WO1994016752A1

WO1994016752A1 - Self-injection device

Info

Publication number: WO1994016752A1
Application number: PCT/EP1993/000180
Authority: WO
Inventors: Philippe Meyer
Original assignee: Med-Plastic Ag
Priority date: 1992-01-10
Filing date: 1993-01-27
Publication date: 1994-08-04

Abstract

A self-injection device has a tubular sleeve (1) in which is axially arranged an ampule (5) closed at its front end by a membrane (6) and at its rear end by a piston (8). An injection cannula (3) is axially slidable in the ampule. A tubular actuating cap (13) is slidably guided on the rear end (4) of the sleeve (1) and is secured against removal. A piston rod (16) which acts on the piston (8) starts from the bottom (17) of the cap (13) and is inserted into the sleeve. A central bore (18) extends through the bottom of the cap and the piston rod. A locking pin (19) is inserted into the bore (18) in the initial position, in which the cap is partially slid on the sleeve and the piston rod engages the piston. At its inserted end, the locking pin (19) has radially projecting elastic tongues (20) which extend through lateral slots (21) in the piston rod and bear on the rear end (22) of the sleeve.

Description

Self-injection device

The invention relates to a device for self-injection, with a tubular sleeve in which an .Ampoulle .axially arranged, which is closed at the front end by a membrane and at the rear end by a piston, and with one in the ampoule axially displaceable guided injection cannula, which is designed at the front end for piercing the membrane and for injection and at the rear end abuts the piston via an end flange. However, the invention can also be applied to devices for self-injection, which have a tubular sleeve in which an ampoule is guided axially displaceably, which is closed at the front end by a membrane and at the rear end by a piston, and further have an injection cannula axially displaceably guided in the sleeve in front of the ampoule, which is designed at the front end for injection and at the rear end for piercing the membrane.

Devices of this type are used primarily for administering emergency medications, such as, for example, antidotes. For this purpose, the device must be ready for use immediately, work absolutely immune to malfunction and ensure the sterility of the medicament contained and the enclosed cannula for a long time. From DE-PS 1,094,932, US-PS 3,320,955, US-PS 4,624,660 and EP-PS 0 107 874 devices of the aforementioned types are known in which the advance of the injection cannula out of the sleeve and the advance of the piston in the ampoule is made by spring force. A piston rod acts on the piston, which is suspended at the rear end of the device with a plurality of snap hooks in an axial opening of a rear sleeve wall and is pretensioned by a strong spring which is pushed onto the piston rod and strives to follow it to drive in front. The spreading of the snap hooks of the piston rod at the rear end of the sleeve is ensured by a locking pin, which is inserted centrally from the rear between the clamping hooks that engage behind the edge of the hole in the rear wall of the sleeve. To initiate the injection, the locking pin is first pulled axially backwards, and then the clamping hooks of the piston rod are forced together by slightly shifting an actuating sleeve which is pushed onto the sleeve and has corresponding projections on the inside. Since the tensioning hooks no longer reach behind the opening edges, the suspension of the piston rod in the sleeve is released and the biasing spring drives the piston rod forward. The forward movement of the piston rod in the first type of device mentioned at the outset simultaneously pierces the injection cannula through the ampoule membrane and releases the medicament contained in the ampoule into the body during the advancement of the piston and the injection cannula. In the case of the second type of device described at the outset, the advance of the piston causes the entire ampoule and the injection cannula arranged in front of it to be advanced until it has penetrated into the body, and then the ampoule membrane is pierced through the rear end of the cannula and finally one Feed the plunger in the ampoule while simultaneously expelling the medication into the body via the cannula.

In these known devices, therefore, the injection process takes place fully automatically after removal of the locking pin, if the actuating sleeve is slightly displaced relative to the inner sleeve for triggering, ie when the actuating sleeve is gripped and pressed against a body part, as a result of which the inner sleeve contacts the body part comes and shifts slightly relative to the actuating sleeve. The injection process runs like a shot. This trigger mechanism has the disadvantage, however, that after removing the locking pin, the automatic injection is caused by slight vibrations, impacts or by a Dropping the device is triggered and the medication is wasted and the device becomes worthless. The known devices therefore do not meet the requirements for an operation which is absolutely not susceptible to malfunctions under the harshest conditions, such as are typical for emergency use.

The invention sets itself the goal of developing devices of the type mentioned in such a way that an unintentional triggering can be excluded and that simple handling while maintaining the constant operational readiness and ensuring sterility is made possible. This object is achieved according to the invention in that a tubular actuating cap is displaceably guided on the sleeve at the rear end of the sleeve and is secured against being pulled off, which has a piston rod which starts from the cap bottom and is inserted into the sleeve and acts on the piston, the cap bottom and the piston rod is penetrated by a central bore, into which a locking pin is inserted in the starting position with the cap partially pushed onto the sleeve and the piston rod engaging the piston, the locking pin having radially projecting resilient tongues at its inserted end which pass through lateral slots in the piston rod and rest on the rear face of the sleeve.

With this new type of actuation and locking mechanism, the actuation cap has to be moved at will in order to effect the injection. An unintentional triggering by vibrations, shocks, etc., as in the known devices, is excluded. The design of the locking pin according to the invention ensures extremely simple handling, in that the locking pin only has to be pulled backwards in order to make the device ready for use. The injection itself is achieved by gripping the actuating cap and pressing the entire device against a body part with simultaneous advancement of the actuating cap. This has the further distribution, that the entire handling is carried out as in the known devices, ie that no retraining is required for use and operational safety is ensured by the usual operation. It should be mentioned that it is known from US Pat. No. 3,943,927 for an injection device of a different type to provide a tubular actuating cap of the design described.

In an advantageous embodiment of the invention, axially extending grooves are provided on the inside of the central bore, the number and circumferential distribution of which correspond to the number and circumferential distribution of the tongues on the locking pin. Both when inserting and when removing the locking pin, these grooves serve as sliding guides for the tongues, which facilitates both the assembly of the device and the intended use.

It is particularly advantageous if the tongues on the circumference of the locking pin extend in the axial direction in a first straight section and protrude beyond the locking pin and then run obliquely outwards in the radial-axial direction in a second straight section deflected at an obtuse angle. Since the tongues are made of elastic material, this configuration of the tongues enables the tongues to be forced together in an excellent manner, so that they can be inserted and removed via the central bore.

Furthermore, it is advantageous if the ends of the tongues are deflected outward in the radial direction and engage in recesses on the inside of the actuating cap, which offers an additional locking effect.

In all of the configurations according to the invention, it is advantageous if the end of the locking pin that is not inserted has a grip part whose diameter is larger than the diameter of the central bore. As a result, the locking pin is further fixed, so that the locking pin in particular when using the recesses on the inside of the actuating cap is fixed in both directions. Furthermore, the handle part enables easy handling.

In a particularly preferred embodiment of the invention, the rear side walls of the slots of the piston rod are chamfered, the edges of the chamfered slot side walls lying further back being on the inside of the bore. This facilitates the engagement and disengagement of the tongues engaging in the slots. A simpler construction and improved sterility compared to the known devices of the second type is obtained if the rear end of the injection cannula is guided in a manner known per se through a cannula guide piston which is displaceably mounted in the sleeve, projects beyond it and is fixed therein and if this protruding cannula end is covered by an elastic protective cap serving as a spacer spring or is sealingly connected to the ampoule by an elastic protective tube serving as a spacer spring. Further features and advantages of the invention result from the following description of the enclosed drawings, in which:

1 shows a longitudinal section of a device of the first type designed according to the invention; FIG. 2 shows a reduced view of the device according to FIG. 1;

Fig. 3 is a reduced view of the device of Figure 1 in two different operating positions, each half. 4 shows a device of the second type designed according to the invention in longitudinal section;

FIG. 5 shows a reduced view of the device according to FIG. 4;

FIG. 6 is a reduced view of the device according to FIG. 4 in two different operating positions, each half;

A view of the actuating cap according to the invention in detail; 8 shows the actuating cap according to FIG. 7 in longitudinal section;

9 seen the actuating cap in front view from behind; Figure 10 seen the actuating cap in front view from the front.

Figure 11 shows the locking pin with the handle part and the attached tongues in longitudinal section.

12 shows a view of the locking pin with the handle part and the tongues in a position rotated by 90 ° with respect to FIG. 11;

Figure 13 shows the locking pin with the handle part and the tongues in front view from the front. and the

14 to 16 each show a section of FIG. 4 with further details of the device according to the invention in section.

1, a first type of device for self-injection has a tubular sleeve 1 which has an opening 2 of small diameter at the front end for the passage of an injection cannula 3 and is essentially open at the rear end 4. In the sleeve 1 is an ampoule 5 made of glass or metal, e.g. a standard glass ampoule. The ampoule 5 is at the front end through a disc-shaped membrane 6 made of e.g. Rubber sealed, which is held by an aluminum cap 36 pressed onto the neck 7 of the ampoule with a central opening 37 on the ampoule neck. At the rear end the ampoule 5 is closed by a piston 8, e.g. a rubber stopper that can be sealed in the ampoule. The ampoule 5 lies at the front end via the membrane 6. On the inside of the front end wall of the sleeve 1 and is held in its rear end by an inwardly flanged edge 9 of the sleeve 1.

The injection cannula 3 is slidably mounted in the ampoule 5, etc. in a cannula guide 10, which fills the front part of the ampoule and a central one

Has bore for the slide bearing of the cannula 3. The cannula

3 is at the front end to break through the membrane 6 and tapered for injection in the usual way and has at its rear end a flange 11 with which it abuts the piston 8. Furthermore, the cannula bore, not shown, is connected to the interior of the ampoule via a lateral opening 12 in the rear cannula part. Through this opening 12 when the plunger 8 penetrates into the ampoule 5, the medicament contained in the ampoule is expelled and injected via the cannula bore.

The following arrangement is used to actuate the piston 8. At the rear end of the sleeve, a tubular actuating cap 13 is guided so that it can be pushed on the sleeve 1 and secured against being pulled off by a projection 14 arranged on the inside of the cap, which cooperates with a corresponding projection 15 on the outside of the rear end of the sleeve 4. The actuating cap 13 is shown in more detail in FIGS. 7 to 10. The length of the actuating cap 13 in relation to the length of the sleeve 1 and the arrangement of the projections 14, 15 is selected so that when the actuating cap is displaced from the position shown in the left half of FIG. 3 to that in the right half of FIG 3 corresponds to the distance that the piston 8 has to travel in order to expel the medicament dose contained in the ampoule 5. The outside of the actuating cap 13, as can be seen in FIGS. 2 and 3, is designed as a handle by ribbing.

The actuating cap 13 is fixedly connected to a piston rod 16 acting on the piston 8, which extends from the bottom 17 of the actuating cap 13 in the axial direction into the interior of the cap and has a diameter such that it can be inserted into the ampoule 5 from its rear end . The piston rod 16 and the cap base 17 are penetrated by a common central axial bore 18, so that the piston rod 16 can also be regarded as a tube or the entire arrangement of the actuating cap 13 and the piston rod 16 as a double-jacket jacket closed on one side.

In the bore 18 is from the rear end Locking pin 19 insertable and removable to unlock the device from this hole. This locking pin is shown in more detail in FIGS. 11 to 13 and has two resilient tongues 20 on its circumference which are opposite one another and extend in the axial direction and which pass through lateral slots 21 in the piston rod 16 and at their end on the backward face 22 of the sleeve 1 abut. In this case, the tongues 20 extend in a first straight section in the axial direction on the circumference of the locking pin 13 and beyond the locking pin, are then angled at an obtuse angle and run obliquely outward in the radial-axial direction in a second straight section. At its end, the tongues are deflected outward in the radial direction and engage in recesses 23 on the inside of the actuating cap 13. At least these tongues 20 of the locking pin 19 are made of elastic material and can therefore be squeezed together during insertion or removal of the locking pin into or out of the bore 18, spring apart when the slots 21 are reached and snap into place in the position shown in FIG. 1 in recesses 23 of the actuating cap 13. The snap-in of the resilient tongues 20 in this position is facilitated by the fact that the rear side walls 24 of the slots 21 are chamfered, the edges 25 of these chamfered slot side walls 24 lying further back being those that lie on the inside of the bore 18.

The rear end of the locking pin 19 has a grip part 26, the diameter of which is larger than the diameter of the central bore 18.

To unlock the device, the locking pin 19 is pulled back in the axial direction using the handle part 26, the ends of the tongues 20 first disengaging from the recesses 23 and then the entire tongues 20 being pressed against one another until they are approximately parallel lie and can be deducted together with the pin 19 through the bore 18. Axial grooves 27 are provided on the inside of the central bore 18, the number and circumferential distribution of which correspond to the number and circumferential distribution of the tongues 20 on the locking pin 19. The tongues 20 therefore slide into this groove 27 during the insertion or removal of the locking pin 19.

For the actual injection, after pulling off the locking pin 19, the entire device is attached with its front end to a body part, normally the upper arm, and the actuating cap 13 is pushed forward, whereby the piston 8 and simultaneously the injection cannula 3 are pushed forward over the piston rod 16 becomes, which breaks through the membrane 6 and enables the injection of the medicament contained in the ampoule 5 through the opening 12 during penetration into the body.

4 to 6 show a second type of device for self-injection, which is also designed in a manner according to the invention. The unlocking and actuating mechanism is constructed in exactly the same way as in the embodiment according to FIGS. 1 to 3, and the corresponding parts have therefore been provided with the same reference numerals. The only * difference is the actual injection mechanism, which is described below. In this embodiment, the sleeve 1 is longer and contains the injection cannula 3 and the ampoule 5 in a row. For assembly purposes, the sleeve 1 consists of two parts which are screwed together at their joint 28 via a thread. The ampoule 5 is slidably mounted in the sleeve 1. As before, the ampoule 5 is closed at its front end by the membrane 6, which is held by the open aluminum cap 36 on the ampoule neck 7, and at the rear end, the ampoule is closed by the piston 8. In front of the ampoule 5 is the injection cannula 3, which is guided through and fixed in a cannula guide piston 29 which lies in the region of the rear end of the cannula 3. The cannula guide piston 29 is over εinεn O-ring 30 guided on the inside of the sleeve 1 in a sliding seal. The front opening 2 of the sleeve 1 is closed by a protective membrane 31. The end of the cannula 3 protruding behind the cannula guide piston 29 is provided with a flange 34 and covered with a protective cap 32 made of soft rubber and placed over this flange. Pushed onto this protective cap 32 and fixed to the cannula guide piston 29, a spacer spring 33 is arranged, which holds the cannula guide piston and thus the rear end of the cannula 3 at a distance from the membrane 6 which closes the ampoule 5 such that the spring 33 is not subjected to any force the rear, tapered end of the cannula 3 or its protective cap 32 penetrates so that the protective cap 32 touches the ampoule membrane 6. The spacer spring 33 must also be dimensioned such that when the actuating cap 13 is actuated and thus the piston 8 is displaced by means of the piston rod 16, because of the friction between the piston 8 and the inside of the ampoule, the ampoule 5 is carried along by the piston 8 and advanced. The ampoule 5 pushes the cannula guide piston 29 with the cannula 3 through the protective membrane 31 via the spacer spring 33 until the cannula guide piston 29 strikes the inside of the front wall of the sleeve 1. Only when the piston 8 continues to act is the distance spring 33 compressed, whereupon the rear end of the cannula penetrates the protective cap 32 and the cannula membrane 6. As a result, the connection between the interior of the ampoule and the interior of the body is established and, finally, the piston 8 penetrates into the ampoule 5 when it is acted on further, and the medicament contained in the ampoule is expelled via the injection channel.

The somewhat longer construction of this embodiment is compensated for by the advantage that standardized glass ampoules can be used without first having to insert a special cannula and a special cannula guide, as in the embodiment according to FIG. 1. Furthermore, the injection of the First of all, after the injection cannula 3 has completely penetrated into the interior of the body, whereas in the first embodiment the cannula penetrates and the injection takes place simultaneously. Instead of using a spacer spring 33, the protective cap 32 itself can act as a spring. FIG. 14 shows a protective cap 32 'designed as a plastic bellows, which is welded or glued to the cannula guide piston 29 in a sealing manner and which bears against the ampoule membrane 6. The protective cap 32 "shown in FIG. 15 is made of silicone rubber and also has a corresponding deformation resistance which replaces the spacer spring 33. FIG. 16 shows a particularly advantageous variant in which a protective tube 35 is attached to one instead of a protective cap Is sealingly connected at the end to the cannula guide piston 29 and at the other end to the ampoule neck 7. In this way, the membrane 6 of the ampoule 5 is also covered in a sterile manner. The deformation and protection tube 35 is again selected so that it replaces the spring force of the spacer spring 33. It is understood that the deformation properties of the protective cap variants 32 'and 32 "and the protective tube 35 must be selected in the same way as the spring properties of the spacer springs 33.

Claims

Claims:

1. Device for self-injection, with a tubular sleeve in which an ampoule is arranged axially, which is closed at the front end by a membrane and at the rear end by a piston, and with an injection cannula guided axially displaceably in the ampoule, that is formed at the front end for piercing the membrane and for injection and rests against the piston at the rear end via an end flange, characterized in that at the rear end of the sleeve (4) on the sleeve (1), as is known per se, a tubular one Actuating cap (13) is slidably guided and secured against pulling off, which has a piston rod (16) starting from the cap base (17), inserted into the sleeve and acting on the piston (8), and that the cap base (17) and the Piston rod (16) are penetrated by a central bore (18) into which, in the initial position, the cap (13) is partially pushed onto the sleeve (1) d on the piston (8) engaging piston rod (16), a locking pin (19) is inserted, which has radially projecting resilient tongues (20) at its inserted end, which engage through the lateral slots (21) in the piston rod and on the rear end (22) of the sleeve.

2. Device for self-injection, with a tubular sleeve in which an ampoule is axially displaceably guided, which is closed at the front end by a membrane and at the rear end by a piston, and with one in the sleeve in front of the ampoule axially displaceable injection cannula, which is designed at the front end for injection and at the rear end for piercing the membrane, characterized in that, as is known per se, a tubular actuating cap (13) on the sleeve (1) on the rear sleeve end (4) is displaceably guided and secured against being pulled off, which has a piston rod (16), which starts from the cap cover (17), is inserted into the sleeve and on the piston (8), and that the cap base (17) and the piston rod (16 ) of through a central bore (18), in which a locking pin (191) is inserted in the initial position with the cap (13) partially pushed onto the sleeve (1) and the piston rod (16) engaging the piston (8), dεr has radially projecting resilient tongues (20) at its inserted end, which pass through lateral slots (21) in the piston rod and rest against the rear end face (22) of the sleeve.

3. Device according to .Anspruch 1 or 2, characterized gεkεnnzεichnεt that on the inside of the central bore (18 ⁱ axially extending grooves (27) are provided, the number and circumferential distribution of the number and circumferential distribution of the tongues (20) on the locking pin (19i correspond.

4. Apparatus according to claims 1 to 3, characterized in that the tongues (20) on the circumference of the locking pin (19) extend in a first straight section in the axial direction and protrude beyond the locking pin and then in a second deflected at an obtuse angle straight section run obliquely in the radial-axial direction to the outside.

5. Device according to one of claims 1 to 4, characterized in that the ends of the tongues (20) are deflected radially outwards and engage in recesses (23) on the inside of the actuating cap (13).

6. Device according to one of claims 1 to 5, characterized gekennzεichnεt that the uninserted end of Verriegεlungsstiftεs (19) has a handle part (26) whose diameter is larger than the diameter of the central bore (18).

7. Device according einεm of claims 1 to 6, characterized gekennzεichnεt that diε rückwärtigεn Sεitenwände (241 d _it dεr piston rod (bevelled 161 Schlitzε (21), wherein the more rearward edges (25) of the tapered slot side walls (241 on the inside the central bore (18).

8. The device according to one of claims 2 to 7, characterized in that the rear end of the injection cannula (3) is guided in a manner known per se through a cannula guide piston (29 ⁾ which is displaceably mounted in the sleeve (1), projects over it and is fixed therein, and that this projecting cannula ¬ end is covered by an elastic, serving as a spacer spring cap (32 ', 32 ") - or by an elastic, serving as a spacer spring protective tube (35) with the ampoule (5) sealingly connected.