U.S. patent application number 11/387645 was filed with the patent office on 2007-07-26 for injection device.
This patent application is currently assigned to The Medical House plc. Invention is credited to Kevin Stamp.
Application Number | 20070173770 11/387645 |
Document ID | / |
Family ID | 37491318 |
Filed Date | 2007-07-26 |
United States Patent
Application |
20070173770 |
Kind Code |
A1 |
Stamp; Kevin |
July 26, 2007 |
Injection device
Abstract
An injection device comprising a housing in which can be mounted
a syringe comprising a barrel for holding a volume of medicament, a
needle at one end of, the barrel and a plunger axially-moveable in
the barrel to a forwardmost position, the injection device further
comprising a syringe support means for supporting the barrel at an
axial location at or forward of the forwardmost position of the
plunger and having a reaction surface for the syringe, whereby in
use said reaction surface provides an axial compressive force on
said barrel when a forward axial force is applied to the
plunger.
Inventors: |
Stamp; Kevin; (Chapeltown,
GB) |
Correspondence
Address: |
SHERIDAN ROSS PC
1560 BROADWAY
SUITE 1200
DENVER
CO
80202
US
|
Assignee: |
The Medical House plc
Sheffield
GB
|
Family ID: |
37491318 |
Appl. No.: |
11/387645 |
Filed: |
March 22, 2006 |
Current U.S.
Class: |
604/187 |
Current CPC
Class: |
A61M 5/2033 20130101;
A61M 5/326 20130101; A61M 2005/3118 20130101; A61M 5/3202 20130101;
A61M 2005/206 20130101; A61M 5/3129 20130101 |
Class at
Publication: |
604/187 |
International
Class: |
A61M 5/00 20060101
A61M005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2006 |
GB |
GB0601309.8 |
Feb 7, 2006 |
GB |
GB0602411.1 |
Mar 21, 2006 |
GB |
GB0605644.4 |
Claims
1. An injection device comprising a housing in which can be mounted
a syringe comprising a barrel for holding a volume of medicament, a
needle at one end of the barrel and a plunger axially-moveable in
the barrel to a forwardmost position, the injection device further
comprising a syringe support means for supporting the barrel at an
axial location at or forward of the forwardmost position of the
plunger and having a reaction surface for the syringe, whereby in
use said reaction surface provides an axial compressive force on
said barrel when a forward axial force is applied to the
plunger.
2. Injection device as claimed in claim 1 wherein, in use, said
reaction surface provides an axial compressive force to the front
shoulder of the syringe barrel.
3. Injection device as claimed in claim 1 wherein, in use, said
reaction surface provides an axial compressive force to the front
cone of the syringe barrel.
4. Injection device as claimed in claim 1 wherein said syringe
support means includes one or more inwardly-directed protrusions
forming said reaction surface.
5. Injection device as claimed in claim 4 wherein said
inwardly-directed protrusions are on the end of one or more
radially-flexible fingers.
6. Injection device as claimed in claim 5 wherein said
inwardly-directed protrusions comprise an inwardly-directed
enlarged head on the or each radially-flexible finger.
7. Injection device as claimed in claim 5 further comprising a
spring retainer, preferably made from steel, for urging the or each
radially-flexible finger inwardly.
8. Injection device as claimed in claim 4 wherein the internal
diameter between said inwardly-directed protrusions is smaller than
the exterior diameter of the syringe barrel.
9. Injection device as claimed in claim 8 wherein, when the device
is fully assembled ready for use, said inwardly-directed
protrusions are axially located between a needle cover and the
front shoulder of the syringe barrel.
10. Injection device as claimed in claim 1 wherein said syringe
support means is generally cylindrical and of a diameter less than
the diameter of the finger flange of the syringe barrel so that the
syringe support means is suitably sized to closely surround the
barrel of the syringe, in use.
11. Injection device as claimed in claim 1 wherein said syringe
support means is capable of supporting said syringe barrel, at a
specific axial location with respect thereto.
12. Injection device as claimed in claim 1 wherein said syringe
support means includes one or more viewing windows, to permit a
user to view the barrel of a syringe supported therein.
13. Injection device as claimed in claim 1 wherein said syringe
support means further comprises one or more alignment tags at the
front end thereof.
14. Injection device as claimed in claim 13 further comprising a
front housing having a bore therethrough, the interior surface of
the bore being provided with one or more longitudinal slots,
positioned so that said alignment tags can locate therein, when
said front housing and syringe support means are assembled
together.
15. Injection device as claimed in claim 14 wherein the or each
longitudinal slot comprises a rear section having a
forwardly-increasing depth and a forward section having
substantially constant depth.
16. Injection device as claimed in claim 15 wherein a boundary
between the rear and forward sections is defined by a step.
17. Injection device as claimed in claim 16 further comprising an
end cap having internal protrusions therein which protrude into the
longitudinal slots in the bore of the front housing, when said end
cap and said front housing are assembled together, so that a space
is defined between said internal protrusions in the end cap and
said step in the front housing.
18. Injection device as claimed in claim 17 wherein the alignment
tags of the syringe support means locate into said defined space to
determine the axial location of the syringe support means with
respect to said front housing.
19. Injection device as claimed in claim 14 wherein said syringe
support means includes a radially-extending flange, of greater
diameter than the interior diameter of said front housing.
20. Injection device as claimed in claim 17 wherein, when assembled
together, said end cap, front housing and syringe support
substantially prevent damage to or movement of a needle cover on
the needle of a syringe mounted in the device.
21. Injection device as claimed in claim 1 wherein the finger
flange of the syringe barrel does not contact the syringe support
means during delivery of the medicament.
22. Injection device as claimed in claim 5, wherein said
radially-flexible fingers can flex sufficiently outwardly to allow
a needle cover or the like of larger diameter than the internal
diameter between said radially-flexible fingers to pass thereby
during assembly of a syringe into said injection device.
23. Injection device as claimed in claim 22 when dependent on claim
18 wherein said axial location of the syringe support means with
respect to the front housing is such that said radially-flexible
fingers are not confined within said front housing and are free to
flex radially, when the front housing and syringe support means are
assembled together and before assembly of a rear part-assembly of
the device thereto.
24. Injection device as claimed in claim 22 wherein, when the
device is fully assembled ready for use, said, inwardly-directed
protrusions closely abut the needle cover to reduce the risk of
said needle cover becoming loose or detached from the needle.
25. An injection device as claimed in any of the preceding claims,
in which is mounted a syringe comprising a barrel for holding a
volume of medicament, a needle at one end of the barrel and a
plunger axially-moveable in the barrel to a forwardmost
position.
26. A method of assembling an injection device comprising the steps
of: providing a first part-assembly comprising a front housing and
a closely fitting end cap; providing a second part-assembly
comprising a rear part of the injection device; providing a syringe
comprising a barrel for holding a volume of medicament, a needle at
one end of the barrel and a plunger axially-moveable in the barrel;
providing a syringe support means; inserting the syringe axially
into the rear end of the syringe support means until said syringe
support means supports the syringe at a predetermined axial
location; inserting the front end of said syringe and syringe
support means into said first part-assembly; assembling said first
part-assembly and second part-assembly together.
27. A method of assembling an injection device comprising the steps
of: providing a first part-assembly comprising a syringe support
means, a front housing and a closely fitting end cap; providing a
second part-assembly comprising a rear part of the injection
device; providing a syringe comprising a barrel for holding a
volume of medicament, a needle at one end of the barrel and a
plunger axially-moveable in the barrel; inserting the syringe
axially into the rear end of the first part-assembly until said
syringe support means supports the syringe at a predetermined axial
location; assembling said first part-assembly and second
part-assembly together.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 U.S.C.
.sctn.119 to United Kingdom Patent Application Nos. GB0601309.8
filed Jan. 23, 2006, GB0602411.1 filed Feb. 7, 2006, and GB ______
filed Mar. 21, 2006. The entire disclosures of the above-referenced
patent applications are incorporated herein by reference in their
entirety.
FIELD
[0002] This invention relates to the field of injection devices for
the administration of liquid medication, for example,
interferon.
BACKGROUND
[0003] One typical known device is described in WO00/09186
(Medi-Ject Corporation) for "Needle assisted jet injector" and this
document gives a useful summary of other prior art devices.
[0004] The device of WO 00/09186 includes a needle which is, in one
embodiment, retractably located within an injector nozzle assembly.
Upon activation of a force-generating source, a portion of the
needle extends past the nozzle assembly and penetrates the outer
layer of skin to deliver medicament via jet injection to a deeper
region. After activation, the needle retracts back into the nozzle
assembly. The retractable needle is housed within the nozzle and is
pushed forward so that it emerges in order to deliver an injection
by the liquid medicament itself, when the medicament is itself
pushed forward by the plunger.
[0005] Another injection device is described in our co-pending
international patent application, published under number WO
2005/070481. Some of the reference numerals in the present
application correspond with the equivalent components in the device
described in WO 2005/070481. This device requires that the needle
is moved axially so that it can appear beyond the end of the nozzle
for the duration of the injection, after which the needle retracts
automatically, so that it is never in sight of the user. The device
also requires that the plunger is moved axially so that medicament
is ejected. The overall complexity of the injection device is
significantly reduced by both of these requirements being effected
by one component, namely an inner housing and the device has the
significant advantage that it can be built around a conventional or
standard syringe presentation.
[0006] The injection device of WO 2005/070481 is designed to be
used in conjunction with a standard drug presentation e.g. a
syringe comprising a needle, barrel preloaded with medicament and a
plunger. There is a significant commercial advantage in being able
to use a standard syringe, which will have been subjected to
numerous clinical trials, drug stability studies and regulatory
approval. Any modification to the standard syringe may require
further trials and approval, adding delay and expense. The present
invention is relevant to any injection device for use in
conjunction with a syringe (whether preloaded or not and whether
single-use or reusable), not only the device described in WO
2005/070481.
[0007] The barrel of a syringe is usually glass, since glass has
the most favourable storage properties for many drugs. However,
glass is notoriously fragile and there is a risk of damage or
breakage of the syringe during injection if the forces to which the
syringe is subjected by the injection device are not properly
controlled. This is particularly so where the liquid medicament is
relatively viscous, requiring greater force to expel it from the
syringe via the needle. Barrels made of materials other than glass,
for example polyethylene or cyclic olefin polymers are less brittle
when subjected to normal forces during injection, but still would
benefit from the invention described below.
[0008] In the known device described in our co-pending patent
application no WO 2005/070481 and illustrated in FIGS. 1-3 of the
present application, the syringe is supported within the injection
device by a barrel or syringe holder 9. The syringe holder 9
comprises an elongate housing which closely surrounds the glass
barrel of the syringe. The annular flange 90 at the rear of the
syringe barrel rests on a barrel seat 91 at the rear of the syringe
holder 9. The annular flange 90 at the rear of the syringe barrel
is often referred to as a "finger flange" because, during a
conventional (manual) injection using a syringe, the user's index
and middle fingers rest naturally in front of the "finger flange"
in order to provide the necessary resistance to allow depression of
the plunger by the thumb to deliver the medicament.
[0009] The barrel seat, for example in the form of an annular
flange, preferably prevents forward axial movement of the syringe
with respect to the syringe holder so that, in use, the syringe
barrel and the syringe holder move axially together as one
unit.
[0010] In use, as described in WO 2005/070481, there are three
stages of delivering an injection. Before delivering an injection
(referring to FIG. 1 of the present application), the end cap 15 is
pulled off, taking the rigid needle cover 17 (if present) and
rubber needle sheath 16 with it. In the first stage of delivering
an injection, as shown in FIG. 2 of the present application, the
tags 7B at the forward end of the inner housing 7 are in contact
with the syringe barrel 90, which is pushed axially forward (taking
the syringe holder 9 with it), so that the needle 10, which is
fixed to the front end of the barrel, moves in the direction
indicated by the arrow so that eventually it protrudes beyond the
nozzle 11 at the front of the device. Forward travel of the barrel
and syringe holder is limited when a surface 9A of the syringe
holder reaches an endstop 11A inside the nozzle or front housing
11.
[0011] Referring now to FIG. 3, the second stage of the injection
is the delivery of the medicament wherein the tags 7A at the rear
of the inner housing 7 depress the plunger 8 into the barrel of the
syringe. During this stage, the barrel of the syringe is held
axially stationary, by abutment of the annular "finger" flange 90
against the barrel seat 91, which results in the barrel being
placed in tension as the plunger pushes the non-compressible liquid
medicament towards the forward end of the barrel. This tension is
undesirable in a glass barrel, which may become damaged or broken,
especially if the medicament comprises a particularly viscous
liquid which requires greater force to expel it from the syringe
via the needle. Viscous medicaments are desirable in certain
applications, where the use of a sustained-release viscous
medicament reduces the frequency that an injection is required.
[0012] It is desirable to minimise the diameter of the needle so
far as is possible, because the smaller the diameter of the needle,
the less painful is the resulting injection. However, for a given
length of needle, the smaller the needle diameter, the greater the
force required to eject the medicament from the syringe.
[0013] It is also desirable to minimise the duration of the
injection, i.e. to maximise the speed at which the medicament is
delivered from the syringe. Particularly when the needle diameter
is small, minimising the duration of the injection also means an
increase in the force used to eject the medicament from the
syringe.
[0014] An increase in the forces on the syringe consequently
increases the likelihood of the syringe breaking during the
injection. The risk of the syringe breaking during injection is
significant, and is not only inconvenient and costly but is also
potentially dangerous. If breakage occurs, it is possible :that
glass fragments and/or the needle may become detached and exit the
front of the device causing injury. Furthermore, there is the risk
that the remaining medicament will leak or be ejected from the
device in an uncontrolled manner, potentially delivering the wrong
dose into the patient, or causing injury e.g. if the medicament
contacts the patient's skin or eyes. These problems are amplified
when the medicament is viscous as a more powerful energy source is
needed in such applications so that the forces involved are
greater. It is known that a typical breakage of the syringe during
injection would occur at the finger flange, whereby the finger
flange 90 on the syringe barrel breaks as a result of its abutment
against the barrel seat 91. It is therefore highly desirable to
minimise the likelihood of breakage of the syringe. In the third
stage of the injection (not illustrated in the present application
but shown in WO 2005/070481), once the medicament has been
delivered and the inner housing 7 is no longer in contact with the
barrel or plunger of the syringe, the secondary spring 12 pushes
the syringe holder (and hence the syringe contained therein)
axially rearwardly so as to retract the syringe back into the
housing so that the used needle is concealed from view.
SUMMARY OF THE INVENTION
[0015] According to a first aspect of the present invention, there
is provided an injection device comprising a housing in which can
be mounted a syringe comprising [0016] a barrel for holding a
volume of medicament, [0017] a needle at one end of the barrel and
[0018] a plunger axially-moveable in the barrel to a forwardmost
position, the injection device further comprising a syringe support
means for supporting the barrel at an axial location at or forward
of the forwardmost position of the plunger and having a reaction
surface for the syringe, whereby in use said reaction surface
provides an axial compressive force on said barrel when a forward
axial force is applied to the plunger.
[0019] According to a second aspect of the invention there is
provided a method of assembling an injection device comprising the
steps of: [0020] providing a first part-assembly comprising a front
housing and a closely fitting end cap; [0021] providing a second
part-assembly comprising a rear part of the injection device;
[0022] providing a syringe comprising a barrel for holding a volume
of medicament, a needle at one end of the barrel and a plunger
axially-moveable in the barrel; [0023] providing a syringe support
means; [0024] inserting the syringe axially into the rear end of
the syringe support means until said syringe support means supports
the syringe at a predetermined axial location; [0025] inserting the
front end of said syringe and syringe support means into said first
part-assembly; [0026] assembling said first part-assembly and
second part-assembly together.
[0027] According to a third aspect of the invention there is
provided a method of assembling an injection device comprising the
steps of: [0028] providing a first part-assembly comprising a
syringe support means, a front housing and a closely fitting end
cap; [0029] providing a second part-assembly comprising a rear part
of the injection device; [0030] providing a syringe comprising a
barrel for holding a volume of medicament, a needle at one end of
the barrel and a plunger axially-moveable in the barrel; [0031]
inserting the syringe axially into the rear end of the first
part-assembly until said syringe support means supports the syringe
at a predetermined axial location; [0032] assembling said first
part-assembly and second part-assembly together.
[0033] Further features of the invention are defined in the
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Preferred embodiments of the present invention will now be
more particularly described, by way of example only, with reference
to the accompanying drawings in which:
[0035] FIG. 1 (PRIOR ART) is a perspective view of a known
injection device;
[0036] FIG. 2 (PRIOR ART) is a plan view, partly in section of the
FIG. 1 device, with the cap and needle cover removed, ready for
actuation;
[0037] FIG. 3 (PRIOR ART) is a plan view, partly in section of the
FIG. 1 device, with the needle exposed, ready for the plunger to be
depressed in order to deliver the medicament;
[0038] FIG. 4 is a perspective view of an injection device
embodying one aspect of the present invention;
[0039] FIG. 5 is a plan view, partly in section of the FIG. 4
device, with the cap and needle cover removed, ready for
actuation;
[0040] FIG. 6 is a plan view, partly in section of the FIG. 4
device, with the needle exposed, ready for the plunger to be
depressed in order to deliver the medicament;
[0041] FIG. 7 is a perspective view of the syringe holder;
[0042] FIG. 8 is a cross-sectional view of the syringe holder of
FIG. 7;
[0043] FIG. 9 is a cross-section view of the syringe holder of FIG.
7, showing a syringe in place;
[0044] FIG. 10 is a cross-section view of the syringe holder of
FIG. 7, showing a syringe and rigid needle cover in place;
[0045] FIG. 11 shows detail, drawn to a larger scale, of the
interface between the front of the glass syringe barrel and the
syringe holder illustrated in FIG. 10;
[0046] FIG. 12, drawn to a larger scale, is a cross-sectional view
of the modified front housing;
[0047] FIG. 13, drawn to a larger scale, is a perspective
cross-sectional view of the front housing;
[0048] FIG. 14 is a cross-sectional view of the front housing, cap
and syringe holder assembled together;
[0049] FIG. 15 is a perspective view of the front housing, cap and
syringe holder assembled together;
[0050] FIG. 16 is a cross-sectional view of the front housing, cap,
syringe holder and syringe assembled together;
[0051] FIG. 17 is a cross-sectional view of an alternative
embodiment of the syringe holder;
[0052] FIG. 18 is a part-assembly view showing the syringe holder
of FIG. 17 together with its spring retainer, a syringe therein and
the end cap and front housing;
[0053] FIG. 19 shows the part-assembly of FIG. 18 with the rigid
needle cover removed;
[0054] FIG. 20 is a perspective view of the syringe holder of FIG.
17 together with its spring retainer;
[0055] FIG. 21 is a perspective view of a syringe holder, end cap
and front housing, showing an alternative means of retaining the
gripping means against the syringe barrel;
[0056] FIG. 22 is a perspective view of the syringe holder of WO
2005/070481, modified in accordance with an alternative embodiment
of the invention; and
[0057] FIG. 23 is a perspective view of another embodiment of the
syringe holder together with a needle cover.
DETAILED DESCRIPTION
[0058] Throughout the description and claims of this specification,
the words "comprise" and "contain" and variations of the words, for
example "comprising" and "comprises", means "including but not
limited to", and is not intended to (and does not) exclude other
components, integers or steps.
[0059] Throughout the description and claims of this specification,
the singular encompasses the plural unless the context otherwise
requires. In particular, where the indefinite article is used, the
specification is to be understood as contemplating plurality as
well as singularity, unless the context requires otherwise.
[0060] Throughout the following description, reference to a
"forward" direction means the direction which is towards the
patient when the injection device is in use. The "forward" end of
the injection device is the end nearest the patient's skin when the
device is in use. Similarly, reference to a "rearward" direction
means the direction which is away from the patient and the
"rearward" end of the device is the end furthest from the patient's
skin when the injection device is in use.
[0061] Features, integers, characteristics or groups described in
conjunction with a particular aspect, embodiment or example of the
invention are to be understood to be applicable to any other
aspect, embodiment or example described herein unless incompatible
therewith.
[0062] As described above, a disadvantage of the known prior art is
that the barrel of the syringe is placed in tension as the plunger
pushes the non-compressible liquid medicament towards the forward
end of the barrel for delivery. This tension is undesirable in a
glass barrel, which may become damaged or broken, especially if the
medicament comprises a particularly viscous liquid which requires
greater force to expel it from the syringe. There is a possibility
that the glass syringe might break in the region of its finger
flanges, as a result of the forces to which it is subjected during
delivery of an injection. One way to mitigate this problem is to
reduce the effect of those forces in the region of the finger
flanges. For example, the syringe holder of WO 2005/070481 can be
modified as illustrated in FIG. 22. The syringe holder 9 has a
helical slit 92 which, in use, provides resilience to the region of
the barrel seat 91 on which is located the finger flange of the
syringe (not. illustrated). The resilient flexing absorbs shock and
reduces the risk of breakage of the syringe in the region of the
finger flanges.
[0063] Other means for reducing the effect of forces in the region
of the finger flanges can be envisaged, for example, providing a
cushion in the form of an O-ring or moulding a relatively soft or
elastomeric material into a harder substrate in the region of the
barrel seat 91.
[0064] It is known that a typical breakage of the syringe during
injection would occur at the finger flange, whereby the finger
flange 90 on the syringe barrel breaks as a result of its abutment
against the barrel seat 91. However, the applicant has recognised
that it is also possible that the syringe could break at the
forward end of the barrel. This is potentially more serious as
larger straight glass fragments may be ejected from the front of
the device, as well as the unsecured needle, and any remaining
medicament will leak out in an uncontrolled manner.
[0065] The risk of breakage or damage to the glass syringe may be
reduced by ensuring that the barrel is held in compression during
delivery of the medicament (stage two of the injection process
described in WO 2005/070481), rather than being in tension. This
can be achieved by supporting the forward end of the barrel and
having a reaction surface at which an axial compressive force can
be applied to the barrel when a forward axial force is applied to
the plunger during delivery of the medicament.
[0066] In the injection device of the present invention, the
conventional syringe holder 9 is replaced with a more complex
syringe holder which is capable of supporting the syringe at the
front end of its barrel instead of at its rear flange 90 during
delivery of the medicament. In the embodiment described below, the
syringe holder supports the syringe at the front shoulder of its
barrel and provides a reaction surface there for the front shoulder
of the barrel. By "front shoulder" is meant the region at which the
largest diameter of the barrel reduces to a smaller diameter at the
nozzle. The front shoulder 92 is indicated in FIG. 9.
Alternatively, the syringe could be supported and the reaction
surface provided at the front end of the syringe barrel, or at the
narrowed "cone" where the needle is attached thereto and these
embodiments are described in more detail below. The syringe can, in
fact, be supported at any place on the barrel which, in use, is
forward of the forwardmost position of the fully-depressed syringe
plunger and where a reaction surface for the syringe can be
provided (so that the barrel is held in compression throughout the
delivery of the medicament).
[0067] However, the desired supporting or holding of the barrel by
the syringe holder at its front end presents an assembly difficulty
for a product where it is desired to keep manufacturing and
assembly costs to a minimum. In the prior art device, the syringe
can simply be dropped into the rear end of the syringe holder until
its flange 90 rests on the barrel seat 91. This determines the
axial position of the syringe with respect to the syringe holder.
In practice, the prior art syringe holder is supplied
ready-assembled with the front part of the device, so that the
pre-filled syringe can simply be dropped into the syringe holder
and then the front part of the device (including the syringe) can
be attached to the ready-assembled rear part of the device in a
simple two-stage assembly operation.
[0068] In the present invention, it is not possible to use the
finger flange 90 and barrel seat to determine the axial position of
the syringe with respect to the syringe holder. This is because the
syringe holder needs to actively support the syringe at its front
end (preferably at the front shoulder 92 of the glass barrel). In
the preferred embodiment there are inwardly-directed gripping means
to retain the front shoulder of the glass barrel at a specific
axial location with respect to the syringe holder. The standard
syringe is usually supplied with a rigid needle cover 17 which has
a diameter almost the same as the largest diameter of the glass
barrel (see FIG. 10). If the syringe is inserted into the syringe
holder needle-first (or rather needle-cover first), any
inwardly-directed gripping means would foul on the rigid needle
cover as it attempts to pass. There is also the risk of the needle
being damaged during assembly, for example if it is pushed into any
inwardly-directed gripping means. Such damage to the needle is
highly undesirable, in particular because it often cannot be
readily detected (if the needle is concealed within a rigid needle
cover and/or a rubber needle sheath. The damage to the needle only
becomes apparent during delivery of the medicament.
[0069] This problem is solved by the use of a syringe holder 100 as
illustrated in FIGS. 7 and 8. The syringe holder 100 comprises an
elongate rear portion 102 in which there are viewing windows 103 so
that the medicament chamber in the barrel of a syringe held therein
would be visible. There is a barrel seat 101 (equivalent to barrel
seat 91 in the prior art device) at the rear end of the rear
portion 102, but in practice this is not intended to abut the
flange 90 of the syringe barrel (unlike in the prior art
device).
[0070] The syringe holder also has an intermediate portion 105 of
comparable diameter to the rear portion, and a front portion 106 of
narrower diameter. The intermediate portion 105 is provided with a
discontinuous annular flange 104. Together, the intermediate and
front portions 105, 106 include radially-spaced slots 107 which
define a plurality of radially flexible fingers 108. In the
illustrated embodiment, there are three flexible fingers 108, but
four or some other number of fingers may be provided. FIG. 23 shows
an embodiment in which four flexible fingers 108 are provided on
the syringe holder 100. The four fingers necessarily each are
thinner than those in the three-finger embodiment. A typical needle
cover 17 is shown in FIG. 23 (illustrated without the rest of the
syringe for simplicity). The needle cover has a slot 17A therein.
If the syringe holder 100 is appropriately aligned with the needle
cover of a syringe held therein, there is a possibility that one of
the relatively thin flexible fingers 108 may undesirably snag or
drop into slot 17A, possibly causing damage to the underlying
needle that would not become apparent until an injection is
delivered. This disadvantage can be overcome by ensuring that each
of the flexible fingers 108 is preferably wider than the needle
cover slot 17A, as illustrated by the three-finger embodiment of
FIG. 7.
[0071] As shown in FIG. 8, gripping means 109 preferably in the
form of a discontinuous annular inwardly-directed protrusion, are
provided on the interior of the flexible fingers 108 in the
intermediate section 105. Referring to FIG. 9, when a syringe is
located within the syringe holder 100, the gripping means 109 abuts
the front shoulder 92 of the barrel in order to define the axial
position of the barrel with respect to the syringe holder.
[0072] The term "gripping means" is not limited to means which grip
radially-inwardly onto the barrel, although in some embodiments
they may do so. More important is the fact that the gripping means
109 (or equivalent) supports the syringe in a desired axial
location and provides a reaction surface for the syringe so that
the barrel will be held in compression during delivery of the
medicament.
[0073] As can be seen from FIGS. 10 and 11, the rigid needle cover
17 has a greater diameter than the diameter normally available at
the gripping means 109. In other words, the internal diameter
between the gripping means 109 is smaller than the exterior
diameter of the needle cover 17. However, as will be explained in
more detail below, when the syringe is inserted into the syringe
holder, as the rigid needle cover 17 passes the gripping means 109,
the flexible fingers 108 flex radially-outwardly to create
sufficient diameter for the needle cover to pass the
inwardly-protruding gripping means, without exerting excessive
force on the needle therein, thus minimising the risk of damage to
the needle. Once the needle cover has passed, the flexible fingers
108 spring back into their normal position (having smaller internal
diameter than the exterior diameter of the needle cover) and the
gripping means 109 locate at the front shoulder 92 of the barrel.
In this position, the gripping means 109 are axially located
between the needle cover and the front shoulder of the barrel.
[0074] The front portion 106 of the syringe support 100 is provided
with a plurality (preferably two) equispaced tags 110, whose
purpose will be described later below.
[0075] The most straightforward way to,assemble the syringe and
injection device is in a three stage procedure, namely: [0076] 1.
inserting the syringe into the syringe holder, until the gripping
means 109 locate at the front shoulder 92 of the barrel; [0077] 2.
inserting the syringe and syringe holder into the front part of the
injection device; [0078] 3. assembling the front part to the rear
part of the injection device.
[0079] Compared with the two-stage assembly procedure of the prior
art device, the extra assembly stage is disadvantageous but
initially seems necessary as it is not obvious how stages 1 and 2
could be readily combined so that the syringe holder can be
supplied ready-assembled with the front part of the device. This is
because, once assembled into the front part of;the device, the
flexible fingers 108 would be prevented from flexing radially
outwardly by their necessarily close abutment with the front
housing, thus preventing insertion of the syringe and rigid needle
cover.
[0080] Therefore, in a further embodiment of the invention, a
modified front housing for the injection device is provided which
enables a two-stage assembly procedure to be used.
[0081] The modified front housing 200 (analogous to nozzle 11 in
the prior art) is illustrated in FIG. 12. The front housing 200 has
a bore 201, of sufficient diameter to allow passage therethrough of
the needle 10, needle cover 17 and the front and intermediate
portions 105,106 of the syringe holder (but not the flange
104).
[0082] The interior surface of the bore 201 is provided with two
(or more) equispaced longitudinal slots 202, each having a rear
section 203 with a tapered surface providing a varying depth and a
forward section 204 of substantially constant depth. The boundary
between the forward and rear sections of each slot 202 is defined
by a step 205.
[0083] The slots 202 are positioned so that they can be aligned
with the tags 110 at the front portion of the syringe holder.
[0084] The slots 202 enable the syringe holder 100 to be assembled
into the front housing 200 at a specific axial position (relative
to the front housing) so that the flexible fingers 108 stand clear
of the front housing instead of being surrounded therein.
[0085] The slots 202 also provide radial location for the syringe
holder 100 as it is inserted therein.
[0086] FIG. 14 shows a modified end cap 300 (analogous to end cap
15 in the prior art) designed for use with the modified front
housing 200 and how the syringe holder 100 is inserted into the
front housing 200. The front housing 200 is inserted into the end
cap 300 so that its leading surface 206 abuts the interior of the
end cap, so that no further forward movement of the front housing
within the end cap is possible.
[0087] The close abutment of the end cap 300, front housing 200 and
syringe holder 100 means that, if present, the rigid needle cover
17 is retained securely in position such that the risk of the
needle cover accidentally becoming loose or detached is minimised,
thereby minimizing possible loss of integrity of the seal between
the rubber needle sheath and the needle, which would otherwise
compromise the sterility of the medicament contained within the
syringe.
[0088] The end cap has an upstanding annulus 301 which protrudes
into and is a close fit in the bore 201 of the front housing 200.
The upstanding annulus 301 has two equispaced protrusions on the
exterior surface thereof which locate in longitudinal slots 202
when the end cap and front housing are assembled together. Once
assembled together, the upstanding annulus of the end cap and the
step 205 together define a space 302 into which tags 110 on the
syringe holder 100 can locate.
[0089] In order to insert the syringe holder 100 into the front
housing 200, the tags 110 are aligned with and pushed into the
slots 202 until the tags 110 "click" over the step 205 and locate
in the space 302. This is the position illustrated in FIGS. 14 and
15. Now the syringe holder 100 is suitably axially located such
that the gripping means 109 and flexible fingers 108 are not
constrained within the front housing 200 and end cap 300.
[0090] The front housing, end cap and syringe holder are supplied
in this ready-assembled condition, together with the
ready-assembled rear part of the injection device, for final
assembly with a pre-filled syringe.
[0091] It is therefore a straightforward two-stage procedure to
finally assemble the syringe into the device, namely: [0092] 1.
inserting the syringe into the ready-assembled front housing, end
cap and syringe holder until the gripping means 109 locate at the
front shoulder 92 of the barrel (as shown in FIG. 16); [0093] 2.
assembling the front part to the ready-assembled rear part of the
injection device (not illustrated).
[0094] FIGS. 4-6 show the fully assembled injection device
including syringe holder 100. With reference to FIG. 5, it can be
seen that (unlike in the prior art device) the flange 90 of the
barrel does not contact the barrel seat 101 of the syringe holder
100, there being a gap G therebetween. This is a result of the
relative axial positions of the syringe holder and syringe being
determined at the front end, by gripping means 109 and front
shoulder 92 and means that undesirable tension is not applied to
the glass barrel during delivery of the medicament.
[0095] An alternative embodiment of the syringe holder is
illustrated in FIGS. 17-20. Where possible, the same reference
numerals as were used in relation to FIGS. 8-9 are used to identify
like components of the alternative embodiment. Note that FIGS.
17-20 show the front end of the device at the left side of the
Figures, whereas FIGS. 8-9 show the front end of the device at the
right side of the Figures.
[0096] In the FIG. 17 embodiment of the syringe holder 100', the
radially-flexible fingers 108' have their free ends extending in
the forward direction (compare with the radially-flexible fingers
108 in FIG. 8 which have their free ends extending in the rearward
direction). The gripping means comprise inwardly-directed enlarged
heads 109' at the end of the flexible fingers 108. As is best seen
in FIG. 19, the enlarged heads 109' are capable of gripping the
cone 93 at the front of the syringe barrel. The cone 93 is the
region where the needle 10 is attached to the syringe barrel.
[0097] As shown in FIG. 18, when a syringe is assembled with the
syringe holder 100', the rigid needle cover 17 (which is of
comparable diameter to the syringe barrel) causes the flexible
fingers 108' to flex radially-outwardly so that the enlarged heads
109' rest on the exterior of the needle cover 17.
[0098] When the end cap 300 and rigid needle cover 17 are removed
axially in the direction of the arrow in FIG. 18, the enlarged
heads 109' should move radially-inwardly into contact with the cone
93 of the syringe so as to grip the front end of the barrel to
provide the compressive force during injection. However, if the
flexible fingers 108' are made from plastic and if the device is
stored in the FIG. 18 configuration for many months before use
(both of which are likely), it is possible that the fingers 108'
will no longer automatically flex properly inwardly upon removal of
the needle cover 17.
[0099] Therefore, a spring retainer 111 is provided. The spring
retainer 111 is made from steel, other metal or other material
which does not significantly lose its resilience over time. The
spring retainer has elongate fingers which cooperate with the
flexible fingers 108' so as to urge them radially-inwardly. Once
the needle cover 17 has been removed, the spring retainer 111 urges
the enlarged heads 109' into firm contact with the cone 93 of the
syringe, even if the flexible fingers 108' are no longer capable of
doing so. This position is illustrated in FIGS. 19 and 20.
[0100] As illustrated in FIG. 21, the gripping means (109 or 109')
could alternatively be provided in the form of a clip 112, inserted
axially into a slot 113 in the syringe holder so as to clip onto
the front of the barrel.
[0101] Other means of providing a reaction surface for the front of
the barrel so as to provide a compressive force during injection
can be envisaged, for example a tapered elastomeric bush which
could be snapped into place once the needle cover has passed during
assembly. It may be possible to grip the frontmost part of the
cone, where the needle enters the cone, rather than gripping the
exterior thereof. Alternatively, other means for gripping the front
shoulder of the barrel, or the exterior of the cone may be
envisaged.
[0102] The reader's attention is directed to all papers and
documents which are filed concurrently with or previous to this
specification in connection with this application and which are
open to public inspection with this specification, and the contents
of all such papers and documents are incorporated herein by
reference.
[0103] All of the features disclosed in this specification
(including any accompanying claims, abstract and drawings), and/or
all of the steps of any method or process so disclosed, may be
combined in any combination, except combinations where at least
some of such features and/or steps are mutually exclusive.
[0104] Each feature disclosed in this specification (including any
accompanying claims, abstract and drawings), may be replaced by
alternative features serving the same, equivalent or similar
purpose, unless expressly stated otherwise. Thus, unless expressly
stated otherwise, each feature disclosed is one example only of a
generic series of equivalent or similar features.
[0105] The invention is not restricted to the details of any
foregoing embodiments. The invention extends to any novel one, or
any novel combination, of the features disclosed in this
specification (including:any accompanying claims, abstract and
drawings), or to any novel one, or any novel combination, of the
steps of any method or process so disclosed.
* * * * *