HK1138527B - Dosing and drive mechanism for drug delivery device - Google Patents

Description

Dosing and drive mechanism for a drug delivery device

Technical Field

The present invention relates to a drive mechanism suitable for use in a drug delivery device, in particular a pen-type injector, in which a plurality of pre-set doses of a medicinal product may be administered. In particular, the present invention relates to such a drug delivery device: wherein the medicament delivery device is actuatable by a user.

Background

Such a drug delivery device has the following applications: in which persons, i.e. patients, without formal medical training need to administer precise and predetermined doses of drugs, such as heparin or insulin. In particular, such a device has applications in which: wherein the drug is irregularly administered in a short or long term.

These circumstances place a lot of demands on such a drug delivery device. The device must be robust in construction while being easy to use in terms of handling of the components, understanding of its operation by the user, and delivering the required dose of medicament. Dose setting must be easy and unambiguous. When the device is disposable and not reusable, the device should be inexpensive to manufacture and easy to dispose of (preferably being suitable for recycling). To meet these requirements, the number of parts required to assemble the device and the number of types of materials that make up the device need to be kept to a minimum.

User operated drug delivery devices are well known in the medical field.

US 6048336 discloses an injection device wherein a pre-selected set dose of medicament to be administered is selected by means of a rotatable dosing element. Once the dose has been set, the end member is pulled axially away from the rest of the pen base until a stop is reached. The dose is dispensed by driving the end member axially towards the base of the pen, which in turn drives the inner plunger engaging member. Although this device provides a useful embodiment for administering a preset dose, the intuitiveness of setting the preset dose is not addressed because two actions need to be performed to prepare the device.

WO 2004/078239a1 teaches a medicament dispensing device having a rotary drive sleeve and a dose dial sleeve with a clutch element between the drive sleeve and the dose dial sleeve to enable independent rotation between the drive sleeve and the dose dial sleeve.

In WO 2003/020347a2 a medicament dispensing device is disclosed having an axially moving actuator which is pulled out of a device body to set a dose and pushed into the body to dispense the set dose, the medicament dispensing device having a clutch element with a number of prongs for selectively transmitting the movement of the actuator member to the drive member.

Surprisingly, it was found that the drive mechanism according to the invention without a clutch element provides a valuable technical alternative to drive mechanisms, wherein the force required for actuating the mechanism is reduced. This is achieved by introducing the piston rod defined in the present invention. Furthermore, the drive mechanism according to the present invention provides the advantage of intuitive and easy to use dose setting.

Disclosure of Invention

According to a first aspect of the present invention, there is provided a drive mechanism for a drug delivery device, comprising:

a housing having a helical thread, preferably an internal helical thread;

an actuation member that is non-rotatable relative to the housing;

a drive sleeve engaged with the housing;

a piston rod engaged with the drive sleeve and the housing;

it is characterized in that the preparation method is characterized in that,

a) when the actuation member is moved proximally relative to the housing, the drive sleeve rotates relative to the actuation member and moves proximally relative to the housing;

b) when the actuation member is moved distally relative to the housing, the drive sleeve is moved distally relative to the housing and prevented from rotating relative to the housing, and the piston rod is rotated relative to the housing, thereby transferring a force in a longitudinal direction towards the distal end of the drug delivery device.

In a preferred embodiment of the drive mechanism of the invention, the piston rod has a substantially circular cross-section.

In another preferred embodiment of the drive mechanism of the invention, the piston rod further comprises a distal threaded part and a proximal threaded part, wherein said distal threaded part and said proximal threaded part are oppositely arranged.

In another preferred embodiment of the drive mechanism of the invention, a drive sleeve is coupled to the actuating member for longitudinal travel and is capable of relative rotation between the drive sleeve and the actuating member.

The term "drug delivery device" according to instant invention shall mean a single-dose or multi-dose or pre-set dose or predefined dose, disposable or reusable device designed to dispense a user selectable or predefined dose of a drug, preferably a plurality of predefined doses of a drug, such as insulin, growth hormone, low molecular weight heparin, and analogues and/or derivatives thereof, etc. The device may be of any shape, for example pocket or pen shaped. Dose delivery may be achieved by a mechanical (optionally manual) drive mechanism or an electric drive mechanism or an electromechanical mechanism or a stored energy drive mechanism such as a spring or the like. Dose selection may be achieved by manual or electromechanical or electronic means. In addition, the device may contain elements designed to monitor physiological properties such as blood glucose levels and the like. Further, the device may or may not include a needle. In addition, the device may include a fixed needle or a replaceable needle or a moving needle or a shielded moving needle. In particular, the term "drug delivery device" shall mean a disposable needle-based pen-type device providing a plurality of predefined doses with mechanical and manual dose delivery and dose selection mechanisms, which device is designed to be used by persons without formal medical training, such as patients. Preferably, the drug delivery device is of the syringe type.

The term "housing" according to instant invention preferably refers to any external housing ("main housing", "body", "outer housing") or internal housing ("insert", "inner body") having one or more helical threads. The housing may be designed such that the drug delivery device or any mechanism thereof can be safely, correctly and comfortably handled. Typically, the housing is designed to house, secure, protect, guide and/or engage any internal components of the drug delivery device (e.g. drive mechanism, cartridge, plunger, piston rod) by limiting exposure to contaminants such as liquid, dust, dirt, etc. In general, the housing may be tubular or non-tubular, unitary or a multi-part component. Typically, the outer housing is used to house a cartridge, which may or may not be replaceable, and from which a dose of a medicinal product may be dispensed.

In a more specific embodiment of the invention, the housing has a plurality of maximum dose stops adapted to abut radial and/or axial stops provided on the actuation part.

The term "engaged" according to instant invention especially refers to an interlocking of two or more elements of the drive mechanism/drug delivery device, such as a keyway, a thread or a meshing tooth connection, preferably an interlocking of helical threads of the elements ("threaded engagement").

The term "coupled" according to instant invention refers to a connection of two or more elements of a drive mechanism/drug delivery device, e.g. using flanges or the like, wherein the elements have a limited degree of freedom with respect to each other. In a preferred embodiment, one element is allowed to rotate about an axis relative to the other element, but is restricted from all other rotational and/or translational movements relative to the other element.

In a more particular embodiment of the invention, the drive sleeve has a flange coupled to the actuation member allowing relative rotation about the main longitudinal axis of the drug delivery device, but substantially preventing all other relative movements.

The term "drive sleeve" according to instant invention shall mean any substantially tubular element having a substantially circular cross-section, which element is also releasably connected to the dose dial sleeve. In a preferred embodiment, the drive sleeve is also engaged with the piston rod.

In a more particular embodiment of the invention, the drive sleeve has first and second flanges at the distal end with an intermediate helical thread between the first and second flanges, a nut is disposed between the first and second flanges and the nut is keyed to the housing by a splined member. Optionally, a first radial stop may be provided on the proximal face of the nut and a second radial stop may be provided on the distal face of the second flange.

The term "piston rod" according to instant invention refers to an element adapted to be operated by/in a housing, designed to transmit axial movement to a piston by/in a drug delivery device, preferably from a drive sleeve, in order to expel/dispense an injectable product. The piston rod may be flexible or inflexible. The piston rod may be a simple rod, a lead screw, a rack and pinion system, a worm gear system, or the like. It may also be a one-piece construction or a multi-part construction. The term "piston rod" also refers to an element having a circular or non-circular cross-section. It may be made of any suitable material known to those skilled in the art.

In a preferred embodiment the piston rod comprises at least one, more preferably two, external and/or internal helical threads. In another preferred embodiment of the piston rod according to the invention a first helical thread is located at the distal end of the piston rod and a second helical thread is located at the proximal end of the piston rod, wherein the threads may have the same or preferably opposite arrangement. In another preferred embodiment, the piston rod of the present invention comprises threads with the same lead at the proximal and distal ends.

In another preferred embodiment of the invention the lead of the second helical thread of the piston rod should be larger than the lead of the first helical thread. More preferably, the ratio of the leads of the first helical thread and the second helical thread is from 1: 1 to 1: 20, more preferably from 1: 1 to 1: 10, most preferably 1: 2. Preferably, one of said threads is designed to engage with a drive sleeve.

The term "actuation member" according to instant invention refers to any element designed to transmit a force from a user to a drive sleeve. Preferably, the term "actuation member" refers to an element that does not rotate relative to the housing but is capable of moving longitudinally relative to the housing in order to transfer force from a user to the drive sleeve. In a more preferred embodiment of the invention, the actuation member has a gripping surface at a proximal end to enable a user to actuate the device. In another preferred embodiment of the invention, the actuation member has a contact surface to enable a user to dispense a selected dose of medicament.

The term "illustrated status indicator" according to instant invention preferably refers to any marking, symbol, number or the like, e.g. printed on the outer surface of a component of the device, e.g. the drive sleeve or the distance meter or the dose dial sleeve or the actuation member, preferably the actuation member, for indicating to a user when the device has been actuated and/or is operating and/or the direction of operation and/or has delivered a dose of a drug.

The "proximal end" of the device or of an element of the device refers to the end furthest from the dispensing end of the device.

The "distal end" of a device or of an element of a device refers to the end closest to the dispensing end of the device.

A second aspect of the invention provides an assembly for a drug delivery device comprising a drive mechanism according to the invention.

A third aspect of the invention provides a medicament delivery device comprising a drive mechanism or assembly according to the invention.

A fourth aspect of the invention provides a method of assembling a drug delivery device comprising the step of providing a drive mechanism or assembly according to the invention.

A fifth aspect of the present invention relates to the use of a drug delivery device according to the present invention for dispensing a pharmaceutical product, preferably a pharmaceutical formulation (e.g. solution, suspension, etc.) comprising an active compound selected from the group consisting of insulin, growth hormone, low molecular weight heparin, and analogues and derivatives thereof.

Drawings

Without any limitation, the invention will be described in more detail below in connection with preferred embodiments with reference to the accompanying drawings, in which:

fig. 1 shows a cross-sectional view of an embodiment of a medication delivery device according to the present invention in a first position where the cartridge is full;

fig. 2 shows a cross-sectional view of an embodiment of a medicament delivery device according to the invention in a second position of a first dose setting;

fig. 3 shows a cross-sectional view of an embodiment of a medicament delivery device according to the present invention in a third position of final dose dispensing.

Detailed Description

Referring to fig. 1 and 2, a medicament delivery device according to the present invention is shown.

The drug delivery device 1 comprises a cartridge holding part 2 and a main (outer) housing part 3. The proximal end of the cartridge retaining part 2 and the distal end of the main housing 3 are secured together by any suitable means known to the person skilled in the art. In the illustrated embodiment, the cartridge retaining portion 2 is secured in the distal end of the main housing portion 3.

In the cartridge holder 2 a cartridge 4 is arranged from which cartridge 4 a dose of a medicinal product can be dispensed. The piston 5 is held in the proximal end of the cartridge 4.

A removable cap (not shown) is releasably retained on the distal end of the cartridge retaining portion 2. The removable cap (not shown) optionally has one or more windows 42 through which the position of the piston 5 in the cartridge 4 can be seen.

In the illustrated embodiment, the distal end of the cartridge retaining portion 2 has a distal threaded region 6, which region 6 is designed for attachment of a suitable needle assembly (not shown) to enable dispensing of a medicament from the cartridge 4.

In the embodiment shown, the main housing part 3 has a threaded round opening 8. In the embodiment shown, the threaded round opening 8 comprises a series of partial threads instead of full threads. Alternatively, the threaded circular opening 8 may be formed on a separate element which may be fixed against axial and/or rotational movement relative to the main housing part 3.

The main housing part 3 also has an inner housing 7. The inner housing 7 is fixed to be non-rotatable and/or axially movable relative to the main housing part 3. Furthermore, the inner housing 7 has a plurality of longitudinally extending guide slots (not shown). A track 30 is formed between the inner housing 7 and the main housing part 3. In the illustrated embodiment, the track 30 includes a helically threaded portion and a longitudinally extending linear portion. The helical thread portion extends for a full turn and the straight portion joins the ends of the helical thread portion to form a continuous track. The distal end of the linear portion of the track 30 has a stop 31. Optionally, the inner housing 7 may be transparent. Alternatively, the inner housing 7 may be integrally formed with the main housing portion 3.

A first thread 9 is formed at the distal end of the piston rod 10. The piston rod 10 has a substantially circular cross-section. The first thread 9 of the piston rod 10 extends through and is threadedly engaged with the threaded circular opening 8 of the main housing part 3. A pressure foot 11 is located at the distal end of the piston rod 10. The pressure foot 11 is arranged to abut against the proximal end face of the piston 5. A second thread 12 is formed at the proximal end of the plunger rod 10. The lead of the second thread 12 of the piston rod 10 is substantially equal to the lead of the helical part of the track 30 formed between the inner housing 7 and the main housing part 3.

The first thread 9 and the second thread 12 of the piston rod 10 are oppositely arranged.

A drive sleeve 14 extends around the piston rod 10. The drive sleeve 14 has a generally cylindrical cross-section. A first thread 32 is formed on the inner surface of the drive sleeve 14. A flexible projection 36 is formed at the distal end of the drive sleeve 14. A first radially extending flange 35 and a second radially extending flange 34 are formed on the drive sleeve 14. The second thread 33 is formed on the outer surface of the drive sleeve 14 and is located between a first radially extending flange 35 and a second radially extending flange 34. A third radially extending flange 37 is formed at the proximal end of the second radially extending flange 34. A radially extending detent member 39 is formed on the drive sleeve 14 and is located distally of the third radially extending flange 37. A bearing surface 38 is formed at the proximal end of the drive sleeve 14.

The first thread 32 of the drive sleeve 14 engages the second thread 12 of the piston rod 10.

The flexible protrusions 36 of the drive sleeve 14 are designed to engage with the tracks 30 formed between the main housing part 3 and the inner housing 7.

The nut 43 is located between the drive sleeve 14 and the inner housing 7, and between the first flange 35 and the second flange 34. In the illustrated embodiment, the nut 43 is a half nut (half-nut). This facilitates assembly of the device. The nut 43 has internal threads that threadedly engage the second threads 33 of the drive sleeve 14. The outer surface of the nut 43 and the inner surface of the inner housing 7 are splined together (not shown) to prevent relative rotation between the nut 43 and the inner housing 7 while allowing relative longitudinal movement therebetween.

The actuating member 16 has a gripping surface 18 and a dispensing surface 19. Ratchet teeth (not shown) are formed on the inner cylindrical surface of the actuation member 16. A radially inwardly projecting retaining member 40 is formed on the actuating member 16 and is designed to abut against a distal end face of the third flange 37 of the drive sleeve 14.

A plurality of guide protrusions (not shown) are formed on the outer surface of the actuating member 16. The guide projections (not shown) are located in guide slots (not shown) of the inner housing 7. The interaction of the guide projections (not shown) with the guide slots (not shown) of the inner housing 7 defines the range of permissible axial movement of the actuation member 16 relative to the main housing portion 3. In the embodiment shown, the guide projection (not shown) also prevents rotational movement of the actuation member 16 relative to the main housing portion 3.

A bearing point 41 is formed on the inner proximal surface of the actuation member 16 and is arranged to abut the bearing surface 38 of the drive sleeve 14.

To increase the intuitiveness of the operation of the device, the main housing portion 3 may optionally have a window 42 through which an optional illustrated status indicator provided on the actuation member 16 may be seen.

The operation of the medication delivery device according to the present invention will now be described.

To set a dose, the user grips the gripping surface 18 of the actuation member 16. The user then pulls the actuation member 16 in a proximal direction away from the main housing part 3.

When the actuation member 16 is moved in the proximal direction, the drive sleeve 14 is also moved in the proximal direction due to the interaction between the retaining member 40 of the actuation member 16 and the third flange 37 of the drive sleeve 14. When the flexible projections 36 of the drive sleeve 14 abut the stops 31 of the track 30, the drive sleeve 14 is caused to rotate along the helical portion of the track 30. Since the lead of the track 30 is substantially equal to the lead of the first thread 32 of the drive sleeve 14 and the lead of the second thread 12 of the piston rod 10, the piston rod 10 does not move relative to the main housing part 3.

The proximal travel of the actuation member 16 is defined by the guide slot of the inner housing 7 by a distance corresponding to one thread lead of the helical portion of the track 30. At the end of the stroke of the actuation member 16, the pawl member 39 of the drive sleeve 14 engages with ratchet teeth (not shown) of the actuation member 16. By this action, the drive sleeve 14 is displaced in the proximal direction with respect to the piston rod 10 by a distance equal to one lead of the first thread 32 of the drive sleeve 14, as shown in fig. 2. The action of the pawl member 39 of the drive sleeve 14 engaging the ratchet teeth shape of the actuation part 16 produces an audible and tactile feedback to the user to indicate that a dose has been set. In addition, visual feedback relating to dose setting may optionally be indicated by a pictorial status indicator provided on the actuation member 16, which is visible through an optional window 42 in the main housing part 3.

When a dose has been set, the user may dispense this dose by pressing the dispensing face 19 of the actuation member 16. By this action, the drive sleeve 14 is axially moved in the distal direction relative to the main housing part 3 by the interaction between the bearing points 41 of the actuation member 16 and the bearing surfaces 38 of the drive sleeve 14. When the pawl members 39 of the drive sleeve 14 engage the ratchet teeth of the actuating member 16, the drive sleeve 14 is prevented from rotating along the helical portion of the track 30, such that the flexible projections 36 of the drive sleeve 14 move distally along the linear portion of the track 30. When the second thread 12 of the piston rod 10 is form-engaged with the first thread 32 of the drive sleeve 14, the piston rod 10 is caused to rotate relative to the main housing part 3 by axial movement of the drive sleeve 14 in the distal direction. When the piston rod 10 is rotated, the first thread 9 of the piston rod 10 is rotated in the threaded circular opening 8 of the main housing part 3, so that the piston rod 10 is axially moved in the distal direction with respect to the main housing part 3.

The distal axial movement of the piston rod 10 causes the pressure foot 11 to press against the piston 5 of the cartridge 4, thereby dispensing a dose of medicament through the connected needle.

The distal travel of the actuation member 16 is limited by the guide slots of the inner housing 7. Audible and tactile feedback indicating that a dose has been dispensed is provided by the interaction of the flexible projections 36 of the drive sleeve 14 with the stops 31 of the track 30. In addition, visual feedback regarding the dispensing of a dose may optionally be indicated by a pictorial status indicator provided on the actuation member 16, which is visible through an optional window 42 in the main housing part 3.

Other doses may be delivered as needed up to a predetermined maximum dose. Figure 3 shows the drug delivery device of the present invention in a situation where a maximum dose has been delivered. In this case, the nut 43 has passed completely through the second thread 33 of the drive sleeve 14, abutting the distal end face of the second flange 34 of the drive sleeve 14. In this case, the nut 43 prevents further rotational movement of the drive sleeve 14, thereby preventing selection of a further dose.

Claims (13)

1. A drive mechanism for a drug delivery device, comprising:

a housing having a helical thread;

an actuation member that is non-rotatable relative to the housing;

a drive sleeve engaged with the housing;

a piston rod comprising a distal threaded portion and a proximal threaded portion;

it is characterized in that the preparation method is characterized in that,

a) the distal threaded portion of the piston rod is in threaded engagement with the housing;

b) the proximal threaded portion of the piston rod is in threaded engagement with the drive sleeve;

so that:

c) when the actuation member is moved proximally relative to the housing, the drive sleeve rotates relative to the actuation member and moves proximally relative to the housing;

d) when the actuation member is moved distally relative to the housing, the drive sleeve is moved distally relative to the housing and cannot rotate relative to the housing, and the piston rod rotates relative to the housing, thereby transferring a force in a longitudinal direction to the distal end of the drug delivery device.

2. The drive mechanism of claim 1, the helical thread being an internal helical thread.

3. The drive mechanism as recited in claim 1, wherein the piston rod has a substantially circular cross-section.

4. The drive mechanism according to claim 1, wherein the piston rod further comprises a distal threaded portion and a proximal threaded portion, wherein the distal threaded portion and the proximal threaded portion are oppositely arranged.

5. The drive mechanism as recited in claim 1, wherein the drive sleeve is coupled with the actuation member for longitudinal travel and is capable of relative rotation between the drive sleeve and the actuation member.

6. An assembly for a drug delivery device, the assembly comprising a drive mechanism as defined in any one of claims 1-5.

7. A medicament delivery device comprising a drive mechanism as defined in any of claims 1 to 5 or an assembly of claim 6.

8. The drug delivery device of claim 7, wherein the drug delivery device is a pen-type device.

9. The drug delivery device of claim 7, wherein the drug delivery device is a syringe-type device.

10. The drug delivery device of claim 7, wherein the drug delivery device comprises a needle.

11. The drug delivery device of claim 7, wherein the drug delivery device is a needle-free device.

12. A drug delivery device as defined in claim 7, configured for dispensing a drug.

13. A drug delivery device according to claim 12, configured for dispensing a pharmaceutical preparation comprising an active compound selected from the group consisting of insulin, growth hormone, low molecular weight heparin, analogues and derivatives thereof.