HK1091762B - Dose dial and drive mechanism suitable for use in drug delivery devices - Google Patents

Description

Dose dial and drive mechanism for a drug delivery device

Technical Field

The present invention relates to a dose dial and drive mechanism suitable for use in a drug delivery device, in particular a pen injector, and having a dose setting means and enabling a multiple dose cartridge to be used to administer a drug. In particular, the present invention relates to a drug delivery device in which a user can set a dose.

Background

Such drug delivery devices are used for timed injections by persons without formal medical training, i.e. patients. This is increasingly common in patients with diabetes, and this self-treatment allows these people to have effective management of their diabetes.

These circumstances set a number of requirements for such drug delivery devices. Such devices must be robust in construction and easy to use in terms of the manipulation of the components and the understanding of the user of their manipulation and delivery of the required dose of medicament. The dose setting must be easy and unambiguous. In the case of users with diabetes, many users are physically weak and may have impaired vision, which requires the drive mechanism to have a low dispensing force and the dose setting display to be easily readable. Where the device is disposable rather than 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 from which the device is made need to be kept to a minimum.

User operated drug delivery devices comprising a dose dial and a drive mechanism are well known in the medical field.

DE3814023a1 discloses an injection device based on the ball-point pen principle. The device has a cartridge containing a drug, in particular insulin, from which two insulin units can be injected by pressing a button. Movement of the button causes the longitudinally movable tubular piston rod to engage and move a longitudinally movable syringe piston located within the cartridge. The device of DE3814023a1 does not solve the problem of inaccurate doses being set by the user.

EP0554996a1 discloses an injection device comprising a drive mechanism and a dose setting device comprising a unit counter ring and a tens counter ring. The tens counter ring is disposed adjacent to the unit counter ring, and the two rings are connected by a transfer device. The transmission means includes means for rotating the tens counter ring a selected number of degrees as the unit counter ring rotates through a selected angular displacement. The (injection) device further comprises means responsive to the dose setting means for controlling the axial movement of the piston rod. The (injection) device allows the user to select a dose and allows correction of an overdose situation without dispensing a drug. However, resetting the dose setting device to the zero position requires the user to rotate the dose setting device back to the zero position, requiring additional manipulation by the user.

Surprisingly, it has been found that a dose dial and drive mechanism according to the present invention may provide a user with an automatic reset of the dose dial mechanism, which makes it easy to reset the dose display without requiring additional actions by the user. This automatic reset to zero facilitates safe dose dialing and dispensing.

Disclosure of Invention

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

a housing;

dose dial sleeve (sleeve);

a piston rod;

a drive sleeve threadedly connected to the piston rod;

a reset sleeve positioned between the drive sleeve and the housing; and

a dose display is provided on the housing for displaying the dose,

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

a) as the dose dial sleeve travels towards the second end of the housing, the dose dial sleeve carries the reset sleeve towards the second end of the housing, resetting the dose display to a zero position; and

b) when the dose dial sleeve and/or the reset sleeve is advanced towards the first end of the housing, the dose dial sleeve and/or the reset sleeve engages with the drive sleeve, thereby advancing both the drive sleeve and the piston rod towards the first end of the housing.

The term "drug delivery device" according to instant invention shall mean a single-dose or multi-dose, disposable or reusable device designed to dispense a selected dose of a medicinal product, preferably a plurality of selected doses, such as insulin, growth hormone, low molecular weight heparin, and analogs and/or derivatives thereof, and the like. The device may be of any type, for example a small or pen type. Dose delivery may be achieved by a mechanical (optionally manual) or electrical drive mechanism or a stored energy drive mechanism such as a spring or the like. Dose selection may be achieved by a manual mechanism or an electronic mechanism. In addition, the device may include elements designed to monitor physiological characteristics such as blood glucose levels, etc. Further, the device may include a needle or be needle-free. In particular, the term "drug delivery device" refers to disposable, multi-dose pen-type devices having mechanical and manual dose delivery and dose selection mechanisms, which are designed to be used regularly 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 an external housing ("main housing", "body", "housing") or an internal housing ("insert", "inner body"). The housing is designed such that the drug delivery device or any mechanism thereof can be safely, correctly and comfortably handled. Generally, 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, piston rod) by limiting exposure to contaminants such as liquid, dust, dirt, etc. In general, the housing may be a tubular or non-tubular unitary or multipart component. Typically, the outer housing is intended to receive a cartridge from which a plurality of doses of a medicinal product may be dispensed.

The term "engaged" according to instant invention shall mean inter alia an interlocking or abutment of two or more components of the dose dial and drive mechanism/drug delivery device, such as a key way or a threaded connection, preferably an interlocking of helical threads of the components ("threaded engagement").

The term "helical thread" according to instant invention preferably refers to a full or partial thread, e.g. a cylindrical spiral of ribs/grooves, on the inner and/or outer surface of an element of a drug delivery device, which thread is substantially triangular or square or circular in cross-section and designed to allow continuous free rotation and/or axial movement between the elements. Optionally, the threads may also be designed to prevent rotation or axial movement of a particular element in one direction.

The "dose dial sleeve" according to the present invention should allow the user to select the amount of drug to be dispensed. It refers to a substantially tubular element of substantially circular cross-section, optionally arranged for axial movement within the housing, preferably comprising a first cylinder of a first diameter and a second cylinder of a second diameter arranged concentrically with respect to each other, wherein the value of said first diameter is smaller than the value of said second diameter. Preferably, the "dose dial sleeve" extends from the second end of the housing and engages both the dose display, preferably the first cylindrical wheel, and the reset sleeve.

The dose dial sleeve according to the present invention is designed to be driven between the first and second ends of the housing, e.g. by the driving force of a user and/or by the stored energy of a spring means, an electric motor or the like.

The term "dose display" according to instant invention refers to a device for displaying a dose of a drug to be dispensed by a user. This may be achieved by using, for example, markings, symbols, numbers or the like printed on the outer surface of the dose dial sleeve or distance meter (odometer). In an alternative embodiment, the dose display may be an electronic display device.

In a more specific embodiment of the invention, the dose display comprises two adjacent cylindrical wheels located within the housing and arranged to rotate relative to the housing, wherein one cylindrical wheel displays a unit dose measurement and the other cylindrical wheel displays a tens dose measurement.

The term "reset sleeve" according to instant invention shall mean any substantially tubular element of substantially circular cross-section located between the drive sleeve and the housing, which element is engaged with the first and second cylindrical wheels of the dose display, optionally via a gear element. The reset sleeve is designed to reset the first and second cylindrical wheels of the dose display to a zero position when the reset sleeve is moved towards the second end of the housing. Preferably, the reset sleeve engages the inner surfaces of the first and second cylindrical wheels by teeth.

The term "drive sleeve" according to instant invention shall mean any substantially tubular element having a substantially circular cross-section, which is engaged, preferably threadedly engaged, with the piston rod.

In a more particular embodiment of the invention, the drive sleeve is disposed within the first cylinder of the dose dial sleeve.

The term "piston rod" according to instant invention shall mean any element adapted to operate through/within the housing and designed to transfer axial movement through/within the drug delivery device, preferably from the drive sleeve to the piston, in order to expel/dispense an injectable product. The piston rod may or may not be flexible. It may comprise a single rod, lead screw, rack and pinion system, worm gear system or the like. The piston rod of the present invention 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.

The term "zero position" according to instant invention refers to when both of the cylindrical wheels of the dose display indicate the number 0.

The term "first end" according to instant invention refers to the proximal end. The proximal end of the (drug delivery) device or a component of the device refers to the end closest to the dispensing end of the device.

The term "second end" according to instant invention refers to the distal end. The distal end of the (drug delivery) device or a component of the device refers to the end which is furthest away from the dispensing end of the device.

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

A third aspect of the invention provides a drug delivery device comprising a dose dial and drive mechanism or assembly according to the invention.

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

A fifth aspect of the present invention is the use of a drug delivery device according to the present invention for dispensing a pharmaceutical product, preferably dispensing 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/or derivatives thereof.

Drawings

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

figure 1 shows a side cross-sectional view of a syringe according to the invention in a first position;

FIG. 2 shows a side cross-sectional view of the syringe of FIG. 1 (with the drive sleeve omitted for clarity) in a second position;

FIG. 3 shows a side cross-sectional view of the syringe of FIG. 1 in a third position;

FIG. 4 shows a side cross-sectional view of the syringe of FIG. 1 in a fourth position; and

fig. 5 shows a side sectional view of the syringe of fig. 1 in a fifth position.

Detailed Description

Referring first to fig. 1, a syringe according to the present invention can be seen. The injector comprises a housing 2 within which there is a cartridge 4 containing a medicinal product, means for selecting or setting a dose of medicinal product to be expelled, and means for expelling the selected dose of medicinal product. The housing 2 is generally cylindrical in shape and is divided into two chambers.

The cartridge 4 is located in a first chamber of the housing 2 and the dose setting means and the means for expelling a selected dose of a medicinal product are located in a second chamber of the housing 2. The medicinal product may be expelled from the cartridge 4 by advancing the piston 8 towards the first end of the injector. In use, a needle assembly (not shown) is mounted on the first end of the housing 2 through which the drug can flow.

The piston 8 is advanced by a threaded piston rod 10. The insert 12 is located within the housing 2. The insert 12 includes an inner portion 14 and an outer portion 16 connected by a central web 18. The inner part 14 comprises an opening 20 through which the piston rod 10 can pass. The opening 20 is surrounded by a generally cylindrical portion extending from the insert towards the second end of the syringe. The generally cylindrical portion includes a keyway (not shown) against which the gear member 22 is disposed. The outer portion 16 of the insert 12 comprises a generally cylindrical portion. The outer portion 16 of the insert 12 is secured within the housing 2 by any suitable means, such as clips, adhesives, etc. A passageway is formed between the generally cylindrical portion of the inner portion 14 of the insert 12 and the generally cylindrical portion of the outer portion 16 of the insert 12.

A first sleeve in the form of a drive sleeve 26 is located between the piston rod 10 and the generally cylindrical portion 14, the drive sleeve being of generally cylindrical configuration surrounding the piston rod 10. The second end of the drive sleeve 26 has a molded spring 28. The drive sleeve 26 has an internal thread (not shown) for threaded engagement with the threaded piston rod 10.

The reset sleeve 30 is located about the generally cylindrical portion of the interior portion of the insert 12 and thus also about the drive sleeve 26. The reset sleeve 30 is conveniently keyed to the generally cylindrical portion 14 of the insert 12 in the region of the generally cylindrical portion 14 of the insert 12. Outside of the generally cylindrical portion of the insert 12, the reset sleeve 30 includes a radially inward projection or flange 32. A compression spring 34 is disposed about the drive sleeve 26 between the second end of the generally cylindrical portion 14 of the insert 12 and the first face of the inward flange 32 of the reset sleeve 30. The gear element 22 is supported by a first end of the reset sleeve 30. The gear element 22 is conveniently supported by snap-fitting within a moulded support so that the gear element 22 can rotate about an axis defined by the support. The reset sleeve 30 also includes a shoulder 36 disposed between the first and second ends of the reset sleeve 30.

A first cylindrical wheel 42 is located within the housing 2 and adjacent the outer portion 16 of the insert 12. The first cylindrical wheel 42 is adapted to rotate within the housing 2. A second cylindrical wheel 40 is located within the housing 2 adjacent the first cylindrical wheel 42. The second cylindrical wheel 40 is also adapted to rotate within the housing 2. Each of the first and second cylindrical wheels 42, 40 has means for releasably engaging the gear element 22. In this way, the gear element 22 is adapted to control the relative movement of the first and second cylindrical wheels 42, 40. Each of the first and second cylindrical wheels 42, 40 is provided with numerals around the outer circumference. This reference number is visible through a window 44 in the housing 2. The second cylindrical wheel 40 may be used to represent a unit dose of the pharmaceutical product, while the first cylindrical wheel 42 may be used to represent a ten unit dose. In this case, the gear element 22 is used to advance the first cylindrical wheel 42 one increment each time ten increments of the second cylindrical wheel 40 are made.

The dose dial sleeve 50 comprises a first cylinder 52 and a second cylinder 54 disposed substantially concentrically around the first cylinder 52. An end web 56 spans the second end of the first cylinder 52 and the second end of the second cylinder 54. The second end of the drive sleeve 26 comprising the moulded spring 28 is disposed within the first cylinder 52 of the dose dial sleeve 50. The second end of the dose dial sleeve 50 passes through an opening in the second end of the housing 2.

The first end of the first cylinder 52 is adapted to abut the second face of the inward flange 32 of the reset sleeve 30.

The second cylinder 54 extends axially beyond the first cylinder 52. The first end of the second cylinder 54 is adapted to abut the shoulder 36 of the reset sleeve 30. The first end of the second cylinder 54 also has means for engaging the first cylindrical wheel 42. In the illustrated embodiment, the first end of the second cylinder 54 has two radially extending lugs 58, 60 that axially drive radially inwardly extending lugs (not shown) formed on the interior of the first cylindrical wheel 42.

A third sleeve 62 is located within the housing 2 and axially between the second cylindrical wheel 40 and the second end of the housing 2. The third sleeve 62 includes a plurality of internal passages (not shown) including a set of interconnected alternating open and closed passages. The second cylinder 54 of the dose dial sleeve 50 further comprises at least one radially outwardly extending projection 64 for engagement within the passageway.

In the starting position of fig. 1, the at least one radially outwardly extending projection 64 engages one of the closed passages within the third sleeve 62.

To release the dose dial sleeve 50, the user presses on the end of the dose dial sleeve 50 (as shown in figure 2). This causes the at least one radially outwardly extending projection 64 to move in the internal passageway of the third sleeve 62 towards the first end of the housing 2. As the dose dial sleeve 50 moves towards the first end of the housing, the dose dial sleeve 50 is guided by the passageway to rotate slightly. This slight rotation aligns the at least one radially outwardly extending projection 64 with one of the open passages in the third sleeve 62. The dose dial sleeve 50 is then ejected out of the second end of the housing 2 under the action of the compression spring 34.

As the dose dial sleeve 50 travels outwardly (under the action of the compression spring 34), the dose dial sleeve 50 carries the reset sleeve 30 along. The reset sleeve 30 has teeth that engage internal features of the first and second cylindrical wheels 42, 40. This movement of the reset sleeve 30 causes the teeth of the reset sleeve 30 to reset the first and second cylindrical wheels 42, 40 of the dose display to zero.

In the third position (fig. 3), the gear element 22 is disposed within the cut-out region of the generally cylindrical portion of the insert 12 and is free to rotate.

The user may then rotate the dose dial sleeve 50 which in turn causes the drive sleeve 26 threaded on the piston rod 10 to travel towards the second end of the housing 2 and the end web 56 of the dose dial sleeve 50 (figure 4). Rotation of the dose dial sleeve 50 causes the two radially extending lugs 58, 60 to drive the second cylindrical wheel 40. Sufficient rotation of the dose dial sleeve 50 will cause the first cylindrical wheel 42 to be driven by the second cylindrical wheel 40 through the gear element 22.

To dispense a dose, the user presses on the web 56 of the dose dial sleeve 50. The dose dial sleeve 50 drives the reset sleeve 30 axially. The dose dial sleeve 50 engages the drive sleeve 26 and advances both the drive sleeve 26 and the piston rod 10 against the cartridge piston 8. The selected dose remains displayed by the first and second cylindrical wheels 42, 40. In the home position (shown in figure 5) the dose dial sleeve 50 locks the first and second cylindrical wheels 42, 40 to prevent rotation of the first and second cylindrical wheels 42, 40 when the syringe is not in use.

The moulded spring 28 at the dial end of the drive sleeve 26 ensures that the piston rod 10 does not retract from the second face of the cartridge piston 8 after the dose dial sleeve 50 has been released.

Claims (6)

1. A dose dial and drive mechanism for a drug delivery device comprising:

a housing having a first end and a second end, the first end being the end closest to the dispensing end of the drug delivery device and the second end being the end furthest from the dispensing end of the drug delivery device;

a dose dial sleeve;

a piston rod;

a drive sleeve threadedly connected to the piston rod;

a reset sleeve positioned between the drive sleeve and the housing; and

a dose display is provided on the housing for displaying the dose,

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

a) as the dose dial sleeve travels towards the second end of the housing, the reset sleeve is carried by the dose dial sleeve towards the second end of the housing, resetting the dose display to a zero position; and

b) when the dose dial sleeve and reset sleeve are advanced towards the first end of the housing, the dose dial sleeve and reset sleeve engage the drive sleeve, thereby advancing both the drive sleeve and the piston rod towards the first end of the housing.

2. A mechanism according to claim 1, wherein the dose display comprises a first cylindrical wheel adapted to rotate within the housing and a second cylindrical wheel adapted to rotate within the housing, the first and second cylindrical wheels being provided with numerals around an outer circumference, one of the cylindrical wheels being for displaying a measured unit dose and the other cylindrical wheel being for displaying a measured tens dose.

3. The mechanism of claim 2, wherein the first and second cylindrical wheels are reset to a zero position when the reset sleeve is moved toward the second end of the housing, and the reset sleeve engages the inner surfaces of the first and second cylindrical wheels via the teeth.

4. The mechanism of claim 1, wherein the reset sleeve includes a shoulder disposed between the first end and the second end of the reset sleeve.

5. A drug delivery device comprising a dose dial and drive mechanism according to claim 1.

6. A method of assembling a drug delivery device, the method comprising the step of providing a dose dial and drive mechanism according to claim 1.