Patent Description:
Medical injection devices such as syringes typically include a container for containing a medical composition. Said container of said medical injection devices usually comprises an end piece in a form of a longitudinal tip defining a fluid path through which the medical solution is expelled from the container and/or reservoir. A needle is attached to the tip in order to prick the patient's skin and to perform the injection of the composition.

In order to prevent any injury prior to final use, a needle cover is mounted on the tip so as to enclose the needle. This renders the needle physically inaccessible by the persons around the device. The needle cover comprises an inner needle shield, in a material with elastomeric properties, and may further comprise an outer needle shield, in rigid plastic, surrounding the inner needle shield.

The inner needle shield ensures the sealing of the medical injection device. To that purpose, the inner needle shield comprises a sealing portion that sealingly contacts the outer surface of the syringe's tip to provide a tight seal. The inner needle shield prevents any contamination of the medical composition from the outside environment, thereby assuring the container closure integrity. The inner needle shield further prevents any leakage of composition from the outlet of the needle to the external environment. To that purpose, the needle is preferably pricked in the inner needle shield.

The needle cover may be removed from the medical injection device tip shortly prior to the use of the medical injection device.

A drawback of the known needle covers is that it may be relatively difficult to remove them from the tip. In order to do so, the user has to grip both the injection device and the needle cover, and to pull the needle cover. Pulling the needle cover requires the user to exert a quite important effort.

The force needed to remove a needle cover is measured by a physical parameter called "pull out force" (acronym POF). The pull out force necessary for removing the known needle covers from an injection device, such as a syringe, may be quite high and is due in particular to the pressure exerted onto the tip by the inner needle shield which results in friction between the inner needle shield and the tip.

As a consequence, a user having a reduced strength, for example weakened by a disease, may not be able to remove the needle shield and use the injection device for his treatment.

Moreover, healthcare professionals who often use injection devices, such as nurses, have a high risk of injuring themselves, since they may not control the force they apply for pulling off the needle cover from the injection device, which may result in uncontrolled and dangerous movements. Lastly, the needle of the syringe may be bent during the removing of the needle shield because of this high required pull out force.

The patent application <CIT> teaches an alternative method for reducing the pullout force for removing a needle shield of a syringe.

The invention aims to provide a needle cover for a medical injection device that allows reducing the pull out force while still providing a tight sealing with the tip of the medical injection device.

To this end, one object of the invention is a needle cover for protecting a needle mounted on a tip of a barrel of a medical injection device, wherein the tip extends from a distal face of the barrel, the needle cover comprising:.

the needle cover being mainly characterized in that it comprises at least one actuator integral with the outer needle shield, said at least one actuator comprising a proximal inner surface which is tilted relative to the longitudinal axis, the actuator being radially movable inwardly relative to the longitudinal axis to slidingly engage the proximal inner tilted surface with the distal face of the barrel so as to cause the needle cover to move in a distal direction along the tip by a wedge effect.

In this application, the "distal direction" is to be understood as meaning the direction of injection. The distal direction corresponds to the travel direction of the plunger rod during the injection, the medical composition contained initially in the barrel being expelled from the latter. The "proximal direction" is to be understood as meaning the opposite direction to said direction of injection.

By "wedge effect" is meant in the present text the conversion, by the tilted proximal inner surface, of a radial force exerted by a user onto the actuator into an axial force which facilitates removal of the needle cover.

According to other optional features of the connector of the invention:.

Another object of the invention is a medical assembly comprising:.

The barrel and the tip of the medical injection device are preferably made of glass.

The medical assembly may comprise an axial clearance between the needle cover and the distal face of the barrel, the proximal inner tilted surface facing said axial clearance.

Another object of the invention is a method for removing a needle cover as described previously, from the tip of a medical injection device, comprising the following steps:.

Advantageously, said pinching and pulling may be carried out in a single step, with the user's fingers located in a same position. Preferably, the user's fingers are positioned around the tilted surface to maximize the wedge effect.

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 relates to a needle cover <NUM> configured to be sealingly mounted to the tip <NUM> of a medical injection device <NUM> provided with a needle <NUM>, so as to protect the needle.

When the needle cover <NUM> is attached to the injection device <NUM>, the combination of the needle cover and the injection device forms a medical assembly <NUM> that prevents a user from contacting the needle enclosed in the needle cover, while protecting the needle from any external contamination.

The assembly <NUM> is stored before use, meaning before injection of the composition contained in the barrel to a patient.

The medical injection device <NUM> is preferably a syringe.

As illustrated in <FIG> and <FIG>, the medical injection device <NUM> comprises a barrel <NUM> extending along a longitudinal axis A from a proximal face <NUM> to a distal face <NUM> and adapted to contain a medical composition to be injected, and a plunger rod (not represented) translationally movable inside the barrel <NUM> from a proximal position to a distal position for injecting the composition.

The medical injection device <NUM> further comprises a distal tip <NUM> extending along the axis A from the distal face <NUM> of the barrel. The distal tip <NUM> is at least partially hollow so as to form a fluid path in fluidic communication with the barrel.

A needle <NUM> is attached to the tip <NUM> of the injection device and is in fluid communication with the fluid path.

The medical injection device <NUM> is preferably made of glass, and more preferably is a glass syringe. Such glass syringes are largely used in hospital environment and readily sterilizable. The medical injection device is preferably a prefilled syringe. The medical injection device is more preferably a syringe with a staked needle.

The needle cover <NUM> comprises an inner needle shield <NUM> provided with a body <NUM> that extends along a longitudinal axis B. The axis B coincides with the axis A when the needle cover is mounted on the tip of the injection device. The needle cover <NUM> further comprises an outer needle shield <NUM> configured to surround at least partially the inner needle shield <NUM>, thereby at least partially enclosing said inner needle shield.

The outer needle shield <NUM> comprises at least one proximal actuator <NUM>.

The actuator is preferably integral with the outer needle shield, i.e. formed of the same material, in one piece (not requiring any assembly). For example, if the outer needle shield is made by injection molding, the actuator is formed using the same step of injection molding.

The actuator is preferably integral with the outer needle shield by the distal part of the actuator.

The outer needle shield <NUM> comprises at least one lug <NUM> that project radially inwardly. The lug <NUM> advantageously flares inwardly, thereby defining a first inner surface <NUM> oriented proximally and a second surface <NUM> oriented distally, up to a pointy end.

In reference to <FIG>, the needle cover <NUM> at least partially encloses the tip <NUM> of the injection device, thereby sparing an axial clearance G<NUM> between the needle cover <NUM> and the distal face <NUM> of the barrel. This means that the needle cover <NUM> does not abut onto the distal face <NUM> of the barrel.

The axial clearance G<NUM> advantageously acts as a housing <NUM> configured to accommodate the lugs <NUM>.

The first inner surface <NUM> is advantageously curved, the curvature being oriented inwardly towards the axis B.

The first inner surface <NUM> is tilted relative to the axis B. In other terms, the first inner surface <NUM> and the axis B are not parallel. As such, the first inner surface is also tilted relative to an axis C perpendicular to the axis A, that extends along the distal face of the barrel (see <FIG>). In the following of the present text, the first inner surface <NUM> will be called "tilted surface". The angle between the tilted surface and the axis C, referred to as "angle α", is preferably comprised between <NUM>° and <NUM>°. The angle between the tilted surface and the axis B, equals to <NUM>° minus α, is preferably comprised between <NUM>° and <NUM>°. Since the barrel extends parallel to the axis B, the angle between the tilted surface and the axis B is also the angle between the tilted surface of the arms and the barrel.

According to a preferred embodiment, the proximal actuator <NUM> comprises one or more flexible arms <NUM>.

In the embodiment represented in <FIG>, the outer needle shield <NUM> comprises two flexible arms <NUM>, which are opposite with respect to the axis B. Alternatively, the outer needle shield may comprise only one flexible arm.

Each flexible arm <NUM> extends from the body <NUM> of the outer needle shield in the proximal direction.

Each flexible arm <NUM> advantageously comprises a first portion <NUM> that extends radially outwardly from the body <NUM> of the outer needle shield in the proximal direction, and a second portion <NUM> joined at a junction <NUM> to the first portion that further extends in the proximal direction.

In the represented embodiments, the flexible arms <NUM> extend radially outwardly from the outer needle shield. Hence, when no effort is exerted thereon, the flexible arms <NUM> are remote from the barrel of the injection device, and in particular from the distal face of the barrel, as particularly visible in <FIG> and <FIG>. The distance between the arms <NUM> and the barrel <NUM> may of course be adjusted. This configuration of the flexible arms is required when the diameter of the outer needle shield is equal or less than the diameter of the barrel, in order to spare a predetermined distance between the flexible arms and the barrel.

When the outer needle shield <NUM> comprises at least one arm <NUM>, the lug <NUM> projects radially inwardly from the arm.

When the outer needle shield <NUM> comprises arms <NUM> which are in the actuation position, the axial clearance G<NUM> accommodate the lugs <NUM> of said arms <NUM>.

Alternatively, when the diameter of the outer needle shield <NUM> is greater than the diameter of the barrel <NUM>, the flexible arms <NUM> may simply extend longitudinally without flaring outwardly, since a distance between the arms and the barrel is already spared.

Each flexible arm <NUM> is radially movable inwardly relative to the longitudinal axis B in response to an effort oriented radially inwardly applied onto said arm.

In more details, said arm <NUM> is movable between a rest position and an actuation position wherein the tilted surface engages the distal face <NUM> of the barrel <NUM>. Preferably, in the rest position, the second portion <NUM> of the arm is remote from the barrel <NUM> of a predetermined distance. The engagement of the tilted surface <NUM> with the distal face <NUM> of the barrel causes the needle cover <NUM> to move in a distal direction along the tip <NUM> by a wedge effect. This aspect will be described in more details in the following.

Preferably, the flexible arm <NUM> is configured to deform elastically. In other terms, the flexible arm can move back from the actuation position to the rest position with no intervention of the user.

According to a preferred embodiment, the needle cover comprises two arms which are symmetrical with respect to the axis B. This means that the arms have the same dimensions, are arranged similarly relative to the body of the needle cover, and define the same angle α with the axis C.

The dimensions of the arms <NUM> may be adjusted in order to provide a good flexibility, providing a sufficient wedge effect, and allowing insertion of the lugs <NUM> into the housing <NUM> between the needle cover and the injection device. For information, the ratio of the length of a lug on the total length of an arm is comprised between <NUM> and <NUM>. Also, a ratio of the ratio of the thickness (or height) of a lug on the total thickness of an arm including the lug is comprised between <NUM> and <NUM>.

The body of the inner needle shield preferably has a cylindrical shape and a circular cross section.

The body of the inner needle shield comprises an inner proximal connection part <NUM> configured to sealingly engage the tip <NUM> of the injection device. The inner proximal connection part <NUM> has preferably a larger diameter that the rest of the body. The inner proximal connection part is thus easier to distinguish from the rest of the body and the fixation of the inner needle shield <NUM> to an outer needle shield <NUM> is improved as described in the following.

When the needle cover <NUM> is mounted on the injection device <NUM>, the inner needle shield <NUM> encloses at least a portion of the tip <NUM>, and the proximal connection part firmly contacts a proximal portion of the tip. Advantageously, the inner needle shield <NUM> encloses at least the outer surface of the bulge <NUM>. The needle cover is thus tightly and sealingly connected to the tip. The inner needle shield <NUM> is preferably made in a material with elastomeric properties. In this way, the proximal connection part may slightly deform when connecting the inner needle shield to the injection device so as to match the shape of the tip. Meanwhile, the needle tip may penetrate the inner needle shield. This further reduces the risk of leakage of the medical composition via the needle to the external environment.

The material with elastomeric properties is preferably a thermoplastic elastomer, an elastomer, or a rubber. Preferably, the material with elastomeric properties is sterilizable.

The outer needle shield <NUM> is preferably made in a rigid material. Preferably, the rigid material is rigid plastic. The rigid material confers rigidity to the outer needle shield, which allows said outer needle shield to better protect the needle shield from shocks. The structural integrity of the needle cover is thereby improved.

An embodiment of the outer needle shield is illustrated in <FIG>.

According to this embodiment, the outer needle shield <NUM> comprises a body <NUM> that extends along the longitudinal axis B. The body preferably has a cylindrical shape.

The body <NUM> comprises a proximal portion <NUM> that surrounds the inner proximal connection part <NUM> of the inner needle shield.

The proximal portion <NUM> has preferably a larger diameter than the rest of the body <NUM>, for enclosing the inner proximal connection part <NUM> of the inner needle shield.

The outer needle shield <NUM> is fixed to the inner needle shield <NUM>. To this end, the proximal portion <NUM> of the outer needle shield is advantageously provided with a through notch <NUM> comprising an upper part <NUM>, a lower part <NUM> and side parts <NUM>; and that at least partially extends along the circumference of the proximal portion. Hence, the inner proximal connection part <NUM> of the inner needle shield is partially inserted in the through notch <NUM>, in a snap-fit connection. The inner proximal connection part <NUM> of the inner needle shield abuts both the upper part <NUM> and the lower part <NUM> of the notch, thereby preventing any translational movement of the inner shield along the axis B relative to the outer needle shield.

Advantageously, the inner proximal connection part <NUM> also abuts the side parts <NUM> of the notch <NUM>, thereby preventing any rotational movement of the inner shield around the axis B relative to the outer needle shield.

The through notch <NUM> is also advantageous as it forms a window for the user, who can make sure that the inner needle shield <NUM> is enclosed in the outer needle shield <NUM>.

The inner needle shield <NUM> and the outer needle shield <NUM> may be fixed together by other fixing means than the snap-fit connection of the notch <NUM> and the inner proximal connection part <NUM>, or in addition to said snap-fit connection. Alternatively, the outer surface of the inner needle shield and the inner surface of the outer needle shield may comprise structural elements having matching shapes.

The functioning of the medical assembly <NUM> of the invention will now be described in reference to <FIG>.

<FIG> illustrates a medical assembly 100A of the prior art. In order to remove the needle cover 1A from the medical injection device 40A, the user first presses or pinches the outer needle shield 20A from both sides, thereby exerting an effort oriented radially inwardly onto an intermediate portion of the outer needle shield. The effort exerted by the user, called "pinch force", is noted P(f<NUM>).

This effort deforms the inner needle shield 10A. The intermediate portion of the inner needle shield is pressed against the tip whereas the inner proximal connection part slightly comes off from the tip. This leads to a modification of the pressure distribution over the contact interface between the inner surface of the inner needle shield and the outer surface of the tip.

The user then pulls the needle cover 1A in the distal direction relative to the barrel 41A, while still pinching the needle cover <NUM>, to remove said needle cover from the tip of the injection device.

Despite achieving the removal of the needle cover 1A from the injection device 40A, the pressure exerted onto the tip by the inner needle shield is high. Indeed, the force exerted by the user to pinch the needle cover 1A is high and causes friction between the inner needle shield and the tip. Such friction limits translational movement of the needle cover 1A relative to the tip 42A, which results in a high pull out force.

<FIG> illustrate a medical assembly <NUM> according to the invention, wherein two arms <NUM> of the actuator are in the rest position and in the actuation position respectively.

In reference to <FIG>, an axial clearance noted G<NUM> is spared between the needle cover <NUM> and the distal face <NUM> of the barrel <NUM>, thereby defining a housing <NUM>. The tilted surface <NUM> of each arm frictionally engages the distal face <NUM> of the barrel, and defines an angle α with the axis C. Note that alternatively, the arms may be remote from the barrel in the rest position.

In order to remove the needle cover <NUM> from the medical injection device <NUM>, the user first pinches the two arms, thereby exerting an effort oriented radially inwardly onto said arms. The pinch force is noted P(f<NUM>). Preferably, the pinching effort is exerted around the axial clearance.

This effort causes the arms to move radially inwardly from the rest position to the actuation position as illustrated in <FIG>.

The junction <NUM> between the first portion <NUM> and the second portion <NUM> of each arm bends heading radially outwardly.

The tilted surface <NUM> of each arm slides over the distal face <NUM> of the barrel as the lugs <NUM> get into the housing. This aspect will be described in more details in the following.

The sliding of the tilted surface <NUM> of the arms over the distal face <NUM> of the barrel causes a force transfer from the radial direction to the distal direction by a wedge effect. In other terms, the pinch force is converted into a translational force towards the distal direction.

This causes the needle cover <NUM> to be moved of a determined distance, noted Δx, in the distal direction by the wedge effect, with no pull out force exerted by the user. The distance between the position of the needle cover moved of Δx and the distal face of the barrel is noted G<NUM>. As such, Δx = G<NUM> - G<NUM>.

The determined distance Δx depends on the angle α. Indeed, the greater the angle α, the greater the distance Δx. However, the greater the angle α, the greater the pinch force as well. Therefore, a balance shall be found between the desired distance Δx and the maximum pinch force required, while keeping in mind that a high pinch force required to remove the needle cover may be detrimental to the user.

The user then pulls the needle cover <NUM> in the distal direction relative to the barrel <NUM>, while still pinching the arms, to remove said needle cover from the tip <NUM> of the injection device.

The distance that the needle cover has to travel for being removed from the tip of the injection device, when the user pulls said needle cover, is thus reduced by the distance Δx.

Moreover, compared to the medical assembly 100A of the prior art, the user does not pinch the body of the needle cover, but the arms <NUM> of the actuator. Hence, the inner surface <NUM> of the inner needle shield is not pressed against the outer surface of the tip <NUM>, and resulting friction between these two surfaces is thus prevented.

The wedge effect provided by the sliding of the tilted surface <NUM> over the distal face <NUM> of the barrel, and the pinching force exerted onto the arms <NUM> instead of the body of the needle cover 1A, strongly reduces the pull out force. The pull out force is reduced by about <NUM>% to <NUM>% (see examples below).

According to the embodiment illustrated in <FIG>, the lugs <NUM> provided on the second part of the arms are configured to insert in the housing <NUM>.

In more details, when the arms <NUM> are in the rest position, the lugs <NUM> are remote from the housing <NUM> and may contact or may be remote from the distal face <NUM> of the barrel.

When the arms <NUM> are moved from the rest position to the actuation position, the lugs <NUM> enter the housing <NUM> while the tilted surface <NUM> slides over the distal face <NUM> of the barrel.

After further pinching of the arms, the lugs <NUM> contact the proximal portion <NUM> of the outer needle shield, and preferably the inner proximal connection part of the inner needle shield. In the illustrated embodiment, the base <NUM> of the lugs, delimited by the slope discontinuity between a lug and the second part of an arm, abuts the periphery of the proximal portion <NUM> of the outer needle shield.

Further pinching of the arms <NUM> causes the second inner surface <NUM> of the lugs <NUM> to abut the proximal portion <NUM> of the outer needle shield. The arms <NUM> thereby push the needle cover <NUM> in the distal direction. This additional effort adds to the wedge effect, for further moving the needle cover in the distal direction relative to the tip <NUM> of the injection device, before the user pulls the needle cover <NUM> to remove it from the injection device. The pull out force is thereby further decreased.

The medical assembly of the invention also lead to a reduction of the pinch force.

Indeed, in the case of the known medical assemblies wherein the user pinches the body of the needle cover, since the outer needle cover is usually made of a rigid material, the pinching force to be applied by the user is high. In particular, the pinching force must be sufficient to deform the outer needle shield, which in turn, exerts an effort onto the inner needle shield so as to allow the needle cover to move in a distal direction relative to the tip when the user further pulls said needle cover.

In the case of the medical assembly of the invention, the user pinches arms that are flexible, which means that such arms are configured to deform radially inwardly under a corresponding effort of the user. The mechanical features of the arms, such as their dimensions and constitutive material in particular, are adjusted for this purpose.

Of course, as already mentioned, the pinch force also depends on the angle α, which may be adjusted, as well as the mechanical features of the arms, so as to achieve reasonable pinch force.

Needle covers of the prior art (which do not comprise any actuator, such as lug or arm) and needle covers of the invention, both being previously mounted onto the tip of a glass syringe, are compared herein. The glass syringes are identical for the needle covers of the prior art and the needle covers of the invention, and belong to the same production batch.

In these assays, ten needle covers of the prior art and ten needle covers of the invention provided with two flexible arms were assessed.

Measurements of the force needed to remove the needle cover from the syringe are carried out. The test is performed with a traction bench (<NUM>/min). The method comprises the steps of:.

For each needle cover of the invention, the flexible arms are manually pinched to the end of clearance. As a result, the needle cover moved in the distal direction relative to the tip of the syringe of a maximum distance Δx. Then the needle covers are positioned in the traction bench to measure the remaining force to be exerted so as to remove the needle cover from the tip of the syringe.

The needle covers of the prior art are directly positioned in the traction bench.

The force needed to pull the needle cover so as to remove it from the tip is recorded, in function of the displacement of the needle cover and the time.

<FIG> illustrates the evolution of the pulling force F exerted onto the needle cover of the prior art (curve F1) and onto the needle cover of the invention (curve F2) so as to remove it from the syringe tip, relative to the course C of the needle cover. The course C represents the gap between the needle cover and the tip of the injection device. The course of the needle cover of the invention starts after the course of the needle cover of the prior art because the needle cover of the invention was manually pinch press to the end of clearance.

The force needed to remove the needle cover increases at the beginning of the movement of the needle cover, until it reaches a maximum value, named "POF value", that corresponds to the pull out force. As visible on curve F1 of <FIG>, the pull out force is about <NUM> N (Newton). This result is confirmed by <FIG>, which represents the average value of the POF measured for all the needle covers of the prior art (POF (F1)) and the average value of the POF measured for the needle covers of the invention (POF (F2)). The mean value of the POF measured for the needle covers of the prior art is <NUM> N. On curve F1 of <FIG>, the force then increases again in a second peak which is due to the slip-stick effect resulting from the sliding of the needle cover relative to the syringe tip.

The curve F2 illustrates the evolution of the pulling force F exerted onto the needle cover of the invention so as to remove it from the syringe tip, relative to the course C of the needle cover. The force defines only one peak. Indeed, the first peak visible on curve F1 of <FIG> is absent. This is because the pinching of the flexible arms before the measure already moved the needle cover relative to the syringe tip. As such, part of the force needed to pull the needle cover so as to remove it from the tip is converted into pinch force exerted onto the flexible arms prior to pulling the needle cover. As a result, the pull out force is greatly reduced to about <NUM> N. This result is confirmed by <FIG>, which shows that the mean value of the pull out force for the needle covers of the invention is <NUM> N.

Claim 1:
Needle cover (<NUM>) for protecting a needle (<NUM>) mounted on a tip (<NUM>) of a barrel (<NUM>) of a medical injection device (<NUM>), wherein the tip (<NUM>) extends from a distal face (<NUM>) of the barrel, the needle cover (<NUM>) comprising:
- an inner needle shield (<NUM>) extending along a longitudinal axis (B), comprising an inner proximal connection part (<NUM>) configured to sealingly contact the tip (<NUM>) of the barrel (<NUM>),
- an outer needle shield (<NUM>) surrounding at least partially the inner needle shield (<NUM>), and fixed to said inner needle shield,
the needle cover (<NUM>) being characterized in that it comprises at least one actuator (<NUM>) integral with the outer needle shield (<NUM>), said at least one actuator comprising a proximal inner surface (<NUM>) which is tilted relative to the longitudinal axis (B),
the actuator (<NUM>) being radially movable inwardly relative to the longitudinal axis (B) to slidingly engage the proximal inner tilted surface (<NUM>) with the distal face (<NUM>) of the barrel (<NUM>) so as to cause the needle cover (<NUM>) to move in a distal direction along the tip (<NUM>) by a wedge effect.