CA2714606C

CA2714606C - Three-chamber automatic injector

Info

Publication number: CA2714606C
Application number: CA2714606A
Authority: CA
Inventors: Bohuslav Dolezal; Karel Ledvinka; Filip Behensky; Kamil Kuca; Daniel Jun; Jiri Kassa; Jan Dolezal
Original assignee: VAKOS XT AS
Current assignee: VAKOS XT AS
Priority date: 2008-02-22
Filing date: 2009-02-20
Publication date: 2015-06-09
Anticipated expiration: 2029-02-20
Also published as: EP2259817A1; CA2714606A1; WO2009103251A1; SK288151B6; SK500382010A3; WO2009103251A4

Abstract

Injector allowing to mix, dissolve and apply medicine stored in mutually separated chambers consists of the body (1) where its inside contains a pushing mechanism and a part with three separated chambers (19, 18 and 30) with injection needle (16). The chambers (19, 18 and 30) are mutually separated by pistons (10, 11 and 12), the second chamber (18) contains bypass connection (29). In the third chamber (30), an injection needle (16) is fixed inside the guide cylinder (17) located below the third piston (12), and the guide cylinder (17) is equipped with bypasses (22) connecting the third chamber (30) with the entry of the injection needle (16). The third chamber (30) is equipped with the second section (21) with diameter by to 10 % larger than diameters of the other chambers and is closed by end cap (13). The part with three separated chambers (19, 18 and 30) is formed by replaceable cartridge (7).

Description

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.

2 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

3 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-

4 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 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.

6 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 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

8 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.

9 Industrial Applicability Three-chamber automatic injector according to the invention may be exploited in pharmaceutical industry for preparation of medicine in emergency situations.

Claims

WHAT IS CLAIMED IS:

1. An automatic injector for mixing and applying a medicament stored in separated chambers, the automatic injector comprising:
a pushing mechanism comprising a pull-rod, a driving spring and a safety lock, the pull-rod passing through a safety lock and a bottom of an interior of the injector, the safety lock being placed at a top part of the bottom of the interior, the driving spring placed around the pull-rod, the pull-rod having two catches allowing the pull-rod to fall gradually down through an aperture created in the safety lock into a first operating position and a second operating position;
and a body for receiving a cartridge, the cartridge comprising:
a first chamber, a second chamber and a third chamber separated by a first piston, a second piston and a third piston, the first piston, the second piston and the third piston having a first diameter, the pull-rod contacting the first piston, the first piston closing the first chamber, the first chamber and the second chamber filled with solutions and/or powder of pharmaceutically active substance, the first chamber being separated from the second chamber by the second piston, the second chamber defining a bypass connection formed in the inner wall, the third piston separating the second chamber and the third chamber, the third chamber comprising a first section and a second section, the second section defining a diameter 5 to 10 %
greater than the first diameters of the first chamber and the second chamber, and a length shorter than the sum of the heights of the first piston, the second piston and the third piston, the second section closed by an end cap;
a guide cylinder located below the third piston and having a second diameter smaller than the first diameter; and an injection needle located in the third chamber and attached to the guide cylinder, a top portion of the guide cylinder having bypasses connecting the third chamber with an entry of the injection needle.

2. The automatic injector according to claim 1 wherein the safety lock is covered by a cap.

3. The automatic injector according to claim 1 wherein the safety lock is placed on the top part of the bottom of the interior rotationally and serves as a cap.

4. The automatic injector according to any one of claims 1 to 3 wherein the bypass connection is formed by a segment created by a peripheral recess or a groove in the inner wall of the second chamber of the replaceable cartridge and defines a length longer than the length of the second piston.

5. The automatic injector according to any one of claims 1 to 3 wherein the bypass connection is formed by a segment with bypass channels parallel to a body axis, formed with slight recess in axial direction in the inner enclosing wall of the replaceable cartridge.

6. The automatic injector according to any one of claims 1 to 5 wherein a front side of the third piston has a hollow space for placing the guide cylinder.

7. The automatic injector according to any one of claims 1 to 6 wherein the end cap touches a screw stopper with an aperture allowing the injection needle to pass.