Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Three-Chamber Automatic Injector.
Technology Field
The invention belongs to a group of devices, which inject liquids into living
organism
in cases when it is necessary to inject medicine immediately and under
conditions
unknown in advance. The invention deals with a three-chamber automatic
injector
with mutually separated chambers containing individual ingredients, which will
mix
together prior injecting.
Existing Conditions of Technology
At present, we know numerous manual or automatic devices designed to allow
injection of medicinal solution into patient's body or into other receiver.
Also, we
know cases when certain persons need to inject themselves medicinal solution
in
a moment in time, which cannot be foreseen. Such persons should be equipped
with
injectors allowing activation by simple and quick action while maintaining
reliability.
For such cases, automatic injectors were developed. They should comply with
the
requirement to allow storing for several years without any changes to chemical
or
pharmacological properties of ingredients they contain; even regardless of
storage
temperatures. Further, such automatic injectors are exposed to harsh
conditions during
the time their potential users keep carrying them with themselves. We may say
that
apart from the automatic injectors' storage lifetime, their endurance in
conditions they
are exposed to prior application is equally critical. In this connection we
should note
that medicinal solutions' stability may deteriorate during long-term storing.
This is the
case of antidotes against nerve gas, which remain stable in powder form,
however
their stabilization in solution for long storage periods is difficult.
Therefore we are
facing a requirement to create multi-chamber automatic injector for
application of
medicinal solution, which will be simple in function, quick and reliable,
which will
allow to store ingredients separately for long periods of time and which will
create
medicinal solution when mixed; and which contains mechanism that upon
injector's
activation causes mixing of ingredients and their subsequent application in
form of
their solution.
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We know numerous patents of similar devices, such as YU-P-616/88. Its
disadvantages include the need to follow five steps in prescribed order
preceding the
activation itself. This decreases its reliability and possibility to use it
quickly in
unexpected and challenging conditions. Another known device described in
patent
EP-A 0 219 899 has the disadvantage that it is designed as a single-use device
only.
Once the autoinjector is used, the cartridge with medicine cannot be replaced
and the
automatic injector must be discarded after use. Another disadvantage of this
device is
that the bypass connection is designed outside the cartridge containing the
medicine
and this solution requires big internal diameter of the autoinjector and other
inserts
allowing telescopic movement of the cartridge inside the automatic injector's
body.
Another disadvantages of the mentioned autoinjectors include the need to hold
them
prior application by both hands to remove the cap of the injection needle, to
make
twisting movement or apply certain force causing the separated ingredients to
mix and
activate the injection unit. Significant shortcomings include also the fact
that mixing
of separate ingredients and injection of medicine as such is not performed by
sequential steps of single type of action but consists of different actions,
such as the
telescopic shifting of the autoinjector's body causing the ingredients to mix
and
subsequently the driving device must be unlocked to apply the medicine, mostly
by
releasing a latch on pull-rod with pre-stressed spring.
In summary, the shortcoming of known devices intended for injecting single-,
two- or
multi-component medicine into organism is that the application of medicine as
such is
preceded with the need to make multiple steps in prescribed order to mix
separated
ingredients and to activate the autoinjecting unit. Other disadvantages
include the fact
that these autoinjectors do not provide protection of injection needle against
contamination, that they do not allow re-use, that they do not allow quick
mixing of
liquid ingredient and ingredient in powder form, that their individual safety
elements
that must be removed before use of autoinjectors are rather small in size,
thus creating
an obstacle when getting autoinjectors ready for action in challenging
conditions.
Summary of the Invention
Three-chamber automatic injector for mixing and application of medicine stored
in
mutually separated chambers consisting of a body, which inside contains in-
built
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pushing mechanism and part with separated chambers and injection needle,
consists according to this invention in the fact that the body contains part
with three
separated chambers filled with solutions and/or powder of pharmaceutically
active
substance. The part with three separated chambers is enclosed inside the body.
The
first chamber is closed from the top by the first piston, above which the
pushing
mechanism is located. The first chamber is separated from the second chamber
by the
second piston, the second chamber contains bypass connection of the second
piston
while the length of the bypass connection is longer than the second piston's
height but
shorter than the sum of the first and the second pistons' heights. The third
piston
mutually separates the second chamber from the third chamber where injection
needle
is fixed inside the guide cylinder located below the third piston. Top part of
the guide
cylinder is equipped with bypasses connecting the third chamber with the
injection
needle entry. The third chamber consists of the first section and the second
section,
diameter of the second section is by 5 to 10 % larger than diameters of
preceding
chambers and its length is shorter than the sum of all pistons' heights. The
third
chamber is closed by end cap below the point of the needle.
Bypass connection is formed by a segment created by a perimeter recess or a
groove
in the wall of the second chamber, which has larger diameter than the diameter
of the
second piston. Or by a segment with bypass channels created inside the
internal
enclosing wall in parallel with the body axis, which are equipped with leading
edge
allowing smooth motion of the piston over this edge.
The part with three separated chambers is advantageously formed by replaceable
cartridge located inside the body.
The body is advantageously shaped as a hollow cylinder and its bottom part is
closed
by a cap nut.
The third piston's front side is equipped with a recess allowing placing the
guide
cylinder. Diameter of the guide cylinder is advantageously smaller than
diameter of
pistons.
End cap touches the cap nut, which is equipped with the aperture to allow the
injection
needle to pass.
Pushing mechanism consists of the pull-rod, driving spring and safety lock,
the pull-
rod is formed by a stem and in its top part it is equipped with the first
catch and the
second catch. Stem's bottom part is enhanced, driving spring is put around the
pull-
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rod, and spring's one end presses against the stem's bottom enhanced part and
the
other end presses against the bottom inside the body; in the top part of
inside of the
body is a safety lock, through which the stem of the pull-rod with catches
passes.
Aperture is created in the safety lock to allow the first catch on the pull-
rod to fall
down when the safety lock unlocks to the first operating position and to allow
the
second catch on the pull-rod to fall down when the safety lock unlocks to the
second
operating position. Safety lock and the top end of the pull-rod are covered by
a cap,
firmly connected with the top part of the inside of the body.
Safety lock can be placed on the top part of the inside of the body
rotationally and
serves as a cap at the same time.
In cases when more different substances requiring separate storing prior
application of
the injection should be mixed, it is also possible to add more chambers as
well as add
more catches on the pull-rod.
Three-chamber automatic injector is a device allowing to automatically inject
solution
of medicine created from three and more ingredients stored, separately in a
cartridge.
With ingredients separated as described the injector may be stored even for
several
years without any changes of their chemical or pharmacological properties.
Automatic
injector according to this invention can be easily operated by thumb of one
hand.
Moving the safety lock from one operating position to the second triggers the
stage of
mixing one ingredient with the other. In case of design with more than three
chambers
moving the safety lock back triggers the stage of mixing the next ingredient
with the
solution, which was created in preceding operating stage. When all ingredients
are
mixed, next move of the safety lock triggers the stage of injecting the
medicinal
solution into organism or other receiver. In the beginning of this stage, the
injection
needle moves forward and subsequently the created medicinal solution is
applied.
Automatic injector is ready to be re-used once the driving spring of the
pushing
mechanism is pressed back, pull-rod is secured by the safety lock, new
cartridge with
separated ingredients is inserted and secured by cap nut.
Advantage of the three-chamber automatic injector according to this invention
is in
particular easy manipulation and possibility to use the autoinjector even in
challenging
conditions. Injection needle is protected by the cartridge and end cap before
use. Prior
application it is not necessary to remove any needle cover, as it is required
by all
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injectors known so far. Stages of mixing, dissolving the active substance and
injecting the medicine into organism can be controlled by one hand only. Steps
required to prepare and activate the autoinjector, to mix the liquid
ingredient and
ingredient in form of powder, take 3 seconds.
5 Force required to activate the injector is minimum.
Cartridge with separated ingredients of solutions and powder allows long-term
storing
of substances in different states, which are required to maintain their
chemical or
pharmacological stability.
Cartridge is replaceable and allows the mechanism of the injector as such to
be re-
used multiple times.
Design of catches and the pull-rod and safety lock is very simple and
guarantees high
reliability of the pull-rod's falling down through the safety lock in both the
first and
the second operating positions.
Manufacture and assembly of the autoinjector are simple and production costs
are
low.
Overview of Figures in Drawings
Fig. 1 shows longitudinal section of the automatic injector before use.
Fig. 2 shows longitudinal section of the automatic injector after moving the
safety
lock to the first operating position, at which the liquid ingredient mixes
with the
ingredient in form of powder.
Fig. 3 shows longitudinal section of the automatic injector after moving the
safety
lock to the second operating position, at which the medicinal solution is
moved to the
section, from which it will be applied.
Fig. 4 shows longitudinal section of the automatic injector after application
of the
medicinal solution into organism or other receiver.
Fig. 5 shows plan view and side view of the pull-rod with the system of
catches
created on its stem.
Fig. 6 shows plan view and side view of the safety lock.
Fig. 7 shows detail of middle part of the cartridge with bypass channels in
scale 5:1.
Fig. 8 shows detail of bottom part of the cartridge with in scale 5:1.
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Detailed Description of the Preferred Embodiments
Three-chamber automatic injector shown in the figures is formed by hollow
cylindrical body 1, where in its top part a pushing mechanism is located
consisting of
a pull-rod 2, steel driving spring 3 and safety lock 4. To the top part of the
cylindrical
body 1 a cover 5 is attached securing the safety lock 4.
To the inside of the cylindrical body I is inserted the cartridge 7 equipped
with
separated chambers 19, 18 and 30 filled with solutions and/or powder of
pharmaceutically active substance. The cartridge 7 is secured in the
cylindrical body I
from the bottom by cap nut 6. Bottom enhanced part 26 of the pull-rod 2 leans
against
the first piston 10, which encloses from the top both the cartridge 7 and the
first
chamber 19. This chamber 19 is separated from the second chamber 18 by the
second
piston 11. In the cylindrical wall of the second chamber 18 are created bypass
channels 14 equipped with leading edge 15 allowing smooth motion of the piston
over
this edge 15. The third, last, piston 12 separates the second chamber 18 and
the third
chamber 30, in which the injection needle 16 is fixed in the guide cylinder 17
placed
under the third piston 12. Diameter of the guide cylinder 17 is smaller than
diameter
of pistons 10, 11 and 12. Guide cylinder 17 is in its top part equipped with
bypasses
22 connecting the external space of guide cylinder 17, or the third chamber 30
respectively, with the entry of the injection needle 16. The third chamber 30
is formed
by the first section 20 and the second section 21, which is in its bottom part
below the
point of the needle 16 closed by end cap 13. The second section 21 has
diameter by
7 % bigger than the diameter of other chambers in the cartridge 7. End cap 13
touches
the cap nut 6 described above.
Pull-rod 2 of the pushing mechanism is formed by a stem 23 and in its top part
it is
equipped with the first catch 24 and the second catch 25. Bottom part 26 of
the stem
23 is enhanced, steel driving spring 3 is put around the pull-rod 2, and the
spring's 3
one end presses against the bottom enhanced part 26 of the stem 23 and the
other end
presses against the bottom 27 of the inside of the body 1. In the top part of
the bottom
27 of the inside of the body I is a safety lock 4, through which passes the
stem 23 of
the pull-rod 2 with catches 24 and 25. Pull-rod 2 then passes through the
inside of the
cylindrical body 1, and the bottom enhanced part 26 of the stem 23 pushes on
the first
piston 10. Inside the safety lock 4 is created the aperture 28 to allow the
first catch 24
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on the pull-rod 2 to fall down when the safety lock 4 unlocks to the first
operating
position and to allow the second catch 25, on the pull-rod 2 to fall down when
the
safety lock 4 unlocks to the second operating position. Safety lock 4 and top
end of
the pull-rod 2 are covered by a cap 5, firmly connected with the top part of
the bottom
27 of the inside of the body 1.
The first chamber 19 contains the solvent necessary for creating the medicinal
solution
from the ingredient in form of powder, which is stored in the second chamber
18 in
the middle part of the cartridge 7 between pistons 11 and 12. The third
chamber 30 is
filled with suitable liquid or gaseous phase. Three-chamber automatic injector
described above is shown in fig. 1 in the embodiment, in which it is stored
and
simultaneously ready to use.
The injector can be controlled by one hand by moving the safety lock 4 from
standby
position (fig. 1) to the first operating (mixing) position (fig. 2). By moving
the safety
lock 4 back (the second operating position is identical with the initial
standby
position) the injector enters to the second operating position (injection)
(fig. 3 and 4).
By moving the safety lock 4 from the standby position to the second operating
position the first catch 24 of the pull-rod 2 falls down through the aperture
28 in the
safety lock 4. Driving spring 3 pushes on the pull-rod 2 and this pressure
moves the
first piston 10 and hydraulically transfers the pressure onto the second
piston 11,
which moves to the second chamber 18 with bypass connection, which is formed
by
bypass channels 14 created in the internal enclosing wall of the second
chamber 18 in
parallel with axis of the body 1. Length of the channels 14 equals to five
quarters of
the height of the second piston 11.
Pressure on the third piston 12 is partially compensated by the layer of gas
in the third
chamber 30 in the first section 20. Through bypass channels the liquid from
the first
chamber 19 gets to the second chamber 18 where it dissolves the medicine in
powder
form (fig.2).
Length of the first piston's 10 and the second piston's 11 movement depends on
distance of the first catch 24 and the second catch 25.
By moving the safety lock 4 to the opposite, second operating position, or in
this case
to the original standby position respectively, the second catch 25 falls down
through
the aperture 28 of the safety lock 4, and the pull-rod 2, by means of pressure
created
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by the driving spring 3, moves the piston 10 as far as to the piston 11, and
immediately thereafter the injection needle 16 moves out through the end cap
13 (fig.
3). Further, pistons 10 and 11 move towards the piston 12 (fig. 4 and 8).
At the moment when the end cap 13 is pierced, the gaseous phase releases
through
bypasses 20 created in the guide cylinder 17 to the entry of the injection
needle 16.
Subsequently, the solution flows to the injection needle 16 from the third
chamber 30
from the first section 20.
At the moment when the third piston 12 gets to the enhanced section 21, all
sections
described above, which were created during individual operating stages,
interconnect
into single common section. Content of the third chamber 30 now mixes with the
solution from the second chamber 18.
Medicinal solution flows through bypasses 22 in the top part of guide cylinder
17 to
the entry of the injection needle 16 and thereafter it is injected into
organism or other
receiver.
Fig. 4 shows position of individual parts of the automatic injector and fig. 8
shows
detail of bottom part of the cartridge 7 in scale 5:1 after the medicinal
solution was
applied. Fig 5 shows the pull-rod 2 and fig. 6 shows the safety lock 4 for
three-
chamber design of the automatic injector.
By procedure described above, individual required stages of the automatic
injector's
operating actions are realized, which in case of three-chamber design include
creating
the medicinal solution from liquid ingredient and solid ingredient in form of
powder
and its subsequent injection into organism or other receiver.
Internal bypass connection allows for immediate mixing of powder and liquid
ingredients. Further mixing and homogeneity of injected active substance is
ensured
by enhanced diameter of the second section 21 in the third chamber 30 and by
turbulences in bypasses 22.
Prior use the injection needle 16 is protected by cartridge 7 and an end cap
13. Before
application there is no need to remove any possible needle cover as it is
required by
injectors known so far.
Design of catches 24 and 25 of the pull-rod 2 and the safety lock 4 is very
simple and
guarantees high reliability of the pull-rod's 2 falling down through the
safety lock 4
both in the first as well as in the second operating position.
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Industrial Applicability
Three-chamber automatic injector according to the invention may be exploited
in
pharmaceutical industry for preparation of medicine in emergency situations.
