Patent Description:
Prefilled injection devices are common containers to deliver drugs or vaccines to patients and include syringes, cartridges and autoinjectors or the like. They usually comprise a sealing stopper in gliding engagement into a container, the container being filled with a pharmaceutical composition in order to provide the practitioners with a ready-to-use injection device for patients.

A container has a substantially cylindrical shape, and comprises a proximal end able to be stoppered by a sealing stopper, a distal end wherein the pharmaceutical composition is expelled from the container, and a peripheral wall extending between the proximal end and the distal end of the container. In practice, the sealing stopper is aimed at gliding, upon the pressure exerted by a piston rod, from a proximal end of the container body towards the distal end of the container body, thereby expelling the drug contained into the container body.

When compared to empty injection devices that are filled with a vial-stored pharmaceutical composition just prior to the injection to the patient's body, the use of prefilled injection devices leads to several advantages. In particular, by limiting the preparation prior to the injection, the prefilled injection devices provide a reduction of medical dosing errors, a minimized risk of microbial contamination and an enhanced convenience of use for the practitioners. Furthermore, such prefilled containers may encourage and simplify self-administration by the patients which allows reducing the cost of therapy and increasing the patient adherence. Finally, prefilled injection devices reduce loss of valuable pharmaceutical composition that usually occurs when a pharmaceutical composition is transferred from a vial to a non-prefilled injection device. This results in a greater number of possible injections for a given manufacturing batch of pharmaceutical composition thus reducing buying and supply chain costs.

In certain cases, the injection of the composition contained in the container with a manual injection device such as a syringe can be difficult to carry out, due to the force that needs to be applied onto the piston rod for expelling the composition. It occurs for example when the composition has a high viscosity, and/or when the injection is carried out manually by a user that cannot push on the piston rod strongly enough with his fingers, for example when suffering from rheumatoid arthritis or from any type of disease affecting the user's hand or fingers. The injection may be a self-injection or may be performed by a user, such as a health care professional, to another person. In the case of healthcare professionals performing repetitive injections of viscous drugs to patients, the repetition of the same gesture requiring high force applied on the plunger rod to make the injection may cause repetitive strain injuries.

Autoinjectors can assist the user in performing an automatic injection of the pharmaceutical composition. They usually comprise an injection button the user needs to press in order to start the injection.

However, the user cannot change the injection rate (or injection speed) while performing the injection with an autoinjector. In other terms, it is not possible to increase or decrease the injection rate while performing the injection.

This lack of control of the injection rate can generate pain and anxiety to the user, and may lead the user to be unable to perform the injection correctly.

Moreover, similarly to manual injection devices, autoinjectors can encounter difficulties for injecting a composition with a high viscosity, mainly due to an insufficient force applied to the piston by the injection mechanism. Hence, the composition is not expelled from the container, or at most expelled at a very low speed.

Documents <CIT>, <CIT>, <CIT>, <CIT> teach medical injection devices.

In view of the foregoing, there is a strong need for an injection device for injecting a pharmaceutical composition contained in a medical container which allows for an easier injection of the composition compared to the existing injection devices, in particular when the composition has a high viscosity and/or when the user has a reduced physical strength. There is also a need for such an injection device that allows the user to control the injection, in particular to adjust the injection rate while performing the injection.

An object of the invention is thus to provide an assisted injection device for injecting a pharmaceutical composition contained in a medical container that overcomes the drawbacks of the known devices. The invention is defined according to claim <NUM>, dependent claims <NUM>-<NUM> defining further embodiments.

The invention is directed at an assisted injection device for injecting a composition contained in a medical container, comprising:.

wherein the piston rod includes a proximal end extending out of the body and configured to be pushed by the user in a distal direction to accelerate the movement of the piston rod to the distal operative position when the locking member is in the released position.

In this application, the "distal direction" is to be understood as meaning the direction of injection, with respect to the medical container the device of the invention is to be mounted on. The distal direction corresponds to the travel direction of the piston rod during the injection, the medical composition contained initially in the medical container being expelled from the latter. The "proximal direction" is to be understood as meaning the opposite direction to said direction of injection.

Another object of the invention is an assisted injection device assembly, comprising an assisted injection device as described previously and a medical container mounted thereon.

The assisted injection device assembly comprises optionally comprises a spacer configured to be fixed to the stopper, the spacer being configured to be contacted and pushed by the piston rod along with the stopper when the piston rod is moving from the proximal rest position to the distal operative position.

Further features and advantages of the invention will become apparent from the detailed description to follow, with reference to the appended drawings, in which:.

The invention proposes an assisted injection device for injecting a composition contained in a medical container.

Prior to the injection, the medical container <NUM> is filled with the composition intended to be injected, and stoppered with a stopper <NUM> inserted therein. The stoppered medical container <NUM> is then mounted on the device to constitute an injection device assembly, and the injection of the composition can be carried out.

In reference to <FIG> and <FIG>, the injection device <NUM> comprises a body <NUM> extending along a longitudinal axis (A). The body <NUM> comprises a peripheral wall <NUM> that includes a grip surface <NUM> limited proximally and distally by respectively a first flange <NUM> and a second flange <NUM> that extend radially outwardly from the longitudinal axis (A). Hence, when moving or using the device, the user can easily grab the body between the flanges <NUM>, <NUM>. The palm of his hand contacts the grip surface <NUM> and the upper and lower ends of his hand abut the flanges <NUM>, <NUM>, thus securing the implementation of the device. Or the user can hold the grip surface <NUM> between his index finger and his middle finger, both abutting the flange <NUM>, like he would normally hold a standard syringe. The device is thus handheld and the dimensions and the weight of the device are advantageously adapted for this purpose.

The medical container <NUM> comprises a body <NUM> including a proximal end <NUM>, and a distal end having a tip <NUM> and a needle <NUM> extending from thereon. The needle <NUM> may be covered by a cap (not represented) to prevent any injury when handled before use.

The body <NUM> comprises a container holder system <NUM>.

According to an embodiment illustrated in <FIG>, the container holder system <NUM> includes a slot <NUM> provided in the peripheral wall <NUM> of the body, advantageously in the second flange <NUM>, that leads to a housing <NUM> adapted to receive the proximal end <NUM> of the medical container <NUM>.

The container holder system <NUM> further includes a through groove <NUM> provided in the distal wall <NUM> of the body, continuous with the slot <NUM> and extending in the distal wall from the slot. In a practical way, the proximal end of the medical container <NUM> is inserted through the slot <NUM> and moved in a radial direction along the groove <NUM> until the container <NUM> is in a fixed position in the housing <NUM> relative to the body <NUM>. The groove separates two projecting parts <NUM> against which the proximal end <NUM> of the medical container <NUM> abuts, thereby preventing the medical container <NUM> from falling off the device.

To this end, the inner surface of the groove <NUM> contacts the body of the container <NUM>. In particular, the groove <NUM> can be configured to prevent the container <NUM> inserted herein from moving radially, unless the container is moved by a user. The groove is preferably made of a rigid and smooth material, such as rigid plastic or metal (aluminum, stainless steel) for example, for making the insertion of the container therein easier, as well as contributing to maintain the container in a fixed position in the housing <NUM> during the injection.

The structure of both the slot <NUM> and the groove <NUM> may be adapted according to the type of container <NUM> intended to be stoppered by the device <NUM>.

This embodiment is particularly useful when the medical container <NUM> is a syringe or the like, as the proximal end <NUM> of the container <NUM> is a flange that abuts the projecting parts <NUM>.

Alternatively, when the container <NUM> is a cylinder or the like (with no proximal flange), the configuration of the container holder system <NUM> may be adapted accordingly. According to the embodiment illustrated in <FIG> and <FIG>, the dimensions of the slot <NUM> and the housing <NUM> are adapted to receive the entire body <NUM> of the medical container <NUM> inserted therein, while the tip <NUM> of the container <NUM> is moved in a radial direction along the groove <NUM> until being positioned in the housing <NUM> where the medical container <NUM> is maintained in a fixed position relative to the body <NUM>. When the container <NUM> is positioned in the housing <NUM>, the shoulder <NUM> (between the body <NUM> and the tip <NUM>) abuts the projecting parts <NUM> thereby avoiding the medical container <NUM> to fall off the device <NUM>. Advantageously, in this situation, only the tip <NUM> and a needle <NUM> of the medical container <NUM> project distally out of the body <NUM> of the device. Of course, this embodiment may also be appropriate when the medical container <NUM> is a syringe or the like, the housing <NUM> being adapted accordingly to accommodate the flange of the medical container.

Of course, other embodiments of the container holder system are possible without departing from the scope of the invention. For example, the medical container <NUM> could be inserted longitudinally through an opening provided in the distal wall of the body <NUM>, and secured with an insert inserted radially in a slot provided in the peripheral wall <NUM> of the body <NUM>.

The device <NUM> comprises a piston rod <NUM> that extends in an internal volume <NUM> of the body <NUM> along the axis A. A spring <NUM> is arranged in the internal volume <NUM>, coaxially and in contact with the piston rod <NUM>. In that way, the spring-loaded piston rod <NUM> is translationally movable inside the body <NUM> under the force of the spring <NUM> along the axis (A), between a proximal rest position, and a distal operating position wherein the piston rod <NUM> engages the stopper <NUM> of the medical container <NUM> and pushes said stopper in the medical container.

In reference to <FIG> and <FIG>, the piston rod <NUM> comprises advantageously a radially enlarged proximal end <NUM> that serves as a pushing surface allowing the user to push the piston rod <NUM> in the distal direction with his thumb and as a handle allowing the user to pull the piston rod <NUM> back in the proximal direction by grabbing the radially enlarged proximal end <NUM> for example in order to carry out another injection with another container.

The injection device <NUM> further comprises a blocking system for retaining the piston rod <NUM> in the proximal rest position. The blocking system comprises a locking member <NUM> configured to engage the piston rod. The locking member is movable between a locked position wherein the locking member retains the piston rod <NUM> in the proximal rest position, and a released position wherein the locking member allows the piston rod <NUM> to move from the proximal rest position to the distal operative position under the force of the spring <NUM> in order to carry out the injection of the composition contained in the medical container <NUM>. The blocking system will be described according to several embodiments in the following of the present text.

According to a first embodiment, the locking member is an insert <NUM> adapted to be removably inserted in a transversal hole <NUM> provided in the piston rod <NUM>. The transversal hole <NUM> extends perpendicularly to the axis (A) and is preferably a through hole that extends across the piston rod. The insert <NUM> is represented in a non-limitative embodiment as a pin in <FIG>, but may be of another form provided that the insert can fulfill its function as described.

According to a first alternative of the first embodiment illustrated in <FIG>, the insert <NUM> is adapted to be slid on the proximal wall <NUM> of the body <NUM>, opposite the medical container <NUM>. Preferably, the insert <NUM> is adapted to be slid towards or away from the piston rod <NUM> in a notch <NUM> arranged on the proximal wall <NUM> of the body <NUM> that extends radially to the piston rod <NUM>. In other words, the longitudinal axis (B) of the notch <NUM> is perpendicular to the axis (A) of the piston rod <NUM>. When the hole <NUM> of the piston rod is a through hole, the notch <NUM> preferably extends through the proximal wall <NUM> of the body <NUM> from one point to another of the periphery of the proximal wall, on both sides of the piston rod <NUM>. The notch may alternatively extend through a portion only of the proximal wall <NUM> of the body <NUM>, on one side only of the piston rod <NUM>.

As illustrated in <FIG>, when the piston rod <NUM> is in the proximal rest position, the transversal hole <NUM> of the piston rod <NUM> is substantially radially aligned with the proximal wall <NUM> of the body, and the notch <NUM> is radially aligned with the transversal hole <NUM>, thus allowing the insert <NUM> to be inserted therein. In this position, the spring <NUM> is compressed, and the distal end of the piston rod <NUM> is away from the stopper <NUM>.

In order to perform the injection, the insert <NUM> is removed from the transversal hole <NUM> of the piston rod <NUM> and slid back away from the piston rod, as illustrated in <FIG>. As a result, the spring <NUM> causes the piston rod <NUM> to move translationally in a distal direction, from the proximal rest position to the operative position wherein the piston rod <NUM> engages the stopper <NUM>, and the composition is expelled from the syringe <NUM> via the needle <NUM>. This movement of the piston rod <NUM> is due to the spring force of the spring <NUM> that causes the spring to return to a relaxed state wherein said spring is released. Hence, the piston rod <NUM> can move without any input of the user, which makes the injection easier.

At the end of the injection, illustrated in <FIG>, the entirety of the composition has been injected. The stopper <NUM> abuts the distal end <NUM> of the medical container <NUM>, and the piston rod <NUM> cannot move further distally. The spring <NUM> is in an at least partially relaxed state, and a proximal portion of the piston rod <NUM> in the vicinity of its proximal end <NUM> remains outside the body <NUM> in order to allow the user to pull the piston rod <NUM> back to the proximal rest position for a subsequent injection to be carried out. The piston rod <NUM> is then blocked by the insert <NUM>, and the empty medical container <NUM> is removed from the container holder system and may be replaced by another prefilled medical container to carry out another injection.

In the following, the features of the device other than the blocking system will not be described again since these features and their functioning are similar to what has been described above, taking into account the structural differences of the device according to the different embodiments.

According to a second alternative of the first embodiment illustrated in <FIG>, the insert <NUM> is adapted to be slid towards or away from the piston rod <NUM> in a transversal opening <NUM> provided in the peripheral wall <NUM> of the body <NUM> that forms a passage extending radially to the piston rod <NUM>, preferably from one side of the peripheral wall <NUM> to the other. In other words, the longitudinal axis (B) of the transversal opening is perpendicular to the axis (A) of the piston rod <NUM>.

When the piston rod <NUM> is in the proximal rest position, the transversal opening <NUM> is aligned with the hole <NUM> of the piston rod <NUM>. The insert <NUM> is inserted radially in the transversal opening <NUM> of the body <NUM> and the hole <NUM> of the piston rod <NUM>, thereby maintaining the piston rod in the proximal rest position. The transversal opening <NUM> may be positioned at different locations of the peripheral wall <NUM>. For example, the transversal opening may be positioned between the first flange <NUM> and the inner volume <NUM> of the body <NUM>. Otherwise the transversal opening may be positioned radially aligned with the internal volume <NUM> of the body <NUM> so as to lead to said internal volume. In this latter case, the coils of the spring are advantageously adapted so that the insert <NUM> can pass through the piston rod <NUM> via the transversal hole <NUM>. For example, the distance between adjacent coils of the spring is greater than the diameter of the insert <NUM>.

In order to perform the injection, the insert <NUM> is removed from the hole <NUM> of the piston rod, and from the transversal opening <NUM>, to allow the piston rod <NUM> to move to the distal operative position.

According to a second embodiment illustrated in <FIG>, the piston rod <NUM> does not comprise a transversal hole as described above. The locking member is an insert <NUM> as described in the first embodiment. The insert <NUM> is adapted to be slid in a transversal opening <NUM> provided in the peripheral wall <NUM> of the body <NUM>. The transversal opening <NUM> has a similar structure as in the first embodiment. Said transversal opening <NUM> is radially aligned with the internal volume <NUM> of the body <NUM> so as to lead to said internal volume, and positioned distally from the piston rod <NUM> when said piston rod is in the proximal rest position. In particular, the transversal opening <NUM> may be provided between the second flange <NUM> of the body <NUM> and the piston rod <NUM> when said piston rod <NUM> is in the proximal rest position. When the insert <NUM> is inserted in the transversal opening of the body <NUM>, the piston rod <NUM> being in the proximal rest position, said insert <NUM> extends across the inner volume of the body <NUM>, and the distal end <NUM> of the piston rod <NUM> abuts the insert <NUM>, thereby maintaining the piston rod in the proximal rest position.

In order to perform the injection, the insert <NUM> is removed from the transversal opening <NUM>. Hence, the distal end <NUM> of the piston rod <NUM> no longer abuts the insert <NUM>, and the piston rod moves to the distal operative position.

According to a third embodiment illustrated in <FIG> and <FIG>, the piston rod <NUM> is provided with a narrowed section <NUM> having a reduced diameter compared to that of the piston rod <NUM>. The locking member is a latch <NUM> provided with a first hole <NUM> and a second hole <NUM> in communication with each other. The diameter of the first hole <NUM> is smaller than the diameter of the piston rod <NUM>, and is configured to accommodate only the narrowed section <NUM> of the piston rod. The diameter of the second hole <NUM> is greater than the diameter of the piston rod <NUM>, and is configured to accommodate the piston rod.

The latch <NUM> is radially slidable relatively to the body <NUM> and the piston rod <NUM>, preferably on the proximal wall <NUM> of the body <NUM>, by pushing or pulling the actuation zone <NUM>.

As illustrated in <FIG> when the piston rod <NUM> is in the proximal rest position, the first hole <NUM> is aligned with the piston rod <NUM> and accommodates the narrowed section <NUM> of the piston rod. The piston rod abuts the latch <NUM> and is thereby maintained in the proximal rest position.

In order to perform the injection, the latch <NUM> is slid radially and inwardly by pushing the actuation zone <NUM>, as illustrated in <FIG>, causing the second hole <NUM> to align with the piston rod <NUM>. The piston rod <NUM> passes through the second hole <NUM> and is thus allowed to move from the proximal rest position to the operative position.

An advantage of this embodiment is that the latch remains attached to the device throughout its use, and thus cannot be lost once the piston rod is released.

According to a fourth embodiment illustrated in <FIG> and <FIG>, the piston rod <NUM> is provided with a toothed rack <NUM>. The blocking system comprises a button <NUM>, preferably a spring-loaded button, mounted on the body <NUM> of the device <NUM> and coupled to the locking member which is a wing <NUM>. The wing <NUM> is pivotably mounted on a structure fixed to the body <NUM>, in a form of two branches <NUM>, advantageously curved, joining the first flange <NUM> and the peripheral wall <NUM> of the body <NUM>. The body <NUM> of the device is provided with a housing <NUM> configured to accommodate the wing.

As illustrated in <FIG>, the button is released and the wing engages the toothed rack. The piston rod <NUM> is in the proximal rest position.

In order to perform the injection, the button <NUM> is pushed radially and inwardly (represented by the arrow), causing the wing <NUM> to pivot about the curved branches <NUM> away from the piston rod <NUM> and disengage the toothed rack <NUM>, thereby allowing the piston rod to move from the proximal rest position to the operative position.

Regardless the embodiment of the blocking system, at the end of the injection, the device may be reset manually by the user, so as to proceed to another injection. To do so, the piston rod <NUM> is pulled by the user in a proximal direction back to the proximal rest position, preferably by grabbing the radially enlarged proximal end <NUM>, and the locking member is moved in the locked position. Then, the empty medical container <NUM> is removed from the container holder system <NUM>, and a new filled medical container <NUM> may be positioned in the container holder system <NUM>.

The spring <NUM> is advantageously selected depending on the viscosity of the composition to be injected, and more generally, depending on the difficulty of performing the injection. For example, for a composition of a high viscosity, a spring with a high spring force should be preferentially selected.

While performing the injection, the user can push the proximal end <NUM> of the piston rod <NUM> in a distal direction. In this case, the force applied to the piston rod <NUM> is a combination of the spring force and the force exerted by the user. The movement of the piston rod <NUM> can thus be accelerated, and the injection rate is thus increased. If the user stops pushing the piston rod <NUM>, said piston rod becomes again driven by the spring <NUM> only.

According to the first, second, and third embodiment of the device, once the locking member <NUM>, <NUM>, <NUM> is in the released position, the piston rod <NUM> moves in a distal direction and keeps moving until the end of the injection.

According to the fourth embodiment of the device, the injection keeps going as long as the user pushed the button <NUM>. If the user releases the button, the injection stops. As such, the user can selectively start and stop the injection by respectively pushing or releasing the button.

The injection device assembly is advantageously provided with a spacer <NUM> positioned in the container <NUM> in contact with the stopper <NUM>, prior to the mounting of the container <NUM> on the device <NUM>. The spacer <NUM> preferably includes a protrusion <NUM> on its distal end which is inserted into a corresponding recess <NUM> on the proximal end of the stopper <NUM>, so that the stopper <NUM> and the spacer <NUM> are fixed together and glide together in the container <NUM> when pushed by the piston rod <NUM>.

The spacer <NUM> absorbs a part of the mechanical effort transmitted by the piston rod <NUM> to the stopper <NUM> when the piston rod indirectly contacts the stopper. Hence, when pushed by the piston rod <NUM> via the spacer <NUM>, the stopper <NUM> moves continuously and smoothly. To this end the spacer <NUM> is advantageously made of a rigid material, such as plastic or metal for example, and its length is adapted relatively to the volume of the composition contained in the medical container so as to reduce the space between the proximal end of the medical container and the surface of the composition: the smaller the volume of the composition, the longer the spacer.

Claim 1:
Assisted injection device (<NUM>) for injecting a composition contained in a medical container (<NUM>), comprising:
- a body (<NUM>) adapted to receive a medical container (<NUM>) in a fixed position relative to the body (<NUM>), the body (<NUM>) being configured to be held in a user's hand,
- a spring-loaded piston rod (<NUM>) translationally movable inside the body (<NUM>) between a proximal rest position allowing inserting of the medical container (<NUM>) in the body (<NUM>) and a distal operative position wherein the piston rod (<NUM>) engages a stopper (<NUM>) of the medical container (<NUM>) and pushes the stopper (<NUM>) in the medical container (<NUM>),
- a blocking system comprising a locking member (<NUM>, <NUM>, <NUM>) mounted on the body (<NUM>) and configured to engage the piston rod, the locking member being movable between a locked position wherein the locking member cooperates with the body to retain the piston rod (<NUM>) in the proximal rest position, and a released position wherein the locking member cooperates with the body to allow the piston rod (<NUM>) to move from the proximal rest position to the distal operative position under the force of the spring (<NUM>) to perform an injection,
wherein the piston rod (<NUM>) includes a proximal end (<NUM>) extending out of the body (<NUM>) and configured to be pushed by the user in a distal direction to combine, while the injection is performed, the force exerted by the user with the spring force to accelerate the movement of the piston rod (<NUM>) to the distal operative position while the injection is performed when the locking member (<NUM>, <NUM>, <NUM>) is in the released position such that the injection rate is increased, the piston-rod (<NUM>) being further configured, in absence of a force exerted by the user, to move under the force of the spring only.