Device for automatic injection of drug doses

A device for the automatic injection of doses of a drug compound is described. The device has a sliding sheath which, when depressed with its front end against the injection site, interacts with cam means to activate triggering of a plunger, thus controlling delivery of a drug dose. Plunger guide means are provided for controlling the triggering sequence and means for arming the device in the dose delivery condition. Automatic needle re-sheathing and resetting of a lock-out condition after each dose is delivered are also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is the US national stage of International Patent Application PCT/EP2012/067438 filed on Sep. 6, 2012 which, in turn, claims priority to Italian Patent Application FI2011A000194 filed on Sep. 8, 2011.

FIELD OF THE INVENTION

The present invention relates generally to devices for the injection of medicaments and more precisely relates to a device for the automatic injection of medicaments especially a medicament for allergic emergencies, such as epinephrine or adrenaline, according to a requested time sequence. In particular, the invention refers to a device for the automatic injection of two doses of a medicament at two successive times.

BACKGROUND OF THE INVENTION

Many devices of the above mentioned type allowing a patient to self-administer one or more (generally two) doses of a medicament are known. U.S. Pat. No. 6,575,939 discloses an autoinjector device comprising a syringe housed in a casing formed by an inner part and an outer part capable of sliding in relation to each other. By pressing the end of the inner part (the needle outlet end) against the patient's skin at the injection site, the outer part slides forward along the inner part, thus unlocking a push-button. By depressing the button, the syringe and the relevant plunger are triggered to first thrust in the needle and then deliver the medicament. The needle retraction in the casing is obtained by stopping pressing the outer part end against the skin. This auto-injector allows a single dose of medicament to be administered.

An autoinjector device for automatic administering a single dose of a medicament is also known from U.S. Pat. No. 4,031,893. The autoinjector is equipped with an unlocking device with a deformable member for the driving device. The syringe plunger is axially connected to a rod comprising four flexible axial arms having a toothed end engaged on the edge of an opening formed on a cap placed at the end of the syringe housing. Cap sliding causes the arm ends to deform and their teeth to release from the opening edge. In this way the driving device is triggered. The autoinjector according to this document also comprises a safety device to prevent accidental deformation of the arm ends and triggering of the driving device, consisting of an insert centrally extending from the cap and capable of coming between the rod arms to prevent them from bending.

EP700307 discloses a two-dose autoinjector allowing the automatic delivering of a first dose of a medicament and the manual administration of a second dose. The autoinjector device according to this patent foresees the use of a syringe housed slidably in a tubular housing in two parts that can be separated to allow positioning of the syringe containing two doses of the medicament to be delivered and removal after use. The sliding of the syringe in the housing to penetrate the needle and inject the medicament is operated by an actuator movable between an armed position and an extended position. A releasable locking device is provided to limit the syringe plunger sliding to an extent corresponding to the volume of the first dose. The syringe is mounted in the tubular housing in a movable way to enable the locking device to be removed after the first dose is delivered and the plunger drive means to be armed again, if the second dose is to be automatically administered, or the syringe to be removed, if the second dose is to be manually administered. Furthermore the drive means is provided with a safety lock formed by a member engaging with a deformable pin of the drive means to keep it in a deformed condition, thereby preventing it to trigger. An autoinjector of this type is commercially available under the trade mark Twinject® and allows the first dose to be administered automatically, but the second dose must be manually administered.

The autoinjector according to EP651662 is designed to carry out a sequence of injections from a single syringe that is capable of performing a limited sliding movement in a tubular housing. The syringe has a plunger to deliver doses of a medicine through the needle and spring drive means engage with a plunger rod and, once they are armed, retain the rod in a first position, while, when they are triggered, cause the rod to move forward and this causes first the syringe sliding and needle projection and then a controlled sliding of the plunger to deliver a medicine dose. Manual arming means are provided and means to trigger again the spring drive means.

The plunger rod has a toothed profile on which a catch of the drive means engages and the syringe is housed in a bushing capable of moving in a limited way in the tubular housing and provided with a further catch that is also engaged with the toothed profile of the rod. When the device is armed by the manual arming means, both the drive means and the bushing in which the syringe is placed are displaced toward the rear end of the tubular housing, the two catches engaging with the toothed profile of the rod. An axial groove connection between the bushing and the drive means allows a further sliding between the catch integral to the drive means and the toothed profile of an extent equal to the pitch of the profile. When the device is triggered, first the drive means cause the syringe bushing to slide up to a front stop and then the rod start sliding relative to the bushing catch for an extent corresponding to the profile pitch, whereby the displacement of a volume of medicine is enabled together with its deliver through the needle.

There is a strong need for an injector device for the automatic injection of a medicament in two successive doses which is user-friendly and is easier to manufacture as compared to the conventional devices. The object of the present invention is therefore to meet these requirements by providing a medicament autoinjector device capable of enabling the patient to self-administering two successive doses of a medicament in the easiest possible way, thus sparing the patient of performing potentially dangerous, complex dismounting/re-arming operations.

SUMMARY OF THE INVENTION

The general object of the present invention is to provide a device for the automatic injection of multiple discrete nominal volumes of a drug compound, especially two doses of the drug compound from the same syringe.

A particular object of the present invention is to provide a device of the above mentioned type in which the automatic injection of discrete nominal volumes of drug compound is achieved by combination of rotational and translational movements of device components.

Another object of the present invention is to provide a device of the above mentioned type in which the automatic injection of a prescribed dose is triggered by use of a patient activated linear sliding of a component in combination with the angular displacement of plunger means being guided by cam means in an encapsulated chassis.

It is a further object of the present invention to provide a device of the above mentioned type with an automatic sheathing lock-out feature for needle protection and prevention of inadvertent triggering of the device before a dose is selected by the user.

Still another object of the present invention is to provide a device of the above mentioned type capable of automatic re-sheathing the needle and resetting the lock-out condition after a dose is injected.

Another object of the invention is to provide a device of the above mentioned type in which the triggering function and the driving function are integrated on same support to lower tolerances, increase reliability and reduce the number of components of the device, this also resulting in a simple device structure and production cost reduction.

Still another object of the invention is to provide an autoinjector device of the above mentioned type in which the production and assembling thereof are easy to carry out.

The above objects are achieved with the device for the automatic injection of doses of a medicament according to the present invention, whose main features are set forth in the attached claim1. Further important features are set forth in the dependent claims.

According to an important aspect of the device for the automatic injection of doses of a drug compound according to the present invention, the axial movement of a sliding sheath, caused by the user by depressing its front end against the injection site, causes the angular displacement of cam trigger means, which, in cooperation with stepped guide means, controls the movement of plunger means of a syringe group and thus the delivery of prefixed doses of a drug compound. The movement of the plunger means is produced by axially operating first elastic means, while the axial movement of the sliding sheath is hindered by second elastic means that reinstate the initial needle covering condition of the sheath when the pressure action ceases. To make the device ready for the delivery of a dose, device arming means are provided which, when operated, unlock the sheath axial sliding. The lock-out condition, as well as the needle retraction in the sliding sheath, are automatically reinstated when the pressure ceases under the action of the second elastic means.

According to another important aspect of the invention, the cam trigger means are formed on the same support, axially pivotable, as cam drive means with which the sliding sheath interacts to control the triggering of the plunger means of the syringe group.

According to a further aspect of the invention the means allowing the device to be kept in a rest state are formed on the support of the cam trigger means and the cam drive means and are unlocked as a result of a rotation of a dose selection knob pivotally mounted on the device body and temporarily connected to the support.

DETAILED DESCRIPTION OF THE INVENTION

With reference toFIGS. 1 to 5, the autoinjector device according to the present invention comprises an outer body1of tubular shape, in particular a cylindrical body, extending along an axis X and containing the majority of the device components. The outer body is formed by two coaxially aligned body portions1a,1bhaving different diameter separated by a step1c, against which the end of a removable end cap2abuts, said cap2concealing the front end3of the device. In the proximity of the other end, the rear end, of the device angularly spaced reference marks are formed or labelled, for example the numerals 0, 1, 2, indicating a rest o stored state (0), and two operating states (1, 2) of the device, as will be explained later on. In the present description the terms “front”, “rear” and equivalents relate to the part of the device intended for the needle outlet and, respectively, the axially opposed part. It is also stated that in the present description reference is always made to a device for the automatic injection of two doses of a drug, but it is understood that the invention also comprises devices capable of delivering more than two doses of a drug at successive times, through changes and alteration to the device which will be obvious for a person skilled in the art.

A dose selection knob4, on which a reference indicator5is formed, is provided at the rear end of the device. The dose selection knob4is axially pivotable relative to the outer body1to allow the indicator5to align to the reference marks4formed thereon.

A syringe group, generally indicated at6, is housed in the outer body1. As shown inFIG. 13the syringe group comprises a drug preloaded syringe7, with needle7a, needle shield7b, barrel7cand inner plunger stopper7d. In the barrel7cthere engages the end of a plunger rod8, formed by a tubular element in two parts8aand8bof different diameter. The part8ahas a cross section that is in a clearance condition with respect to the inner section of the barrel7cso that it can slide therein, and an end shaped in a way to engage with plunger stopper7das a result of an axial movement to push it forward on drug delivery. The part8bof the plunger rod8has a larger diameter and is formed with internal radial ribs9for aligning a power spring10extending axially in the plunger rod8. The power spring10is in a compressed state and abuts against the closed end of the part8aof the plunger rod8with one end and against the bottom wall4aof the dose selection knob4with its other end. The power spring10also winds up around a support rod11extending from the same bottom wall4aof the dose selection knob4up to the closed end of the part8aof the plunger rod8. The arrangement of the power spring10between the radial ribs9and the part8aof the plunger rod and the support rod11helps to minimize buckling of the power spring10.

In the device stored state the dose selection knob4is connected to part8bof the plunger rod8by a bayonet connection, shown in particular inFIGS. 5 to 9, comprising a pair of substantially L-shaped slots12formed circumferentially on part8bat diametrically opposed positions and a pair of retention clips13internally projecting from the dose selection knob4at diametrically opposed positions. The substantially L-shaped slots12comprise a retention slot branch12a, extending circumferentially, and a release slot branch12b, extending axially up to the edge of the part8bof the plunger rod8. When the indicator5on the knob4is aligned to the reference mark0, the two retention clips13are engaged in the respective retention slot branches12aof the slots12, thus preventing the plunger rod8to slide axially. As a result of an angular displacement of the plunger rod relative to the knob4, the retention clips13slide in the retention slot branches12auntil they come into alignment to respective release slot branches12bextending rearward up to the free end of part8bof the plunger rod8, thereby allowing the plunger rod8to travel forward under the action of the power spring10, as will be explained later on about the device operation.

Two radial pegs15outwardly project from the part8bof the plunger rod at diametrically opposed parts. The two radial pegs15, which slide in trigger cam means, provide a means to guide the movement of the plunger rod8which controls the drug dose delivery, as will be explained later on.

As shown inFIGS. 4,5and6, the dose selection knob4is formed with a perimetrical groove16in which an undercut17at the rear end of the outer body1slidably engages, whereby the dose selection knob4is pivotable relative to the outer body1so that the selection of the dose to be delivered is allowed.

The dose selection knob4may rotate in only one direction and to this end the connection between the knob4and the outer body1comprises means for preventing the rotation in the direction opposite to that of dose selection. These means comprise a pair of ratchet legs18(seeFIGS. 6 and 7) perimetrically extending from the edge of the knob4, suited to slidably abut, when the knob4is rotated, on an indexing ramp surface19defining two ramp steps19a, b(only one shown inFIGS. 10 and 11). When the legs18slide on the ramp surface19, first they flex and then, once the ramp has overcome, they trigger at the ramp step19a, bpresent at the end of the ramp, abutting against it and preventing the reverse rotation. A stop rib20is also provided on the ramp surface, against which the ratchet legs18abut to prevent any further knob rotation after the knob reaches the position corresponding to the second dose delivery.

As shown inFIGS. 6-8, a pair of diametrically opposed feet21axially extend from the free edge of the dose selection knob4over the part8b of the plunger rod8and engage in respective seats22of a support23of tubular shape, referred to as cam sleeve23(FIGS. 18 to 20) in the present description, formed at the rear end thereof. The seats22have a leading edge22aagainst which the feet21abut to bring the cam sleeve23into rotation integrally with the dose selection knob4. A positioning flange24outwardly extends around the same end of the cam sleeve23designed to rest on a corresponding rim25within the outer body1near its rear end, thereby preventing mutual axial sliding.

As shown inFIGS. 18 to 20, the cam sleeve23is formed with two sections with different functions: a first section23atoward the front end, called front section, and a second section23btoward the rear end, called rear section. The front section23ais operatively connected to a slidable sheath30(seeFIG. 14), whose axial sliding causes the cam sleeve23to displace angularly, as will be explained later on, while the rear section23bis operatively connected to the plunger rod8through its radial pegs15and, as already said, to the dose selection knob4(see especiallyFIG. 20).

The cam sleeve23is pivotable in the outer body1and is kept into axial alignment by the positioning flange24.

The rear section23bof the cam sleeve23is provided with trigger cam means to control the movements of the plunger rod8. The trigger cam means comprise two windows26diametrically opposed and symmetrical to the axial rotation as regard their shape, opened toward the rear edge of the cam sleeve through a respective axially extending channel27defining a first dose trigger cam track27a. Each window is delimited by two parallel circumferential sides26a,26b, by an axial side26clinking two ends of the sides26a,26b, and by an inclined side26d, opposed to the axial side26c, linking the other end of the side26bopposite to the channel27to one side of the channel27. The channel27opens in the window26at the inclined side26dand the axial side26cforms the second dose trigger cam track. The first dose trigger cam track26cis angularly spaced from the second dose trigger cam track27a.

Drive cam means28are embossed on the outer surface of the front section23aof the cam sleeve23. The drive cam means28is formed by a cam profile repeated four times in an angularly equispaced fashion on said surface. The cam profile comprises a first drive cam track28a, extending from the end of the sleeve cam23, called upward track for sake of simplicity, and inclined with respect to the axis X, and a second drive cam track28b, called downward track for sake of simplicity, extending from the same end of the cam sleeve23and incident with the first drive cam track28a. On the upward track28aand, successively, on the downward track28ba pair of drive pins32is designed to slide. The drive pins32project inwardly from two diametrically opposed, axial drive legs31of the sliding sheath30(FIGS. 15-17). When a pressure action is exerted on the free end3of the sliding sheath30, the cam sleeve23is rotated in the opposite direction to the inclination direction of the upward track28a, and, respectively, when the pressure action ceases.

In the downward track28bof the drive cam means28relevant cantilever legs29are formed to be inwardly deflected to allow passage of the drive pins32. In the stored state of the device the drive pins32abut on an axial lock-out edge29a(FIGS. 4 and 14) at the free end of the cantilever legs29, thereby preventing the sliding sheath30from moving toward the rear end of the device. A stop edge28c, placed sideways of the axial lock-out edge29a, serves as abutment for drive pins32to prevent the dose selection knob4from rotating beyond the positions of first dose and second dose delivery, as will be explained later on.

The end of the sliding sheath30at the side opposite to the drive legs31constitutes the front end3of the device, i.e. the end intended to be brought into contact with the patient skin at the injection site. The needle7aof the syringe7will project from said front end3through a central aperture33thereon. A central spring boss34for slidably housing the syringe7extends from the inner face of the front end3of the sliding sheath30. A return spring35is wound around the central spring boss34and abuts against the inner face of the front end3with one end and against a surface of the outer body1with its other end.

The drive legs31are slidingly engaged with axial guides36formed in the outer body1, whereby the sliding sheath30may only move axially in the outer body1. Two wide axial openings37, arranged at 90° relative to drive legs31, are formed on sliding sheath30. The axial openings37are axially aligned to corresponding transparent inspection windows38formed on the outer body1, through which the barrel7cof the syringe7is visible, whereby the user can control the drug delivery condition. The abutment surface for the return spring35on the outer body1is constituted by the bottom wall38aof said inspection windows38. The axial openings37allow the sliding sheath30to travel axially by the required distance whilst not clashing with the windows in the outer body1.

A pair of assembly clips39extends from the bottom of, and within the axial openings37of the sliding sheath30to snap engage with corresponding end stops40formed at the front end of the outer body1, so as to allow the assembly of the sliding sheath30within the outer body1and prevent release thereof.

The front edge of the outer body1abuts on respective lead edges41aof a pair of flexible tines41formed on the sliding sheath30at diametrically opposed sides. The lead edge41aof these tines is inclined so as to provide resistance to the movement of the sliding sheath30and make this movement possible only as a result of a moderate thrust that deflects the tines41inwardly until the edge of the outer body1overcomes the most projecting end of the tines41. The motion subsequently created by the release of the tines41helps to quickly insert the needle7aof the syringe7into the injection site.

A tubular housing42for the syringe7is formed in the outer body1and a flange42ais formed at one end thereof, on which a corresponding flange7eof the barrel7crests. The two flanges are locked to each other by retention clips43inwardly projecting from the outer body1(seeFIGS. 5,11and13).

As shown inFIG. 11, guide means44are embossed on the inner surface of the outer body1to control the axial movement of the plunger rod8and limit in this way the volume of delivered drug. These guide means are in the form of a stepped track with a first location face44a, a second location face44band a stop ledge44c, lying on planes perpendicular to the axis X. The edge of the first location face44ais connected to the second location face44bby a first axial side44d, and the edge of the second location face44bis connected to the stop ledge44cby a second axial side44e. A pair of diametrically opposed stepped tracks, symmetrical to the axial rotation as regards their shape, are formed in the outer body1. The radial pegs15of the plunger rod8are designed to slide along the first and the second location faces44aand44bas a result of the rotation of the cam sleeve23and fall off from the first location face44ato the second location face44band from the latter to the stop ledge44con delivering the first and the second dose of drug, while moving along the first axial side44dand, respectively, the second axial side44e, as will be explained later on.

A needle shield remover45(FIGS. 2 to 5) is removably secured to the outer body1by snap engageable retention fingers45aand is provided with an inner tubular grip45bfit for engaging with the needle shield7b, in such a way that, by pulling the needle shield remover45before the first dose is administered, the user can remove the needle shield7band free the needle7afor the injection.

The following is a description of the way the auto-injector device according to the invention is used.

In the initial state, the stored state, the power spring10is compressed between the closed end of the part8aof the plunger rod8and the bottom wall4aof the dose selection knob4. The bayonet connection between the knob4and the plunger rod8secures the power spring10in compression until the first dose is selected. Any buckling of the power spring10is prevented thanks to its being arranged between the radial ribs9and the part8aof the plunger rod8at one side and the support rod11at the other one. The needle shield7bis secured to the syringe7and the needle shield remover45secured to the needle shield7b. The cap2is secured to the outer body1and the sliding sheath30is prevented from moving axially because the drive pins32of the of the drive legs31abut against the respective lock-out edges29aof the cam sleeve23.

The dose selection knob4is connected to the outer body1through its external perimetrical groove16, with which slidingly engages the undercut17on the rear end of the outer body1. Once assembled, the dose selection knob4cannot move axially, but can only rotate in one direction. The rotation direction is indicated by the reference marks on the outer body: in other words, indicator5starts from the position1, rotates to the position1when the first dose is selected, and then rotates to the position2when the second dose is selected.

In the stored state the device is “locked-out”, i.e. the sliding sheath30cannot move in the outer body1, because the drive legs31of the sliding sheath30abut against the axial lock-out edges29aof the cam sleeve23. This condition is shown in particular inFIG. 14. On selecting the first dose (position1), the device is unlocked as shown inFIG. 21. As a matter of fact, by rotating the dose selection knob4the cam sleeve23is pushed in the same direction by the feet21of the knob4that abut on the leading edge22aof the seats22of the cam sleeve23. The dose selection knob4cannot rotate past the position1until the first dose is delivered, because the drive pins32of the legs31abut on the circumferential stop edge28dof the cam track28on the cam sleeve23. The slidable sheath30is prevented from rotating because the legs31can only move axially forward and backward in the axial guides36on the outer body1.

First the user must slide back and remove the end cap2in order to expose the needle shield remover45. The end cap2will have to be replaced once the first dose is delivered when the device is not in use. The end cap2protects the drug from light exposure and prevent particulates from coming into contact with the front end3of the device.

To perform the first injection the user must remove the needle shield remover45. In this way the needle shield7bis also removed leaving the needle7auncovered, but still sub-flush of the front end3and not readily visible to the user. To unlock the device and select the delivery of the first dose, the user rotates the dose selection knob4from position0(stored state) to position1(first dose armed).

The rotation of the dose selection knob4from position0to position1causes the rotation of the cam sleeve23, whereby the axial lock-out edges29aof the cantilever legs29displace relative to the drive pins32of the legs31of the slidable sheath30, which abut against the circumferential stop edge28dto prevent the knob4to further rotate until the first dose is delivered and are aligned to the upward portions28aof the cam track28free to move along them. The user recognizes the end of rotation to position1when he/she sees that the indicator5lines up with the position1marker, feels the increase in rotation resistance of the drive pins32contacting the cam track28and also hears the “click” as produced by the ratchet legs18falling off the step19aof the ramp surface19. The contrast between legs18and steps19aprevent the knob4from rotating in the reverse direction.

The device is triggered by the user pressing the front end3of the sliding sheath30against the injection site by keeping the device through the outer body1. The movement of the sliding sheath30in the outer body1finds a resistance due to the contrast between the flexible tines41and the end of the outer body1. Due to their flexibility and the inclined contact surface, the flexible tines41depress and fully deflect inwardly to allow the passage of the sliding sheath30which can slide in the outer body1leaving the needle7ato project from its front end3, so that the needle can penetrate in the injection site. The motion subsequently created by the release of the flexible tines41helps to quickly insertion of the needle7ain the injection site.

The axial movement of the sliding sheath30in the outer body1causes the rotation of the cam sleeve23and the latter would frictionally draw into rotation also the dose selection knob4. To prevent the knob4from rotating during the step of first dose delivery, between the dose selection knob4and the outer body1temporary stop means are provided that mutually engage when the free ends of the ratchet legs18fall off the step19aof the ramp surface19of the outer body1. In the present embodiment the temporary stop means comprise retention pips46of the outer body engaging with corresponding catches47of the knob4, as shown inFIGS. 6,11and22c. The rotational force acting on the dose selection knob4upon triggering is less than the retention force provided by the pips46. However, the rotational force that the user is able to provide is much larger than that of pips. Therefore, the user can overcome the pip force and rotate the knob4to arm the device for the second dose.

The rotation of the cam sleeve23causes the plunger rod8to rotate because of the engagement of its radial pegs15in the corresponding axial channels27. After a few degrees of rotation the bayonet connection between the dose selection knob4and the plunger rod8decouples because the retention clips13of the knob4reach the relevant axial release slot branches12bof the plunger rod8and, under the action of the power spring10, the plunger rod8is pushed forward to bring the radial pegs15to lean on the first location face44aof the stepped guide44of the outer body1.

While the cam sleeve23keeps rotating, the radial pegs, pushed by the first dose trigger cam track27a, slide on the first location face44auntil they reach the end thereof and fall off the second location face44bof the stepped guide44under the action of the power spring10. This sequence is shown inFIGS. 23aand23b. The resulting axial sliding of the plunger rod8causes the delivery of the first dose.

After delivery of the first dose, the user removes the device from the injection site and the needle7awithdraws therefrom. The return spring35is no longer hindered by the forced contact between the front end3and the injection site and thereby pushes the slidable sheath30axially forward thus resheathing the needle. At the same time the drive pins32of the drive legs31slide down in the downward portion28bof the cam track28depressing inwardly the cantilever legs29until the device returns to a “lock-out” condition, wherein the drive pins32contact the free end29aof the cantilever legs29and the assembly clips39of the sliding sheath30again engage with end stops40of the outer body1, as shown inFIG. 24. The needle7ais again not accessible as being covered by the sliding sheath30, which, in this state, is prevented from sliding until the user rotates the dose selection knob4to position2. The user then recaps the device. The end cap2snap fits with outer body1to securely hold on the device.

If the delivery of a second dose is necessary, the user un-caps the device to enable access to the sliding sheath30. To unlock the device the user must rotate the dose selection knob4from the position1(first dose armed position) to the position2(second dose armed position).

To that end the user must overcome the reaction of the catches47of the knob4on retention pips46of the outer body1. The feet21of the knob4take up the free travel on seat22of the cam sleeve23until they reach the leading edge22ato rotate the cam sleeve23to position2, as shown inFIGS. 25aand25b. At the same time the rotation of the cam sleeve30causes the device to unlock because the drive pins32of the drive legs31of the sliding sheath30line up the upward portion28aof the cam track28while contacting the circumferential stop edge28dto prevent a further rotation of the knob4once the position2is reached. The reverse rotation of the dose selection knob4is prevented by the ratchet legs18snap abutting on step19aof the ramp surface19. The rotation of the cam sleeve23also causes the repositioning of the radial pegs15from the outlet of the axial channel27within the window26to the opposite axial side26c, while their position on the second location face44bof the stepped guide44is unchanged.

The device is triggered for the delivery of the second dose by the user pressing the front end3of the sliding sheath30against the injection site by keeping the device through the outer body1. The movement of the sliding sheath30in the outer body1finds a resistance due to the contrast between the flexible tines41and the end of the outer body1. Due to their flexibility and the inclined contact surface, the flexible tines41depress and fully deflect inwardly to allow the passage of the sliding sheath30which can slide in the outer body1leaving the needle7ato project from its front end3, so that the needle can penetrate in the injection site. The motion subsequently created by the release of the flexible tines41helps to quickly insert the needle7ain the injection site.

To prevent any further rotation of the knob4, once the position2is reached, at the end of the following rotation of the cam sleeve23the base of the ratchet legs18contacts the stop rib20of the indexing ramp19, by what the ratchet legs19are retained between the step19aand said stop rib20.

While the cam sleeve23keeps on rotating, the radial pegs15slide on the second location face44bof the stepped guide44as pushed by the axial side26cof the window26until they reach the end of said face, from which they fall off the stop ledge44cof the stepped guide44due to the action of the power spring10. This operating sequence is shown inFIGS. 26aand26b. The resulting axial sliding of the plunger rod8causes the second dose to be delivered.

It is worth noting that a small drug volume always remains in the syringe barrel. In fact, the position of the stop ledge44cof the stepped guide44is designed in the way that, when the radial pegs15reach the stop ledge44c, the plunger stopper7ddoes not touch the bottom of the barrel7c. In this way, not only the delivery of the prescribed volume of drug is allowed to be controlled, but also any manufacturing variability with respect to the internal length of the syringe barrel is ensured to be mitigated. Therefore the dose accuracy is improved.

After delivery of the second dose, the user removes the device from the injection site and the needle7awithdraws therefrom. The return spring35is no longer hindered by the forced contact between the front end3and the injection site and thereby pushes the slidable sheath30axially forward thus resheathing the needle. At the same time the drive pins32of the drive legs31slide down in the downward track28bof the drive cam means28and depress inwardly the cantilever legs29until the device returns to a “lock-out” condition, wherein the drive pins32contact the free end29aof the cantilever legs29and the assembly clips39of the sliding sheath30again engage with end stops40of the outer body1, as at the end of the delivery of the first dose. The needle7ais again not accessible as being covered by the sliding sheath30. The user then recaps the device with its end cap2before disposal/handling to paramedic.

Even if the autoinjector device according to the invention described above is equipped with two radial pegs15to guide the movements of the plunger rod8, this solution being the preferred one to have a symmetrical distribution of the forces acting on the various components, it is clear that the solution in which only one radial peg15is provided is comprised in the scope of the invention as being an obvious variation thereof. In this case, the stepped guide means44, the trigger cam means26,27and the drive cam means28will be modified consequently.

FIGS. 27 to 48show a second embodiment of the autoinjector device according to the invention featured by a different configuration of some components, while maintaining a substantially equal operation relative to the autoinjector device described above.

With reference toFIGS. 27-31, in the autoinjector device according to the second embodiment of the present invention the outer body, generally indicated at100, is formed by two distinct components100aand100b, called chassis and outer sleeve respectively, which can be secured to each other coaxially. In particular, a portion of the chassis100aengages within sleeve100band is secured thereto by teeth101asnap fitting in corresponding grooves101bof sleeve100b(seeFIG. 36). The outer diameter of sleeve100bis greater than that of the chassis100a, thus forming a step101c, against which the end of a removable end cap102abuts, said cap102concealing the front end103of the device. The removable end cap102is removably fixed to the chassis100aby cap retention teeth101dsnap fitting in corresponding grooves102aformed on end cap102. A pen-type clip100cextends along the side wall of sleeve100bto hang the autoinjector device, for example, to a pocket.

In the proximity of the other end, the rear end, of the outer body100angularly spaced reference marks are formed or labelled, for example the numerals 0, 1, 2, indicating a rest or stored state (0), and two operating states (1, 2) of the device, as will be explained later on.

A dose selection knob104, from which a reference indicator105axially extends, is provided at the rear end of the outer body100. The dose selection knob104is axially pivotable relative to the outer body100to allow the indicator105to align to the reference marks formed thereon.

In the present embodiment of the invention a substantially cup-shaped ratchet204is housed underneath the dose selection knob104. The ratchet204is made integral to knob104through a pair of wings205internally extending in the knob at diametrically opposite parts and formed with cuts206for snap fitting with side axial retention ribs204cof the ratchet204(seeFIGS. 32 and 33).

A syringe group, generally indicated at106, is housed in the outer body100. As shown inFIG. 39the syringe group comprises a drug preloaded syringe107, with needle107a, needle shield107b(see alsoFIG. 29), barrel107cand inner plunger stopper107d. In the barrel107cthere engages the end of a plunger rod108, formed by a tubular element in two parts, front part108aand back part108bof different outer diameter. The front part108ahas a cross section that is in a clearance condition with respect to the inner section of the barrel107cso that it can slide therein, and an end configured for engagement with the plunger stopper107das a result of an axial movement to push it forward on drug delivery. The back part108bof the plunger rod108has a larger diametrical size.

The inner diameter of the plunger rod108is sized to house a power spring110axially extending all over its length. As shown inFIGS. 30 and 31, the power spring110is in a compressed state and abuts against the closed end of the front part108aof the plunger rod108with one end and against a bottom wall204aof the ratchet204with its other end. The power spring110also winds up around a support rod111extending from a retention hole204bcentrally formed in the bottom wall204aof the ratchet204up to the closed end of the front part108aof the plunger rod108. The arrangement of the power spring110between the support rod111and the inner wall of the front part108aof the plunger rod helps to minimize buckling of the power spring110.

From the bottom wall of the dose selection knob104there extend inwardly a pair of diametrically opposed bosses109(FIG. 35) configured to engage with corresponding cut-outs207formed on the bottom of the ratchet204, whereby a rotational torque exerted by the user on the dose selection knob104is transferred to the ratchet204through the bosses109and the cut-outs207and from the ratchet204to the autoinjector device components connected thereto, as will be explained herebelow.

The plunger rod108and the ratchet204are coupled by a bayonet connection that keeps the power spring in a compressed state until the device is triggered. With reference toFIGS. 33 to 35, the bayonet connection comprises a pair of retention feet112inwardly projecting from the ratchet204at diametrically opposed parts and corresponding actuation slots113extending from the plunger rod108and hanging on the retention feet112. The holding stability is ensured by axial force provided by the compressed power spring110, but the connection does not have any circumferential constraints other than that due to the mutual friction between feet112and slots113.

Two radial pegs115outwardly project from the rear part108bof the plunger rod108at diametrically opposed parts. The two radial pegs115, shown in particular inFIGS. 32-34, provide a means to guide the movement of the plunger rod108, which controls the drug dose delivery, by sliding in trigger cam means, as will be explained later on.

The connection between the outer sleeve100band the knob-ratchet assembly is made (seeFIGS. 30 and 31) through an inwardly facing flange150of the sleeve100babutting on a running rim151of the ratchet204, while the free edge of the knob104abuts on the rear edge of the outer sleeve100b. In this way the sleeve100bis held captive between the selection knob104and the ratchet204during the snapping together process. Centering ribs152extend from the running rim151on the ratchet204to provide axial alignment between the ratchet204and the sleeve100b.

The dose selection knob104may rotate in only one direction relative to sleeve100band to this end the connection between the ratchet204and the sleeve100bcomprises means for preventing the rotation in the direction opposite to that of dose selection after the knob reaches one of the operating positions. These means comprise a pair of flexible ratchet legs118(seeFIGS. 35 and 36) perimetrically extending from the edge of the ratchet204, suited to slidably abut, when the knob104is rotated, on respective anti-back-rotation ribs119, visible inFIG. 43c, of the sleeve100b. When the legs118slide, first they flex due to the presence of ribs119and then, once the ribs have overcome, they trigger abutting against it and preventing the reverse rotation of knob104. A stop rib120(visible inFIG. 43c) is also provided along the face of the sleeve100bon which the ratchet204slides. A corresponding protrusion120aof the ratchet204abuts against the stop rib120to prevent any further knob forward rotation after the knob reaches the position corresponding to the dose delivery. However, the protrusion120amust deflect, as a result of a moderate force, to overcome the stop rib120and allow the passage from an operating position to the other.

As shown inFIGS. 33 and 41a,b,c, a pair of diametrically opposed feet121axially extend from the ratchet204over the part108bof the plunger rod108and engage in respective grooves122of a support123of tubular shape, referred to as cam sleeve123in the present description, formed at the rear end thereof. The grooves122have a leading edge122aagainst which a turning leg121aof the feet121abut to bring the cam sleeve123into rotation integrally with the dose selection knob104through the ratchet204. A positioning flange124(see alsoFIGS. 30 and 31) outwardly extend around the same end of the cam sleeve123designed to rest with one face on a corresponding rim125within the outer sleeve100bnear its rear end, and with the other face on the back edge of the chassis100a, thereby preventing the mutual axial sliding.

As shown inFIGS. 41a,41band41c, the cam sleeve123is formed with two sections with different functions: a first section123atoward the front end of the device, called front section, and a second section123btoward the rear end, called rear section. The front section123ais operatively connected to a slidable sheath130(seeFIG. 30), whose axial sliding causes the cam sleeve123to displace angularly, as will be explained later on, while the rear section123bis operatively connected to the radial pegs115of the plunger rod108and, as already said, to the dose selection knob104(see especiallyFIG. 42) through the ratchet204.

The cam sleeve123is pivotable in the outer sleeve100band is kept into axial alignment by the positioning flange124. The rotation stop end is made by a pair of side ribs124aon the outer edge of flange124abutting on corresponding abutments, not shown, formed in the sleeve100b.

The rear section123bof the cam sleeve123is provided with trigger cam means to control the movements of the plunger rod108. The trigger cam means comprise two windows126diametrically opposed and symmetrical to the axial rotation as regard their shape, opened toward the rear edge of the cam sleeve through a respective axially extending channel127defining a first dose trigger cam track127a. Each window126is delimited by two parallel circumferential sides126aand126b, by an axial side126clinking two ends of the sides126a,126b, and by an inclined side126d, opposed to the axial side126c, linking the other end of the side126b, opposite to the channel127, to one side of the channel127. The channel127opens in the window126at the inclined side126dand the axial side126cforms the second dose trigger cam track. The first dose trigger cam track127ais angularly spaced from the second dose trigger cam track126c. In the present embodiment the side126bis placed at the end of a widened gap in windows126to account for clearances and tolerances associated with manufacturing variation of component features.

Drive cam means128are embossed on the outer surface of the front section123aof the cam sleeve123. The drive cam means128is formed by a cam profile repeated four times in an angularly equispaced fashion on said surface. The cam profile comprises a first drive cam track128a, extending from the end of the cam sleeve123, called upward track for sake of simplicity, and inclined with respect to the axis X, and a second drive cam track128b, called downward track for sake of simplicity, extending from the same end of the cam sleeve123and incident with the first drive cam track128a. On the upward track128aand, successively, on the downward track128ba pair of drive pins132is designed to slidingly urge. The drive pins132project inwardly from two diametrically opposed, axial drive legs131of the sliding sheath130(FIGS. 40a,40band40c). Sliding occurs when a pressure action is exerted on the free end103of the sliding sheath130, whereby the cam sleeve123is rotated in the opposite direction to the inclination direction of the upward track128a, and, respectively, when the pressure action ceases.

In the downward track128bof the drive cam means128relevant cantilever legs129are formed to be inwardly deflected to allow passage of the drive pins132during the drive pin return stroke in the downward track. In the stored state of the device the drive pins132abut on an axial lock-out edge129aat the free end of the cantilever legs129, thereby preventing the sliding sheath130from moving toward the rear end of the device. A stop edge128c, placed sideways of the axial lock-out edge129a, serves as abutment for drive pins132to prevent the ratchet204from rotating beyond the positions of first dose and second dose delivery, as will be explained later on.

The end of the sliding sheath130at the side opposite to the drive legs131constitutes the front end103of the device, i.e. the end intended to be brought into contact with the patient skin at the injection site. The needle107aof the syringe107will project from said front end103through a central aperture133thereon. A return spring135abuts with one end against the inner face of the front end103of the sliding sheath130and against pushing surface of chassis100awith its other end. Sideways the return spring135is guided by alignment ribs134formed inside the sheath130.

A pair of assembly clips139extends outwardly from the ends of the legs131to snap engage with axial guide slots147formed along the chassis100a. The legs131deflect when the device is being assembled so as to allow the assembly clips139to engage in the slots147and the axial movement of the sliding sheath130while preventing release thereof.

Since the drive legs131are slidingly engaged with axial guide slots147formed in the chassis100a, the sliding sheath130may only move axially in the outer body100along axial alignment tracks136inwardly projecting from the inner face of the chassis100a. Two wide axial openings137, arranged at 90° relative to drive legs131, are formed on sliding sheath130. The axial openings137are axially aligned to corresponding transparent inspection windows138formed on the chassis100a, through which the barrel107cof the syringe107is visible, whereby the user can control the drug delivery condition. The abutment surface for the return spring135on the chassis100ais constituted by the bottom wall138aof said inspection windows138. The axial openings137allow the sliding sheath130to travel axially by the required distance whilst not clashing with the windows138of the chassis100a.

Flexible tines141project from diametrically opposed parts of the sliding sheath130and have an active surface inclined so as to provide resistance to the movement of the sliding sheath130when it abuts against corresponding inner protrusions141aat the front end of the axial alignment tracks136of the chassis100a(seeFIGS. 30 and 37) and make this movement possible only as a result of a moderate thrust that deflects the tines141inwardly to overcome the protrusions141a. The motion subsequently created by the release of the tines141helps to quickly insert the needle107aof the syringe107into the injection site.

A tubular housing142for the syringe107is formed in the chassis100aand an inward edge142ais formed at the front end thereof, on which the front end of the barrel107cseats. At the other end of the tubular housing142the barrel107cprojects with a flange107e, above which the front face of the cam sleeve123lies (seeFIGS. 30 and 31).

As shown inFIG. 37, guide means144for the radial pegs115are embossed on the inner surface of the chassis100ato control the axial movement of the plunger rod108and limit in this way the volume of drug delivered. These guide means are in the form of a stepped track with a location face144aand a stop ledge144c, lying on planes perpendicular to the axis X. The edge of the location face144ais connected to the rear edge of the chassis100aby a first axial side144dand to the stop ledge144cby a second axial side144e. A pair of diametrically opposed stepped tracks, symmetrical to the axial rotation as regards their shape, are formed on the inner face of the chassis100a. The radial pegs115of the plunger rod108are designed to jump down from a position at the rear of the chassis100a, whereby the relative axial position of the pegs115is defined by the connection of the bayonet feature between retention feet113and actuation slots112, onto the location face144aat the first dose delivery, and to slide on it as a result of the rotation of the cam sleeve123, finally falling off from the location face144ato the stop ledge144con delivering the second dose of drug, while moving along the first axial side144dand, respectively, the second axial side144e, as will be explained later on.

A needle shield remover145is removably secured to the sliding sheath130by snap engageable retention fingers145aabutting against a flange at the front end of the sheath130and is provided with an inner tubular grip member145bin which an insert146is arranged for engaging on the needle shield107bthrough retention hooks (not shown) digging into the rubber needle shield, in such a way that, by pulling the needle shield remover145before the first dose is administered, the user can remove the needle shield107band free the needle107afor the injection.

The operation of the auto-injector device according to the second embodiment of the invention is described here below. As already said, the operation is substantially equal to that of the previously described embodiment of the invention. Reference is made toFIGS. 42 to 48hidden line149, where present, in these figures indicates the position of the front end of chassis100a.

In the initial state, the stored state, the power spring110is compressed between the closed end of the part108aof the plunger rod108and the bottom wall204aof the ratchet204integral to the dose selection knob104. The bayonet connection between the ratchet204and the plunger rod108secures the power spring110in compression until the first dose is triggered. Any buckling of the power spring110is prevented thanks to its being arranged between the part108bof the plunger rod108and the support rod111.

The needle shield107bis secured to the syringe107and the needle shield remover145is secured to the needle shield107bthrough the insert146. The cap102is secured to the chassis100aand the sliding sheath130is prevented from moving axially because the drive pins132of the drive legs131abut against the respective lock-out edges129aof the cam sleeve123.

The dose selection knob104is connected to the outer body100as the sleeve100bis held captive between the knob104and the ratchet204integral to each other. Once assembled, the assembly formed by the dose selection knob104and the ratchet204cannot move axially, but can only rotate in one direction. The rotation direction is indicated by the reference marks on the outer body100: in other words, indicator105starts from the position1, rotates to the position1when the first dose is selected, and then rotates to the position2when the second dose is selected.

In the stored state the device is “locked-out”, i.e. the sliding sheath130cannot move in the outer body100, because the drive legs131of the sliding sheath130abut against the axial lock-out edges129aof the cam sleeve123. This condition is shown in particular inFIGS. 42e43a. On selecting the first dose (position1), the device is unlocked as shown in43b. As a matter of fact, by rotating the dose selection knob104the cam sleeve123is pushed in the same direction by the feet121of the ratchet204that abut on the leading edge122aof the grooves122of the cam sleeve123with their turning legs121a. The dose selection knob104cannot rotate past the position1until the first dose is delivered, because the drive pins132of the legs131abut on the stop edge128cof the cam track128on the cam sleeve123. The slidable sheath130is prevented from rotating because the legs131can only move axially forward and backward in the axial guide slots147on the chassis100a.

It must be pointed out that, as shown inFIG. 43a, in the rest position there is a design clearance Y between the trigger cam track127aand the respective radial peg115. A design clearance Z of lower extent exists between the turning legs121aof the feet121of the ratchet204and the respective leading edges122aof the grooves122of the cam sleeve123. When the user rotates the dose selection knob104, at the beginning he/she must overcome the resistance opposed by the stop rib120of the sleeve100babutting against the protrusion120aof the ratchet204(FIG. 43c). The small rotation necessary to do this, brings the turning legs121ainto contact to the leading edges122a, while a residual clearance still exists between the trigger cam track127aand the respective radial peg115.

First the user must slide back and remove the end cap102in order to expose the needle shield remover145. The end cap102will have to be replaced once the first dose is delivered when the device is not in use. The end cap102protects the drug from light exposure and prevents particulates from coming into contact with the front end103of the device.

To perform the first injection the user must remove the needle shield remover145. In this way the insert146and the needle shield107bare also removed leaving the needle107auncovered, but still sub-flush of the front end103and not readily visible to the user. To unlock the device and select the delivery of the first dose, the user rotates the dose selection knob104from position0(stored state) to position1(first dose armed).

The rotation of the dose selection knob104from position0to position1causes the rotation of the cam sleeve123, whereby the axial lock-out edges129aof the cantilever legs129displace relative to the drive pins132of the legs131of the slidable sheath130, which abut against the stop edge128cto prevent the knob104to further rotate until the first dose is delivered and are aligned to the upward portions128aof the cam track128free to move along them (seeFIGS. 43band45). The user recognizes the end of rotation to position1when he/she sees that the indicator105lines up with the position1marker, feels the increase in rotation resistance of the drive pins132contacting the cam track128and also hears the “click” as produced by the ratchet legs118clicking as a result of their falling off the relevant ribs119. The contrast between the legs118and the relevant ribs119prevents the reverse rotation of the knob104, whereas any forward rotation is hindered by the abutment between the stop rib120of the sleeve100band the protrusion120aof the ratchet204(FIG. 43c)

The device is triggered by the user pressing the front end103of the sliding sheath130against the injection site by keeping the device through the outer body100. The movement of the sliding sheath130in the outer body100finds a resistance due to the contrast between the flexible tines141of the sliding sheath130and the inner protrusions141aof the chassis100a. Due to their flexibility and the inclined contact surface, the flexible tines141depress and fully deflect inwardly while overcoming the protrusions141ato allow the passage of the sliding sheath130which can slide in the chassis100aleaving the needle107ato project from its front end103, so that the needle can penetrate in the injection site. The motion subsequently created by the release of the flexible tines141helps to quickly insert the needle107ain the injection siteFIG. 44a).

The axial movement of the sliding sheath130in the outer body100causes the rotation of the cam sleeve123and the latter would frictionally draw into rotation also the ratchet204and the dose selection knob104. To prevent the knob104from rotating during the step of first dose delivery, between the ratchet204and the sleeve100btemporary stop means are provided that mutually engage when the free ends of the ratchet legs118fall off the ribs119of the sleeve100b. In the present embodiment the temporary stop means comprise the stop ribs120of the sleeve100babutting on the corresponding protrusions120aof the ratchet204, as shown inFIG. 43c. The rotational force acting on the ratchet204upon triggering is less than the retention force provided by the stop ribs120. However, the rotational force that the user is able to provide is much larger than that of stop ribs120. Therefore, the user can overcome the rib force and rotate the knob104to arm the device for the second dose.

The rotation of the cam sleeve123causes the plunger rod108to rotate because of its radial pegs115, engaged in the corresponding axial channels127are pushed by the trigger cam track127a. The angular displacement of the plunger rod108causes the bayonet connection to decouple as the actuation slots113of the plunger rod108slide on the respective retention feet112of the ratchet204until the slots113get free of the feet112. This sequence is shown inFIG. 49. At this point the power spring110, no longer retained by the bayonet connection, applies its elastic thrust on the plunger rod108which moves forward in the cam sleeve123until radial pegs115, sliding in the axial channels127, lean on the location face144aof the stepped guide144of the sleeve100b(seeFIG. 47a). The resulting axial sliding of the plunger rod108causes the delivery of the first dose.

After delivery of the first dose, the user removes the device from the injection site and the needle107awithdraws therefrom. The return spring135is no longer hindered by the forced contact between the front end103and the injection site and thereby pushes the slidable sheath130axially forward thus resheathing the needle. At the same time the drive pins132of the drive legs131slide down in the downward portion128bof the cam track128depressing inwardly the cantilever legs129until the device returns to a “lock-out” condition, wherein the drive pins132contact the free end129aof the cantilever legs129and the assembly clips139of the sliding sheath130again engage with end stops140ain the axial guides136of the chassis100a, as shown inFIG. 46a

The needle107ais again not accessible as being covered by the sliding sheath130, which, in this state, is prevented from sliding until the user rotates the dose selection knob104to position2. The user then recaps the device. The end cap102snap fits with outer body100to securely hold on the chassis100a.

If the delivery of a second dose is necessary, the user un-caps the device to enable access to the sliding sheath130. To unlock the device the user must rotate the dose selection knob104from the position1(first dose armed position) to the position2(second dose armed position) (seeFIGS. 46aand46b).

To that end the user must overcome the reaction of the stop ribs120of the sleeve100bon the protrusions120aof the ratchet204. Deflection of protrusions120aallows the knob104to rotate. The feet121of the ratchet204take up the free travel on grooves122of the cam sleeve123until the turning legs121areach the leading edges122ato rotate the cam sleeve123to position2, as shown inFIGS. 46aand46b. In this case too, reaching the position2is announced by a click as for the position1.

The rotation of the cam sleeve123causes the device to unlock because the drive pins132of the drive legs131of the sliding sheath130line up the upward portion128aof the cam track128while contacting the stop edge128cto prevent a further rotation of the knob104once the position2is reached. The reverse rotation of the dose selection knob104is prevented by the ratchet legs118snap abutting on the protrusions119of the sleeve100b. The rotation of the cam sleeve123also causes the repositioning of the radial pegs115from the outlet of the axial channel127within the window126to the opposite axial side126c, while their position on the location face144aof the stepped guide144is unchanged (FIGS. 46band47a).

The device is triggered for the delivery of the second dose by the user pressing the front end103of the sliding sheath130against the injection site by keeping the device through the outer body100. The movement of the sliding sheath130in the chassis100acaused by the drive pins132of the legs131pushing against the upward track128afinds a resistance due to the contrast between the flexible tines141of the sliding sheath130and the inner protrusions141aof the chassis100a. Due to their flexibility and the inclined contact surface, the flexible tines141depress and fully deflect inwardly overcoming the protrusions141ato allow the passage of the sliding sheath130which can slide in the chassis100aleaving the needle107ato project from the front end103, so that the needle can penetrate in the injection site. The motion subsequently created by the release of the flexible tines141helps to quickly insert the needle107ainto the injection site. The thrust produced by the drive pins132does not cause any significant axial movement of the cam sleeve123, because its positioning flange124axially abuts against the rim125of the sleeve100b.

To prevent any further rotation of the knob104, once the position2is reached, at the end of the following rotation of the cam sleeve123the free end of the ratchet legs118abut on the stop ribs119thus preventing the reverse rotation of the knob104, whereas the forward rotation is hindered by the contrast between the stop rib120of the sleeve100band the protrusion120aof the ratchet204(FIG. 43c).

While the cam sleeve123keeps on rotating, the radial pegs115slide on the location face144aof the stepped guide144as pushed by the axial side126cof the window126until they reach the end of said face, from which they fall off the stop ledge144cof the stepped guide144due to the action of the power spring110. This operating sequence is shown inFIGS. 47ato47c. The resulting axial sliding of the plunger rod108causes the second dose to be delivered.

After delivery of the second dose, the user removes the device from the injection site and the needle107awithdraws therefrom. The return spring135is no longer hindered by the forced contact between the front end103and the injection site and thereby pushes the slidable sheath130axially forward thus resheathing the needle. At the same time the drive pins132of the drive legs131slide down in the downward track128bof the drive cam means128and depress inwardly the cantilever legs129until the device returns to a “lock-out” condition, wherein the drive pins132contact the free end129aof the cantilever legs129and the assembly clips139of the sliding sheath130again engage with end stops140ain the axial guides136of the chassis100a, as at the end of the delivery of the first dose. The needle107ais again not accessible as being covered by the sliding sheath130. The user then recaps the device with its end cap102before disposal/handling to paramedic.

The autoinjector device according to the invention is suitable to the delivery of medicaments in solution, especially epinephrine (also known as adrenaline).

In particular, the doses of epinephrine that can be administered with the device of the invention are preferably in the range of 0.05 mg to 0.5 mg for each delivered dose (from 0.1 mg to 1 mg if two doses are considered).

The above doses are based on a concentration of the epinephrine solution preferably ranging from 0.05 mg/ml to 0.5 mg/ml, the concentrations 0.05 mg/ml, 0.1 mg/ml, 0.16 mg/ml, 0.3 mg/ml and 0.5 mg/ml being particularly preferred.