U.S. patent application number 13/474042 was filed with the patent office on 2012-09-13 for dose display mechanism for a drug delivery device.
This patent application is currently assigned to TERUMO CORPORATION. Invention is credited to Masaru Saiki.
Application Number | 20120232517 13/474042 |
Document ID | / |
Family ID | 34926839 |
Filed Date | 2012-09-13 |
United States Patent
Application |
20120232517 |
Kind Code |
A1 |
Saiki; Masaru |
September 13, 2012 |
Dose Display Mechanism for a Drug Delivery Device
Abstract
This invention relates to a dose display mechanism for a drug
delivery device that allows the user to select multiple doses of an
injectable drug and for the dispensing of the set dosage of the
drug and applying said drug to a patient, preferably by
injection.
Inventors: |
Saiki; Masaru;
(Hamanashi-ken, JP) |
Assignee: |
TERUMO CORPORATION
Tokyo
JP
SANOFI-AVENTIS DEUTSCHLAND GMBH
Frankfurt am Main
DE
|
Family ID: |
34926839 |
Appl. No.: |
13/474042 |
Filed: |
May 17, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11690984 |
Mar 26, 2007 |
8202255 |
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13474042 |
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PCT/EP05/09840 |
Sep 14, 2005 |
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11690984 |
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Current U.S.
Class: |
604/500 ; 29/428;
604/189 |
Current CPC
Class: |
A61M 5/31595 20130101;
A61M 5/31563 20130101; A61M 5/31551 20130101; A61M 2205/583
20130101; Y10T 29/49826 20150115; A61M 2005/3126 20130101; A61M
5/31585 20130101; A61M 5/3156 20130101 |
Class at
Publication: |
604/500 ;
604/189; 29/428 |
International
Class: |
A61M 5/31 20060101
A61M005/31; B23P 17/04 20060101 B23P017/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 4, 2004 |
EP |
04023628.3 |
Claims
1. A dose display mechanism for a drug delivery device having a
dispensing end, the dose display mechanism comprising: a dose
setting dial having a proximal end, a distal end, and an external
surface, the distal end being closer to the dispensing end of the
drug delivery device than the proximate end, the dose setting dial
having an external helical thread and external grooves extending
from the proximate end to the distal end, the external surface
having indices thereon, the indices being arranged lengthwise along
the dose setting dial for visual display of a dose setting of the
drug delivery device; and a counter ring having an external
surface, the external surface of the counter ring having indices
thereon positionable adjacent to the indices on the external
surface of the dose setting dial, the indices on the counter ring
cooperating with the indices on the dose setting dial to provide a
visual display of the dose setting of the drug delivery device
wherein the indices on both the counter ring and the dose setting
dial are visible, the counter ring being in an interlocking
relationship with the external grooves of the dose setting dial
such that the counter ring is free to move axially along the
external grooves with respect to the dose setting dial while being
prevented from rotation with respect to the dose setting dial.
2. A drug delivery device comprising a) a drive mechanism; and b)
the dose display mechanism as defined in claim 1.
3. The device according to claim 2 containing insulin, heparin, or
a derivative or analogue thereof.
4. A method of delivering a pharmaceutical formulation to a human
or animal body comprising administering the pharmaceutical
formulation from a drug delivery device comprising the dose display
mechanism according to claim 1.
5. A method of delivering a pharmaceutical formulation to a human
or animal body comprising administering the pharmaceutical
formulation from a drug delivery device according to claim 2.
6. A method according to claim 4, wherein the pharmaceutical
formulation contains insulin, heparin, a derivative thereof or an
analogue thereof.
7. A method according to claim 5, wherein the pharmaceutical
formulation contains insulin, heparin, a derivative thereof or an
analogue thereof.
8. A method of assembling a drug delivery device comprising a drive
mechanism and a dose display mechanism according to claim 1,
comprising mounting the dose display mechanism to any other
components of the drug delivery device.
9. A method of assembling a drug delivery device comprising a drive
mechanism and a dose display mechanism according to claim 1, and
containing insulin, heparin, or a derivative or analogue of insulin
or heparin, comprising mounting the dose display mechanism to any
other components of the drug delivery device.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 11/690,984, filed Mar. 26, 2007, which is a continuation of
PCT/EP2005/009840, filed Sep. 14, 2005, which is based upon and
claims priority to EP 04023628,3, filed Oct. 4, 2004, all of the
aforementioned documents being incorporated by reference herein in
their entirety.
FIELD OF THE INVENTION
[0002] This invention relates to a dose display mechanism for a
drug delivery device that allows the user to select multiple doses
of an injectable drug and for the dispensing of the set dosage of
the drug and applying said drug to a patient, preferably by
injection. In particular, the present invention relates to such
devices, which are handled by the patients themselves.
BACKGROUND OF THE INVENTION
[0003] Drug delivery devices, which allow multiple dosing of the
required dosage of liquid drug and administration of the liquid to
a patient, are well known in the art. Generally, such devices have
substantially the same purpose as that of an ordinary syringe.
[0004] Pen-type injectors of this kind must meet a number of
requirements to meet user needs. These devices need to be robust in
construction, yet easy to use both in terms of the manipulation of
the parts and understanding by a user of its operation. In the case
of those with diabetes, many users will be physically infirm and
may also have impaired vision. Where the injector is to be
disposable rather than reusable, the injector should be cheap to
manufacture and easy to dispose of (preferably being suitable for
recycling).
[0005] WO 01/87386 A1 teaches a mechanical dose display for a
medicine administration device consisting of at least one flexible
disk which is driven by the dose setting actuator and which carries
a band of numbers along its perimeter. By folding the disc in such
a way that the diametrical opposite points of the perimeter just
meet, allows each digit along the perimeter to be about three times
as high as corresponding digits written on a drum having a diameter
corresponding to the diameter of the tube formed by the folded
disc. Through the addition of a second disc it is possible to show
a two-digit number.
[0006] WO 98/10813 A1 discloses a dose setting mechanism by which
doses are indicated on a dock dial having a first part secured to
the housing and a second part which is rotatable relative to the
first part and which is coupled to the dose setting element. One of
the parts carries the scale and the other carries an indicating
member indicating a point on the scale. By using a dock dial the
dial can be made arbitrarily large being limited only by the fact
that the device must not be too bulky.
[0007] U.S. Pat. No. 5,279,585 A discloses an injection device for
injecting fluids such as insulin within body tissue. The dose
setting means of the device includes a units counter ring, a tens
counter ring positioned in adjoining relation to the units counter
ring, and a transmission means connecting the units counter means
and the tens counter ring.
SUMMARY OF THE INVENTION
[0008] Accordingly, the problem to be solved by the instant
invention is to provide a dose display that displays in clear and
large indices, i.e., numbers, symbols, letters, etc., the set dose
and is suitable for use by visually disabled users, particularly
for use with pen-type drug delivery devices.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view of the counter ring in position
on the dose setting dial.
[0010] FIG. 2 is a schematic showing the numerical value of the
first digit of the counter ring (a) and a perspective view of the
counter ring (b).
[0011] FIG. 3 is a schematic showing the numerical value of the
second digit of the dose setting dial.
[0012] FIG. 4 is a perspective view of the entire device indicating
the display window.
[0013] FIG. 5 is a sectional side view illustrating a dose setting
operation of the device.
[0014] FIG. 6 is a sectional side view showing the drive mechanism
of the device in an initial state.
[0015] FIG. 7 is a sectional side view illustrating a dose setting
operation of the device.
[0016] FIG. 8 is a sectional side view illustrating a dose delivery
of the device.
[0017] FIG. 9 is an enlarged scale of FIG. 2.
[0018] FIG. 10 shows the plunger rod, the lead screw, and the
plunger rod holder of the device.
[0019] FIG. 11 is a sectional side view showing the device in a
clutched state.
[0020] FIG. 12 is a sectional side view showing the device in a
declutched state.
[0021] FIG. 13 is a sectional side view showing an alternative of
the free lock.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0022] A first aspect of the instant invention is to provide a dose
display mechanism for a drug delivery device comprising: [0023] a
dose setting dial having an external thread and external grooves
extending from the proximal end to the distal end; and [0024] a
counter ring in interlocking relationship with the external grooves
of the said dose setting dial such that said counter ring is free
to move axially along said external grooves with respect to the
said dose setting dial whilst being prevented from rotation with
respect to the said dose setting dial.
[0025] It is a second aspect of the instant invention to provide a
drug delivery device comprising a) a drive mechanism and b) the
dose display mechanism of the instant invention.
[0026] A third aspect of the instant invention is the use of a dose
display mechanism according to the invention in a method of
assembling a device according to the invention.
[0027] A fourth aspect of the instant invention is the use of a
device according to the invention for the administration of a
pharmaceutical formulation to the human or animal body.
[0028] Another aspect of the instant invention is a method of
assembling a drug delivery device according to the invention,
comprising the step of mounting the mechanism according to the
invention to any components in order to assemble a drug delivery
device.
[0029] The terms, which are used in order to define the instant
invention, are generally to be understood in accordance with the
general knowledge of the person skilled in the art. Further, the
following terms shall have the following, optionally preferred,
meaning in accordance with the instant invention.
[0030] The term "drug delivery device" according to the instant
invention shall preferably mean a multi-dose, disposable, mobile,
hand-held device designed to dispense a selected dose of
medicament, e.g., insulin, insulin analogues, growth hormones, low
molecular heparins, and their derivatives, etc., optionally
suitable for self-administration. Said device is usually of the
mechanical type. More preferred, the term "drug delivery device"
shall mean a disposable, multi-dose, pen-type device having
mechanical dose delivery and dose selection mechanisms designed for
regular injection by persons without formal medical training, e.g.,
patients.
[0031] Usually, the "drug delivery device" of the instant invention
comprises a cartridge, which contains a pharmaceutical formulation,
which can be administered via a needle, and, optionally a cartridge
holder.
[0032] The term "pharmaceutical formulation" shall preferably mean
a liquid or suspension or the like contained in the cartridge,
comprising a drug or vaccine. The drug may contain one or more
proteins, peptides, or small molecules, which may be administered
subcutaneously. Preferably, the drug is one or more hormone or
antithrombotic, especially selected from the group consisting of
insulins, heparins, derivatives, analogous, and substitutes
thereof.
[0033] The term "dose setting dial" according to the instant
invention shall preferably mean an essentially tubular component of
essentially circular cross-section having an external thread
engaged with the housing by means of a first screw structure,
allowing the dose setting dial to rotatably move towards the
proximal end during dose setting and rotatably move towards the
distal end during dose dispensing. The "dose setting dial"
according to the instant invention is designed to indicate a
selected dose of the dispensable pharmaceutical formulation. This
may be achieved by use of markings, symbols, numerals, etc., e.g.,
printed on the external surface of the dose setting dial.
[0034] Additionally, the dose setting dial may be releasibly
connected to the inner cylinder by a dutch means. To set the dose,
the dose setting dial may be rotated and the dose setting dial and
the inner cylinder rotate together towards the proximal end. During
dose dispensing, the dutch means may disengage the dose setting
dial from the inner cylinder, such that the dose setting dial may
rotate relative to the inner cylinder towards the distal end.
Further, the dose setting dial may comprise one or more stops to
limit the maximum amount of a single dose.
[0035] The term "original position" according to instant invention
shall mean the starting position of the dose setting dial, i.e.,
when the set amount of dosage is zero ("00"). This is usually the
case, when the device has not yet been used, a full cartridge has
been loaded, or the device is in use and the set amount of drug has
been completely expelled, respectively, dispensed.
[0036] The term "inner cylinder" according to the instant invention
shall preferably mean any essentially tubular component of
essentially circular cross-section, releasibly connected to the
dose setting dial, such that relative rotation between said dose
setting dial and said inner cylinder is prevented during dose
setting but is allowed during dose dispensing. In a preferred
embodiment, the inner cylinder is further engaged with the piston
rod by means of a free lock. In another preferred embodiment, the
inner cylinder is further engaged with the piston rod in order to
allow the lead screw to rotate with the inner cylinder during dose
setting, e.g., by means of splined projections located in a key way
in the inner surface of the inner cylinder. During dose dispensing,
the inner cylinder is disengaged from the dose setting dial by a
dutch means and is moved towards the distal end without rotation
(with respect to the housing).
[0037] The term "releasibly connected" according to the instant
invention shall mean that two components of the instant mechanism
or device are reversibly joined with each other, allowing coupling
and decoupling. This is achieved, e.g., by a dutch means.
[0038] The term "dutch means" according to the instant invention
shall mean any means, which releasibly connects the dose setting
dial and the inner cylinder and which is designed to allow rotation
of the dose setting dial and the inner cylinder with respect to the
housing when the dose setting dial and the inner cylinder are
coupled and, when both are de-coupled, allows rotation of the dose
setting dial with respect to the housing, but does not allow
rotation of the inner cylinder with respect to the housing and
allows axial movement of the inner cylinder. Accordingly, the term
"dutch means" is any dutch engaging for the purpose of reversibly
locking two components in rotation, e.g., by use of axial forces to
engage a set of face teeth (saw teeth, dog teeth, crown teeth) or
any other suitable frictional faces.
[0039] The term "counter ring" according to the instant invention
shall preferably mean a component, which is in an interlocking
relationship to the dose setting dial. In a preferred embodiment,
the counter ring is assembled concentrically on the outer
circumference of the dose setting dial (essentially circular
shape), optionally adjacent to the front side (at the distal end)
of the threaded insert [screw lead].
[0040] In another preferred embodiment, a positioning means is
provided to prevent the counter ring from axial movement with
respect to the housing during dose setting and dose dispensing, but
allowing rotational movement of the counter ring with respect to
the housing during dose setting and dose dispensing. This may be
achieved by assembling a positioning collar on the outer
circumference of the dose setting dial adjacent to the distal end
of the counter ring, which is optionally integrated into the
housing.
[0041] The "counter ring" shall serve to indicate one digit of the
amount of the set dose by means of indices along its outer
circumference, whereas one or more further indices of the set dose
are indicated along the outer circumference of the dose setting
dial. Preferably, dialing of the "counter ring" shall enable the
smallest increments of the dose (e.g., terms, eights, quarters, or
halves of a unit, or single units) to be set.
[0042] The term "interlocking relationship" according to the
instant invention shad mean any constructive connection of the
counter ring and the dose setting dial, which allows both, the
counter ring and the dose setting dial, to rotate together with
respect to the housing, preferably by means of a screw structure
(e.g., thread, groove, rib), and also allows longitudinal axial
movement of the dose setting dial with respect to the counter ring,
when the dose setting dial is moved (either towards the proximal
end or the distal end). Preferably, the counter ring remains
visible in the display window and displays the set dose (amount of
drug) when the dose setting dial is screwed out in order to set the
dose.
[0043] The term "drive mechanism" according to the instant
invention shall mean any mechanism (e.g., lead screw, rack and
pinion, gear box), which allows force transmission from the
proximal to the distal end of a drug delivery device for the
purpose of dispensing a pharmaceutical and which is engaged with
the dose dialing mechanism of the instant invention.
[0044] The term "housing" according to the instant invention shall
preferably mean an exterior or interior ("insert") cover. The
housing may be designed to enable the safe, correct, and
comfortable handling of the drug delivery device (e.g., the drive
mechanism). Usually, it is designed to house, fix, protect, guide,
and/or engage with the inner mechanism(s) or components of the drug
delivery device (e.g., the drive mechanism) by limiting the
exposure to contaminants, such as liquid, dust, dirt, etc. In
general, the housing may be unitary or a multipart component of
tubular or non-tubular shape. Preferably, the "housing" is designed
to contain a cartridge and optionally a cartridge holder, which is
preferably mounted at the distal end of the housing.
[0045] The term "engaged" according to the instant invention shah
mean the interlocking of two or more components of the dose display
mechanism/drug delivery device, preferably the interlocking of
screw structures of components.
[0046] The term "screw structure" according to this application
shall mean a full or part thread, e.g., a cylindrical spiral
rib/groove located on the internal and/or external surface of a
component of the drug delivery device, having an essentially
triangular or square or rounded section designed to allow
continuous free rotational and/or axial movement between
components. Optionally, a screw structure may be further designed
to prevent rotational or axial movement of certain components in
one direction. Screw structures are incorporated between the
threaded insert and the dose setting dial (hereinafter the "first
screw structure"), between the inner cylinder and the free lock
(hereinafter the "second screw structure") and between the lead
screw and the plunger rod (hereinafter the "third screw
structure"). The said screw structures according to instant
invention shall preferably have different screw pitches to allow
force transmission from the proximal end to the distal end during
dose delivery. Therefore, the screw pitch ratios between the 1st,
2nd, and 3rd screw structures are about 1.8-4.2:1.8-4.2:1,
preferably about 2.4-3.6:2.4-3.6:1.
[0047] It is further preferred that the screw pitches of the 1st
screw structure and the 2nd screw structure are the same.
[0048] The term "plunger rod" according to this application shah
mean a component of the drive mechanism, which is adapted to
operate through/within the housing, designed to transfer forces
from the proximal end to the distal end of the drug delivery
device, preferably to the cartridge piston, for the purpose of drug
dispensing. According to instant invention, the "plunger rod" is
essentially cylindrical, hollow and has a non-circular
cross-section. The "plunger rod" is a component of the drive
mechanism, which is prevented from rotation with respect to the
housing by means of the plunger rod holder. The "plunger rod" abuts
the cartridge piston at the distal end of the plunger rod. In a
particular embodiment, the "plunger rod" has ratchet teeth or the
like which interact with the plunger rod holder.
[0049] The term "plunger rod holder" according to instant invention
shall mean any component which prevents movement of the plunger rod
towards the proximal end during dose setting, but allows movement
of the plunger rod towards the distal end during dose dispensing.
Optionally, the plunger rod is also prevented from rotation by the
plunger rod holder. In order to achieve the aforementioned, the
plunger rod holder engages with the plunger rod, e.g., by means of
ratchet teeth and ratchet teeth arms.
[0050] The plunger rod holder may be a separate component or be an
integral part of the housing or any other component. Furthermore,
there are many other suitable solutions within the knowledge of the
person skilled in the art in order to essentially prevent the
plunger rod from movement in the proximal direction.
[0051] The term "distal end" according to the instant invention
shah mean the end of the device or a component of the device, which
is closest to the dispensing end of the device.
[0052] The term "proximal end" according to the instant invention
shall mean the end of the device or a component of the device,
which is furthest away from the dispensing end of the device.
[0053] The term "periphery" according to the instant invention
shall usually mean the surface of any part, preferably the surface
along the longitudinal axis.
[0054] The term "lead screw" according to the instant invention
shall mean any essentially cylindrical component, which is engaged
with the plunger rod, preferably threadedly engaged, and rotates
with respect to the plunger rod when moving towards the proximal
direction during dose setting, and moving axially towards the
distal end without rotation during dose dispensing. In a preferred
embodiment, the lead screw is further engaged with a free lock,
(e.g., a friction dutch, a thrust bearing or the like), preferably
threadedly engaged.
[0055] The term "free lock" shall mean an essentially cylindrical
component, which is engaged between the inner surface of the inner
cylinder and the lead screw, preferably at the proximal end of the
lead screw. The "free lock" rotates and moves axially relative to
the inner cylinder by means of a screw structure.
[0056] The free lock is rotatable relative to the lead screw,
whilst movement of the free lock in the axial direction is not
possible with respect to the lead screw. Preferably, during dose
setting and dose dispensing, relative rotational movement between
(a) the free lock and the inner cylinder, and (b) the free lock and
the lead screw is allowed and relative axial movement between the
free lock and the inner cylinder is allowed, whilst relative axial
movement between the free lock and the lead screw is
restricted.
[0057] In a more particular embodiment, the free lock is threadedly
engaged between the inner surface of the inner cylinder and the
external surface of the lead screw, optionally at the proximal end
of the lead screw.
[0058] In yet another preferred embodiment, the free lock is fixed
to the plunger rod holder, whereby relative axial movement between
the free lock and the lead screw is not restricted. Accordingly,
the term "free lock" means a mechanism combining the
characteristics of both a dutch mechanism (e.g., a slip dutch) and
a force reduction mechanism.
[0059] The term "display window" according to the instant invention
shall mean any opening in the housing, e.g., a hole, or a
transparent section in the housing, which allows the status of the
device to be displayed, preferably, the status of dose setting,
particularly, the amount of set dose. This may be achieved by means
of a dose indicator, which exhibits one or more numerical and/or
graphical symbols, values and/or characters, preferably two or
three digits, in order to indicate the set dose. In another
preferred embodiment, the "display window" displays the value of
the selected dose consisting of one or more digits indicated along
the outer circumference of the counter ring, and one or more digits
indicated along the outer circumference of the dose setting dial.
In another embodiment, the display window is located essentially at
the proximal end of the device.
[0060] The present invention describes a dose display mechanism
consisting of a dose setting dial and a counter ring each
displaying indices on their outer circumference arranged such that
a two-indices representation of the selected dose can be displayed.
By such an arrangement it is possible to maximize the size of the
indices of the display, thus, making it suitable for use by
visually impaired users.
[0061] According to the drug delivery device of instant invention,
the distal end of the plunger rod abuts the cartridge piston and
the proximal end of the plunger rod is engaged with the lead screw.
During dose setting, the lead screw is driven to rotate by the
inner cylinder towards the proximal end with respect to the
plunger. The plunger rod and lead screw are configured in a
telescopic-like structure, thereby reducing the overall length of
the drive mechanism.
[0062] Further, the plunger rod is engaged with the plunger rod
holder, such that rotational movement during both dose setting and
dose dispensing is prevented. The plunger rod holder is also
designed to prevent linear movement of the plunger rod towards the
proximal end during dose setting but allow distal linear movement
of the plunger rod during dose dispensing. The mechanism of instant
invention allows dose setting to be performed repeatedly with great
accuracy.
[0063] Proximal axial movement of the plunger rod during dose
setting is prevented by the use of ratchet teeth formed along the
outer periphery of the plunger rod which engage with a plurality of
ratchet teeth arms formed on the plunger rod holder.
[0064] Rotational movement of the non-circular cross-section
plunger rod is prevented by it being inserted in a corresponding
non-circular passage way formed in the plunger rod holder.
[0065] The invention is described in further detail with reference
to the following figures.
[0066] FIG. 1 shows a perspective view of the dose display
mechanism consisting of the said dose setting dial (22) and the
counter ring (30) indicating the helical thread (111), rib grooves
(64) and a preferred starting position of the counter ring (30).
FIG. 1 shows only one digit (66b) on the outer surface of the dose
setting dial (22) for more clarity in accordance with the display
window (62).
[0067] FIG. 2a shows schematically a plan and perspective view of
the counter ring (30). In this embodiment, the counter ring (30)
has unit numbers (66a) on the external surface. Preferably, the
interior diameter of the counter ring (30) is essentially the same
size as the exterior diameter of the dose setting dial (22). FIG.
2b indicates a preferred embodiment of the counter ring (30). The
inner surface of the counter ring (30) is provided with ribs (63)
formed, preferably, in the longitudinal axis and designed to mesh
with rib grooves (64) located on the external surface of the dose
setting dial (22) as indicated in FIG. 1.
[0068] FIG. 3 shows schematically a plan view of the dose setting
dial (22). In this embodiment, the dose setting dial (22) has tens
numbers (66b) on the external surface, preferably arranged so that
each single digit, e.g., 1, 2, 3, . . . , 9, occurs ten times so
that it corresponds with the counter ring during one full rotation
of 360.degree. to make a two-digit number, e.g., 10, 11, 12, . . .
, 19. A further full rotation of 360.degree. will present two-digit
numbers in the order 20, 21, 22, . . . , 29. Further full rotations
will yield corresponding two-digit numbers relating to 30's, 40's,
50's, etc., up to the maximum possible dose. The digits are
preferably arranged helically on the outer surface of the dose
setting dial (22) in a pitch corresponding to the pitch of the
helical thread (111) of the dose setting dial (22). The helical
thread (111) and the grooves (62) are not shown in FIG. 3.
[0069] FIG. 4 indicates a preferred embodiment of the dose display
mechanism in a drug delivery device (1) showing the preferred
position of the digits (66b) of the dose setting dial (22) and the
digits (66a) of the counter ring (30) in the display window
(62).
[0070] FIG. 5 shows schematically a preferred embodiment of a drug
delivery device in which the dose setting dial (22) and the counter
ring (30) are assembled to a drive mechanism as disclosed in the
co-application to this entitled, "Drive Mechanism for a Drug
Delivery Device", PCT/EP2005/009839, which is herewith incorporated
by reference. In this embodiment, the dose setting dial (22) is
engaged with the housing (2) via the first screw structure (35),
which incorporates the threaded insert (31). The dose setting dial
(22) is free to rotate with respect to the housing (2) and also to
move towards the proximal end during dose setting and towards the
distal end during does delivery with respect to the housing (2).
The counter ring (30) is prevented from axial movement towards the
proximal end during dose setting and axial movement towards the
distal end during dose dispensing with respect to the housing (2)
by a positioning collar (65) preferably secured to the inner
surface of the housing (2) and more preferably formed as an
integral part of the housing (2). However, the counter ring (30) is
free to rotate with respect to the housing (2) due to its
engagement with the dose setting dial (22).
[0071] An exemplary drive mechanism for the device (1) is described
with reference to FIGS. 4 and 6.
[0072] The device is of the mechanical pen type and consists of:
[0073] a housing (2); [0074] a cartridge-holder (2a) coupled to the
distal end of the housing (2); [0075] a cartridge (3), sealed by a
piston (8) mounted in the proximal end of the cartridge and
containing a liquid (4) drug, mounted in the cartridge-holder (2a);
[0076] a removable cap (12) attached to the distal end of the
device; [0077] a piston driving assembly (21) assembled in the
proximal end of the housing (2).
[0078] The piston driving assembly transfers an activation force
from the proximal end to the distal end during dispensing. The
piston driving assembly (21) consists of a dose setting dial (22),
an inner cylinder (23), a free lock (24), a lead screw (25), a
plunger rod (26), a plunger rod holder (27), a release knob (28), a
dose indicator (or counter) (29), a counter ring (30) and a
threaded insert (31).
[0079] Screw structures are incorporated between the threaded
insert (31) and the dose setting dial (22) the "first screw
structure"), between the inner cylinder (23) and the free lock (24)
(i.e., the "second screw structure"), and between the lead screw
(25) and the plunger rod (26) the "third screw structure").
[0080] Operation of the device will now be described. To set a
desired dose to be delivered, a user rotates the rotating knob
(22a) of the dose setting dial (22), thus moving the dose setting
dial towards the proximal end by means of the first screw structure
(35). During dose setting relative rotation between the dose
setting dial (22) and the inner cylinder (23) is prevented by a
dutch (56), thus allowing the inner cylinder.
[0081] When the inner cylinder (23) rotates towards the proximal
end during dose setting, the lead screw (25) rotates integrally
with the inner cylinder (23) with respect to the plunger rod (26)
by virtue of a pair of splined projections (50) located in a key
way (51) in the inner surface of the inner cylinder (23). When the
lead screw (25) rotates out of the plunger rod (26) towards the
proximal end, the plunger rod holder (27) locks the plunger rod
(26) to prevent the plunger rod from being displaced towards the
proximal end, thus, maintaining the abutment with the piston
(8).
[0082] The rotation of the inner cylinder (23) further moves the
free lock (24) towards the distal end through the second screw
structure (44).
[0083] The set dose in the current embodiment is indicated by
numerical values (66) on the indicator (counter) (29) and the dose
setting dial (22) displayed in the display window (62).
[0084] To administer a selected dose to a patient, the user
depresses the release knob (28) towards the distal end, uncoupling
the dose setting dial (22) from the inner cylinder (23) allowing
the dose setting dial to rotate relative to the inner cylinder and
move towards the distal end. The inner cylinder (23) moves axially
towards the distal end, thus, rotating the free lock (24) in a
proximal direction at a predetermined speed-reducing ratio
transferring the axial movement of the inner cylinder (23) to the
lead screw (25) moving it axially towards the distal end. The lead
screw (25), thus, pushes the plunger rod (26) towards the distal
end. This, in turn, pushes the piston (8) towards the distal end
expelling the contents from the cartridge (3) through the needle
(5) into the patient.
[0085] Details of the device of embodiment 1 are described with
reference to FIGS. 6-10.
[0086] The threaded insert (31) is concentrically assembled and
secured to the inside of the proximal end portion (2b) of the
housing (2) by suitable methods known by those skilled in the art.
The threaded insert (31) is threadedly engaged with the essentially
cylindrically shaped dose setting dial (22) forming the first screw
structure (35). The dose setting dial (22) is mounted to allow
rotational movement towards the proximal end during dose setting
and the distal end during dose delivery. Stops (22d), preferably in
the form of a pawl, are formed on the distal end of the dose
setting dial (22).
[0087] A cylindrical rotating knob (22a) haying a diameter equal to
the outer diameter of the housing is attached to the proximal end
of the dose setting dial (22). Serrations (22b) are formed on the
outer surface of the rotating knob (22a) to improve grip for the
user.
[0088] The inner cylinder (23) is assembled concentrically within
the dose setting dial (22) and is releasibly connected to the dose
setting dial (22) by a dutch means (56). An essentially
cylindrically shaped flange portion is formed at the proximal end
(23a) of the inner cylinder (23) and inserted into the hollow
recess (22c) of the rotating knob (22a).
[0089] The outer surface of the free lock (24) is threadedly
engaged with the inner surface of the inner cylinder (23) forming
the second screw structure (44). The free lock (24) is free to
rotate and move axially towards the distal end and the proximal end
within the inner cylinder (23).
[0090] The inner surface of the free lock (24) is threadedly
engaged with the outer surface of the proximal end of the
essentially non-circular cross section lead screw (25). The free
lock (24) is free to rotate on the outer surface of the lead screw
(25) and move axially towards the distal end and the proximal end
of the lead screw (25).
[0091] The distal end of the lead screw (25) is threadedly engaged
with the proximal end of the plunger rod (26) forming the third
screw structure (47).
[0092] The essentially non-circular cross-section, preferably a
square tube shape, plunger rod (26) has small pitch ratchet teeth
(38) on its outer surface, preferably on two opposing faces of the
outer surface.
[0093] The plunger rod holder (27) is secured to the inner side of
the distal end of the housing (2) by any suitable means known by a
person skilled in the art. A square passageway (37), having a
dimension equal to the outer diameter of the plunger rod (26), is
formed in the centre of the plunger rod holder (27). The plunger
rod (26) is engaged with the square passageway (37), such that
rotation of the plunger rod (26) is prevented by the plunger rod
holder (27).
[0094] A plurality of pairs of flexible ratchet teeth arms (39),
preferably two, is formed on the plunger rod holder (27). These
form the ratchet mechanism (40) of the device. Further embodiments
could be envisaged where three or four ratchet teeth arms are
formed on the plunger rod holder (27) having, for example,
90.degree. (e.g., 4 arms) or 120.degree. (e.g., 3 arms) offset or
the like.
[0095] The ratchet mechanism (40) is engaged with the ratchet teeth
(38) of the plunger rod (26) such that axial movement of the
plunger rod (26) towards the proximal end is prevented but axial
movement of the plunger rod (26) towards the distal end is
allowed.
[0096] A plurality of spline grooves (49), preferably two, is
formed on the inner surface of the inner cylinder (23). A plurality
of splined projections (50), preferably two, is formed on the outer
surface of the proximal end of the lead screw (25). The splined
projections (50) engage with the spline grooves (49) of the inner
cylinder (23) permitting axial movement of the lead screw (25)
towards the distal end and the proximal end with respect to the
inner cylinder (23). The spline grooves (49) and the splined
projections (50) together form a splined structure (51).
[0097] A release knob (28) of essentially cylindrical shape, open
at the distal end and dosed at the proximal end, is assembled
concentrically in the hollow (22c) on the inner side of the
rotating knob (22a). An annular rib (53) is formed on the outer
circumference of the release knob (28) and is engaged with an
annular groove (52) on the inner circumference of the rotating knob
(22a). The release knob (28) is thus free to rotates and move
axially towards the distal end and the proximal end with respect to
the rotating knob (22a). Movement of the release knob (28) towards
the distal end and the proximal end is limited by the width of the
annular groove (52).
[0098] The release knob (28) moves such that it can be brought in
and out of abutment with the flange portion (23b) of the inner
cylinder (23).
[0099] A wave-shaped annular (54), e.g., as teeth or the like, is
formed on the distal end face of the flange portion (23b) of the
inner cylinder (23) and is engaged with a corresponding wave-shaped
shoulder (55) on the dose setting dial (22). The wave-shaped
annular (54) and the wave-shaped shoulder (55) together form a
first dutch (56) releasibly connecting the dose setting dial (22)
and the inner cylinder (23) such that relative rotational movement
is prevented during dose setting.
[0100] A second dutch (60) is formed between the proximal end of
the inner cylinder (23) and the inner face of the release knob
(28). The second dutch (60) consists of two complementary
wave-shaped configurations, teeth-shaped configurations or the like
located on the release knob (28) and the inner cylinder (23).
[0101] In the present embodiment, the set dose is indicated as a
numerical value on the counter ring (30) and the dose setting dial
(22). The set dose is viewed through a display window (62) located
at the proximal end of the housing (2). The display window (62) of
the present embodiment is open, although a transparent lens could
be used to cover the display window (62) to prevent the ingress of
dirt, dust, liquid, etc., into the mechanism and/or act as a
magnifier.
[0102] The counter ring (30) is engaged with the dose setting dial
(22) by means of a plurality of rib grooves (64) formed on the
outer circumference of the dose setting dial (22) from its distal
end to its proximal end, and a corresponding number of ribs (63)
formed on the inner surface of the counter ring (30). The counter
ring (30) can move axially towards both the proximal end and distal
end of the dose setting dial (22). To prevent axial movement of the
counter ring (30) with respect to the dose setting dial (22), a
positioning collar (65) is assembled on the outer circumference of
the dose setting dial (22) and secured to the inner surface of the
housing (2) adjacent to the proximal end of the counter ring (30).
A cylindrical positioning collar (65), integrated into the housing
(2), abuts the distal end of the counter ring (30). Thus, the
counter ring (30) is able to rotate with the dose setting dial (22)
with respect to the housing during dose setting and dose delivery,
but is prevented from axial movement with respect to the housing
(2).
[0103] In the present embodiment, the counter ring (30) displays
the "unit" values for the set dose from "0" to "9". The "tens"
values are indicated on the dose setting dial (22) such that during
on complete revolution of the counter ring (30) the corresponding
"tens" value is continuously displayed.
[0104] All three screw structures in the device according to
instant invention (i.e., 35, 44, and 47) have differing screw
pitches. The ratio in the screw pitches between the first (35), the
second (44) and the third screw structure (47) is about 3:2:1, in
order to achieve an efficient reduction of transmission forces
("speed reduction") of the screw structures.
[0105] Embodiment 2 of the device (1) is described with reference
to FIGS. 11 and 12.
[0106] The present embodiment 2 includes a modification to the
first dutch (56), between the dose setting dial (22) and the inner
cylinder (23).
[0107] FIG. 11 indicates an alternative dutch (57) that is located
at the proximal end of the inner cylinder (23). The dutch (57)
consists of conical cam faces (57a) and a plurality of
equidistantly spaced first engaging portions (54a). Through the
axial movement of the release knob (28) either towards the distal
end or towards the proximal end, the dutch (57) can be compressed
or expanded to cause the first engaging portions (54a) to engage
with or disengage from the corresponding second engaging portion
(54b) formed on the inner face of the rotating knob (22a). The
first engaging portions (54a) and the second engaging portion (54b)
are engaged, e.g., by the spring force of a pair of spring acting
portions (not shown).
[0108] During dose setting, the first engaging portions (54a) and
second engaging portion (54b) are engaged under the spring force,
thus, coupling the inner cylinder (23) with the dose setting dial
(22) and preventing relative rotation between the inner cylinder
(23) and the dose setting dial (22).
[0109] During dose dispensing, the release knob (28) is pushed in
the distal direction disengaging the first engaging portions (54a)
from the second engaging portion (54b), thereby disconnecting the
dose setting dial (22) from the inner cylinder (23) and allowing
the dose setting dial (22) to rotate with respect to the inner
cylinder (23).
[0110] The mechanism and the device of the present invention is not
limited to the embodiments 1 and 2 described above, but allows
various effective alterations based on the technical idea of the
present invention. For example, FIG. 13 shows an alternative
solution, wherein the free lock is fixed to the plunger rod holder.
In this case, the screw pitch ratios between the 1st, 2nd and 3rd
screw structures are about 3:3:1.
* * * * *