Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
INJECTION TOOL AND METHOD OF ITS USE
Technical Field
This invention relates to an injection tool for
administering drugs at sites of a very small range that are
located comparatively deep in the body to develop comparatively
high internal pressure.
Background Art
A known technique for injecting chymopapain for such
purposes as the treatment of herniated intervertebral disks in
dogs is depicted by rough sketch in Fig. 8 and comprises the
l0 following steps: an injection needle 52 that has an inner
needle (mandolin) 51 inserted therein is allowed to pierce
through the skin 61 and then muscle 62 so that its distal end
reaches the vertebral pulp 64 in an intervertebral disk 63
( Fig . 8A) ; then, the inner needle 51 is withdrawn so that a
connector 53 at the basal end of the in jection needle 52 is
filled with part of the drug to be injected; a lure lock 55 at
the distal end of the injection barrel 54 into which the drug
has been aspirated is coupled to the connector 53; and the
piston 56 is pushed, thereby injecting the drug into the
2o vertebral pulp 64 (Fig. 8B) (see "Kachiku Chiryo (Domestic
Treatment)", No. 1, Treatment of Herniated Intervertebral Disks
in Dogs by Chymopapain Injection, compiled under the
supervision of Masashige Nakayama, published by Inters
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Videotape Co., Ltd., 1992).
Stated more specifically, the vertebral pulp 64 in the
intervertebral disk 63 is a closed space surrounded with a
fibrous ring 66 and it is located at a comparatively deep site
in the body; hence, in order to assure penetration through the
skin 61, muscle.62 and even the fibrous ring 66, the injection
needle 52 must have a reasonable thickness and, at the same
time, it is necessary to use the spacer inner needle 51 so that
the injection needle 52 will neither bend nor undergo
to obstruction by tissue fragments during piercing.
To this end, the injection needle 52 is handled as a
separate member from the injection barrel 54 in the current
method and when the needle tip has reached the intended site,
the inner needle 51 is withdrawn and the injection barrel 54 is
connected. However, with the means of coupling the lure lock
55 to the drug filled connector 53, it is impossible to avoid
inaccuracy in the dose of drug to be injected. What is more,
complete rejection of air is difficult to achieve by the means
of connecting the injection barrel after the connector 53 is
2o filled with the drug and any residual air will cause further
inaccuracy in the dose of drug to be injected.
In addition, when the injection needle 52 is pulled out
after injection, a considerably large piercing hole will remain
in the fibrous ring 66 due to the injection needle 52 and the
drug that has been injected into the vertebral pulp 64
developing high internal pressure is prone to flow out of the
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piercing hole and this can be a cause of not only introducing
inaccuracy in the dose of administration but also damaging the
surrounding tissue by the drug outflow.
Therefore, even if one attempts to employ the
aforementioned technique for administering drugs at sites of a
very small range that are located comparatively deep in the
body to develop comparatively high internal pressure not only
in the treatment of herniated intervertebral disks in dogs but
also in the treatment of similar diseases such as herniated
l0 intervertebral disks in humans, difficulty is involved in
administering predetermined doses in an accurate manner and, at
the same time, a considerably large piercing hole remains,
requiring a long time for its restoration, during which not
only the drug but also blood and other body fluids can
potentially flow out in large quantities.
The problem to be solved by the present invention is
that there has not been available any injection-based drug
administering means by which predetermined doses of drugs can
be administered in an accurate manner at sites of a very small
2o range that are located comparatively deep in the body to
develop comparatively high internal pressure and which yet will
not leave a large piercing hole open at the intended site.
Disclosure of Invention
The present invention provides (1) an injection tool
characterized by comprising an injection device comprising an
injection barrel and an injection needle that is to be mounted
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at the distal end thereof, a piercing hollow needle having a
connector portion that is to be connected to the aforementioned
injection device and a needle portion that allows the
aforementioned injection needle to be inserted almost tightly,
and an inner needle having a basal portion that is to be fitted
tightly in the aforementioned connector portion and a solid
needle that is to be inserted almost tightly in the
aforementioned needle portion, and (2) a method of using an
injection tool that is characterized in that a solid needle is
to inserted almost tightly in the needle portion of a piercing
hollow needle having a connector portion that is to be
connected to an injection device comprising an injection barrel
and an injection needle mounted at the distal end thereof and
said needle portion that enables the injection needle of the
aforementioned injection device to be inserted therethrough
almost tightly and, at the same time, the aforementioned needle
portion is allowed to pierce to a predetermined site in the
body of interest with an inner needle having said solid needle
being fixed in said piercing hollow needle and, subsequently,
2o said inner needle is withdrawn and the injection needle of the
aforementioned injection device is passed through said needle
portion while, at the same time, the aforementioned injection
device is connected to the aforementioned connector portion
and, thereafter, the substance to be injected that is held
within the aforementioned injection barrel is injected into
said body of interest. These can solve the aforementioned
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problem, permitting a predetermined dose of drug to be
administered in an accurate manner at a site of a very small
range that is located comparatively deep in the body to develop
comparatively high internal pressure without causing a large
piercing hole to open at the intended site.
The injection tool of the present invention comprises
an injection device, a piercing hollow needle and an inner
needle, with its basic structure being such as to permit
injection of drugs and the like by a conventional method of
to injection, and it is characterized in that a mechanism that
establishes connection between the piercing hollow needle and
the connector portion is provided on the injection device,
which mechanism allows the position of the tip of the injection
needle to be restricted by the needle portion of the piercing
hollow needle so as to ensure easy and accurate injection.
Further, the piercing hollow needle which is comparatively
thick and rugged and which has the solid needle inserted for
reinforcement and for closing the hollow portion is
preliminarily forced to reach the neighborhood of the intended
2o site and, thereafter, the injection needle of the injection
device is inserted through the interior of said hollow needle;
hence, even if said in jection needle used is comparatively thin
and has low strength, it can be allowed to reach the intended
site in an accurate manner without bending. What is more, the
. use of such injection tool of the present invention enables the
use of an injection device such as a microsyringe that
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comprises a thin injection needle and barrel, with the result
that a small dose of drug can be injected at a site of a very
small range without any resistance and in an accurate manner.
A preferred structure of the injection device to be
used in the present invention is such that an end portion of
the injection needle is provided with a member that fits in
said connector portion (which is hereunder referred to as a
needle base) and that a connecting piece that holds said needle
base tightly and which establishes communication between the
injection needle and the injection barrel is provided as said
connecting means. Said needle base has a mechanism that
permits it to be held in the piercing hollow needle and it also
has the ability to allow the position of the tip of the
injection needle to be restricted by the needle portion of the
piercing hollow needle so as to ensure easy and accurate
injection. Furthermore, said needle base may be adapted to be
movable along the connecting piece parallel to the longitudinal
direction of the injection needle and this is preferred since
it offers the additional advantage of contributing to fine
2o adjustment of the position of the tip of the injection needle.
In this case, a graduation may be provided that indicates the
amount of movement.
The injection needle and the needle base may be
separate members or they may be integrated in a unitary member.
Further, the connecting piece may be rendered integral with the
injection barrel.
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In the present invention, the needle portion of the
piercing hollow needle has preferably such a length that when
the basal portion of the inner needle is fitted in the
aforementioned connector portion, the distal end aligns with
that of the aforementioned solid needle and that when the
aforementioned needle device is connected to the aforementioned
connector portion, the distal end portion of the aforementioned
injection needle will project from the distal end.
To implement the method of the present invention, the
to inner needle is inserted into the piercing hollow needle and
the basal portion of said inner needle is fitted to be fixed in
the connector portion of said hollow needle, which is then
allowed to pierce into the body with the solid needle of said
inner needle being mounted in the needle portion of said hollow
needle and, preferably, it is desired to withdraw the inner
needle when the distal end has reached close to the intended
site. When a drug or the like is injected in the next step,
the injection needle is inserted through the needle portion of
said hollow needle so that the injection device is coupled to
2o the connector portion of said blood and the distal end of that
injection needle is preferably allowed to project beyond the
needle portion of said hollow needle by a predetermined amount
in order to have said distal end reach the intended site. This
is because when injecting a drug to an intended site such as
vertebral pulp that has high internal pressure, one only need
allow the needle portion of the piercing hollow needle to reach
CA 02144450 2001-O1-22
the outer side of the fibrous ring surrounding that
vertebral pulp and then the drug can be injected into the
vertebral pulp leaving only a very small piercing hole in
the neighbourhood of the intended site that forms on
account of the injection needle which has substantially
the same diameter as the inside diameter of the needle
portion of the piercing hollow needle.
Accordingly, in another aspect the invention
provides an injection tool comprising: an injection
device comprising an engagement device, an injection
barrel having a distal ends and an injection needle
mounted at said distal end; a piercing hollow needle
having a connector portion with a corresponding
engagement device for connecting said piercing hollow
needle to said injection device and a needle portion that
allows said i_njecti..on needle to be inserted therethrough
almost tightly, wherein, upon connecting said connector
portion of said piercing hollow needle to said injection
device, said engagement device engages with said
corresponding engagement device to provide a non-rotating
reciprocal relationship therebetween such that said
injection needle of_ said injection device is translatable
and non-rotatable within said needle portion of said
piercing hollow needle; and an inner needle having a
basal portion tightly fittable into said connector
portion of said piercing hollow needle when said
connector portion is not connected to said injection
device and a solid needle portion, for reinforcing said
needle portion of said piercing hollow needle, insertable
a:Lmost tightly in said needle portion of said piercing
hollow needle when said injection needle is not inserted
in said needle portion.
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In a further aspect, the invention provides a method
for using an injection tool comprising the steps of:
inserting an inner needle almost tightly in a piercing
hollow needle for reinforcing said piercing hollow
needle, said piercing hollow needle having an engagement
device; following the piercing of a body with said
piercing hollow needle to a predetermined site;
withdrawing said inner needle from said piercing hollow
needle; inserting an injection device having an
injection barrel, a corresponding engagement device, and
an injection needle into said piercing hollow needle,
such that said engagement device engages with said
corresponding engagement device to provide a non-
rotating reciprocal relationship therebetween such that
said injection needle of said injection device is
translatable and non-rotatable within said piercing
hollow needle to permit the injection of a substance
held in said injection barrel into said body through
said injection needle.
Brief Description of Drawings
Fig. 1 is a longitudinal section showing an example
of the present invention by component, with A showing the
injection device, B the piercing hollow needle and C the
inner needle; Fig. 2 is a section showing the piercing
hollow needle as it has pierced into the body; Fig. 3 is
a section equivalent to Fig. 2 except that the inner
needle has been withdrawn; Fig. 4 is a section showing
the injection device as it is coupled to the piercing
hollow needle for drug injection; Figs. 5, 6 and 7 are
diagrams illustrating two mechanism:a for use in the
present invention, one for aligning the tip of the
piercing hollow needle with that of the solid
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CA 02144450 2001-O1-22
needle of the inner needle or the injection needle, and
the other for adjusting the length by which the injection
needle is to project from said hollow needle, with Fig. 5
being a sectional View, Fig. 6 a perspective view of the
essential part and Fig. 7 showing another embodiment of
the mechanism shown in Fig. 6; and Figs. 8A and 8B are
rough sketches in section that illustrates a prior art
technique for drug injection.
K~~y to Symbols
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1: Injection device
2: Injection barrel
7: Injection needle
8: Needle base
11: Piercing hollow needle
12: Connector portion
13: Needle portion
21: Inner needle
22: Basal portion
l0 25: Solid needle
Best Mode for Carrying Out the Invention
An example of the present invention will now be
described with reference to the drawings. Referring to Fig.
lA, injection device 1 comprises an injection barrel 2 that has
a small-diameter cylinder compartment 3 formed through it on
the central longitudinal axis and which has the basal end
portion of a short tubular connecting piece 4 fitted into and
fixed at the distal end of the cylinder compartment 3; the
connecting piece 4 has the same outside diameter as the
2o diameter of the cylinder compartment 3 and it also has a
mounting thread portion 5 in the distal end portion; further,
a plunger 6 is fitted into the cylinder compartment 3 from the
basal end. Needle base 8 of an injection needle 7 has an inner
thread portion 9 that fits threadably over the mounting thread
portion 5, whereby the injection needle 7 is mounted at the
distal end of the injection barrel 2.
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Thus, the injection needle 7 can be attached or
detached from the injection barrel 2 so that one may use a
suitable type that is selected from a stock of various types
having different lengths and diameters.
Referring to Fig. 1B, piercing hollow needle 11 has in
unitary assembly a cylindrical connector portion 12 that has an
inside diameter small enough to permit tight fitting of a
small-diameter portion SA at the distal end of the needle base
8 and which is adequately longer than the small-diameter
l0 portion SA, as well as a needle portion 13 that extends forward
from the distal end of the connector portion 12, that has an
inside diameter slightly larger than the outside diameter of
the injection needle 7 and that has such a length that the
distal end portion of the injection needle 7 will project from
the distal end by a predetermined length.
Given the same intended site at which a drug is to be
administered, the depth from the skin surface to the intended
site and the hardness of the tissue reaching that site will
vary differently depending upon the physical constitution of
each individual and, hence, the needle portion 13 is designed
to have an adequate length in consideration of maximum depth
and in order to prevent the occurrence of bending or
obstruction by a tissue fragment during piercing, the needle
portion 13 is fitted with an inner needle 21 to be described
later.
Referring to Fig. 1C, the inner needle 21 has in
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unitary assembly a basal portion 22 consisting of a cylindrical
fit-in portion 22A that is to be fitted deep and tightly into
the middle part of the connector portion 12 of the piercing
hollow needle 11 and an annular hugging portion 22B that is
located outside said fit-in portion 22A and which is to make
intimate contact with the outer circumference of the basal
portion of the connector portion 12, as well as a knob 24
formed at the basal end of the basal portion 22, and a solid
needle 25 that extends forward from the distal end of the fit-
to in portion 22A, that has an outside diameter slightly smaller
than the inside diameter of the needle portion 13 and which has
such a length that its distal end will align with that of the
needle portion 13.
The example under consideration which has the structure
described above may be used to administer a drug for .the
treatment of herniated intervertebral disks, such as
chymopapain, collagenase or chondroitin and a case of this use
will now be described with reference to Fig. 2 and the drawings
that follow.
2o First, the inner needle 21 is inserted into the
piercing hollow needle 11 from the connector portion 12 and
fixed as the fit-in portion 22 is fitted in the connector
portion 12 and the hugging portion 22B is placed in intimate
contact with its periphery. In this case, the solid needle 25
is inserted into the needle portion 13 almost tightly and their
distal ends will align each other but it is also necessary to
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insure that the inclinations of the oblique needle tips will
not stagger but align in direction. To this end, it is
preferred that a projection is provided, for example, on the
outer circumference of the basal end of the connector portion
12 while, at the same time, a cutout is provided at the distal
end of the hugging portion 22B (both the projection and the
cutout are unshown), with them being brought into mutual
engagement, thereby establishing an in-phase relationship to
assure directional alignment between those inclinations. The
piercing hollow needle 11 having the inner needle 21 thus
fitted therein is allowed to penetrate the skin 61 and the
muscle 62 until its distal end reaches the outer portion of the
fibrous ring 66 of an intervertebral disk 63 (see Fig. 2).
It should be mentioned here that the piercing hollow
needle 11 and the inner needle 21 are sometimes supplied i_n a
coupled state by manufacturers of injection tools and, in that
case, they are allowed to pierce into the body as such.
In the next step, the piercing hollow needle 11 is
fixed by holding the connector portion 12 with fingertips so
2o that it will not move and, then, the knob 24 is pulled to
withdraw the inner needle 21 (see Fig. 3).
With the piercing hollow needle 11 being thus detained,
the injection needle 7 of the injection device 1 that has
aspirated a drug into the cylinder compartment 3 is inserted
through the needle portion 13 from the connector portion 12 and
its distal end is allowed to project beyond the needle portion
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13 so that it will penetrate the fibrous ring 66 to reach the
vertebral pulp 64 at the intended site. In this case, the
small-diameter portion 8A at the distal end of the needle base
8 is fitted tightly into the basal portion of the connector
portion 12 so that the injection device 1 becomes coupled to
the piercing hollow needle 11 (see Fig. 4). Then, the plunger
6 is pushed so that a predetermined dose of the drug in the
cylinder compartment 3 is injected via the injection needle 7
into the vertebral pulp 64 and when the injection ends, the
l0 injection device 1 and the piercing hollow needle 11 are
withdrawn either together or separately.
It should also be mentioned that since the injection
needle 7 of the injection device 1 which is illustrated as an
example in Fig. lA has an extremely fine inside diameter, it is
difficult to aspirate a viscous drug via the injection needle
7 for drug aspiration into the cylinder compartment 3. In a
case such as this, one may use a drug aspirating hollow needle
having a larger inside diameter than the injection needle 7,
connect it to the injection barrel 2, aspirate the drug into
2o the cylinder compartment 3 and thereafter replace said hollow
needle with the injection needle 7.
When administering the drug, the distal end of the
injection needle 7 must be allowed to reach the vertebral pulp
64 as its distal end is permitted to project from that of the
needle portion 13 of the piercing hollow needle 11 by a
predetermined length in an accurate manner. To this end, a
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graduation having a cardinal point in the position where the
distance from the distal end of the injection needle 7 is equal
to the length of the piercing hollow needle 11 may preferably
be provided along the length of the needle base 8 starting at
the basal end portion of the injection needle 7 ( see Fig . 5 ) so
as to ensure projection by a predetermined length by reading
the numeral on the scale that enters the connector portion 12.
Alternatively, a mark may be provided in the position of said
cardinal point on the injection needle 7 and the distance of
l0 movement of this mark relative to a graduation provided on a
transparent connector portion 12 is read, thereby allowing
projection by a predetermined length; this is also a preferred
example.
In the example under consideration, a microsyringe in
which the cylinder compartment 3 does not have a much greater
diameter than the injection needle 7 so that it is suitable for
micro-injection is used as the injection device 1 and due to
the small drug resistance that develops in the cylinder
compartment 3, only a small force is required to push the
2o plunger 6. Further, the absence of the need to fill the
connector portion with a drug as in the prior art and the very
small dose of the drug that is injected per unit stroke length
of the plunger 6 and, further, the injection of the drug
through the injection needle 7 which is preliminarily mounted
on the injection barrel 2, combine together to permit injection
of a predetermined dose in an accurate manner.
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Further, in the example under consideration, the
connector portion 12 is designed to be adequately long compared
to the length by which the needle base 8 is fitted in it so
that blood or other body fluids will not immediately spread to
the surrounding area even if they should flow out through the
needle portion 13; in addition, the resistance or backset that
would otherwise occur due to the compression of filled air when
the needle base 8 is tightly fitted in the connector portion 12
is practically absent, assuring high stability when coupling
to the injection device 1 to the piercing hollow needle 11.
It should be noted that the injection barrel 2 may be
coupled to the connector portion 12 by a lure lock mechanism
whereas the inner needle 21 may be coupled to the piercing
hollow needle 11 by merely slipping the hugging portion 22B
over the connector portion 12.
It should also be noted that while the foregoing
description concerns the case of using the example in the
administration of a drug for the treatment of a herniated
intervertebral disk, the use of the injection tool of the
2o present invention is by no means limited to intervertebral
disks but it can be used appropriately at any sites of a very
small range such as eyeballs that are located comparatively
deep in the body to develop comparatively high internal
pressure.
A specific embodiment of each of the mechanism for
aligning the tip of the piercing hollow needle with that of the
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solid needle of the inner needle or the injection needle and
the mechanism for adjusting the length by which the injection
needle is to project from said hollow needle of the injection
needle will now be described with reference to Figs. 5 to 7.
Fig. 5 is a sectional view showing the in jection needle
1 that has a graduation 16 provided in the small-diameter
portion 8A at the needle base and which has the injection
needle tip 14 align with the needle portion's tip 15 of the
piercing hollow needle by reference to numeral zero on the
l0 scale; Fig. 6 is a perspective view of the essential part which
illustrates the relationship of coupling between the connector
portion 12 of the piercing hollow needle 11 and the small-
diameter portion 8A at the needle base of the injection device
1 which are shown in Fig. 5.
Said small-diameter portion 8A at the needle base is
provided with not only the graduation 16 but also a groove 17
for withdrawing air from the connector portion, as well as a
ridge 18, whereas the connector portion 12 of the piercing
hollow needle 11 is provided with a recess 19 that fits tightly
with said ridge. Therefore, one only need fit said ridge 18 in
the recess 19 to assure that the directions of openings in the
respective needle tips are in alignment as shown in Fig . 5 and,
at the same time, the tip of the injection needle can be
allowed to project beyond the needle portion 13 by a desired
length by using the graduation 16 as an index.
The provision of the groove 17 in said small-diameter
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portion at the needle base offers the added advantage of
permitting smooth movement of the needle tip.
The groove 17 may be replaced by a plurality of
recesses that are provided in the connector portion 12 of the
piercing hollow needle. An embodiment of this case is shown in
Fig. 7A or 7B, A showing the case of providing two recesses and
B four recesses. The small-diameter portion 8A at the needle
base does not have the groove 17 shown in Fig. 6 but is
provided with one ridge 18; a register mark 20 for positioning
to the injection needle tip is provided in the connector portion.
With a plurality of recesses being thusly provided in
the connector portion 12 of the piercing hollow needle, the
degassing groove 17 in the needle base can be eliminated and,
at the same time, the tip of the piercing hollow needle and
that of the injection needle can be set in a desired
relationship. It should particularly be mentioned that in the
case where the distal end of the injection needle is to be
provided with a lateral hole, a desired position of the opening
can be selected, thereby permitting the selection of an
2o effective direction for drug ejection.
Thus, the case of providing the ridge 18 on the small-
diameter portion 8A at the needle base and the recess 19 in the
connector portion 12 has been described above as a fit-in
mechanism but this is not the sole case of the fit-in mechanism
and other embodiments having the same capability may also be
adopted. For example, one or more recesses may be provided in
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the~small-diameter portion 8A at the needle base and a ridge
that fits in this recess is provided on the connector portion.
The mechanism that is shown in Figs. 6 and 7 and which
allows the connector portion 12 of the piercing hollow needle
to f it with the small-diameter portion 8A at the needle base of
the injection device may be applied to the mechanism for
allowing said connector portion 12 to fit with the basal
portion 22 of the inner needle 21. Stated more specifically,
groove 17 and ridge 18 which are provided on said small-
l0 diameter portion 8A at the needle base may be provided in the
basal portion 22 of the inner needle so that the tip of the
solid needle 25 of the inner needle can be easily aligned with
the tip 15 of the piercing hollow needle.
Industrial Applicability
According to the present invention, the injection
needle is inserted through the needle portion of the piercing
hollow needle as it is guided and protected by the latter and
its distal end portion is allowed to project beyond the latter
so that it reaches the intended site; therefore, by permitting
2o the distal end of the needle portion to reach close to the
intended site, one only need allow the injection needle to
project by a small amount; hence, the intended site can be
reached by piercing even through a deep or hard tissue without
potential hazards such as bending and the drug in the injection
barrel can be injected at the intended site of a very small
range by a predetermined dose in an accurate manner.
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As a further advantage, the piercing hole that remains
open at the intended site is equal in diameter to the fine
vestige of the injection needle and, hence, even at high
internal pressure, the outflow of the drug is extremely small
and, in addition, owing to rapid restoration of that hole, the
outflow of blood and other body fluids is also small.
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