Drive mechanism for a drug injection device comprising adhesive to block drive at end of device life to prevent reuse

Abstract

A drive mechanism of a drug delivery device is presented having, a piston rod to operably engage with a piston of a cartridge containing a medicament, a first functional component and a second functional component whose position or orientation relative to each other is unambiguously correlated to a predefined axial position of the piston rod, wherein the first and/or the second functional component comprise at least one engaging portion to inseparably and to adhesively engage the first and the second functional component with each other for rendering the drive mechanism inoperable when the predefined axial position of the piston rod has been reached.

Claims

1. A drive mechanism of a drug delivery device, comprising: a piston rod to operably engage with a piston of a cartridge containing a medicament; a first functional component; and a second functional component, where position or orientation of the first functional component and the second functional component relative to each other is unambiguously correlated to a predefined axial position of the piston rod, wherein at least one of the first functional component and the second functional component comprises at least one engaging portion to inseparably and to adhesively engage the first functional component and the second functional component with each other for rendering the drive mechanism inoperable when the predefined axial position of the piston rod has been reached, wherein the at least one engaging portion comprises a pressure sensitive adhesive, and wherein the first functional component comprises the piston rod which is adapted to exert distally directed thrust to the piston of the cartridge, wherein the second functional component comprises an insert having a through opening through which the piston rod extends, wherein the piston rod comprises an outer thread engaged with an inner thread of the through opening, and wherein the at least one engaging portion is arranged at a proximal end of the piston rod.

2. The drive mechanism according to claim 1, wherein the engaging portion comprises adhesive microspheres adapted to rupture when at least one of the engaging portion of the first functional component and the second functional component gets in mechanical contact with the other one of the first functional component and the second functional component.

3. The drive mechanism according to claim 1, wherein the engaging portion comprises a lacquer containing rupturing adhesive microspheres.

4. A drug delivery device for dispensing a dose of a medicament, comprising: xa housing, a cartridge holder interconnected with the housing, and a cartridge at least partially filled with the medicament and being arranged in the cartridge holder, and a drive mechanism assembled inside the housing, the drive mechanism comprising: a piston rod to operably engage with a piston of the cartridge containing the medicament; a first functional component; and a second functional component, where position or orientation of the first functional component and the second functional component relative to each other is unambiguously correlated to a predefined axial position of the piston rod, wherein at least one of the first functional component and the second functional component comprises at least one engaging portion to inseparably and to adhesively engage the first functional component and the second functional component with each other for rendering the drive mechanism inoperable when the predefined axial position of the piston rod has been reached, wherein the at least one engaging portion comprises a pressure sensitive adhesive, and wherein the first functional component comprises the piston rod which is adapted to exert distally directed thrust to the piston of the cartridge, wherein the second functional component comprises an insert having a through opening through which the piston rod extends, wherein the piston rod comprises an outer thread engaged with an inner thread of the through opening, and wherein the at least one engaging portion is arranged at a proximal end of the piston rod.

5. A drive mechanism of a drug delivery device, comprising: a piston rod to operably engage with a piston of a cartridge containing a medicament; a first functional component; and a second functional component, where position or orientation of the first functional component and the second functional component relative to each other is unambiguously correlated to a predefined axial position of the piston rod, wherein at least one of the first functional component and the second functional component comprises at least one engaging portion to inseparably and to adhesively engage the first functional component and the second functional component with each other for rendering the drive mechanism inoperable when the predefined axial position of the piston rod has been reached, wherein the at least one engaging portion comprises a pressure sensitive adhesive, and wherein the first functional component comprises a nut threadedly engaged with the second functional component comprising a drive sleeve, wherein the nut is axially slidably engaged with a housing and rotationally locked to the housing and wherein the nut is further adapted to at least one of axially and tangentially abut against a flange portion of the drive sleeve when the predefined axial position of the piston rod has been reached, and wherein at least one of the nut and the flange portion comprise the at least one engaging portion to inseparably engage the nut and the flange portion when getting in mutual contact.

6. A drug delivery device for dispensing a dose of a medicament, comprising: a housing, a cartridge holder interconnected with the housing, and a cartridge at least partially filled with the medicament and being arranged in the cartridge holder, and a drive mechanism assembled inside the housing, the drive mechanism comprising: a piston rod to operably engage with a piston of the cartridge containing the medicament; a first functional component; and a second functional component, where position or orientation of the first functional component and the second functional component relative to each other is unambiguously correlated to a predefined axial position of the piston rod, wherein at least one of the first functional component and the second functional component comprises at least one engaging portion to inseparably and to adhesively engage the first functional component and the second functional component with each other for rendering the drive mechanism inoperable when the predefined axial position of the piston rod has been reached, wherein the at least one engaging portion comprises a pressure sensitive adhesive, and wherein the first functional component comprises a nut threadedly engaged with the second functional component comprising a drive sleeve, wherein the nut is axially slidably engaged with a housing and rotationally locked to the housing and wherein the nut is further adapted to at least one of axially and tangentially abut against a flange portion of the drive sleeve when the predefined axial position of the piston rod has been reached, and wherein at least one of the nut and the flange portion comprise the at least one engaging portion to inseparably engage the nut and the flange portion when getting in mutual contact.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, preferred embodiments of the invention will be described by making reference to the drawings, in which:

(2) FIG. 1 schematically illustrates a perspective exploded view of a pen-type injector,

(3) FIG. 2 shows a cross section through a typical pen-type injector having a piston rod with an engaging portion,

(4) FIG. 3 schematically illustrates a partial cross section through another drive mechanism of a drug delivery device in an initial configuration,

(5) FIG. 4 shows the drive mechanism according to FIG. 3 after setting of a dose and

(6) FIG. 5 shows another cross-sectional view of the drive mechanism according to FIGS. 3 and 4.

DETAILED DESCRIPTION

(7) The drug delivery device 10 as illustrated in an exploded view in FIG. 1 comprises a proximal or main housing 14 to accommodate a drive mechanism 11. The drive mechanism 11 inter alia comprises a threaded piston rod 24 which is adapted to operably engage with a piston 20 of a cartridge 18 as illustrated in the cross-sectional view according to FIG. 2. The drive mechanism 11 further comprises a dose dial 15 and a dose button 17 at its proximal end by way of which a dose of the medicament can be set and dispensed, respectively.

(8) In distal direction 1, the housing 14 comprises a receptacle 30 adapted to receive an insert portion 32 of a cartridge holder 26. The cartridge holder 26 featuring an inspection window 27 allowing to visually control the filling level of the vitreous cartridge 18 is connected with the housing 14 in an interleaved or nested configuration as shown in FIG. 2. The cartridge holder 26 further comprises radially protruding portions 28 by way of which a protective cap 12 can be releasably mounted on the cartridge holder 26. At its distal or dispensing end, the cartridge holder 26 comprises a threaded socket 25 which is adapted to removably receive a correspondingly threaded needle hub having a double tipped needle to penetrate a distal septum of the cartridge 18 for injecting a dose of the medicament 19, e.g. into biological tissue.

(9) As illustrated in the cross section according to FIG. 2, the proximal housing 14 comprises a radially inwardly protruding flange-like insert 16 featuring a central through opening 34 that engages with the outer thread 36 of the piston rod 24. At its distal end, the piston rod 24 comprises a rotatable pressure piece 22 which is adapted to abut against a proximal end face of the piston 20 and to exert distally directed pressure thereto. A distally directed forward movement of the piston rod 24 may be induced by a rotative movement of the piston rod 24. Due to its threaded engagement with the through opening 34 of the insert 16, the piston rod 24 advances in distal direction 1 when it becomes subject to a rotational movement.

(10) It is particularly intended, that the drug delivery device 10 is of disposable type. In order to provide an anti-counterfeiting means, the piston rod 24 as a first functional component of the drive mechanism 11 is provided with an engaging portion 40 near an end facing in proximal direction 2. The engaging portion 40 may comprise a lacquer containing rupturing adhesive microspheres. As indicated in FIG. 2, the engaging portion 40 is preferably provided in the root of the thread 36 of the piston rod 24. Once the piston rod 24 advances in distal direction 1, also its proximal end shifts towards the insert 16. When a final or last dose configuration of the drive mechanism is reached, in which the piston rod 24 almost completely extends in distal direction 1 through the through opening 34 of the insert 16, the engaging portion 40 gets in direct mechanical contact with the inner thread of the through opening 34. Then, the pressure sensitive adhesive will be released from the ruptured microspheres and will inseparably bond together the piston rod 24 and the insert 16.

(11) Since the insert as the second functional component of the drive mechanism is integrally formed with the housing 14, the piston rod 24 can be substantially bonded and interlocked with the housing 14 once a last dose configuration has been reached. As soon as the engaging portion 40 near a proximal end of the piston rod 24 engages with the threaded through opening 34 of the insert 16, the adhesive is released, thereby also contaminating the inner thread of the through opening 34. Even with a slowly curing adhesive or with a non-curing but rather greasy adhesive, a substantial increase of frictional forces between piston rod 24 and insert 16 can be established which may be sufficient to render the drive mechanism substantially inoperable.

(12) In the various cross-sectional illustrations of FIGS. 3, 4 and 5, another drive mechanism 50 is illustrated providing two different first and second functional components 58, 56 that are applicable to immobilize the drive mechanism and whose relative position is directly correlated with the axial position of the piston 20 inside the cartridge 18.

(13) Generally, identical or similar components already describe in connection with the drug delivery device 10 as shown in FIGS. 1 and 2 are provided with the same reference numerals here.

(14) The drive mechanism 50 as shown in FIGS. 3, 4 and 5 generally resembles the drive mechanism explicitly illustrated and described in WO 2004/078241 A1, which is hereby incorporated by reference. As shown in FIGS. 3 to 5, a generally cylindrical drive sleeve 52 extends about the piston rod 24. This drive sleeve 52 is provided with a first radially extending flange 54 at a distal end and with a second radially extending flange spaced a distance along the drive sleeve 52 from the first flange 54. Between the two flanges 54, 56 an outer thread 55 is provided that mates with a corresponding inner thread of a nut 58.

(15) In radial direction the nut 58 is located between the drive sleeve 52 and the housing 14. The nut 58 is further disposed between the first flange 54 and the second flange 56. The outer surface of the nut 58 and an internal surface of the housing 14 are keyed together by 18 way of splines which are not explicitly illustrated here. By means of this keyed engagement, relative rotation between the nut 58 and the housing 14 is prevented while a relative longitudinal or axial movement of the nut 58 relative to the housing 14 is still allowed.

(16) As shown in FIGS. 3 and 5, where the drive mechanism 50 and its piston rod 24 is in an initial configuration, the nut 58 is located near the first flange 54. By twisting or rotating a dose dial 15 at the proximal end of the drug delivery device, the drive sleeve 52 reaches a proximally extending configuration as illustrated in FIG. 4. As further shown in FIG. 5, the drive sleeve 52 is threadedly engaged with a second, proximally located thread 62 of the piston rod 24 by means of an inner thread 60. The piston 24 further comprises a first thread 36 which is threadedly engaged with the insert 16. Due to the threaded engagement of drive sleeve 52 and piston rod 24 and due to at least one clutch mechanism not further illustrated here, a rotation of the dose dial 15 leads to a screw-like proximally directed displacement of the drive sleeve 52 as illustrated in FIG. 4.

(17) Due to the threaded engagement of nut 58 and drive sleeve 52 and due to the rotational interlock of the nut 58 with regard to the housing 14, a rotational displacement of the drive sleeve comes along with an axial displacement of the nut 58 relative to the drive sleeve 52 as can be seen in FIG. 4. During dose dispensing, the drive sleeve 52 is only subject to a translational and distally directed displacement thereby inducing a rotational movement to the piston rod 24, which in turn experiences a distally directed displacement due to its threaded engagement with the insert 16 of the housing 14.

(18) During a dose dispensing procedure, the relative position of the nut 58 with respect to the drive sleeve 52 and its flange portions 54, 56 will not vary. However, during a subsequent dose setting procedure, the nut 58 will further move towards the second flange 56.

(19) In effect, the axial position of the nut 58 relative to the first flange 54 or to the second flange 56 is directly indicative of the axial position and configuration of the piston rod 24 and hence of the axial position of the piston 20 in the cartridge 18. Once a final dose dispensing configuration is reached, the nut 58 axially abuts with the second flange 56 thereby inhibiting a further rotation of the drive sleeve 52.

(20) Consequently, and in the context of the present invention the nut 58 serves as a first functional component of the drive mechanism 50 whereas the flange 56 acts as the second functional component of the drive mechanism.

(21) It is of particular benefit to provide an engaging portion 42 between the nut 58 and the second flange 56. For instance and as indicated in FIG. 5, a proximal face of the nut 58 may be provided with an engaging portion 42 or with a comparable engaging member which serves to establish an inseparable connection of nut 58 and second flange 56 once a last dose configuration has been reached.

(22) Alternatively or additionally, also the distal face of the flange 56 may be correspondingly provided with an engaging portion 42 or with an engaging member in order to establish an adhesive, frictional or positive engagement between the nut 58 and the flange portion 56 once these two functional components get in direct mutual contact. Also here, the respective surfaces of the nut 58 and the second flange 56 that face towards each other may be coated or applied with a lacquer containing rupturing adhesive microspheres.

(23) Alternatively, also other types of adhesive materials may be applied to the nut 58 and/or to the flange 56. It is also conceivable to equip the nut 58 and the flange 56 with inseparable engaging positive interlock members not particularly illustrated here, by way of which an inseparable mutual engagement of nut 58 and flange 56 can be equally attained.

(24) Once the nut 58 is inseparably attached to the flange 56, neither a clockwise nor a counter-clockwise rotation of the drive sleeve 52 is possible and the drive mechanism 50 is rendered substantially inoperable. It is only optionally, that the piston rod 24 as shown in FIGS. 3-5 comprises a pressure sensitive adhesive 40 near its proximal end.