Field of the Invention

The invention is an autoin ector designed to deliver doses of medicine intramuscularly, particularly for the administration of active substances, so-called antidotes, in cases of poisoning by nerve agents. More specifically, it is an autoinjector used for the simultaneous administration of two or more drugs with a trigger mechanism, at the bottom of which there is an insert with two or more separate chambers and a sept at the bottom that is syringe penetrable.

Description of Related Art

Autoinj ectors are used as a part of medical equipment of individuals in conditions where treatment by trained personnel is not accessible. The construction of the autoinjector is based on its use and the required dosage of active substances.

Based on the EP 2221 076 patent, the pneumatic powered autoinjector is known, in which pressurised gas acts against the piston in two stages and develops a different power at every stage, which is given by the size of the piston area which the gas affects in the particular stage .

From the published patent application PV 2008-102, a three-chamber autoinjector for delivering medicine is known. The mixing process and injection is controlled by guide elements in the shank rod of the autoinj ector . Thanks to the CZ 303 518 patent, the autoinjector composed of a hollow cylinder divided into three chambers by three pistons is known. A hypodermic syringe is attached to the guide cylinder under the lower piston. The push mechanism comprises of a rod, compression spring and safety fuse. The safety fuse has two working positions and the user must shift the fuse to the second position, during which protrusion of the syringe occurs.

The Principle of the Invention

Based on the invention, an autoinjector for intramuscular self-administration of medical substances can be made. Though it is possible to deliver a number of different substances that may be self -administered using the autoin ector, it is meant primarily for the administration of active substances, so-called antidote, in the case of nerve agent poisoning.

Administering antidote usually entails administration of cholinesterase reactivators, e.g. pralidoxime, obidoxime or methoxime and anticholinergics such as atropine. Subsequently or simultaneously, it is suitable to apply an anticonvulsant with the administration of antidote, for example diazepam. The autoinjector based on the invention has at least two, preferably three chambers, in which each drug is stored and then applied in one step.

The objective of the submitted invention is to increase reliability and comfort during the use of autoinj ectors , and to ensure separate and sterile storage of medicine until just before application. In the invention, this aim is reached by improved construction of the trigger mechanism, tight sealing of the individual chambers and adjusting the inner construction of the insert that enables intensive mixing of individual medical substances during application in one stage.

The body of the autoinjector contains a trigger mechanism with a rod, compression spring and safety fuse, which holds the rod with the compression spring in place. A cylindrical insert is placed in the lower part of the body of the autoinjector, under the trigger mechanism towards the bottom part of the autoinjector, which is the contact area for the user during application itself. The cylindrical insert is closed by a sliding seal with a plug at the top and with a syringe penetrable sept at the bottom, and crimped with a metal cap with a hole to eject the syringe. Furthermore, the insert contains at least one more sliding seal, which divides the insert into at least two chambers. Sliding seals are made of flexible material, e.g. suitable plastic or a butyl rubber and reinforced with a special plug holder or cannula. The lower chamber, placed between the sept and the sliding seal, has a diameter larger than the chamber placed above it. The placement and sizing of changes of the diameters in the lower chamber of the two-chamber insert are based on the viscosity of the solution of the active substance in the upper chamber. The above mentioned sliding seal is equipped with at least two, rather four annular plates, which are sized so that they seal the contents of the upper chamber of active substances tightly, meanwhile, in the lower chamber, enabling flow of solution of active substances through an annulus hole formed by the different diameters of the lower chamber and seal with simultaneous mixing. The seal with the cannula holder and syringe is placed in the sliding seal, separating the lower chamber and the chamber above it . The upper part of the cannula holder has a space connected with the lower chamber by one or more canals, through which the solution of active substances is transported from the lower chamber to the syringe and then administered to the body. The lower part of the insert is crimped with a sept and metal cap. Inserts with more than two separate chambers contain two or more sliding seals, which are equipped with at least two, rather four identical annular plates that are sized so that they immaculately seal the contents of the three or more separate chambers . Mixing the solutions of the active substances occurs in the lower chamber thanks to the annulus, which is formed by the difference in diameters of the upper and lower chambers and seal of the cannula holder. The transport of the solution from the first chamber placed above the bottom mixing chamber, and then from the second and other chambers, gradually occurs through the annulus. The placement and sizing of the various diameters are based on the number of the chambers and viscosity of the solution of the active substances.

When using the autoin ector , the rod is moved along the axis of the body of the autoinjector and is simultaneously moved into the insert of the autoinjector. Thereby, a gradual slide of one of the seals with a plug in two-chamber inserts , or seals with a cannula and plug, occurs through the cannula holder and syringe in the first stage of the shift, and air is expelled from the lower mixing chamber and mixes with the active substances and the solution is then pushed through the cannula holder and syringe into the body. At the same time, the lower chamber serves as a mixing chamber, from which the solution of active substances is pushed through canals in the cannula holder and further through the chamber above the syringe into the cannula syringe . The mixing effect in the lower, mixing chamber is increased thanks to a turbulent flow of the solution through an annulus hole through lamella seals into the lower chamber along the walls of the lower chamber, which is enabled by the different diameters of the lower chamber in comparison to the chamber placed above.

A larger diameter of the lower chamber is a diameter of 1% - 9%, with an advantage of 4% to 8%, e.g. 5.6% larger than the diameter of the second, respectively third chamber. The flexibility of the material of the lamellas enables flow of the solutions of active substances. Thanks to increased mixing efficiency, the active substance may be placed in the bottom chamber, and, in the case of nerve agent re-activator antidote, not only as a solution, but also as a crystalline form of substance.

The crimped sept metal cap allows for, even in the case of the autoinjector, meeting the standards for aseptic filling of drug vials prescribed by law. Aseptic filling of small volume solutions or substances in crystalline form is subject to the approval of the State Office for Drug Control or other state authorities allowing this activity.

In the convenient version, the fuse is arranged so that it can slide perpendicularly to the rod and a cotter pin secures it against inadvertent displacement. After the cotter pin is removed, similarly to a hand grenade, the autoinjector is ready for application and may be applied easily using a thumb grip.

Overview of the Figures in Drawings

The invention is further described in detail in examples as shown in the drawings attached. The drawings depict:

FIG. la autoinjector based on one version of the invention, with a three-chamber insert, in resting position;

FIG. lb autoinjector based on FIG. la after application;

FIG. 2a detail of the safety fuse;

FIG. 2b detail of the upper part of the rod adjusted for mutual effect with the safety fuse;

FIG. 3a detail of the syringe cannula holder;

FIG. 3b detail of seal between chambers; detail of lower part of insert;

detail of lower chamber and chamber above it; three- chamber insert of autoinjector with solution of active substances as in FIG. la;

two-chamber insert with a solution of active substances for the autoinjector based on other versions of the invention; three-chamber insert of the autoinjector with active substances in the upper chamber and salts in crystalline form in lower chamber;

two-chamber insert with solutions of active substances in the upper chambers and salts in crystalline form in the lower chamber based on a different version of the invention .

Examples of Embodiment of the Invention

Example 1 (three -chamber " Triplepen " autoinjector)

FIG. la shows the auto- inj ector with three mutually separate chambers 9, 1_1, 1_5. The upper part of the body 6_ contains a trigger mechanism with a rod _3, a fuse 2 and a compression spring 4. In rest position shown in FIG. la, the rod 3 secures the fuse 2 to hold the compression spring 4 in a compressed state. The fuse 2, shown in detail in Fig. 2a, holding the rod 3_ against the force of the compressed spring 4 by a shank rod 5, which is captured in the narrower part 2_4 of the hole for the peg. By inserting the fuse 2 perpendicularly to the rod 3 to the left into the position of Fig. lb, the shank rod 5 reaches the wider part 2_5 of hole for peg, through which the shank rod 5 passes through the rod and the spring 4 moves the trigger mechanism to the position shown in FIG. lb. The fuse 2 is secured by a cotter pin 18_, tucked in the hole 2_6 for the cotter pin. Below the trigger mechanism (data on its position is relative to the orientation of the images with the trigger mechanism at the top and the application end of the autoinjector at the bottom) , a replaceable, hollow, cylindrical insert 7 is placed. The insert Ί_ ¹⁸ closed in its upper part by a sliding seal 8 with a plug 19 and at the bottom with a sept 17, which is syringe penetrable 3_, and an aluminium cap 16. The body of the insert is closed by a ferrule nut 14 , with an opening for the syringe. Insert Ί_ is divided by two other sliding seals 10 , 12 into three chambers 9, 11, 15. As best seen in FIG. 5, the lower chamber 15 has a larger diameter than the remaining two chambers 9, 11 , located above it . Sliding seals _8, 1_0 , 12 are provided with annular lamellas 21. In sliding seal 12, which delimits the lower chamber 3J5 from above and separates it from the chamber 11, located above it, a cannula holder 2_0, provided with cannula holder lamellas 27 , is placed. In the cannula holder 20, there is a syringe 13, which is connected through the space 22_ above the syringe and through the canals 2_3 to the lower chamber 15, thus providing transport of active substance solution from the lower chamber into the syringe and the body. The syringe 13_ is retained in the cannula holder 2_0 and a valve secures it against displacement into the space 22 above the syringe. Meanwhile, the lower chamber 15_ serves as a mixing chamber from which the mixture is extruded through canals 2_3 extending through the cannula holder 20 and then through the space 2_2 above the syringe into the syringe 13.

The bottom of insert 7_ is provided with a sept 17 and is closed with a crimped aluminium cap 1_6, as shown in FIG. 4. Sept 1_7 is made, for example, of silicone rubber. However, it may also be made of polybutylene , natural rubber or another rubber type, and can be further modified, for example coated with polytetrafluoroethylene Sliding seals 8, 1_0, 12 , as described in the embodiment, are each provided with four annular plates 21. The annular plates 2JL in rest position of the autoinj ector , i.e. during storage, but also when wearing, prevent premature mixing of contents of adjacent chambers 9, 11; 11, 1_5. Once activating the autoinj ector , the sliding seal 12 gets in the lower chamber 15, which has a somewhat larger diameter than the middle chamber 11 and upper chamber 9, turbulent flow of the solution occurs through the annular plates 21 to the lower chamber 15 along the walls of the lower chamber 15.

In the example shown in Fig. 6a, the lower chamber 15 contains a reactivator solution. The middle chamber YL in the described example contains an anticholinergic solution. The upper chamber 9 in the example described contains an anticonvulsive solution.

I am not going to include any specific volumes in this example. They are included in the text. Some changes, particularly in the volume of active substances, are already being made.

Example 2 (two-chamber "Doublepen" autoinj ector )

Containing anticholinergics and a reactivator.

The triggering mechanism of the two-chamber autoinjector is the same as is described above for a three-chamber autoinjector. The only difference is that the fox-ce of spring Ί _, ^v i- ^a the rod 3 acts on the sliding seal 1_0, which closes the middle chamber 11. The arrangement of the insert 7 and the two-chamber and three-chamber autoinjector is illustrated in Fig. 6a, 6b. The same components have the same reference numerals as in Example 1.

As shown in Fig. 6B, the lower chamber 1_5 contains an oxime solution, and chamber 11, located above it, contains an anticholinergic solution . In other versions, there may be an oxime solution in the lower chambe 15 (obidoxime, pralidoxime, methoxime, etc.) . Or in crystalline form in particular HI6 DMS, as shown in Fig. 6c and 6d.

List of references

1 cap 15 lower chamber

2 safety fuse 16 aluminium cap

3 rod 17 sept

4 spring 18 cotter pin

5 shank rod 19 plug

6 body of autoinjector 20 cannula holder

7 insert 21 annular plates

8 sliding seal 22 area above syringe

9 upper chamber 23 canal

10 sliding seal 24 narrower part of the hole

11 middle chamber for the peg

12 sliding seal 25 wider part of the hole for

13 syringe the peg

14 ferrule nut 26 hole for cotter pin

27 cannula holder lamella