrier slidably supported within the
sleeve and having a lug engaged with the guide of the sleeve and
projecting from the outer surface of the sleeve, the needle carrier
supporting a double-ended needle extending axially within the
sleeve; and a shield slidably supported on the sleeve and being
engaged with the projecting part of the needle carrier lug, whereby
forward sliding movement of the shield moves the needle carrier
forwardly within the sleeve, so moving the non-injection end of the
needle further from the one end of the sleeve.
17. A needle assembly as claimed in claim 16, wherein the shield is
provided with a groove extending along the length thereof and in
which the projecting part of the needle carrier lug is engaged
whereby the needle carrier moves through a smaller distance than
the shield, upon the shield moving from an injection position to a
shielding position.
18. A needle assembly as claimed in claim 16, wherein said one end
of the sleeve is formed into two or more divided segments and a
collar is mounted on the sleeve for sliding movement between a
first position at which the collar maintains full radial
interengagement of the segments with the external threads of the
injection pen boss and a second position where the collar is
displaced from said one end so that radial disengagement of the
threads is possible by radial deformation of the segments at said
one end.
19. (canceled)
20. A needle assembly as claimed in claim 18, wherein the internal
profile is defined by an internally-threaded portion at said end of
the sleeve corresponding to the external threads formed on the pen
boss.
21. A needle assembly as claimed in claim 20, wherein there is at
least one generally axially-extending slit in the wall of the
sleeve at said deformable end whereby the effective diameter of the
deformable end may increase by enlargement of the slit.
22. A needle assembly as claimed in claim 21, wherein there is a
plurality of generally axially-extending slits in the wall of the
sleeve at said deformable end thereby dividing said end into a
plurality of segments.
23. A needle assembly as claimed in claim 22, wherein each segment
is provided internally with a respective profile for
interengagement with the threads of the pen boss.
24. A needle assembly as claimed in claim 18, wherein the needle is
mounted on a needle hub and the needle hub is supported internally
within the sleeve.
25. A needle assembly as claimed in claim 24, wherein the needle
hub is mounted within the sleeve for axial sliding movement with
respect thereto.
26. A needle assembly as claimed in claim 18, wherein there is
provided a shield mounted on the sleeve for sliding movement
between an injection position where the injection end of the needle
is exposed and a shielding position where the injection end of the
needle is covered by the shield.
27. A needle assembly as claimed in claim 26, wherein there is
provided means interconnecting the needle hub and the shield.
28. A needle assembly as claimed in claim 27, wherein the
interconnecting means serves to slide the needle hub so that the
non-injection end of the needle moves deeper into the sleeve on
movement of the shield to its shielding position.
29. A needle assembly as claimed in claim 28, wherein the
interconnecting means is arranged to give lost motion between
movement of the shield and movement of the needle hub.
30. A needle assembly as claimed in claim 26, wherein means are
provided to lock the shield in its shielding position once moved to
that position, thereby to restrain movement of the shield back
towards its injection position.
31. A needle assembly as claimed in claim 26, wherein the shield is
integrated with the collar.
32. A needle assembly as claimed in claim 18, wherein the collar is
unitary with a forward section of the sleeve, the needle is
supported on a hub within the forward section of the sleeve and the
deformable end of the sleeve is slidably mounted with respect to
the forward section such that forward movement of the collar to
allow radial enlargement of the deformable end of the sleeve takes
the non-injection end of the needle deeper into the sleeve, with
respect to the forward end thereof.
33. A needle assembly as claimed in claim 32, wherein means are
provided to lock the deformable end of the sleeve with respect to
the forward section thereof when the collar has been moved fully
forwardly.
Description
[0001] This invention relates to a needle assembly for connection
to an injection pen having at its forward end a boss with external
threads for receiving a needle assembly.
[0002] Injection pens are very widely used for self administration
of injections. For example, such pens are used by those suffering
diabetes, to inject an appropriate amount of insulin for control of
the condition. Such a pen has a chamber for a vial of medicament
and a mechanism for ejecting a chosen volume of medicament from the
vial through an attached double-ended needle. The needles are used
only once and then thrown away; the needle is therefore provided
within a mount including a socket with internal screw-threads for
threading engagement with a threaded boss provided at the forward
end of the pen. The non-injection end of the needle is disposed
within the socket such that on threading the mount on to the boss
drives the non-injection end of the needle through a membrane at
the forward end of the vial, so as to communicate with the
medicament within the vial.
[0003] The injection end of the needle is protected by way of a
sheath which is removed immediately before an injection is to be
performed but after the connection of the needle to the pen boss.
Once the injection has been performed, the needle is unthreaded
from the boss and then disposed of in a suitable manner. The
unthreading of the needle from the pen boss exposes the user to
some risk of a needle stick injury and is not very easy to perform,
since the user will attempt to avoid the injection end of the
needle, unlike the situation before an injection has been
performed, where the injection end is sheathed and in any event has
not been contaminated. In an attempt to reduce the likelihood of a
needle stick injury, it is known to provide some kind of protection
for the injection end of the needle but the user still has to
unthread the used needle from the boss at the forward end of the
pen.
[0004] The non-injection end of the needle is located within the
internally-threaded socket of a needle assembly but the relatively
sharp end is accessible within that socket, both before the needle
assembly has been threaded on to a pen boss and subsequently when
the needle assembly has been removed by unthreading from the boss.
Slightly casual handling of the needle assembly as the unthreading
action is completed, so freeing the needle assembly, can result in
a needle stick injury from the non-injection end of the needle.
[0005] It is a principal aim of the present invention to provide a
needle assembly for use with an injection pen, which facilitates
the removal of a used needle assembly from the pen and which, in
its preferred aspects, enhances the protection of the non-injection
end of the needle, following removal of the assembly from an
injection pen.
[0006] According to this invention, there is provided a needle
assembly for connection to an injection pen having a boss with
external threads for receiving the needle assembly, comprising:
[0007] a sleeve supporting internally a double-ended needle to
extend axially of the sleeve, said needle having an injection end
and a non-injection end and the sleeve having a radially deformable
end provided with at least one internal profile for radial
interengagement with the threads of the pen boss such that with
full radial inter-engagement the sleeve is securely connected to
the injection pen, the needle being orientated with the
non-injection end directed towards said deformable end so that on
connection of the sleeve to an injection pen, the non-injection end
of the needle penetrates a drug reservoir within the pen; [0008] a
collar mounted around the sleeve for sliding movement between a
first position adjacent the deformable end at which the collar
maintains full radial inter-engagement of the profile with the
threads of the boss and a second position where the collar is
displaced from said end so that radial deformation of said end
allows radial disengagement of the profile from the threads whereby
the needle assembly may be pulled axially from the boss.
[0009] It will be appreciated that with the needle assembly of this
invention, the unused needle assembly is connected to the threaded
boss at the forward end of an injection pen in the conventional
way, by threading the assembly on to the boss. The needle is then
unsheathed and the injection performed, again in the conventional
way. Following completion of the injection, the needle assembly may
be removed from the pen boss simply by gripping the collar and
relatively separating the needle assembly and injection pen. Thus,
the collar may be pushed forwardly with respect to the rest of the
needle assembly, or the injection pen may be pulled rearwardly with
respect to the needle assembly. Either action allows the deformable
end of the sleeve to expand radially and so free the full
engagement of the internal profile at that end of the sleeve from
the threaded boss of the injection pen. Continued relative
separating force then moves the needle assembly free of the
injection pen, without the need for any rotational unthreading
action.
[0010] Said internal profile is advantageously defined by an
internally-threaded portion at the deformable end of the sleeve,
the threads of which portion correspond to the external threads
formed on the pen boss.
[0011] In a preferred embodiment, the radially deformable end has
at least one axially-extending slit and preferably two or three
such slits, whereby the effective diameter of the deformable end
may increase by the divided segments of the end relatively
separating. Such relative separation has the effect of enlarging
the slits, at the end of the sleeve, with the segments moving in
the radial direction. Each segment of the sleeve may be provided
internally with a respective profile for interengagement with the
threads of the pen boss.
[0012] The sleeve could be manufactured such that those segments
are normally in a cylindrical formation but may move radially
outwardly on being freed by the collar, or are normally in a flared
disposition but are moved radially inwardly upon the collar being
moved to its first position. In the case of the latter, it would be
possible for the needle assembly to be connected to a pen boss by
axial relative movement between the needle assembly and an
injection pen, whereafter the collar is moved axially relative to
the remainder of the needle assembly thereby to close radially the
sleeve segments and engage the threaded portions thereof with the
injection pen boss. Following this, small relative rotation between
the needle assembly and the injection pen may tighten the needle
assembly on the boss. In view of the difficulty of performing
essentially axial relative movement between the needle assembly and
the injection pen, this is not a preferred manner for connecting
the needle assembly to the injection pen.
[0013] Advantageously, the needle is mounted on a needle hub, which
hub is supported internally within the sleeve. In one embodiment,
the hub is fixed axially with respect to the sleeve but in an
alternate embodiment, the hub is mounted for axial sliding movement
with respect to the sleeve. In this case, means may be provided to
move the hub following the completion of an injection such that the
non-injection end of the needle is moved further into the sleeve,
thereby enhancing protection at the non-injection end of the
needle.
[0014] A shield may be provided on the sleeve for sliding movement
between an injection position, where the injection end of the
needle is exposed, and a shielding position where the injection end
of the needle is covered by the shield. Such protection shields are
known in association with medical needles used to perform
injections and may be passive, where the shield moves automatically
to the shielding position following the completion of an injection,
or active where the user has to perform some action to move the
shield to its shielding position. Either kind of protection shield
may be employed in association with the needle assembly of this
invention. In either case, a locking arrangement may be provided to
lock the shield in its shielding position, once moved there
following completion of an injection.
[0015] In a case where a needle hub is provided within the sleeve
and is arranged for movement with respect thereto, means may be
provided for interconnecting the needle hub and shield. That
interconnecting means may serve to slide the needle hub so that the
non-injection end of the needle is moved deeper into the sleeve on
movement of the shield to its shielding position. Advantageously, a
lost motion arrangement may be provided between the shield and
needle hub such that the needle hub moves through a smaller axial
distance than does the shield, on moving to its shielding
position.
[0016] In a preferred embodiment of this invention, the shield is
integrated with the collar, such that on the shield moving to its
shielding position, the radially deformable end of the sleeve may
expand radially to allow disconnection from the threaded pen boss
of the internal profile at the deformable end of the sleeve. Thus,
the sleeve may give active protection to the injection end of the
needle, in that it is gripped and pushed forwardly relative to an
injection pen to which the needle assembly has been connected and
this action then allows the deformable end of the sleeve to expand
radially such that the needle assembly may be pulled free of the
pen boss. In the alternative, the shield may be separate from the
collar and in this case may give passive protection and a separate
action is performed to move the collar forwardly and allow the
needle assembly to be pulled free of an injection pen boss.
[0017] According to another aspect of this invention, there is
provided a needle assembly for connection to an injection pen
having a boss with external threads for receiving the needle
assembly, comprising: [0018] a sleeve having internal threads at
one end for threaded engagement with the external threads of an
injection pen boss, the sleeve defining at least one guide
extending along the length thereof; [0019] a needle carrier
slidably supported within the sleeve and having a lug engaged with
the guide of the sleeve and projecting from the outer surface of
the sleeve, the needle carrier supporting a double-ended needle
extending axially within the sleeve; and [0020] a shield slidably
supported on the sleeve and being engaged with the projecting part
of the needle carrier lug, whereby forward sliding movement of the
shield moves the needle carrier forwardly within the sleeve, so
moving the non-injection end of the needle further from the one end
of the sleeve.
[0021] With this aspect of the invention, the shield may have a
first position where the needle projects from the forward end of
the sleeve and a shielding position where the shield has moved
forwardly and covers the injection end of the needle. For this
arrangement, a lost motion arrangement may be provided between the
slidably mounted needle carrier and the shield, such that the
needle carrier moves through a smaller distance than does the
shield, on moving from its first position to its shielding
position. In this way, when in its shielding position the injection
end of the needle will be covered by the shield and the
non-injection end of the needle will be moved deeper into the
sleeve to enhance the protection of that needle end.
[0022] By way of example only, several specific embodiments of
needle assembly for an injection pen and arranged in accordance
with this invention will now be described in detail, reference
being made to the accompanying drawings in which:--
[0023] FIG. 1 is an isometric view of a first embodiment of needle
assembly, shown in association with the forward end of an injection
pen;
[0024] FIG. 2 shows the needle assembly of FIG. 1 connected to the
pen;
[0025] FIG. 3 shows the first stage of the removal of the needle
assembly of FIGS. 1 and 2 from the pen;
[0026] FIG. 4 shows a further stage in the removal of the needle
assembly;
[0027] FIGS. 5 and 6 are further isometric views corresponding to
those of FIGS. 2 and 4, but partially cut away for clarity;
[0028] FIG. 7 is an isometric view, again partially cut away for
clarity, showing the needle assembly fully removed from the pen
injector;
[0029] FIG. 8 is an isometric view of a second embodiment of needle
assembly including a one-piece collar and protection shield, shown
with the shield separated from the assembly sleeve;
[0030] FIG. 9 shows the assembly of FIG. 8 connected to an
injection pen, ready for performing an injection;
[0031] FIG. 10 shows the first stage of the removal of the needle
assembly of FIGS. 8 and 9, from the pen;
[0032] FIG. 11 shows a further stage of the removal of the needle
assembly of FIGS. 8 and 9, with the shield locked in its shielding
position;
[0033] FIG. 12 is an isometric view of a third embodiment of needle
assembly including a shield for the non-injection end of the
needle;
[0034] FIGS. 13, 14 and 15 respectively show the connection of the
needle assembly of FIG. 12 to an injection pen, and the first and
second stages of the removal of that needle assembly from the
injection pen following the performance of an injection;
[0035] FIG. 16 shows the needle assembly of FIGS. 12 to 15,
following complete removal from an injection pen;
[0036] FIG. 17 is an isometric exploded view of a fourth embodiment
of needle assembly of this invention; and
[0037] FIGS. 18, 19 and 20 show successive stages in the connection
of the needle assembly of FIG. 17 to an injection pen and
subsequently the removal of the needle assembly from the pen.
[0038] The first embodiment of needle assembly for use with an
injection pen is shown in FIGS. 1 to 7. This needle assembly
comprises a sleeve 21 within which is supported a needle mount (not
shown) carrying a double-ended needle (also not shown) of a
conventional form and having an injection end able to project from
the forward end of the sleeve 21 and a non-injection end disposed
within the rearward end of the sleeve. The non-injection end of the
needle penetrates a membrane at the forward end of a vial of
medicament carried within an injection pen such as that shown at
22, when the needle assembly has been threaded on to a threaded
boss 23 provided at the forward end of the pen. The sleeve 21 at
its forward end has a retractable shield 24 which may be slid
rearwardly towards the pen once the assembly has been mounted
thereon, to expose the injection end of the needle, ready for
performing an injection.
[0039] The above features of an injection pen and needle assembly
are well known and form no part of this invention; as such they
will not be described in further detail here.
[0040] The non-injection end region 25 of the sleeve 21 is provided
with three slits 26 extending axially from the end face 27 of the
sleeve such that the end region is divided into three similar
segments 28. Each segment is formed internally with a portion of a
thread which corresponds to the thread on the boss 23 of the pen.
In its normal condition, the segments all lie on a common
cylindrical surface, though each segment may be deformed radially
outwardly such that the end region 25 of the sleeve has a greater
diameter than when the segments lie on a common cylindrical
surface, in the normal condition of the segments.
[0041] A collar 29 is slidably mounted on the external surface of
the sleeve 21 and may be slid between a first position shown in
FIG. 1, where the collar surrounds the segments 28, and a second
position shown in FIG. 3 where the collar is free of the segments
28, so allowing the non-injection end region 25 to expand radially.
The collar 29 is provided with external ribs 30 to assist gripping
of the collar by the fingers of a user and the movement of the
collar from its first position to its second position.
[0042] The external diameter of the end region 25 of the sleeve is
slightly smaller than the main part of the sleeve, a shoulder 31
being formed between the end region and the main part (FIGS. 5 and
6). Internally, the collar 29 has a forward portion 32 which is a
sliding fit on the main part of the sleeve and a rear portion 33
which is a sliding fit on the end region 25 of the sleeve. A
corresponding abutment surface 34 is formed between the forward and
rear portions of the collar which abutment surface engages the
shoulder 31 of the sleeve when the collar is moved to its second
position (FIG. 6).
[0043] FIG. 1 shows the needle assembly ready for threading on to
the threaded boss 23 of an injection pen 22. The needle assembly is
connected thereto in the conventional manner by threading the
needle assembly on to the boss (as shown in FIGS. 2 and 5), such
that the non-injection end of the needle is moved into
communication with a vial in the pen and then an injection is
performed again in the conventional manner.
[0044] Following completion of the injection, the injection pen is
held in one hand while the fingers of a user grip the ribbed part
of the collar 29 and the collar is moved axially away from the pen
22, so bringing the abutment surface 34 into engagement with
shoulder 31 (FIG. 3). This frees the segments 28 to expand radially
as shown in FIGS. 4 and 6 whereafter continued separating force
applied to the collar and pen pulls the entire needle assembly away
from the boss 23 as shown in FIG. 7. It will be appreciated that
removal of the needle assembly may be performed in one smooth
forward thrust on the collar 29 relative to the injection pen and
wholly obviates the need to unthread the used needle assembly from
the injection pen.
[0045] The second embodiment of needle assembly for use with an
injection pen is shown in FIGS. 8 to 11. This needle assembly
comprises a sleeve 36 carrying a needle 37 and a shield 38
incorporating a unitary collar 39. The sleeve is similarly formed
to that described above in relation to the first embodiment and
thus has a non-injection end region 40 divided by slits 41 into
segments 42, each segment having internal threads and normally
lying on a common cylindrical surface, as shown in FIG. 8. Three
projecting locking nibs 43 are provided externally on the main part
of the sleeve, partway along the length thereof and a rib 44 is
formed at the forward end of the sleeve.
[0046] Internally, the sleeve has a hub 45 which supports a
double-ended needle, the injection end of the needle being shown in
FIG. 8 and the non-injection end being disposed within end region
40 of the sleeve.
[0047] The shield 38 has its rearward end 47 to be a close sliding
fit on the external surface of the sleeve and the greater part of
the internal surface of the shield being a sliding fit on the rib
44 of the sleeve. At its forward end, the shield has a radial end
face 48 formed with a central hole 49 for the needle 37.
[0048] In use, the needle assembly is fitted to an injection pen 22
with the shield in its rearward position where the rear end of the
shield is essentially co-planar with the rear end of the sleeve, by
threading the needle assembly on to the boss 23. Though not shown
in FIG. 9, a sheath would extend over the needle during this
action. Following de-sheathing of the needle and the performance of
an injection, the assembly is removed by thrusting the shield 38
forwardly (FIG. 10) so taking the collar 39 clear of the
non-injection end region 40 of the sleeve. A continued forward
thrust on the shield 38 brings the rearward end 47 of the shield 38
into engagement with the rib 44 at the forward end of the sleeve,
with the rearward end of the sleeve forwardly of the nibs 43. The
shield is thus locked in its forward position, shielding the needle
and allowing radial enlargement of the non-injection end region of
the shield 38 (FIG. 11), such that a continued forward thrust on
the shield pulls the needle assembly clear of the injection pen
boss 23.
[0049] The third embodiment of needle assembly for use with an
injection pen is shown in FIGS. 12 to 16. This embodiment is
similar to that described with reference to FIGS. 1 to 7 but
differs from the first embodiment in that it includes enhanced
protection for the non-injection end of the sleeve.
[0050] In this embodiment, the sleeve 51 is formed in two pieces,
with a rearward section 52 being slidably received within a forward
section 53. The rearward section has its forward end portion formed
as a continuous ring 54 slidable within the forward section 53 and
the rearward end portion as separate segments 55 corresponding to
segments 28 of the first embodiment and thus which may be
threadingly engaged with the threaded boss 23 of an injection pen
22. The ring 54 has four externally-projecting nibs 56, for a
purpose to be described below.
[0051] The rear part of the forward section is formed as a collar
57 having external ribs 58 to facilitate gripping of the collar. A
double-ended needle (not shown other than the non-injection end of
which, in FIG. 12) is supported on a hub provided internally within
the forward section. The forward part of the forward section is
similarly formed to that of the first embodiment and so includes a
sliding shield which will not be described in further detail
here.
[0052] In use, the needle assembly is initially as shown in FIG.
12, with the collar 57 closely encircling the segments 55 and so
preventing radial enlargement of the rear end region of the
rearward section 52 of the sleeve. The needle assembly is threaded
on to the pen boss 23 in the conventional way as shown in FIG. 13
and an injection performed as described above. Following completion
of the injection, the collar 57 is gripped and is thrust forwardly
relative to the injection pen, so sliding the forward section 53
forwardly relative to the rearward section 52. Eventually, the
position shown in FIG. 14 is reached where the nibs 56 engage
behind the rear face of the forward section 53 of the sleeve and
prevent rearward movement of the forward section relative to the
rearward section. In effect, this action pulls the rearward section
rearwardly relative to the forward section and so also rearwardly
relative to the non-injection end of the needle, thus enhancing
protection to that non-injection end.
[0053] Once the position of FIG. 14 has been reached, continued
forward thrusting of the collar 57 relative to the pen 22 allows
the segments to expand radially as shown in FIG. 15 and so allow
the needle assembly to come free of the boss 23 without the need to
unthread the sleeve from the pen. FIG. 16 shows the needle assembly
thus separated and with the rearward section 52 of the sleeve
locked in its position extended out of the forward section 53.
[0054] The fourth embodiment of needle assembly for use with an
injection pen is shown in FIGS. 17 to 20. This needle assembly
comprises a sleeve 60 having a rearward end 61 internally threaded
for connection to a threaded boss at the forward end 62 of an
injection pen 63. The sleeve has three equi-spaced slots 64
extending from the forward end face, approximately half way along
the length of the sleeve. Externally, the sleeve is provided with
three projecting nibs 65.
[0055] A needle hub 66 supports a double-ended needle 67 the needle
hub including an annular carrier 68 provided with three lugs 69
receivable in the slots 64 and when so received, projecting beyond
the outer surface of the sleeve.
[0056] A shield 71 is slidably carried on the sleeve 60 and has
three equi-spaced slots 72 within which the projecting parts of the
lugs 69 are received when the shield is assembled to the sleeve. At
its forward end, the shield 71 has an end face 73 formed with a
central hole 74 through which the injection end 75 of the needle 67
may project when the shield has been moved rearwardly.
[0057] The three components shown in FIG. 17 are assembled together
with the shield moved to its rearward position such that the
injection end 75 of the needle projects through central hole 74, as
shown in FIG. 18, but with a sheath (not shown) over the projecting
part of the needle. When in this disposition, the needle assembly
is threaded on to an injection pen threaded boss so that the
non-injection end of the needle penetrates the end membrane of a
vial of medicament within the pen. The needle is unsheathed and the
injection performed in the usual way.
[0058] Following completion of the injection, the shield 71 is slid
forwardly until the closed ends of the slots 72 in the shield
engage the lugs 69 whereupon those lugs prevent further forward
movement of the shield relative to the sleeve 60. When in this
position (FIGS. 19 and 20) the nibs 65 engage behind the rear end
face of the shield 71 and so prevent the shield being moved
rearwardly, towards the injection pen. Thereafter, the assembly may
be unscrewed from the injection pen with the shield remaining
locked and so preventing the risk of needle stick injury.
[0059] Though not shown in FIGS. 17 to 20, the rearward end 61 of
the sleeve 60 may be configured as has been described above with
reference to the first to third embodiments. In this case, the
rearward end 61 may be formed into two or more segments divided by
slits such that the segments may move radially outwardly to
increase the effective diameter of the sleeve at the rearward end.
The shield, when in its rearward position shown in FIG. 18, may act
as a collar for the segments and so prevent radial enlargement of
the rearward end of the sleeve. When the shield is gripped and is
slid forwardly away from the injection pen, the segments are freed
to expand radially and so allow the needle assembly as a whole to
be pulled axially away from the injection pen.
* * * * *