INJECTION DEVICE

The invention provides an injector comprising a body and a container. The body has an injection opening and including a drive mechanism which can be actuated to move the container within the body and inject medication from the container through the injection opening. The container comprises an outlet and includes an injection needle releasably coupled thereto. The injection needle comprises a hub and a needle. The hub extends along a first axis between a connecting end and a needle end. The connection end comprises connection means for connecting to the container and the needle connecting to the hub at a needle end. The needle extends from the hub along the first axis to an injection end. The injection needle comprises a channel extending from the connection end of the hub to the injection end of the needle. The hub comprises at least one reference shoulder extending radially from the hub and directed towards the injection end. The injection needle further comprises a needle shield, the needle shield releasably coupled to the needle hub and substantially covering the needle. The body further includes a body stop, the body stop comprises a shoulder extending radially inwardly from the body to define an aperture though which the needle shield, but not the reference shoulder can pass. The body stop being configured to contact the at least one reference shoulder extending from the hub to limit the distance the injection end of the needle extends out of the injection opening.

The present invention relates to an injection device, specifically an injection device comprising a needle having a removable needle shield, a container, such as a syringe, and an injector body.

Controlling depth of injection is important to ensure that the drug is delivered to the correct tissue. During a manual injection the user has direct control of the injection depth. However, when using an injection device, such as a autoinjector, the user may be able to select a desired depth of injection, but it is the device that directly controls the injection depth. The depth of injection is often controlled by a stop within the injection device that interacts with part of the drug container, for example a syringe, to limit injection depth. However, there are various components within the tolerance chain of prior art autoinjectors that can result in a potentially significant variability in injection depth. A prior art syringe is shown inFIGS. 1aand1b.

FIG. 1ashows an end of an injector1, in this case an autoinjector which includes a body2and a syringe4. The syringe4includes an outlet6to which an injection needle8(better shown inFIG. 1b) is coupled. In this case the outlet6comprises a luer type connector10with a screw thread12into which a connection end14of the injection needle8is screwed. The injection needle8is protected by a needle shield16which is coupled to a shield portion18of the hub22of injection needle8by a connection sleeve20.

As can be seen inFIG. 1b, the injection needle8comprises a hub22and a needle24which extend along a first axis26. A flange28is provided at the connection end14for engaging with the screw thread12.

The autoinjector1also includes a body stop30. The body stop30is arranged a predetermined distance from an injection opening32. The body stop30comprises an annular shoulder34around an opening through which the needle24, the needle shield16and the hub20are able to pass, but through which the screw part12of the luer type lock10cannot pass. This means that the distance between the syringe4and injection opening28is controlled by the body stop30.

The present invention provides an injector comprising a body and a container, the body having an injection opening and including a drive mechanism which can be actuated to move the container within the body and inject medication from the container through the injection opening, the container comprising an outlet and including an injection needle releasably coupled thereto, the injection needle comprising a hub and a needle, the hub extending along a first axis between a connecting end and a needle end, the connection end comprising connection means for connecting to the container and the needle connecting to the hub at a needle end, the needle extending from the hub along the first axis to an injection end, the injection needle comprising a channel extending from the connection end of the hub to the injection end of the needle, the hub comprising at least one reference shoulder extending radially from the hub and directed towards the injection end, the injection needle further comprising a needle shield, the needle shield releasably coupled to the needle hub and substantially covering the needle, the body further including a body stop, the body stop comprising a shoulder extending radially inwardly from the body to define an aperture though which the needle shield, but not the reference shoulder can pass, the body stop being configured to contact the at least one reference shoulder extending from the hub to limit the distance the injection end of the needle extends out of the injection opening.

By providing a forward directed, (i.e. away from the connection end and towards the injection end), reference shoulder on the hub a tighter control over the distance that an injection end of the needle extends through an injection opening of an injector is made possible. The reference shoulder on the hub results in fewer components in the axial tolerance chain since, for example, the axial tolerances of the depth of connection of the luer engagement between the injection needle and container is removed. Such tolerances can be quite large, especially in cases where diameter tolerances in the luer cone dimensions are amplified by a small cone angle. It is also possible that the change in load path may reduce the chance of injector needle flange breakage in an autoinjector in which the forces can be quite high. This sort of tolerance chain consideration is particularly relevant for removable needles since needles permanently attached to the container do not suffer from the attachment tolerances mentioned above.

The injector body provides a housing adapted to contain the container and cover some or all of the container. The injection opening is an opening into the body through which the needle attached to the container within the injector body can be caused to protrude so that it can penetrate the body of a human or animal to deliver medication thereto.

The body stop may be a complete, circumferential annular shoulder or may comprise one or more gaps in the shoulder. In one embodiment the shoulders and gaps may be substantially evenly distributed around the circumference.

It should be noted that the term “container” herein includes syringes, cartridges and other medicament delivery or containing devices to which an injection needle can be, or is, attached and which include a variable volume chamber sealed by a movable stopper. In a preferred embodiment the container is a syringe which is filled with a medicament and then inserted into the injector. Having the body stop configured as an aperture through which the shield can pass, but not the reference stop means that the shielded needle can be attached to the container and the container and needle assembly subsequently inserted into the injector body such that the needle shield extends from the injection outlet. This means that the assembly is ‘safe’ as the needle is shielded throughout. The needle shield can then be removed by a user through the injection outlet prior to use without risking contact with the needle. The container may be filled, either pre-filled or filled by a user prior to assembling the container into the injector body, with a medicament intended for injection into the body of a human or animal patient. In one embodiment the medicament is interferon beta-1b.

It should be noted that there are many suitable drive mechanisms that should be used in the injector of the invention. In one embodiment the drive mechanism comprises one or more mechanical springs that can be primed and subsequently released to drive the container and attached needle towards the patient so that the needle pierces the skin and the drive mechanism then causes he medicament within the container to be forced through the needle and thereby delivered to the patient. In other embodiments one or more of the functions of causing the needle to pierce the skin, causing the injection of medicament through the needle or causing other movements of parts of the injector can be accomplished or assisted using motors, gas springs or other mechanisms.

In one embodiment the injection needle may be substantially standard with the exception of the addition of the reference shoulder. The hub may be fabricated for any suitable material, for example a plastic, metal, glass or combination thereof. The needle may be any suitable material, for example a surgical grade metal.

The connection end of the hub may include a radial flange for connection to an internal screw fitting on a container to facilitate connection of the injection needle to the container. The connection end of the hub may include an opening into a female part of a luer type connector.

The needle may be connected to the hub in any suitable way (many are known in the art), for example glued or staked. The injection end of the needle may be sharpened to facilitate piercing the skin or other target material. Such sharpening can take many forms and is well known in the art.

The injection needle comprises a channel extending from the connection end of the hub to the injection end of the needle to allow fluid from within a container connected to the injection needle to be expelled through the injection end of the needle. The channel may be located substantially centrally through the injection needle and may extend substantially along the first axis, although deviations from the first axis or non-central channels are also possible.

The at least one reference shoulder extending radially from the hub and directed towards the injection end may be formed from any suitable material. The reference shoulder may be formed integrally with the hub, for example during a moulding operation, or could be formed by attaching a component to the hub. The reference shoulder need not be fabricated from the same material as the hub. In some embodiments the reference shoulder is integrally moulded with the hub and may be fabricated from the same material or materials. The reference shoulder must be securely coupled, or integrally formed, to the hub so that it substantially cannot move in the axial direction as this ensures that the location of the shoulder remains substantially as intended and the injection depth is therefore consistent and substantially as intended.

In one embodiment the hub extends for a length L along a first axis between the connecting end and the needle end and the at least one reference shoulder may be located less than a distance of 3L/4 from the needle end, or less than 5L/8 from the needle end, or less than L/2 from the needle end. In the same, or other embodiments, the at least one reference shoulder may be located at least a distance of L/6 from the needle end, or at least a distance of L/4 from the needle end.

In one embodiment the at least one reference shoulder may be provided on a circumferential ridge extending from the hub. The ridge may take the form of a flange. The flange could be supported by one or more buttresses extending from the flange towards the connection end. The ridge may take the form of a shoulder directed to the injection end from which an outer surface tapers to the hub towards the connection end.

The needle hub may include a shield stop to prevent the needle shield from being pushed too far onto the hub. The shield stop is a shoulder extending perpendicular to the first axis. The shield stop may be located between the reference stop, and the needle end of the hub. In another embodiment the shield stop and the reference stop may be located at substantially the same axial location on the hub.

In a different embodiment the reference shoulder may be provided at an end of a cylindrical extension that extends from the hub towards the injection end, thereby providing an annular reference shoulder. An inner wall of the cylindrical extension may have a diameter greater than the shield stop. This allows the needle shield to fit within the cylindrical extension.

In another embodiment the at least one reference shoulder may be provided on an end of a rib extending along the hub. In some embodiments a plurality of reference shoulders may be provided on ends of a plurality of ribs extending along the hub. There may be at least 3 such ribs, at least 5 such ribs, at least 7 such ribs or at least 9 such ribs. In these, or other, embodiments there may be fewer than 20 such ribs or fewer than 15 such ribs. In one embodiment there may be between 7 and 15 ribs. In one embodiment there are exactly 8 ribs.

If a plurality of reference shoulders are provided on the hub, by a plurality of ribs, or otherwise, the plurality of reference shoulders may be substantially equally circumferentially distributed around the hub.

In one embodiment the at least one reference shoulder is provided on a sleeve extending around the hub. The sleeve may be a separate component added to an injection needle, for example a substantially standard injection needle. The sleeve may be substantially unable to move away from the injection end such that the reference shoulder is in a fixed axial position relative to the injection end. The sleeve may be a friction fit to the hub or may be held in place using a positive connection such as a snap-fit, a screw-fit. The sleeve could be held in place with an adhesive. The sleeve could also be fabricated integrally with the hub, for example by making the hub wall thicker and providing the reference shoulder in that way.

In one embodiment the distance between the injection end and the reference shoulder may be less than 30 mm, may be less than 25 mm, less than 20 mm or less than 15 mm.

The injection needle is provided with a removable needle shield releasably coupled to a shield portion adjacent the connection end. The needle shield may be coupled to the shield portion by a sleeve or any other suitable means. The reference shoulder may extend radially beyond the radial extent of the sleeve of the needle shield and/or the radial extent of a shield stop on the hub.

In one embodiment the reference shoulder may extend radially at least 0.2 mm, or at least 0.3 mm, or at least 0.5 mm or at least 1 mm away from the first axis. If a shield stop is provided, the reference shoulder may extend radially at least 0.2 mm, or at least 0.3 mm, or at least 0.5 mm or at least 1 mm radially beyond the shield stop. The reference stop may extend to an outer diameter of at least 5 mm, at least 6 mm, at least 6.5 mm.

In one embodiment of the injector the distance between the body stop and the injection opening may adjustable. Such adjustment may be provided in many ways, for example those known in the art. The adjustment may be by sliding adjustment, screw adjustment, rack and pinion adjustment or other suitable mechanisms.

It should be understood that throughout this specification and in the claims that follow, unless the context requires otherwise, the word “comprise”, or variations such as “comprises” or “comprising”, implies the inclusion of the stated integer or step, or group of integers or steps.

FIGS. 1aand1bshow prior art injection needles and assemblies and have already been discussed.

FIG. 2ashows an injector101in a primed condition which includes a body102and a container, in this case a syringe104. An injection needle108is coupled to an outlet106of the syringe104. At a forward end of the injector101there is provided an injection opening132.

In the primed condition the syringe101is arranged within the body such that an injection end36of the needle124is arranged within the body102. A drive mechanism38, for example a spring or other suitable mechanism is arranged within the body102at an end opposite the injection opening132. A button46is arranged to actuate the drive mechanism38.

The syringe104comprises a syringe body40, a plunger42and a stopper44. The syringe body40includes an outlet106to which the injection needle108is coupled.

In the primed state a needle shield116is attached to a shield portion118of the needle hub108.

FIG. 2bshows the syringe101in a post-delivery condition. The drive mechanism38has extended towards the injection opening132causing the syringe104to move towards the injection opening132until such movement is prevented. The movement of the syringe104towards the injection opening132is prevented when a reference shoulder50on the hub108makes contact with the body stop130. The body stop is an annular shoulder134within the body102arranged a predetermined distance away from the injection opening132. The predetermined distance being such that when the reference shoulder50is in contact with the body stop130the injection end36of the needle124extends from the body102through the injection opening132. The drive mechanism38has also caused the stopper44to move towards the outlet106causing the fluid previously within the syringe104to be expelled through the injection needle108. The drive mechanism38first causes the syringe104to move to the body stop and then causes the stopper to move towards the outlet106. This sequence of actions causes the injection end36of the needle124to pierce the skin and then deliver the fluid from within the syringe104. The fluid may be an injectable medicament.

FIG. 3shows an injection needle208comprising a hub222and a needle224. The hub222extending along a first axis26between a connecting end214and a needle end52. The connection end214comprises connection means for connecting to a syringe. In this case the connection means comprises a flange228and an opening into a female luer type connection54.

The needle224connecting to the hub222at a needle end52and extending from the hub222along the first axis26to an injection end36which is sharpened. The injection needle208comprising a channel extending from the connection end214of the hub222to the injection end52of the needle224. The hub222also comprises a reference shoulder150extending radially from the hub222and directed towards the injection end36.

The shield portion218of the hub222comprises four axial shield ridges56that engage with the sleeve20of a needle shield16. This means that a user can hold the injection needle208by the needle shield, connect it to a syringe4and screw it to a screw thread such as that shown inFIG. 1aas12or inFIGS. 2aand2bas112. The needle shield16is prevented from being pushed too far onto the hub222by a shield stop58. The shield stop58is a shoulder extending perpendicular to the first axis26.

In this example the reference shoulder150is provided by a circumferential ridge or flange60extending around the hub222. The reference shoulder150extends radially beyond the extent of the shield stop58.

FIG. 4shows a different injection needle308. The injection needle308is substantially the same as that shown inFIG. 3except that reference shoulders250are provided on a plurality of axially extending hub ridges62. There are between nine and eleven axially extending hub ridges62which are substantially evenly circumferentially distributed around the hub222.

FIG. 5shows a further injection needle408. The injection needle408is substantially the same as that shown inFIG. 3except that reference shoulder350is provided on a sleeve64that is fitted to, and substantially surrounds, the hub222. The sleeve64covers the shield stop58, thereby creating a new shield stop158closer to the injection end by the thickness of the sleeve in the shield stop area. In this embodiment the new shield stop158and reference shoulder350are in substantially the same axial location. The sleeve64extends to the flange328. The sleeve64is a separate component and is fitted to the hub222after manufacture of the hub222.

FIG. 6shows an injection needle508. The injection needle508includes a sleeve164which provides the reference shoulder450. The injection needle508and sleeve164are substantially the same as that shown inFIG. 5. The sleeve164is shorter than the sleeve64ofFIG. 5, in that it covers the shield stop58and extends along the hub222towards, but not reaching the flange328. At an end70of the sleeve164there is an outwardly directed flange72which may assist with automated handling of the sleeve164during production. Such a flange72could be added to any sleeve.

FIG. 7shows an injection needle608. The injection needle608includes a sleeve264which provides the reference shoulder550. The injection needle608and sleeve550are substantially the same as that shown inFIG. 5. The sleeve264is shorter than the sleeve64ofFIG. 5, in that it extends from the flange328, but does not cover the shield stop58.

InFIGS. 3,4,5,6,7and8the injection needles have substantially the same key dimensions. From the connection end214to the reference stop150,250,350is between 7.5 to 8.5 mm. From the connection end214to the needle end52is between 16 to 17 mm.

FIG. 6shows a cross section of the injection needle208ofFIG. 3. The hub222extends for a length L along a first axis26between the connecting end214and the needle end52. The reference shoulder150is located a distance x from the needle end and a distance y from the connection end. In this case the distance x is about L/2 and the distance y is about L/2.

It should be understood that the invention has been described above by way of example only and that modifications in detail can be made without departing from the scope of the claims.