U.S. patent application number 09/825395 was filed with the patent office on 2001-08-02 for intradermal delivery device including a needle assembly.
Invention is credited to Alchas, Paul G..
Application Number | 20010011171 09/825395 |
Document ID | / |
Family ID | 23654944 |
Filed Date | 2001-08-02 |
United States Patent
Application |
20010011171 |
Kind Code |
A1 |
Alchas, Paul G. |
August 2, 2001 |
Intradermal delivery device including a needle assembly
Abstract
A drug delivery device including a needle assembly facilitates
making intradermal injections using a variety of drug container
types such as a syringe. A hub supports the needle while a limiter
surrounds the needle. The limiter includes a skin engaging surface
that is adapted to be received against the skin of an animal to be
intradermally injected. A forward end of the needle extends beyond
the skin engaging surface a selected distance to limit a depth that
the needle penetrates into the animal's skin.
Inventors: |
Alchas, Paul G.; (Wayne,
NJ) |
Correspondence
Address: |
Becton, Dickinson and Company
1 Becton Drive
Franklin Lakes
NJ
07417-1880
US
|
Family ID: |
23654944 |
Appl. No.: |
09/825395 |
Filed: |
April 3, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09825395 |
Apr 3, 2001 |
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09417671 |
Oct 14, 1999 |
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Current U.S.
Class: |
604/506 ;
604/117 |
Current CPC
Class: |
A61M 5/3278 20130101;
A61M 5/46 20130101; A61M 5/282 20130101; A61M 37/00 20130101; A61D
7/00 20130101; A61M 2202/0445 20130101; A61M 5/3202 20130101 |
Class at
Publication: |
604/506 ;
604/117 |
International
Class: |
A61M 005/00; A61M
031/00 |
Claims
What is claimed is:
1. A hypodermic needle assembly for use in making intradermal
injections, comprising: a hub portion that is able to be attached
to a drug container; a needle supported by the hub portion, the
needle having a hollow body with a forward end extending away from
the hub portion; and a limiter portion that surrounds the needle
and extends away from the hub portion toward the forward end of the
needle, the limiter portion having a skin engaging surface that is
adapted to be received against skin of an animal to receive an
intradermal injection, the needle forward end extending beyond the
skin engaging surface a selected distance such that the limiter
portion limits an amount that the needle is able to penetrate
through the skin of an animal.
2. The assembly of claim 1, wherein the hub portion and the limiter
portion are integrally formed as a single piece made from a plastic
material.
3. The assembly of claim 1, wherein the hub portion and the limiter
portion are formed as separate pieces.
4. The assembly of claim 3, wherein the limiter portion includes an
inner cavity that receives at least a portion of the hub portion
and the inner cavity includes an abutment surface that engages
corresponding structure on the hub portion to thereby limit the
amount that the needle forward end extends beyond the skin engaging
surface.
5. The assembly of claim 3, wherein the limiter portion is
integrally formed as part of the syringe and the hub portion is
received within the limiter portion.
6. The assembly of claim 5, wherein the skin engaging surface
surrounds the needle, and has a thickness defined between an inner
diameter and an outer diameter and wherein the inner diameter is at
least five times greater than an outside diameter of the
needle.
7. The assembly of claim 6, wherein the skin engaging surface is
generally circular.
8. The assembly of claim 1, wherein the skin engaging surface
includes a central opening that is slightly larger than an outside
dimension of the needle and the skin engaging surface is
continuous.
9. The assembly of claim 1, wherein the skin engaging surface is
generally flat and extends through a plane that is generally
perpendicular to an axis of the needle.
10. The needle assembly of claim 1, wherein the selected distance
that the forward end of the needle extends beyond the skin engaging
surface is fixed.
11. The assembly of claim 1, wherein the selected distance is in
the range from approximately 0.5 mm to approximately 3 mm.
12. The assembly of claim 1, wherein the skin engaging surface
includes a contact surface area that is large enough to stabilize
the assembly in a desired orientation relative to the skin.
13. The assembly of claim 12, wherein the desired orientation is
generally perpendicular to the skin.
14. The assembly of claim 1, wherein the drug container is a
syringe and the animal is human.
15. An intradermal delivery device for use in making intradermal
injections, comprising: a drug container having a reservoir adapted
to contain a selected substance and an outlet port that allows the
substance to exit the reservoir during an injection; a needle in
fluid communication with the outlet port, the needle having a
forward end that is adapted to penetrate an the skin of an animal;
and a limiter that surrounds the needle and has a skin engaging
surface that is adapted to be placed against the skin of the animal
to receive an intradermal injection, the needle forward end
extending away from the skin engaging surface a selected distance
such that the limiter limits an amount that the needle forward end
penetrates the skin.
16. The device of claim 15, wherein the drug container is a syringe
including a generally hollow, cylindrical body portion and a
plunger that is received within the reservoir, the plunger being
selectively movable within the reservoir to cause the substance to
be forced out of the outlet port during an injection.
17. The device of claim 15, including a hub portion that supports
the needle and the hub portion is selectively secured to the drug
container near the outlet port.
18. The device of claim 15, wherein the drug container is a syringe
includes a generally flat body portion that at least partially
surrounds the reservoir, the body portion and the reservoir are
made from two sheets of thermoplastic material such that side walls
of the reservoir are selectively deflected toward each other to
expel a substance from the reservoir during an injection.
19. The device of claim 18, including a hub that supports the
needle and is selectively secured to the syringe near the outlet
port and a receiver adjacent the outlet port that is generally
circular and the hub is completely received within the receiver and
wherein the limiter is integrally formed with the receiver such
that the limiter is permanently supported by the body portion
adjacent the outlet port.
20. The device of claim 19, wherein the skin engaging surface
surrounds the needle, and has a thickness defined between an inner
diameter and an outer diameter and wherein the inner diameter is at
least five times greater than an outside diameter of the
needle.
21. The device of claim 20, wherein the skin engaging surface is
generally circular.
22. The device of claim 19, wherein the needle forward end extends
away from the hub in a first direction and a needle back end
extends away from the hub in a second direction, and including a
sealing membrane that closes off the outlet port and wherein the
needle back end pierces the sealing membrane when the hub is
received by the receiver.
23. The device of claim 18, including a hub that supports the
needle and is selectively secured to the syringe near the outlet
port and a receiver adjacent the outlet port that is generally
circular and the hub is completely received within the receiver and
wherein the limiter is formed separately from the receiver and is
at least partially received by the receiver.
24. The device of claim 23, wherein the limiter and the hub are
integrally formed into a single piece structure.
25. The device of claim 15, wherein the needle has a length and
wherein the selected distance is much less than the needle
length.
26. The device of claim 25, wherein the selected distance is fixed
and is in the range from approximately 0.5 mm to approximately 3
mm.
27. The device of claim 15, wherein the skin engaging surface is
generally flat and extends through a plane that is generally
perpendicular to an axis of the needle.
28. The device of claim 15, wherein the skin engaging surface
includes a central opening that is slightly larger than an outside
dimension of the needle and the skin engaging surface is
continuous.
29. The device of claim 15, wherein the skin engaging surface
includes a contact surface area that is large enough to stabilize
the assembly in a desired orientation relative to the skin.
30. The device of claim 15, wherein the desired orientation is
generally perpendicular to the skin.
31. The device of claim 15, wherein the drug container is prefilled
with a substance.
32. A method of intradermally injecting at least one substance such
as a drug, vaccine or the like into the skin, comprising the steps
of: pressing a needle perpendicularly to the skin of the animal to
receive an injection, said needle in fluid communication with an
outlet port of a drug container having a reservoir adapted to
contain a selected substance and the outlet port allows the
substance to exit the reservoir during an intradermal injection;
injecting the substance into the skin of the animal with the depth
of penetration of the needle being limited to the intradermal space
by a limiter that surrounds the needle and has a skin engaging
surface that is adapted to be placed against the skin of the animal
and a forward end of the needle extending away from the skin
engaging surface a selected distance such that the limiter limits
an amount that the needle forward end penetrates the skin of the
animal.
33. The method of claim 32, wherein the step of pressing the needle
perpendicularly to the skin of the animal includes orienting the
needle perpendicularly to the skin.
34. The method of claim 32, wherein the step of injecting the
substance includes moving a plunger that is received within the
reservoir, with the plunger being selectively movable within the
reservoir to cause the substance to be forced out of the outlet
port during the injection.
35. The method of claim 32, wherein the step of injecting the
substance into the skin of the animal includes deflecting at least
two sheets of thermoplastic material forming a generally flat body
portion that at least partially surrounds the reservoir toward each
other to expel the substance from the reservoir during an
injection.
36. The method of claim 32, further comprising the step of filling
the drug container with the substance to be intradermally
injected.
37. The method of claim 32, wherein said drug container is a
syringe and said animal is human.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to delivery devices
for delivering substances such as drugs, vaccines and the like, and
more specifically relates to a drug delivery device for injecting
such substances intradermally, i.e., into the skin. In addition,
the present invention relates to a needle assembly that is
adaptable for use with a variety of drug containers such as
syringes for making intradermal injections.
BACKGROUND OF THE INVENTION
[0002] A wide variety of hypodermic injection devices are
commercially available. Most hypodermic injections are intended to
be intramuscular so that the hypodermic needle penetrates through
an individual's skin layer and subcutaneous tissue and into the
muscle tissue. Under some circumstances, however, limited needle
penetration is desired. Under some circumstances, for example, an
intradermal injection is desired where the needle does not
penetrate beyond the dermis layer.
[0003] One technique for administering intradermal injections is
known as the Mantoux procedure. A Mantoux procedure is relatively
complicated and requires technical skill from the medical
professional or individual administering the injection.
Additionally, the Mantoux procedure can prove painful for the
individual receiving the injection, especially when somebody
without experience is administering the injection.
[0004] Devices have been proposed for providing intradermal
injections, which include shortened needles compared to
conventional needle sizes. The smaller needles are not intended to
penetrate beyond the dermis layer of the individual. Such devices
are shown in U.S. Pat. Nos. 5,527,288, which issued on Jun. 18,
1996; 4,886,499, which issued on Dec. 12, 1989; and 5,328,483,
which issued on Jul. 12, 1994. The proposed devices, however are
not without shortcomings and drawbacks.
[0005] For example, the devices shown in U.S. Pat. Nos. 5,527,288
and 4,886,499 are highly specialized injectors. The designs for
these injectors include relatively complex arrangements of
components that cannot be economically manufactured on a mass
production scale. Therefore, such devices have limited
applicability and use.
[0006] Similarly, the device shown in U.S. Pat. No. 5,328,483
requires a specially designed injector and, therefore, it is not
readily adapted to be used with a variety of syringe types.
Additionally, the assembly of that patent is not conducive to
economical mass production.
[0007] There is need for an intradermal injection device that is
suitable for use with a variety of syringe bodies. Additionally,
there is a need for an intradermal injection device that can be
economically manufactured on a mass production scale. This
invention addresses those needs and avoids the shortcomings and
drawbacks discussed above.
SUMMARY OF THE INVENTION
[0008] In contrast to the prior devices discussed above, it has
been found that a drug delivery device particularly suited for use
in intradermally injecting substances such as drugs, vaccines and
the like can be constructed in accordance with the present
invention. Specifically, the present invention is directed to a
drug delivery device including a needle assembly for use in making
intradermal injections. The needle assembly has an adapter that is
attachable to prefillable containers such as syringes and the like.
The needle assembly is supported by the adapter and has a hollow
body with a forward end extending away from the adapter. A limiter
surrounds the needle and extends away from the adapter toward the
forward end of the needle. The limiter has a skin engaging surface
that is adapted to be received against the skin of an animal such
as a human. The needle forward end extends away from the skin
engaging surface a selected distance such that the limiter limits
the amount or depth that the needle is able to penetrate through
the skin of an animal.
[0009] In addition, the present invention is directed to a method
of intradermally injecting at least one substance into the skin
including the steps of pressing the needle perpendicularly to the
skin of the person to receive an injection, injecting the substance
into skin of the person with the depth of penetration of the needle
being mechanically limited to the intradermal space by the limiter
that surrounds the needle. Also, in the preferred embodiment, the
step of pressing the needle perpendicularly to the skin of the
person includes orienting the needle perpendicularly to the skin,
and the step of injecting the substance either includes moving a
plunger that is received within the reservoir or deflecting two
sheets of thermoplastic material forming the reservoir toward each
other to expel the substance from the reservoir during an
injection.
[0010] The various features and advantages of this invention will
become apparent to those skilled in the art from the following
detailed description of the currently preferred embodiments. The
drawings that accompany the detailed description can be briefly
described as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is an exploded, perspective illustration of a needle
assembly designed according to this invention.
[0012] FIG. 2 is a partial cross-sectional illustration of the
embodiment of FIG. 1.
[0013] FIG. 3 shows the embodiment of FIG. 2 attached to a syringe
body to form an injection device.
[0014] FIG. 4 is an exploded, side view of another embodiment of an
injection device designed according to this invention.
[0015] FIG. 5 is a cross-sectional illustration taken along the
lines A-A in FIG. 4 but showing the components in an assembled
condition.
[0016] FIG. 6 is an exploded, cross-sectional view similar to that
shown in FIG. 5 showing an alternative embodiment.
[0017] FIG. 7 shows the embodiment of FIG. 6 in an assembled
condition.
[0018] FIG. 8 is a flow chart diagram that schematically
illustrates a method of filling a device designed according to this
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] FIGS. 1 and 2 diagrammatically illustrate the needle
assembly 20 of the present invention that is designed to be used
for making intradermal injections, FIG. 3 illustrates the drug
container such as syringe 60 for use with the needle assembly 20,
and FIGS. 4-7 illustrated the intradermal delivery device 80 of the
present invention for making intradermal injections. Intradermal
injections include administering substances such as drugs, vaccines
and the like into the skin of an animal such as a human.
[0020] The needle assembly 20 includes a hub 22 that supports a
needle 24. The limiter 26 receives at least a portion of the hub 22
so that the limiter 26 generally surrounds the needle 24 as best
seen in FIG. 2.
[0021] One end 30 of the hub 22 is able to be secured to a receiver
32 of a syringe. A variety of syringe types can be used with a
needle assembly designed according to this invention, with several
examples being given below. The opposite end of the hub 22
preferably includes extensions 34 that are nestingly received
against abutment surfaces 36 within the limiter 26. A plurality of
ribs 38 preferably are provided on the limiter 26 to provide
structural integrity and to facilitate handling the needle assembly
20.
[0022] By appropriately designing the size of the components, a
distance d between a forward end or tip 40 of the needle 24 and a
skin engaging surface 42 on the limiter 26 can be tightly
controlled. The distance d preferably is in a range from
approximately 0.5 millimeters to approximately 3 millimeters. When
the forward end 40 of the needle 24 extends beyond the skin
engaging surface 42 a distance within that range, an intradermal
injection is ensured because the needle is unable to penetrate any
further than the typical dermis layer of an animal. Typical tissue
layers include an epidermis between 50 and 100 micrometers, a
dermis layer between 2 and 3 mm then subcutaneous tissue followed
by muscle tissue.
[0023] As can be best seen in FIG. 2, the limiter 26 includes an
opening 44 through which the forward end 40 of the needle 24
protrudes. The dimensional relationship between the opening 44 and
the needle 40 can be controlled depending on the needs of a
particular situation. In the illustrated embodiment, the skin
engaging surface 42 is generally planar and continuous and provides
a stable placement of the needle assembly 20 against an animal's
skin. Although not specifically illustrated, it may be advantageous
to have the skin engaging surface be slightly concave or convex in
order to facilitate stretching or gathering the animal's skin in
the vicinity of the needle tip 40 to facilitate making an
injection. Additionally, the ribs 38 may be extended beyond the
skin engaging surface 42 to further facilitate manipulating the
skin in the vicinity where the injection is to be given.
[0024] Regardless of the shape or contour of the skin engaging
surface 42, the preferred embodiment includes enough of a surface
area that contacts the skin to facilitate stabilizing the injector
relative to the animal's skin. In the most preferred arrangement,
the skin engaging surface 42 facilitates maintaining the injector
in a generally perpendicular orientation relative to the skin
surface.
[0025] It is important to note that although FIGS. 1 and 2
illustrate a two-piece assembly where the hub 22 is made separate
from the limiter 26, this invention is not limited to such an
arrangement. Forming the hub 22 and limiter 26 integrally from a
single piece of plastic material is an alternative to the example
shown in FIGS. 1 and 2. Additionally, it is possible to adhesively
or otherwise secure the hub 22 to the limiter 26 in the position
illustrated in FIG. 2 so that the needle assembly 20 becomes a
single piece unit upon assembly.
[0026] Having a hub 22 and limiter 26 provides the advantage of
making an intradermal needle practical to manufacture. The
preferred needle size is a small gauge hypodermic needle, commonly
known as a 30 gauge or 31 gauge needle. Having such a small
diameter needle presents a challenge to make a needle short enough
to prevent undue penetration beyond the dermis layer of an animal.
The limiter 26 and the hub 22 facilitate utilizing a needle 24 that
has an overall length that is much greater than the effective
length of the needle, which penetrates the individual's tissue
during an injection. With a needle assembly designed according to
this invention, manufacturing is enhanced because larger length
needles can be handled during the manufacturing and assembly
processes while still obtaining the advantages of having a short
needle for purposes of completing an intradermal injection.
[0027] FIG. 3 illustrates a needle assembly 20 secured to a drug
container such as a syringe 60. A generally cylindrical syringe
body 62 can be made of plastic or glass as is known in the art. The
syringe body 62 provides a reservoir 64 for containing a substance
to be administered during an injection. A plunger 66 has a manual
activation flange 68 at one end with a stopper 70 at an opposite
end as known in the art. Manual movement of the plunger 66 through
the reservoir 64 forces the substance within the reservoir 64 out
of the end 40 of the needle as desired.
[0028] The hub 22 can be secured to the syringe body 62 in a
variety of known manners. In one example, an interference fit is
provided between the interior of the hub 22 and the exterior of the
outlet port portion 72 of the syringe body 62. In another example,
a conventional luer fit arrangement is provided to secure the hub
22 on the end of the syringe 60. As can be appreciated from FIG. 3,
a needle assembly designed according to this invention is readily
adaptable to a wide variety of conventional syringe styles.
[0029] FIGS. 4 and 5 illustrate an alternative embodiment of an
intradermal delivery device 80 that includes a syringe made from
two sheets of thermoplastic material. The syringe includes a body
portion 82 that is generally flat and surrounds a reservoir 84. An
outlet port 86 allows fluid substance within the reservoir 84 to be
communicated out of the reservoir to administer an injection. The
syringe body preferably is formed using a thermoforming process as
is known in the art.
[0030] A receiver 90 includes a generally cylindrical neck portion
92 that preferably is secured to the outlet port 86 using a heating
or welding process as known in the art. A flange 94 preferably
rests against the body portion 82 of the syringe to provide
structural integrity. An extension 96 extends away from the flange
94 in a direction opposite from the cylindrical portion 92. The
needle assembly 20 preferably is received within the extension 96
as shown in FIG. 5.
[0031] The receiver 90 preferably supports a sealing membrane 100
that closes off the outlet port 86 so that the syringe can be
prefilled. The needle assembly 20 preferably includes a back end
102 of the needle that penetrates the sealing membrane 100 when the
hub 22 is received within the extension 96.
[0032] The side walls of the reservoir 84 preferably are squeezed
between a thumb and index finger so that the side walls collapse
towards each other and the substance within the reservoir 84 is
expelled through the opening in the forward end 40 of the needle
24. In the embodiment of FIGS. 4 and 5, the hub 22 and limiter 26
preferably are integrally molded as a single piece of plastic
material. A snap fit arrangement secures the hub 22 within the
extension 96 of the receiver 90. Another alternative is illustrated
in FIGS. 6 and 7. In this embodiment, the hub 22 is molded
separately from the limiter 26', which is integrated with the
extension 96. A difference between the embodiments of FIGS. 6 and 7
compared to that of FIGS. 4 and 5 includes an elongated extension
96 so that the side wall of the extension 96 provides the skin
engaging surface 42' of the limiter 26'. In this embodiment, the
limiter is supported by the syringe body. By appropriately choosing
the dimensions of the needle 24 and the length of the extension 96,
the desired distant d between the skin engaging surface 42 and the
needle tip 40 can be achieved.
[0033] FIG. 7 also illustrates a needle shield 110, which
preferably is provided on the hub 22 and needle 24. The needle
shield 110 facilitates inserting the hub 22 within the receiver 90
until the hub 22 is appropriately received within the extension 96
so that the intradermal delivery device 80 is ready for use. The
needle shield 110 can be discarded after the hub 22 is in position.
Alternatively, the needle shield 110 can be replaced over the
needle 24 after an injection is complete to avoid the possibility
for a needle stick while handling the intradermal delivery device
80 after it has been used.
[0034] Although the shield 110 is only shown in FIG. 7, it
preferably is utilized with the embodiments of FIGS. 4-7.
[0035] This invention provides an intradermal needle injector that
is adaptable to be used with a variety of syringe types. Therefore,
this invention provides the significant advantage of facilitating
manufacture and assembly of intradermal needles on a mass
production scale in an economical fashion.
[0036] Operation and Use
[0037] Having described the preferred embodiments of the
intradermal delivery device 80 of the present, including the needle
assembly 20 and drug container 60, its operation and use is
described below.
[0038] Use of the delivery device to administer substances such as
drugs, vaccines and the like into the intradermal layer is
significantly easier than with a traditional syringe and needle.
Using a traditional syringe and needle is technique-dependent and
requires considerable skill to develop an acceptable skin wheal. In
particular, the needle must be carefully guided at a shallow angle
under the skin while maintaining correct orientation of the needle
bevel. In contrast, with a prefilled intradermal delivery device of
the present invention, the user simply presses the device
perpendicularly on to the skin and injects the substance. The depth
of penetration of the needle is mechanically limited to the
intradermal space. In this way, there is no need orient the needle
bevel during injection. Orienting the device, particularly the
needle, perpendicularly to the skin, as well as stability while
injecting the substance, is facilitated by the design of the
device.
[0039] Referring now to FIG. 8, an example method of filling
devices designed according to this invention is schematically
illustrated in flow chart format. When the device includes a
syringe of the style illustrated in FIG. 3, the following basic
procedure is useful for prefilling the syringes with a desired
substance.
[0040] A supply of syringe barrels 200 includes the desired form of
syringe, such as those illustrated and discussed above. A locally
controlled environment 202 preferably is maintained in a known
manner. The locally controlled environment 202 preferably is
situated to immediately accept the syringes without requiring any
intermediate cleaning or sterilizing steps between the supply 200
and the environment 202.
[0041] In one example, the syringe barrels are washed with air at
204 to remove any particulates from the syringes. The syringes
preferably are then coated at 206 with a lubricant such as a
lubricating silicone oil on the inner surface. The lubricant
facilitates moving the stopper 70 and plunger rod 66 through the
syringe during actual use of the device.
[0042] The end of syringes that eventually will needle assembly 20
may be capped with a tip cap within the environment 202. In one
example, tip caps are supplied at 208. The tip caps are air washed
at 210. The cleaned tip caps and syringe barrels are conveyed to an
assembly device 212 where the tip caps are secured onto the
syringes. The syringe barrel assemblies are then conveyed to a
filling station 214 to be filled with the desired substance.
[0043] Once filled as desired, the stoppers 70 are inserted into
the open end of the syringes at 220. Prior to inserting the
stoppers 70, they preferably are assembled with the plunger rods 66
at 222 and lubricated at 224 with a conventional lubricant in a
known manner. The assembled, filled syringes preferably are
inspected at 226 for defects and discharged from the locally
controlled environment.
[0044] The syringes typically will be sterilized at 230 and
packaged at 232 into individual packages or into bulk packaging
depending on the needs of a particular situation. Suitable
sterilization techniques are known and will be chosen by those
skilled in the art depending on the needs of a particular situation
or to accommodate the properties of a given substance. Sterilizing
a device designed according to this invention can be completed
before or after packaging.
[0045] Variations of the filling steps are within the scope of this
invention. For example, the stopper can be inserted first, then
fill the syringe, followed by applying a tip cap. Additionally,
when the device includes a syringe body of the type shown in FIGS.
4 and 5, for example, the filling operation obviously does not
include insertion of a stopper nor the lubrication steps described
above. Instead, appropriate filling techniques that are known are
utilized.
[0046] The actual insertion of the desired substance into the
syringe body can be accomplished in any of several known manners.
Example filling techniques are disclosed in U.S. Pat. Nos.
5,620,425 to Hefferman et al.; 5,597,530 to Smith et al.; 5,537,042
to DeHaen; 5,531,255 to Vacca; 5,519,984 to Veussink et al.;
5,373,684 to Veussink et al.; 5,265,154 to Liebert et al.;
5,287,983 to Liebert et al.; and 4,718,463 to Jurgens, Jr. et al.,
each of which is incorporated by reference into this
specification.
[0047] The description given above provides example implementations
of this invention. Variations and modifications may become apparent
to those skilled in the art that do not necessarily depart from the
basis of this invention. The scope of legal protection given to
this invention can only be determined by studying the following
claims.
* * * * *