Note: Descriptions are shown in the official language in which they were submitted.
10805'71
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a disposable injection syringe and in
particular to an injection syringe having a cylindrical liquid container
with a needle hub for attaching an injection needle at one container end,
and a plunger in the container for movement by a plunger rod so as to eject
material to be injected.
In the design of such syringes, reduction of thè amount of liquid
remaining is desirable. The development of new medicines involves steadily
increasing costs for research in an industry which is heavily research-based,
particularly because of the requirements imposed on new medicines by national
authorities and advances in medical science, so that the costs of medicines
are rising continually. Further, in a continuing effort to minimize the
quantity of material being administered to patients, there is a trend to
administer relatively smaller quantities of injection liquid than previously,
and therefore injection syringes are desirable with smaller capacities.
Also, a large quantity of unusable injection liquid can be a disadvantage
because this may needlessly impair the environment when a used syringe is
destroyed.
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2. Description of the Prior Art
Injection syringes, both disposable and re-
usable, have been used for many years for injection of
medicines into patients. All of these syringes have had
the disadvantage that not all the liquid contained
within the syringe can be administered. In part, this
occurs because a quantity of injection liquid remains in
the needle; however, at least part of the disadvantage
arises because the plunger cannot be moved entirely to
the end of the liquid-containing portion of the syringe,
that i9, to the beginning of the needle. Thus there is
often a quantity of injection liquid left between the
; plunger piston and the beginning of the needle.
This problem is particularly noticeable
in disposable syringes which are pre-filled with medicine
by the manufacturer. To permit long storage times of
"~ such pre-filled syringes without excessive degradation of
the medicine, in most cases it is necessary to protect
the injection liquid from deterioration which would
result from extended contact with the material from
which the needle or needle connection means are made,
these devices usually being made from a metal or a
synthetic resin. Therefore a sealing member is often provided
at the needle end of the liquid container, the sealing
member being manufactured from a rubber material of a
pharmaceutical quality, or from a corresponding chemical
inert material. The plunger is made from materials
which are similarly selected . As a result, during storage
the injection liquid contacts only the materials from
which the liquid container, the plunger and the sealing member
are made.
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Disposable syringes of the previously known types have a construc-
tion or an inwardly extending flange which is formed by a portion of the
liquid container itself at the needle connection end. This flange can serve
both for attachment of the needle hub, and as a stop, limiting the motion
of the plunger, and thereby resulting in the formation of a central region
within the constriction, wherein unused injectable liquid collects. Normal
injection syringes of the types described above, depending on their capacity,
generally contain a volume between 0.1 and 0.3 ml of unusable injection
liquid. Reduction of this unusable quantity to a minimum is desirable,
particularly where expensive medicines are involved or injection syringes
of small capacity are to be used.
SU~nlARY OF THE INVENTION
An object of the invention is to minimize the quantity of unusable ~ ,
medication which is wasted whenever an injection is to be made. -
A further object of the invention is to provide a disposable
syringe having a minimum quantity of liquid in the space remaining between
the plunger and the injection needle. ;
In accordance with the invention, a disposable injection syringe
is provided comprising a cylindrical liquid container having a needle hub
for attaching an injection needle at one end, a plunger movable within the
container for expelling material to be injected therefrom, means for moving
the plunger within the container, a rupturable sealing member separating
the interior of said container from said needle hub, and a chamber in the
needle hub between the needle and the sealing member, into which the sealing
member can expand and be ruptured, characterized in that the chamber within
the needle hub is so proportioned that the plunger is movable in it, and that
the sealing member is sufficiently flexible in order that after its rupture
it can be displaced by the plunger, so as to allow the plunger to move past
the ruptured sealing member substantially all the way to the end of the
chamber.
This solution to the problem, which may at first seem almost self-
evident, has in practice not proved possible for a disposable injection
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syringe which has a simple structure and inexpensive manufacturing cost.
For example, British patent specification 704,259 describes a re-usable
syringe which can be easily and rapidly dis-assembled but requires an
expensive and complicated construction with several ground parts, screwed
connections and the like. Of course, this could not reasonably be used or
described as a disposable syringe.
For injection syringes having a capacity of less than approximate-
ly 1 ml, as they are used in large quantities, e.g. for administering
medicines in controlling thrombosis, it proves that in using a syringe
according to the invention, the volume of remaining liquid can be reduced
to less than 0.05 ml, a saving of 50-80% compared with previously known
syringes. This construction is especially advantageous when a sealing
member of the type used in the "Cartrix*" system, having a thin elastic
diaphragm which can be ruptured by pressure, such as the syringe described
in U.K. patents 1,203,098 and/or 1,210,676.
BRIEF DESCRIPTION OF THE DRAWING
The invention is described in detail hereinafter in connection
with the drawing in which:
Figure 1 is a side view, partially in section, of a complete injec-
tion syringe according to the invention,
Figure 2 is a cross-sectional view of a liquid
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~IN ~4 ~
5~ 977
~080S71
container having a thickened outer portion at each end,
Fig. 3 is a cross~sectional view of another
embodiment of a liquid container having a thickened portion
at the needle connec~ion end only.
Fig. 4 is a side view, partially in section, of
the holder end of a syringe having a liquid container
according to Fig. 3,
Fig. 5 is a cross-sectional view of still another
embodiment of a container according to the invention having
notches at each end for connection ~ the needle and a
finger grip,
~ig. 6 is a sectional Vi2W of a finger grip
suitable for use with the container of Fig. 5,
Fig. 7 is a cross-sectional view of the needle
connection portion of a syringe having a tearable diaphragm
as a sealing member, using the container of Figs. 2 or 3,
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and - ~
Fig. 8 is a cross-sectional view of another
embodiment of a syringe according to the invention having
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a Luer cone for a needle connection means.
DES~RIPTION OF THE PREEERRED EMBODIMENTS
In Eig. 1 a complete injection syringe according
to the invention is shown. A circular cylindrical liquid
container 11 communicates with an injection needle 12,
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prior to use the needle being covered by a protection cap
13. A needle connection means 14, for~example a formed
- metal sleeve crimped at one end around the exterior of
~ the needle, is fitted snugly over a needle~ connection end
; 122 of the container 11. Eitted liquid-tight in the
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P~IN 8347
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containsr 11 is a plunger 15 attached to a plunger rod 16,
the rod passing through a finger-grip 17 attached at the end
of the container 11 remote from the needle connection
means 14.
Fig. 2 shows in cross-section a first embodiment
of a liquid container usable in the syringe shown in Fig. 1.
The needle connection end 21 of the container has a
thickened portion 22 protruding outward in comparison with
the main portion of the container, so that a needle or needle
connection means can be fastened thereabout. At the opposite
end 23 a similar thickened portion 24 provides an external
circumferential ridge for attachment of a finger-grip. It
will of course be clear that neither the thickened portion
22 nor the portion 24 need be cylindrical in their
exterior surfaces, although this is a preferred embodiment
leading to simplicity in manufacture. The important feature
is that the entire length of the inner surface be circular
cylindrical, that is, of constant diameter.
~ig. 3 shows similarly in cross-section another
~0 embodiment of a liquid container usable with the syringe
of Fig. 1. This differs from the Fig. 2 embodiment in that
- the finger-grip connection end 31 does not ha~e a
thickened portion. Such a container is readily used with
a holding means such as that described in the United States
patent specification 3,921,633. Such a finger-grip holding
means is shown in ~ig. 4, in which a tensioning ring or
- collet 40 is pressed tightly inward by a tensioning sleeve
41, the ring 40 being held against an end portion 42 of
a liquid container 142. The plunger rod can be attached to
the plunger with means known per se e.g. a screw-thread
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connection or a snap connection.
Fig. 5 shows in cross-sect'ion still another
embodiment of a cylindrical liquid container according
to the invention, having the outside diameter substantially
constant throughout its length. To attach the needle, a
notch 51 is formed in the outer sur~ace of the container
at the needle attachment end, and a notch 52 is formed
in the outer surface at the finger-grip connection end. '
A finger grip 60 suibable for use with either the container ,'
of Fig. 2 or 5 is shown in Fig. 6, the grip having an
inward circumferential ridge 62 adapted for engaging in
the notch 52 of the Fig. 5 container. ~or use with the
container of ~ig. 2, the projection 24 shown in ~ig. 2 fits
in the internal circumferential depression 64 between the
ridge 62 and an~end stop 66 projecting inwardly.
~ig. 7 shows the preferred embodiment of a
needle connect,ion end and needle connection used with the
invention. A liquid container 71 similar to that shown
in Fig. Z or Fig. ,3 has a thickened end portion 222. A
sealing member 72 is held against an end face of the portion
222, the center of the sealing member having an elastic
diaphragm 73 so proportioned that it can be ruptured by
pressure from the interior of the container. Surrounding
the diaphragm 73 is a tubular portion 223 extending a short
distance inside the container 71. At the other end of the
connection means 14 is a needle 74 held firmly in a needle
hub 75 by c'rimping or shrinking; At an upper end 76 of
the hub provision is made for mounting of a needle
protection cap such as the c p 13.
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Because of the flexibility of the sealing member
72, upon movement of a plunger 15 through the container 71
into contact with the extending portion 222, deflects the
extending portion 223 and the diaphragm 73 into a space
78 in the means 14 so as to permit the plunger to pass to
or beyond the end of the container 71 so as to expel a
maximum proportion of injectable liquid which was contained
in the space 78.
Still another embodiment of a connection means is
shown in Figure 8, the container 81, sealing member 82 and
diaphragm 83 being otherwise similar to those shown in
Figure 7 and having related reference numerals. The end of
the attachment means remote from the liquid containér
has a Luer cone 85, of the well-known type to which a
needle can be connected immediately prior to use of the
syringe. Before attaching the needle, the syringe is
activated by causing the elastic diaphragm 83 to tear
against a sharp tip 86 provided on a cap 87 which is used
to seal the Luer cone before use, for example as taught in
Canadian Patent 1,001,033.
By way of example, a syringe constructed accord-
ing to the preferred embodiment of Figure 1 and having an in-
;~ side diameter of the liquid container of approximately 4.7
mm, was found to have a useless remaining liquid which was
less than 0.05 ml. Such a syringe, when constructed with a
capacity of 0.5 ml, may find application in large quantities,
for administering medicine to control thrombosis. The
syringe according to the invention having an unused volume
of less than 10% of the original volume, in contrast with
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a waste of 20 to 600~ when the prior known syringe types -
are used.
It will be clear to those skilled in the art that
- many other modifications of the embodiment shown and
described are possible while incorporating the spirit of
the invention. ~or example, the entire liquid container
may be placed in a holder suitable for that purpose, such
~` as that shown in U.S. patent 3,976,o69. Whether of the
design shown therein, or designs shown in the various
figures of the accompanying drawing, the various parts of
the syringe may be manufactured from any material which
is suitable for the intended purpose and medicament.
Preferably, however, the liquid contalner consists of glass.
The plunger and the sealing member, when used, preferably
` consists of a pharmaceutical grade of rubber.
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