FR2969499A3 - SELF-INJECTION - Google Patents

Abstract

Injection device, characterized in that it comprises a body (10, 12) receiving a syringe (13) or a cartridge having a needle at its front end, a removable needle protector (15) releasably fixed said syringe or cartridge and protecting said needle prior to use, a cap (14) attached to the front end of said body and which is removable forwards, said cap having a passage (116) therethrough for receiving said removable needle shield and having at least one withdrawal surface (120, 164) adjacent to said passage for engaging said needle shield, whereby removal of said cap removes said needle shield, said cap comprising in addition to at least one retaining surface (122) for retaining said needle shield at least partially within said passage (116) when said cap is removed.

Description

SELF-INJECTION

The present invention relates to auto-injectors.

Many auto-injectors have a removable front cap that, when removed, removes a needle protector from the front end of the syringe to expose the needle and prepare it for injection. It is desirable to ensure that the front cap can be manufactured using normal injection molding techniques without the need for extremely complicated mechanisms. However, it is also desirable to ensure that when the front cap is removed, the needle protector is retained by the cap 15 and does not fall. In practical terms, given the usual method of assembling such auto-injectors, the cap needs to have some form of surface to capture the needle protector so that it is pulled out of the syringe at the moment and some form of needle shield retaining means in the cap. Foreseeing these two shapes on an inward facing surface can be problematic. Accordingly, in one aspect, the present invention provides an injection device comprising a body receiving a syringe or cartridge having a needle at its forward end, a removable needle protector releasably attached to said syringe or to said cartridge and protecting said needle prior to use, a cap attached to the front end of said body and which is removable forwards, said cap having a passage therethrough for receiving said removable needle protector and having at least a withdrawal surface adjacent to said passage for engaging said needle protector, whereby removal of said cap removes said needle protector, said cap further comprising at least one retaining surface for retaining said protector; needle at least partially within said passage when said cap is removed. Preferably, the or each retaining surface is disposed to retain the needle protector fully within said passage. Preferably, the or each withdrawal surface comprises at least two opposing ribs engaging opposite sides of said needle shield. Preferably, the or each retaining surface comprises at least two opposing retaining protrusions. Preferably, said withdrawal surface and said retaining surface are oriented substantially perpendicular to each other and relative to the axis of said passage and, in particular, said withdrawal ribs and said retaining projections are oriented substantially perpendicular to each other and to the axis of said passage. Although the invention has been described above, it extends to any inventive combination or sub-combination of new features set forth above, or in the following description. The invention can be realized in various ways and an embodiment thereof, with various modifications, will now be described by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a perspective view of an auto-injector according to an embodiment of the present invention with the first front cap removed prior to injection, but prior to removal of the second rear cap;

Figure 2 is a view of the autoinjector with the rear assembly and the front assembly separated before a syringe is loaded into the front assembly and they are snapped together;

Figure 3 is an exploded view of the front assembly;

Figure 4 is an exploded view of the rear assembly;

Figure 5 is an enlarged view of the syringe holder; Figure 6 is an enlarged view of the needle sleeve;

Figure 7 is an enlarged view of the front body housing;

Figure 8 is an enlarged view of the spring guide;

Figure 9 is a view showing the spring guide 20 and the syringe holder snapped together;

Figure 10 is an enlarged view of the front cap / needle shield removal member;

Figure 11 is a horizontal sectional view taken through the cap of Figure 10 on the major axis thereof;

Figure 12 is an enlarged view of the trigger button;

Figure 13 is an enlarged view of the piston;

Figures 14 (a) and (b) are cross-sectional views of the major and minor planes, respectively, of the auto-injector when in its state prior to use;

Figures 15 (a) and (b) are cross-sectional views of the major and minor planes, respectively, of the autoinjector after use;

Figures 16 (a) and (b) are detail views of the front end of the device showing the forwardly convex skin contact surface;

Figure 17 is a perspective view of a first modified form of interface between the syringe, the syringe holder, the needle protector and the front cap;

Figures 18 (a) and (b) are sectional views through the arrangement of Figure 17 with the syringe in position; Figs. 19 (a) and (b) are sectional views through the arrangement of Fig. 17 with the syringe back;

Figure 20 is a perspective view of a second modified form of interface between the syringe, syringe holder, needle protector and the front cap;

Figures 21 (a) and (b) are sectional views through the arrangement of Figure 20 with the syringe in position, and

Figures 22 (a) and (b) are sectional views through the arrangement of Figure 20 with the syringe removed.

The embodiment of the auto-injector illustrated in the Figures and described below is designed to automatically inject a selected dose of drug when it is offered an injection site and is triggered. Referring first to Figures 1 and 2, it can be seen that the autoinjector comprises a rear assembly 10 containing a drive mechanism and a front assembly 12 for receiving a syringe 13 containing a drug. The front and rear assemblies are snapped together during manufacture. On the front end of the device is a removable cap 14 which also serves as a needle protector removal member as will be described below. On the rear end of the rear assembly is a rear cap 16 which includes a safety pin which prevents premature release of the drive mechanism, the rear cap also covering the release button 18. Referring to FIG. now in Figure 3, it can be seen that the front assembly 12 includes an outer body housing 20 of a generally transparent plastic material defining opposed integral viewing windows 22 through which the syringe can be viewed when the device has been assembled. The windows allow the entire dose volume of the syringe to be viewed. Except for the transparent plastic of the windows 22, the body casing 20 may be opaque. Providing a transparent window element, instead of the current arrangement of an open slot or slot, has the advantage of preventing external access to the syringe. In addition, providing twin sheath springs spaced apart on each side of the longitudinal axis of the device means that the entire length of the dose volume is clearly visible without being hidden by any springs, etc.

Slidably mounted within the housing 20 is a needle sleeve 24 having a chamfered, conical and / or curved convexly curved front face 26 having a central opening 28 therein for providing a domed configuration to the housing. before, through which the needle of the syringe can protrude during the injection. The sleeve 24 comprises two rearwardly extending arms 30, of arcuate cross-section, extending rearwardly from a front tubular section 32. Slidingly coupled to the needle sleeve is a syringe 34 having a front tubular portion 36 telescopically slidable within the tubular portion 36 of the needle sheath 24. Extend rearwardly from the tubular portion 36 of the syringe holder 34 two arms 38 having opposed internal concave surfaces 40 for slidably receiving the body of a syringe and external concave surfaces 42 for defining, with the convex inner arcuate surfaces on the arms 30 of the needle sleeve 24, cylindrical receiving spaces for a pair of leaf springs 44. A spring guide 46 has two forwardly extending fingers 48 which pass through the center of a respective spring 44. The mistletoe The springs 46 have an overmolded coating 50 surrounding a circular opening 52 through which a syringe is passed. The coating acts as a shock absorber for the syringe. The spring guide 46 is snapped with the rear end of the syringe holder 34, as will be described below. The spring guide 46 has a rearwardly extending tubular portion, in a side wall of which there is a recess 53 for captively receiving a disk magnet 54.

Referring now to Figure 4, it can be seen that the rear assembly includes a rear body housing 56 in which is received the main drive spring 58 which acts on the rear end of a piston 60 The piston has a front end 62 for engaging the piston 11 within a syringe and an overmolded colored indicator strip 64. At the rear of the indicator strip 64 is a transverse passage 66 in which which is mounted, for a transverse displacement, a ball magnet 68. At the rear of the passage 66 is provided a recess 70 which receives a ferromagnetic stop ball 72 which is fixedly arranged on the longitudinal axis of the piston 60 The piston 60 has two slotted boom members 74 extending rearward, with barbs 76 at the rear ends bearing around the edge of an annular catching surface 77 in the interior of the housing. rear body 56 (see Figures 14 and 15) for locking the piston in an armed position, with the main spring 58 compressed. The auto-injector is of a modular structure designed to allow all but two components to be the same for auto-injectors with syringes of three different filling volumes. The shape and size of the syringe itself are standard; only the filling volume is different.

The two components that vary are the rear body housing 10 and the piston 60. The front end of the rear body housing 52 contains opposite cutouts or slots 78 which are of variable length depending on the filling volume contained in the syringe. The axial length of the slots 78 in the rear body housing 56 is proportional to the filling volume. In addition, the position of the indicator moves the same distance, so that it arrives at the same location relative to the body at the end of the piston stroke. The piston is also modified according to the filling volume of the syringe to position the passage 66, containing a magnet, so that, at the end of its forward stroke, it reaches the same axial position relative to the housing rear body 56 for each filling volume. In other words, the piston 60 and the axial length of the slots 78 are designed such that, for each of the plurality of filling volumes, the user, before use, will see in the viewing window 22 just the length of the syringe containing the dose, with the window which is framed at the rear end by the slots 78. After the dose has been administered, the indicator will be in the same forward position for each filling volume. We will describe in more detail, with reference now to Figures 5 to 9, the assembly of the main components of the front assembly. The syringe holder 34 has twin linear ribs 82 disposed on each side of the front tubular portion 36. The ribs 82 extend into respective channels 84 on the inside of the tubular portion 32 of the needle sheath.

Immediately behind each rib 82 is an active hinge 85 from which extends an elastic finger 86 having a barb 88 having a front surface inclined rearwardly. When the syringe holder is telescopically assembled into the needle sleeve 24, the barbs 88 protrude through slots 90 in the sleeve 24 (see Figure 6) to limit the forward movement of the sleeve 24 by relative to the syringe holder 34 when the rear ends of the slots 90 come into contact with the barbs 88. The rearward movement of the sleeve 24 relative to the syringe cap is limited by a rear shoulder 92 of the tubular portion of the barrel. the needle, abutting against a forwardly facing shoulder 94 extending from the rear of the tubular portion 36 of the syringe holder 34. At the rear of the barbs 88 on the syringe holder are two 96 ramp surfaces facing backwards. At its rear end, the syringe holder has four lugs 98 which, when the device is assembled, extend into respective slots 100 in the front body portion 20 to limit a linear movement of the syringe holder relative to the portion. 20. The spring guide 46 is snapped onto the rear of the syringe holder as shown in FIG. 8.

This has snap tabs 102 that snap around walls 104 on the rear end of the syringe holder. The tabs also form a bearing surface for the springs 44 of the sheath, the fingers 48 of the spring guide passing through the center thereof. The forward ends of the barrel springs rest on protruding fingers 106 toward the rear of the needle sheath arms 24. At about two-thirds of the way back from the front of each slot 90 are two barbs 108 having inclined front surfaces. Behind each slot 90, on an active hinge, is a rear barb 110, also having an inclined front surface. The barbs 108 and 110 cooperate with respective opposing barbs 112 at about one third of the way forward along the length of the front body housing 20, on the inner walls thereof. The arrangement of the barbs in the position before use can be clearly seen in Figures 14 and 15. In the position before use, the barbs 108 on the needle sleeve cooperate with the barbs 112 on the front body housing to prevent the rearward movement of the needle sleeve 24. The front faces of the barbs 88 on the syringe holder also cooperate with the barbs 112 on the front body housing to prevent forward movement of the front syringe holder 34 and during the removal of the front cap 14. The removal of the cap removes a resistance acting on the barbs 88 which initially prevents the movement of the barbs inwards, so that when triggered, the force of the driving spring causes the barbs 88 to move by cam effect in front of the barbs 112 on the front body housing. During the operation of the device, when triggered, with the needle sleeve 24 held against a forward movement by its contact with the skin around the injection site, the subset consisting of the syringe 13 and the syringe holder 34 is moved forwards, with respect to the front casing, to a limit position defined by the tabs 98 reaching the front ends of the slots 100.

After the injection is complete, the needle sheath 24 moves forward as the skin contact pressure is released from the surface 28 when the device is released from the skin by lifting. This allows the needle sleeve to move forward under the influence of the barrel springs 46, so that the rear barbs 110 move forward and snap in front of the barbs 112 on the front casing. 20 to prevent retraction once the needle sleeve has been extended. The barbs 110 are held in this position by the underlying ramp surfaces 96 on the syringe holder 34. Referring now to Figures 10 and 11, it can be seen that the removable front cap 14 has opposed slots. 114 which align with the slots 78 on the rear body housing 56, to frame the window 22 in the front body housing 20 to allow visualization of the dose volume as described above. Referring more particularly to Figure 11, it can be seen that the cap is elliptical in outer section and has an inner central cylindrical portion 116 extending rearwardly from which two further fingers 118 of arcuate cross section disposed on the major axis of the ellipse. On the inner surface of the fingers, toward the rear ends, are respective inwardly facing barbed ribs 120 having sloped rear surfaces. As can be seen in Figures 14 and 15, the ribs 120 are designed to snap into a space formed between the front shoulder on the body of the syringe 13 and the back surface of the rigid needle protector 15 or in an opening of it. When the syringe 13 is loaded in the front assembly 12 (with the cap 14 fixed) during manufacture, the rigid needle protector 15 snaps in front of the ribs 120 so that they are housed behind the rear edge of the needle protector 15 (or a trailing edge of an opening in the needle protector), as shown. The front cap 14 also has twin shallow hollows 122 that releasably engage projections 124 on the outer surface of the front body housing when the cap is mounted (see Figures 14 and 15). When in the as delivered condition (Figure 14), the fingers 118 of the cap extend under the resilient fingers 86 on the syringe holder 34 and prevent them from flexing inwardly. In this state, the fingers 118 thus hold the elastic fingers 86 against an unlocking movement inwardly. The forward end of the cylindrical portion 116 of the cap 14 also has inward protrusions 123 aligned with the minor axis of the ellipse and which prevent forward movement of the rigid needle protector relative to the cap. In this way, when the front cap 14 is removed from the position shown in Fig. 15, the ribs 120 pull the rigid needle protector 15 to gently remove it from the front end of the syringe 13. In At the same time, the presence of the fingers 118 also temporarily locks the syringe holder 34 (and thus the syringe 13) against forward movement by locking the fingers 86 to a displacement. forward until the needle protector is out of the syringe to prevent the syringe from being pulled forward if there is a tight fit between the syringe and the needle protector. When the front cap is disengaged from the device, the needle protector 15 is captive in the cap 14, trapped by the ribs 120 and the inward protrusions 123. The orientation of the ribs 120 and protrusions inward 123 at 90 ° means that the open end cap can be injection molded into a simple injection mold having a drawer rather than requiring a more complex mold design. Referring to Figures 4, 12 and 15, it can be seen that the trigger button 18 is of elliptical shape having two slotted arrowhead lugs 125 aligned with the minor axis, which abut behind respective ribs on the inner rear surface of the rear housing portion 56 to retain the release button 18 on the back of the housing and limit a movement thereof backward. The inner rear surface of the trigger member has a trigger boss 126 which is of a diameter slightly smaller than the outer diameter of the slotted boom tips 74 on the rear of the piston 60, so that when the trigger button 18 is pressed forward from the position shown, the boss clamps the twin arrowheads 74 with each other to release the barbs 76 from the capture surface 77, to release the piston to moving forward. The release button 18 has an aperture 130 concentric with the boss 126, through which a safety pin 134 on the rear cap 16 passes to keep the slotted arrowheads apart. Two forwardly extending resilient biasing strips 134 are aligned with the major axis of the ellipse, which cooperate with respective biasing bearing surfaces 136 in the rear end of the rear housing 56, as shown on FIG. Figs. 14 (a) and 15 (a) to provide plastic surface contact to plastic with low friction sliding. The bearing surfaces 136 are shaped to provide a predetermined variation of the resistance force as a function of distance. The biasing strips cooperate with the curved rear portion of the bearing surfaces to provide a biasing force tending to return the button to its rearmost position as defined by the slotted arrowhead tabs. It is desirable to provide tactile resistance to movement and to require a displacement of a few millimeters before the trigger boss 126 releases the piston, to avoid premature triggering. A front portion of the bearing surfaces is of a shallower inclination and is designed to provide non-reversible resistance to movement after the device has been triggered, thereby trapping or jamming the trigger button into its most forward position. . This provides another useful visual clue to a user as to whether the device has been triggered or not. Of course, if necessary, the support surface may instead be designed to return the button to its original position after triggering.

The autoinjector as illustrated includes several safety features to prevent inadvertent tripping and to make the device safe after use. It is also highly desirable to resist or prevent disassembly of the device after use. It will be noted from the description and from Figure 2 above that the device is assembled by inserting a syringe into the syringe holder in the front assembly, and then snapping the front and rear assemblies together. the other. The snapping is effected by means of outwardly facing elastic tabs 138, 140 on the rear of the front body housing 20, which simultaneously bear in respective openings 142 in the rear body housing 56. A pair of tabs 138 is aligned with the minor axis and a pair 140 is aligned with the major axis of the device. It will be appreciated that it would be possible, with proper dexterity and strength, to exert pressure on the four legs 138, 140 by driving a tool through the recesses 142 from the outside and thereby disassembling the device. .

However, this is prevented in this embodiment by means of two fin formations 144 disposed on the piston 60, as can be seen in Figures 13 and 15 (b). The piston is designed such that once the device is triggered and the piston is in its position after firing, the fin formations 144 extend under the tabs 138 on the minor axis of the ellipse, as shown in Figure 15 (b), so as to resist bending thereof inward and prevent disassembly.

For use, the user removes the front cap 14 and the rear cap 16, thereby arming the device. The device is then offered the injection site to press the tapered or curved front face 24 of the needle sleeve 24 against the skin of the user. When ready, the release button 18 is pressed, which releases the piston 60 for forward movement under the action of the main drive spring 58. Initially, due to an elastic engagement finger 145 on the plunger, plunger, and syringe move one piece forward to extend the needle to penetrate the flesh, which movement continues until the tabs 98 on the syringe holder reach front end of the slots 100 on the front body housing, thereby introducing the syringe needle to the required depth. When stopping the movement of the syringe, the elastic engaging finger 145 flexes inwardly into the bore of the syringe and the plunger continues to move, driving the plunger 11 along the syringe barrel to expel dose. Alternatively, in other designs of the device, the elastic engagement finger may yield such that the piston begins to move in the syringe before the movement of the latter forward is stopped. In either of the designs, when the piston reaches its foremost position, the ball magnet 68, which until now was contained in the passage 66 on the center line of the piston by magnetic attraction to the stop ball 72 is attracted by the greater force provided by the disk magnet 54 held in the recess of the spring guide, accelerating towards the latter and striking the magnet and / or the guide springs to produce a loud audible click to indicate to the user that the injection is complete. The user then removes the device from its skin and the release of the pressure on the front end of the needle sleeve 24 means that it can now extend forward under the influence of twin sheath springs. to move forward to protect the needle. As it gets closer to its foremost position, the barbs 110 snap in front of the barbs 112 on the inside of the front casing 20, thus preventing a retraction of the needle sheath. Referring now to Figures 17 to 22, there are shown various interface arrangements between the front shoulder of the syringe, the syringe holder, the needle protector and the front cap. One of the difficulties encountered with an automatic auto-injector assembly is that the outer diameter of the needle protector is similar to that of the syringe. Accepted assembly methods require, once the syringe has been filled with medicine and the needle protector has been applied, that the needle protector is not removed during assembly. However, a common way of assembling auto-injectors is to first assemble the front assembly of a device and then slide it into the syringe forwards, as discussed above. In the past, these two factors combined meant that any limiting load transmitted by the syringe holder to the syringe had reacted on the syringe through the enlarged flange at the rear end of the syringe body, especially since the front end of the syringe holder should be large in diameter to allow the needle protector to pass through it during assembly. Our studies have indicated that it would be beneficial, instead, to react the limiting loads on the syringe through the front shoulder of the syringe, and this meant a radical re-design of the front end of the holder syringe and the associated region of the front cap. The embodiments illustrated below are designed so that the syringe holder has a charge-transmitting surface that engages the front shoulder of the syringe, but is designed to allow the needle protector to pass through the syringe holder. here, possibly with some elastic distortion. In addition to the significant constraints referred to above, another design constraint is that the front cap must be able to lock behind a surface on the needle protector, so that the needle protector may be detached from the needle by pulling to prepare the auto-injector for use. We have therefore designed appropriate contact surfaces on the front cap of the needle protector, which are supported close to the reaction surface on the syringe holder and in front of which the needle protector can be made to slide elastically. . Referring more particularly to FIGS. 17 to 19, it can be seen that the syringe holder 34 has support cups 160 in two parts, arcuate, turned towards each other, which cups have a rotated wall forward in the plane perpendicular to the axis of the device and a rear wall which is chamfered. The radius and chamfer of the arcuate portion 160 are carefully selected so that a syringe 13 having a needle protector 15 of a soft rubber-like shape (eg, silicone rubber) can be pushed toward the before such that an annular rib 162 can be pressed to pass the surface 160 (aided by the chamfer) but that the shoulder facing forwards on the front end of the body of the syringe 13 is retained by the -this. In this embodiment, the cylindrical portion of the front cap has two rearwardly extending fingers 118, as previously for the purposes described above. The cylindrical portion extends a little further back than in the arrangement of Figure 11 and a protector recess rib 164 abuts the arcuate surface 160. Their internal radial diameters are the same and the surface 160 thus also helps camming or guiding the annular rib 162 beyond the constriction, so that it can again expand when fully inserted, ready to be captured and removed from the syringe when the cap is removed. Two spaced ventral ribs 166 are provided to grip the needle protector 15 so that it does not fall off the cap when the cap is removed. Referring to Fig. 20, it can be seen that in this slightly modified option, instead of having a needle shield removal rib 164 which extends 360 °, the rib 164 is at the circumferentially interrupted place to form two arcuate portions which are substantially aligned with the portions 160. In this manner, there is an extension region formed by the spaces left between the portions 164 to allow orthogonal extension as and as the needle shield is squeezed by surfaces 160 during syringe loading into the front assembly. Further, in this modified arrangement, the needle protector is retained in the cap by means of two opposed tabs on the inside of the cylindrical portion 116 which cooperate with the annular rib 162.

Claims (5)

CLAIMS1 - Injection device, characterized in that it comprises a body (10, 12) receiving a syringe (13) or a cartridge having a needle at its front end, a removable needle protector (15) fixed by releasably to said syringe or said cartridge and protecting said needle prior to use, a cap (14) attached to the front end of said body and which is removable forwards, said cap having a passage (116) therethrough ci to receive said removable needle protector and having at least one withdrawal surface (120, 164) adjacent to said passage for engaging said needle protector, whereby removal of said cap removes said needle protector, said cap further comprising at least one retaining surface (122) for retaining said needle shield at least partially within said passage (116) when said cap is removed. 2 - Injection device according to claim 1, characterized in that the or each retaining surface is arranged to retain the needle protector entirely within said passage. 3 - Injection device according to claim 1 or 2, characterized in that the or each withdrawal surface comprises at least two opposite ribs engaging opposite sides of said needle protector. 4 - Injection device according to claim 3, characterized in that the or each retaining surface comprises at least two opposite retaining projections. 5 - Injection device according to any one of claims 1 to 4, characterized in that said withdrawal surface and said retaining surface are oriented substantially perpendicularly with respect to each other and with respect to the axis of said passage.