Injection set and injection assistance device

The present invention relates to an injection assistance device for an injection device and to an injection set provided with the said injection assistance device, these devices allowing a product to be injected into an injection site.

In this application, the distal end of a component or of a device is to be understood as meaning the end furthest from the user' s hand and the proximal end is to be understood as meaning the end closest to the user's hand. Likewise, in this application, the "distal direction" is to be understood as meaning the direction of injection, and the "proximal direction" is to be understood as meaning the opposite direction to the direction of injection.

In order to administer a medicinal product to a body, particularly the human body, there are various possible routes depending on the place in the body at which the said product is to be injected: thus, the product may be injected intravenously, intramuscularly, subcutaneously, into a joint, or else intradermally. In many of these latter cases, and, particularly when injecting subcutaneously, the depth to which the needle is inserted and therefore at which the product is injected is particularly significant. Thus, it is possible to observe an adverse immunological reaction if, for example, a product that should have been injected into the subcutaneous tissues is finally injected into the intradermal tissues.

The operation of injecting a product using a syringe is particularly delicate. The patient may make an unforeseen movement or alternatively the person administering the injection might make a wrong move. Thus, errors in the depth to which the needle is inserted are particularly difficult to avoid and

discrepancies of just a few millimetres may, themselves alone, lead to errors in injection depth.

Likewise, once the needle has been inserted, it is important to guarantee that this insertion depth is maintained throughout the injecting of the product so as to guarantee the correct injection depth.

As far as subcutaneous injection is concerned, there are various injection techniques currently used. Some users prefer to pinch the skin before inserting the needles, others prefer not to, and still others angle the syringe before inserting it into the skin, it being possible for this angle to vary from one user to another. The result of all this is that the depth to which the needle is inserted and therefore at which the product is injected may itself also vary, with the unpleasant consequences mentioned above.

Furthermore, in this kind of operation, it is also important to avoid any needlestick injury due to the exposed needle, whether this be before or after injection.

In addition, to limit the apprehension felt by the patient, particularly in the case of injections administered by the patient himself, it is desirable for the injection device not to look like a conventional syringe and/or for the needle not to be visible or to be visible only a little prior to insertion .

Finally, injecting a product using traditional injection devices generally entails at least two manual steps. For example, in the case of syringes, one manual step is to hold the body of the syringe in order to insert the needle into the injection site, another step consists in pressing on the plunger rod in order to perform the injection, the progression from one step to

the other generally entailing moving the fingers with respect to the syringe.

There therefore remains a need for an injection assistance device and for an injection set which are made safe, that is to say which make it possible to limit the impact of undesired movements of the patient and/or of the user in order to prevent a variation in the depth to which the needle is inserted when administering the injection so as to avoid unintentionally injecting the said product at an inadequate depth, limiting the number of manipulations to be carried out by the user, limiting the risk of needlestick injury both to the patient and to the person administering the injection, limiting the apprehension felt by the patient and making the giving of the injection easier.

There also remains a need for such an injection assistance device and an injection set that allow the user to be certain of causing the needle to penetrate the injection site to a predetermined insertion depth and, in addition, guarantee that the injection is administered at this predetermined depth.

There also remains a need for such an injection assistance device and an injection set that are made of a limited number of parts and that are easy to manufacture and assemble.

The present invention remedies these needs by proposing an injection assistance device for an injection device for injecting a product into an injection site, this injection assistance device comprising at least one hollow body intended to receive a product that is to be injected, at least one hollow injection needle intended to penetrate the injection site, and at least one piston plunger housed in the said body , the said body

and the said piston plunger being able to be moved in axial translation one with respect to the other, characterized in that the said injection assistance device comprises at least: - a hollow sleeve provided with at least one bearing surface intended to come into contact with the surface of the said injection site, the said sleeve being intended to receive, at least in part, the said body and being arranged in such a way as to allow the said body axial mobility between at least a first position known as the initial position in which the said needle is not exposed over its insertion length, and a second position known as the insertion position in which the said needle is exposed by a predetermined insertion length L, final protection means arranged in such a way as to cover the said needle in a post-injection final protection position, which means are able to move in translation with respect to the said body between an injection position in which the needle is exposed and a final protection position in which the needle is covered,

- coupling means arranged in such a way as to move the said piston plunger from the said insertion position to an end-of-injection position and to perform the injection, automatic-insertion means arranged in such a way as to cause the said body to move axially in the distal direction and to insert the said hollow needle into the injection site, said automatic-insertion means comprising first elastic return means connected to the said sleeve and intended to urge the said body from the initial position to the said insertion position, automatic-activation means for activating the said final protection means at the end of injection, said automatic activation means comprising second elastic return means connected to the said final protection means intended to urge the said body from the said

injection position to the said final protection position, automatic-injection means arranged in such a way as to urge the said coupling means at the end of the insertion position without manual intervention on the part of the user, said automatic-injection means comprising third elastic return means (83) connected to the said coupling means and intended to urge the said coupling means from the insertion position to the said end-of-injection position,

- said first, second and third elastic return means being under the form of a single elastically deformable element .

In a preferred embodiment of the invention, said elastically deformable element is a spring.

The injection assistance device according to the invention allows the injection to be administered in a minimum number of actions, particularly disposing with at least one of the two manual steps described hereinabove, and preferably dispensing with these two manual steps. Thus, the operation of administering the injection is entirely safe, the step of inserting the needle in particular being done automatically, without the user having to intervene. Any risk of error is thus avoided.

In an embodiment of the invention, said spring is a leaf spring having a fixed end and a moving end, said fixed end being fixed to said sleeve and said moving end being coupled to said coupling means .

In an embodiment of the invention, the injection assistance device further comprises retaining means for retaining the said body in the said initial position, the said automatic-insertion means being activated by the release of the said retaining means.

In an embodiment of the invention, the injection assistance device comprises control means arranged in such a way as to delimit the said insertion position of the said body.

In an embodiment of the invention, the said coupling means comprise at least one plunger rod at least bearing against the said piston plunger between the said injection position and end-of-injection position, and intended to be urged in the distal direction.

In an embodiment of the invention, wherein the said piston plunger has a force needed to overcome the stiction of the hollow body, the said automatic- injection means are activated when the resultant of the forces of the said first and/or second and/or third return means, the resisting force of the said piston plunger and the bearing force of the sleeve on the said injection site is directed in the distal injection.

The present invention also relates to an injection set for injecting a product into an injection site, the said injection set comprising at least: an injection device comprising at least: - a hollow body intended to receive a product that is to be injected, the said body being equipped with a hollow injection needle intended, during a first phase known as the insertion phase, to penetrate an injection site and, during a second phase known as the injection phase, to channel the said product from the said body towards the said injection site, at least one piston plunger housed in a more or less sealed manner in the said body and intended to be moved in the distal direction by movement means in the said injection phase during which it drives the said product through the said needle,

characterized in that it comprises at least an injection assistance device for assisting with the injection device as described hereinabove.

In one embodiment of the invention, the injection set is in the form of a kit that can be assembled prior to use.

Other advantages and alternative forms of the present invention will be specified with the aid of the description which will follow and of the attached drawings in which:

Figures 1 to 5 are sectioned views of an injection set according to the invention in the following respective positions: initial, insertion, during injection, end-of-injection and final protection,

- Figures 6 and 7 are partial perspective views of the injection assistance device of Figures 1 to 5,

In order to make the invention easier to understand, the injection assistance device is described assembled with an injection device with which it forms an injection set.

Figure 1 depicts an injection set 100 according to the invention, comprising an injection assistance device 1 for an injection device 3, this injection device 3 comprising a hollow body 2 intended to receive a product 25 that is to be injected, at least one hollow injection needle 7 intended to penetrate the injection site 27, and at least one piston plunger 26 housed in the said body 2, the said body 2 and the said piston plunger 26 being able to be moved in axial translation one relative to the other as will be visible from Figures 2 to 5. The body 2 also comprises a flange 6 at its proximal end.

The injection assistance device 1 of Figures 1 to 5 comprises a hollow sleeve 4 which houses the said body 2, this sleeve 4 being provided with at least one bearing surface 5 intended to come into contact with the surface of the injection site 27 as shown in Figures 2 to 4.

The injection assistance device 1 of figures 1-7 comprises a plunger rod 10 coupled to said piston plunger 26.

The injection assistance device 1 of figures 1-7 also comprises a leaf spring 83 having a fixed end 86 and a moving end 84.

The fixed end 84 of the said leaf spring 83 is fixed to the internal wall of the distal part of the said sleeve 4. The moving end 86 of the said leaf spring 83 is held, in the initial position, with the aid of a bearing surface coupled to a button 95.

The moving end 86 of the said leaf spring 83 is connected to the proximal end 87 of a deformable moving component 88 of which the distal end 92 is itself linked to the said head 21 of the plunger rod 10 by a pivot connection 89, as shown in Figures 6 and 7.

The said moving component 88 is housed in a rail 90 within which it can move translationally, the said rail 90 having the overall shape of a J, namely a first longitudinal part, a curved part and a second longitudinal part shorter than the said first longitudinal part.

In the initial position, as depicted in Figure 1, the said leaf spring 83 is in the stretched-out state. The body 2 is maintained in its initial position by means of the button 95 which retains the fixed end 86 of the leaf spring 83.

The user grasps the sleeve 4 of the injection assistance device 1 and applies it on the injection site 27. By pressing the said button 95, the said leaf spring 83 is released and tries to return to its state of rest. As it does so, its moving end 86 pushes the component 88 along the rail 90, the said moving component 88 driving the said head 21 of the plunger rod 10, the said moving component 88 being in its undeformed configuration as shown in Figure 6. The said head 21 of the plunger rod 10 itself drives the said body 2 and causes the said needle 7 to be inserted automatically into the injection site 27 as shown in Figure 2.

At the end of the insertion position, as shown in Figure 2, the said leaf spring 83 continues its return to its compressed state at rest and the resultant of the forces of the said leaf spring 83, of the force needed to overcome the stiction of the said piston plunger 26, and with which the said sleeve 4 bears against the said injection site 27 is directed in the distal direction and so the said spring 83 drives the said plunger rod 10 which itself drives the said piston plunger 26 into the said hollow body 2 and performs the injection automatically, as shown in Figure 3.

As can be seen on figures 2 and 3, a gap 801 is present between the flange 6 of the body 2 and a radial rim 91 formed on the internal wall of the sleeve 4.

Therefore, if during the injection step, the user, for instance by inadvertence, releases the distal pressure he exerts on the sleeve 4 when applying it on the injection site 27, causing thereby a limited proximal movement of said sleeve 4, then the spring 83, because it is in a partially expanded state and thanks to the presence of the gap 801, is allowed to dampen said proximal movement by expanding a little more and

thereby causing the body 2, to be urged towards the site injection 27. The needle 7 is therefore maintained at a constant insertion length, namely its predetermined insertion length L.

On the contrary, if during the injection step, the user increases the distal pressure he exerts on the sleeve 4 when applying it on the injection site 27, causing thereby a limited distal movement of said sleeve 4, then the spring 83, because it is in a partially expanded state and thanks to the presence of the space 802 between the distal face of the proximal region for holding of the sleeve 4 and the flange 6 of the body 2, is allowed to dampen said distal movement by being compressed, thereby maintaining the needle 7 at a constant insertion length, namely its predetermined insertion length L.

The influence of any increase or release of the distal pressure exerted by the user on the sleeve 4 during injection is therefore neutralized by the presence of the spring 83 in a partially expanded state.

As shown in Figure 4, the said leaf spring 83 continues its return to its state of rest and the distal end of the said moving component 88 engages in the curved part of the said rail 90 and in so-doing pivots about the pivot connection 89 then rises back up inside the second longitudinal part of the said rail 90 as shown in Figures 5 and 7. As the said distal end 92 of the said moving component 88 rises back up inside the said second longitudinal part of the said rail 90, the said moving component 88, via its pivot connection 89, carries along with the said plunger rod 10, as shown in Figure 7. The said head 21 of the plunger rod 10 itself drives along the said hollow body 2 and therefore the needle 7 which moves up inside the said sleeve 4, as shown in Figure 5. The sleeve 4 then acts as final

protection means and the injection set 100 is therefore completely safe.

In other forms of embodiment, not depicted, the leaf spring may be replaced by a helical springs, pieces of elastomer, sealed gas chambers inside which the gas can be pressurized and expanded in succession, or any other equivalent means.

The injection set and the injection assistance device according to the invention are particularly simple to use and are perfectly safe. They are made of a limited number of parts and therefore easy and cheaper to manufacture than existing injection devices.