Note: Descriptions are shown in the official language in which they were submitted.
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Description
Drive mechanism for a drug delivery device
The invention concerns a drive mechanism for a drug delivery device.
In a drug delivery device, a piston within a cartridge that contains a drug
may be
displaced with respect to the cartridge in the distal direction by a piston
rod which
moves in the distal direction with respect to the cartridge.
A fixed dose pen injector is a device that can be used to inject a number of
set dose
sizes from a pre-filled cartridge which may be made of glass. This may be
ideally suited
for chronic daily therapies where repeat doses of the same size are regularly
required.
The device may be disposable or reusable.
It is an aim of the invention to provide a drive mechanism which can be reset.
For achieving this aim a drive mechanism for a drug delivery device which can
be
switched between a normal operation mode and a reset mode is provided. The
drive
mechanism comprising
- a housing having a proximal end and a distal end,
- a piston rod which is adapted to be displaced in a distal direction with
respect to the
housing for delivering a dose in a normal operation mode of the drive
mechanism, and
which is adapted to be displaced in the proximal direction with respect to the
housing in
a reset mode of the drive mechanism, and
- a drive member which is rotationally moveable in a rotation direction with
respect to
the housing, wherein, in the normal operation mode, the drive member is
coupled with
the piston rod so that rotational movement of the drive member in the rotation
direction
with respect to the housing is converted into movement of the piston rod in
the distal
direction with respect to the housing, and wherein, in the reset mode, the
piston rod is
decoupled from the drive member.
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This drive mechanism can be reset which enables to replace a cartridge after
delivering
all doses and replacing the cartridge by a new one containing a drug. During
this
change the drive mechanism must be reset. The device can be reset easily by
the user.
Moreover, the device is reusable, thus saving the environment.
In the normal operation mode, rotational movement in the rotation direction of
the drive
member with respect to the housing may be converted into rotational movement
of the
piston rod in the same direction, in the reset mode the piston rod being
rotatable with
respect to the drive member. In other words, in the reset mode the piston rod
is
decoupled from the drive member so that the piston can rotate in the proximal
direction
to an initial start position.
In one embodiment the drive member is splined to the piston rod in the normal
operation mode. The drive member is unsplined to the piston rod in the reset
mode. The
splined connection is retractable, which means that the splines engage with
the piston
rod in the normal operation mode, the splines being disengaged from the piston
rod in
the reset mode.
An alternative embodiment of the drive mechanism operates in a different way.
In the
normal operation mode, rotational movement of the drive member with respect to
the
piston rod is converted into distal movement of the piston rod with respect to
the
housing, in the reset mode the piston rod being merely axially moved with
respect to the
drive member. The drive member is threadedly coupled with the piston rod in
the normal
operation mode. In the reset mode the drive member is not threadedly coupled
any
more, which may be achieved by separating the protrusions forming an outer
thread of
the threaded connection from tracks of the piston rod forming an inner thread
of the
threaded connection. This enables to axially shift the piston rod to its
initial start
position.
One embodiment of the drive mechanism is suitable for being releasably
connected with
a cartridge holder, wherein the drive mechanism is switched to the reset mode
when the
cartridge holder is detached from the drive mechanism. In other words,
detaching and
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attaching the cartridge holder serves as a trigger for switching between the
operation
modes.
One embodiment of the drive member, which has an inner side facing the piston
rod
and an outer side facing away from the piston rod, comprises engagement means.
In
the normal operation mode the engagement means protrudes inwardly and engages
with a track in the piston rod. In the reset mode the engagement means
protrudes
outwardly. The engagement means may be integrally formed with the drive
member,
e.g. a tongue-shaped part which can be pushed inwardly, thereby splining the
drive
member with the piston rod. Alternatively the engagement means may be formed
as
separate parts which are coupled to the drive member, e.g. a rivet-shaped
engagement
means which is moveable radially.
In one embodiment engagement means comprises a spring, the engagement means
being biased outwardly. Preferably the drive member is decoupled from the
piston rod in
this position.
The drive mechanism may further comprise a push means which is moved to a
position
so that it pushes the engagement means inwardly when the drive mechanism is
switched to the normal operation mode. In the reset mode the push means is
moved
away from the engagement means so that it moves outwardly. Alternatively, the
drive
mechanism comprises a push means, wherein the drive member is moved with
respect
to push means so that the push means pushes the engagement means inwardly when
the drive mechanism is switched to the normal operation mode. In other words,
the
push means can be pushed towards the engagement means or the engagement means
can be pushed towards the push means.
One embodiment of the engagement means is formed as a spring having a
protruding
element which engages the drive member and the piston rod in the normal
operation
mode, thereby splining the drive member to the piston rod. The protruding
element is
biased so that the drive member is rotatable with respect to the piston rod.
The spring is
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deformable so that the protruding element locks the drive member and the
piston rod in
rotation.
In one embodiment the drive member has a track and the piston rod has a track.
The
protruding element engages with the tracks in the normal operation mode. The
track of
the drive member may be formed as a trench through which the protruding
element may
extend in the track of the piston rod.
In one embodiment a push means is provided which is moveable in a position so
that it
pushes the protruding element in the tracks of the drive member and the piston
rod. The
push member may push on the protruding element, thereby coupling the drive
member
with the piston rod.
The term "drug", as used herein, preferably means a pharmaceutical formulation
containing at least one pharmaceutically active compound,
wherein in one embodiment the pharmaceutically active compound has a molecular
weight up to 1500 Da and/or is a peptide, a proteine, a polysaccharide, a
vaccine, a
DNA, a RNA, an enzyme, an antibody, a hormone or an oligonucleotide, or a
mixture of
the above-mentioned pharmaceutically active compound,
wherein in a further embodiment the pharmaceutically active compound is useful
for the
treatment and/or prophylaxis of diabetes mellitus or complications associated
with
diabetes mellitus such as diabetic retinopathy, thromboembolism disorders such
as
deep vein or pulmonary thromboembolism, acute coronary syndrome (ACS), angina,
myocardial infarction, cancer, macular degeneration, inflammation, hay fever,
atherosclerosis and/or rheumatoid arthritis,
wherein in a further embodiment the pharmaceutically active compound comprises
at
least one peptide for the treatment and/or prophylaxis of diabetes mellitus or
complications associated with diabetes mellitus such as diabetic retinopathy,
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wherein in a further embodiment the pharmaceutically active compound comprises
at
least one human insulin or a human insulin analogue or derivative, glucagon-
like
peptide (GLP-1) or an analogue or derivative thereof, or exedin-3 or exedin-4
or an
analogue or derivative of exedin-3 or exedin-4.
Insulin analogues are for example Gly(A21), Arg(B31), Arg(B32) human insulin;
Lys(B3), Glu(B29) human insulin; Lys(B28), Pro(B29) human insulin; Asp(B28)
human
insulin; human insulin, wherein proline in position B28 is replaced by Asp,
Lys, Leu, Val
or Ala and wherein in position B29 Lys may be replaced by Pro; Ala(B26) human
insulin; Des(B28-B30) human insulin; Des(B27) human insulin and Des(B30) human
insulin.
Insulin derivates are for example B29-N-myristoyl-des(B30) human insulin; B29-
N-
palmitoyl-des(B30) human insulin; B29-N-myristoyl human insulin; B29-N-
palmitoyl
human insulin; B28-N-myristoyl LysB28ProB29 human insulin; B28-N-palmitoyl-
LysB28ProB29 human insulin; B30-N-myristoyl-ThrB29LysB30 human insulin; B30-N-
palmitoyl- ThrB29LysB30 human insulin; B29-N-(N-palmitoyl-Y-glutamyl)-des(B30)
human insulin; B29-N-(N-lithocholyl-Y-glutamyl)-des(B30) human insulin; B29-N-
(w-
carboxyheptadecanoyl)-des(B30) human insulin and B29-N-(w-
carboxyheptadecanoyl)
human insulin.
Exendin-4 for example means Exendin-4(1-39), a peptide of the sequence H-His-
Gly-
Glu-Gly-Thr-Phe-Thr-Ser-Asp-Leu-Ser-Lys-Gln-Met-Glu-Glu-Glu-Ala-Val-Arg-Leu-
Phe-
Ile-Glu-Trp-Leu-Lys-Asn-Gly-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser-NH2.
Exendin-4 derivatives are for example selected from the following list of
compounds:
H-(Lys)4-des Pro36, des Pro37 Exendin-4(1-39)-NH2,
H-(Lys)5-des Pro36, des Pro37 Exendin-4(1-39)-NH2,
des Pro36 [Asp28] Exendin-4(1-39),
des Pro36 [IsoAsp28] Exendin-4(1-39),
des Pro36 [Met(O)14, Asp28] Exendin-4(1-39),
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des Pro36 [Met(O)14, IsoAsp28] Exendin-4(1-39),
des Pro36 [Trp(02)25, Asp28] Exendin-4(1-39),
des Pro36 [Trp(02)25, IsoAsp28] Exendin-4(1-39),
des Pro36 [Met(O)14 Trp(02)25, Asp28] Exendin-4(1-39),
des Pro36 [Met(O)14 Trp(02)25, IsoAsp28] Exendin-4(1-39); or
des Pro36 [Asp28] Exendin-4(1-39),
des Pro36 [IsoAsp28] Exendin-4(1-39),
des Pro36 [Met(O)14, Asp28] Exendin-4(1-39),
des Pro36 [Met(O)14, IsoAsp28] Exendin-4(1-39),
des Pro36 [Trp(02)25, Asp28] Exendin-4(1-39),
des Pro36 [Trp(02)25, IsoAsp28] Exendin-4(1-39),
des Pro36 [Met(O)14 Trp(02)25, Asp28] Exendin-4(1-39),
des Pro36 [Met(O)14 Trp(02)25, IsoAsp28] Exendin-4(1-39),
wherein the group -Lys6-NH2 may be bound to the C-terminus of the Exendin-4
derivative;
or an Exendin-4 derivative of the sequence
H-(Lys)6-des Pro36 [Asp28] Exendin-4(1-39)-Lys6-NH2,
des Asp28 Pro36, Pro37, Pro38Exendin-4(1-39)-NH2,
H-(Lys)6-des Pro36, Pro38 [Asp28] Exendin-4(1-39)-NH2,
H-Asn-(Glu)5des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-NH2,
des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-(Lys)6-NH2,
H-(Lys)6-des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-(Lys)6-NH2,
H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-(Lys)6-NH2,
H-(Lys)6-des Pro36 [Trp(02)25, Asp28] Exendin-4(1-39)-Lys6-NH2,
H-des Asp28 Pro36, Pro37, Pro38 [Trp(02)25] Exendin-4(1-39)-NH2,
H-(Lys)6-des Pro36, Pro37, Pro38 [Trp(02)25, Asp28] Exendin-4(1-39)-NH2,
H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Trp(02)25, Asp28] Exendin-4(1-39)-NH2,
des Pro36, Pro37, Pro38 [Trp(02)25, Asp28] Exendin-4(1-39)-(Lys)6-NH2,
H-(Lys)6-des Pro36, Pro37, Pro38 [Trp(02)25, Asp28] Exendin-4(1-39)-(Lys)6-
NH2,
H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Trp(02)25, Asp28] Exendin-4(1-39)-(Lys)6-
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NH2,
H-(Lys)6-des Pro36 [Met(O)14, Asp28] Exendin-4(1-39)-Lys6-NH2,
des Met(O)14 Asp28 Pro36, Pro37, Pro38 Exendin-4(1-39)-NH2,
H-(Lys)6-desPro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-NH2,
H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-NH2,
des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-(Lys)6-NH2,
H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-(Lys)6-NH2,
H-Asn-(Glu)5 des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-(Lys)6-
NH2,
H-Lys6-des Pro36 [Met(O)14, Trp(02)25, Asp28] Exendin-4(1-39)-Lys6-NH2,
H-des Asp28 Pro36, Pro37, Pro38 [Met(O)14, Trp(02)25] Exendin-4(1-39)-NH2,
H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-NH2,
H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Met(O)14, Trp(02)25, Asp28] Exendin-4(1-
39)-
NH2,
des Pro36, Pro37, Pro38 [Met(O)14, Trp(02)25, Asp28] Exendin-4(1-39)-(Lys)6-
NH2,
H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Trp(02)25, Asp28] Exendin-4(S1-39)-
(Lys)6-NH2,
H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Met(O)14, Trp(02)25, Asp28] Exendin-4(1-
39)-
(Lys)6-NH2;
or a pharmaceutically acceptable salt or solvate of any one of the afore-
mentioned
Exedin-4 derivative.
Hormones are for example hypophysis hormones or hypothalamus hormones or
regulatory active peptides and their antagonists as listed in Rote Liste, ed.
2008,
Chapter 50, such as Gonadotropine (Follitropin, Lutropin, Choriongonadotropin,
Menotropin), Somatropine (Somatropin), Desmopressin, Terlipressin,
Gonadorelin,
Triptorelin, Leuprorelin, Buserelin, Nafarelin, Goserelin.
A polysaccharide is for example a glucosaminoglycane, a hyaluronic acid, a
heparin, a
low molecular weight heparin or an ultra low molecular weight heparin or a
derivative
thereof, or a sulphated, e.g. a poly-sulphated form of the above-mentioned
polysaccharides, and/or a pharmaceutically acceptable salt thereof. An example
of a
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pharmaceutically acceptable salt of a poly-sulphated low molecular weight
heparin is
enoxaparin sodium.
Pharmaceutically acceptable salts are for example acid addition salts and
basic salts.
Acid addition salts are e.g. HCI or HBr salts. Basic salts are e.g. salts
having a cation
selected from alkali or alkaline, e.g. Na+, or K+, or Ca2+, or an ammonium ion
N+(R1)(R2)(R3)(R4), wherein R1 to R4 independently of each other mean:
hydrogen,
an optionally substituted C1-C6-alkyl group, an optionally substituted C2-C6-
alkenyl
group, an optionally substituted C6-C10-aryl group, or an optionally
substituted C6-C10-
heteroaryl group. Further examples of pharmaceutically acceptable salts are
described
in "Remington's Pharmaceutical Sciences" 17. ed. Alfonso R. Gennaro (Ed.),
Mark
Publishing Company, Easton, Pa., U.S.A., 1985 and in Encyclopedia of
Pharmaceutical
Technology.
Pharmaceutically acceptable solvates are for example hydrates.
Further features, refinements and expediencies become apparent from the
following
description of the exemplary embodiments in connection with the figures.
Figure 1 schematically shows a partly sectional side view of an exemplary
embodiment
of a drug delivery device.
Figure 2 schematically shows a perspective sectional view of a part of a drive
mechanism according to a first embodiment with schematically indicated
movements of
elements thereof during setting of a dose.
Figure 3 schematically shows a more detailed side view of a part of Figure 2.
Figures 4 to 6 show side views of the drug delivery device during cartridge
change.
Figure 7 shows a sectional view of a part of one embodiment of the drive
mechanism in
a reset operation mode.
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Figure 8 shows a sectional view of the part of the embodiment of figure 7 in a
normal
mode.
Figure 9 shows a side view of a part of another embodiment of the drive
mechanism.
Figure 10 shows a sectional view of the part of the embodiment of figure 9.
Figure 11 shows an exploded view of a part of a further embodiment of the
drive
mechanism.
Figures 12A, 12B and 12C show sectional views of the embodiment of figure 11
in the
normal operation mode.
Figures 13A, 13B and 13C show sectional views of the embodiment of figure 11
in the
reset mode.
Figure 14A, 14B and 14C show different views of one embodiment of the drive
member.
Figures 15A and 15B show sectional views of the embodiment of figure 14 and a
piston
rod in the normal operation mode.
Figures 16A and 16B show sectional views of the embodiment of figure 14 and
the
piston rod in the reset mode.
Figure 1 shows a drug delivery device 1 which comprises a cartridge unit 2 and
a drive
unit 3. The cartridge unit 2 comprises a cartridge 4. Drug 5 is retained in
the cartridge 4.
The drug 5 is preferably liquid medication. The cartridge 4 preferably
comprises a
plurality of doses of the drug 5. The drug 5 may comprise insulin, heparin, or
growth
hormones, for example. The cartridge 4 has an outlet 6 at its distal end. Drug
5 can be
dispensed from the cartridge through outlet 6. The device 1 may be a pen-type
device,
in particular a pen-type injector. The device 1 may be a disposable or a
reusable device.
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The device 1 may be a device configured to dispense fixed doses of the
medication or
variable, preferably user-settable, doses. The device 1 may be a needle-based
or a
needle free device. The device 1 may be an injection device.
The term "distal end" of the drug delivery device 1 or a component thereof may
refer to
that end of the device or the component which is closest to the dispensing end
of the
device 1. The term "proximal end" of the drug delivery device 1 or a component
thereof
may refer to that end of the device or the component which is furthest away
from the
dispensing end of the device. In figure 1, the distal end of the device 1 was
assigned
reference numeral 7 and the proximal end of the device was assigned reference
numeral 8.
The outlet 6 may be covered by a membrane 9, which protects medication 5
against
external influences during storage of the cartridge. For drug delivery,
membrane 9 may
be opened, e.g. pierced. For example, membrane 9 may be pierced by a needle
unit
(not explicitly shown). The needle unit may be (releasably) attached to the
distal end of
the cartridge unit 2. The needle unit may provide for fluid communication from
the inside
of the cartridge 4 to the outside of the cartridge through outlet 6.
A piston 10 is retained within the cartridge 4. The piston 10 is movable with
respect to
the cartridge. The piston 10 may seal the drug 5 within the cartridge. The
piston 10
expediently seals the interior of the cartridge 4 proximally. Movement of the
piston 10
with respect to the cartridge 4 in the distal direction causes drug 5 to be
dispensed from
the cartridge through outlet 6 during operation of the device.
The cartridge unit 2 furthermore comprises a cartridge retaining member 11.
The
cartridge 4 is retained within the cartridge retaining member 11. The
cartridge retaining
member 11 may stabilize the cartridge 4 mechanically. Additionally or
alternatively, the
cartridge retaining member 11 may be provided with a fixing member (not
explicitly
shown) for attaching the cartridge unit 2 to the drive unit 3.
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The cartridge unit 2 and the drive unit 3 are secured to one another,
preferably
releasably secured. A cartridge unit 2 which is releasably secured to the
drive unit may
be detached from the drive unit 3, for example in order to allow for providing
for a new
cartridge 4, if all of the doses of medication which once were in the
cartridge formerly
attached to the drive unit 3 have already been dispensed. The cartridge
retaining
member 11 may be releasably secured to the drive unit 3 via a thread, for
example.
Alternatively, the cartridge retaining member 11 may be dispensed with. It is
particularly
expedient, in this case, to apply a robust cartridge 4 and to attach the
cartridge directly
to the drive unit 3.
The drive unit 3 is configured for transferring force, preferably user-exerted
force,
particularly preferably manually exerted force, to the piston 10 for
displacing the piston
10 with respect to the cartridge 4 in the distal direction. A dose of
medication may be
dispensed from the cartridge in this way. The size of the delivered dose may
be
determined by the distance by which the piston 10 is displaced with respect to
the
cartridge 4 in the distal direction.
The drive unit 3 comprises a drive mechanism. The drive mechanism comprises a
piston rod 12. The piston rod 12 may be configured for transferring force to
the piston
10, thereby displacing the piston in the distal direction with respect to the
cartridge 4. A
distal end face of the piston rod 12 may be arranged to abut a proximal end
face of the
piston 10. A bearing member (not explicitly shown) may be arranged to advance
the
piston 10, preferably to abut the proximal end face of the piston 10. The
bearing
member may be arranged between piston 10 and piston rod 12. The bearing member
may be fixed to the piston rod 12 or a separate member. If the piston rod 12
is
configured to be rotated during operation of the device, for example during
dose
delivery, it is particularly expedient to provide for a bearing member. The
bearing
member may be displaced together with the (rotating) piston rod with respect
to the
housing. The piston rod may be rotatable with respect to the bearing member.
In this
way, the risk that the rotating piston rod drills into the piston and thereby
damages the
piston is reduced. Accordingly, while the piston rod rotates and is displaced
with respect
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to the housing, the bearing member is preferably only displaced, i.e. does not
rotate.
The piston rod may be bounded by the bearing member.
The drive unit 3 comprises a housing 13 which may be part of the drive
mechanism.
The piston rod 12 may be retained in the housing. A proximal end side 14 of
the
cartridge unit 2 may be secured to the drive unit 3 at a distal end side 15 of
the housing
13, for example via a threaded connection. Housing 13, cartridge 4 and/or
cartridge
retaining member 11 may have a tubular shape.
The term "housing" shall preferably mean any exterior housing ("main housing",
"body",
"shell") or interior housing ("insert", "inner body") which may have a
unidirectional axial
coupling to prevent proximal movement of specific components. The housing may
be
designed to enable the safe, correct, and comfortable handling of the
medication
delivery device or any of its mechanism. Usually, it is designed to house,
fix, protect,
guide, and/or engage with any of the inner components of the medication
delivery
device (e.g., the drive mechanism, cartridge, piston, piston rod), preferably
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.
The term "piston rod" shall preferably mean a component adapted to operate
through/within the housing, which may be designed to transfer axial movement
through/within the medication delivery device, preferably from the drive
member to the
piston, for example for the purpose of discharging/dispensing an injectable
product.
Said piston rod may be flexible or not. It may be a simple rod, a lead-screw,
a rack and
pinion system, a worm gear system, or the like. "Piston rod" shall further
mean a
component having a circular or non-circular cross-section. It may be made of
any
suitable material known by a person skilled in the art and may be of unitary
or multipart
construction.
The drive unit 3 comprises a dose part 16. The dose part 16 is movable with
respect to
the housing 13. The dose part 16 may be movable in the proximal direction with
respect
to the housing for setting of a dose of the drug 5 which is to be delivered
and in the
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distal direction with respect to the housing for delivery of the set dose. The
dose part 16
is preferably connected to the housing 13. The dose part 16 may be secured
against
rotational movement with respect to the housing. The dose part 16 may be moved
(displaced) between a proximal end position and a distal end position with
respect to the
housing 13 (not explicitly shown). The distance by which the dose part is
displaced with
respect to the housing during setting of the dose may determine a size of the
dose. The
proximal end position and the distal end position may be determined by a
respective
stop feature which may limit the proximal or distal travel of the dose member
with
respect to the housing. The device 1 may be a variable dose device, i.e. a
device
configured for delivering doses of medication of different, preferably user-
settable,
sizes. Alternatively, the device may be a fixed dose device.
The device 1 may be a manually, in particular non-electrically, driven device.
The (user-
applied) force which causes the dose part 16 to be moved with respect to the
housing
13 in the distal direction may be transferred to the piston rod 12 by the
drive
mechanism. For this purpose, other elements of the drive mechanism may be
provided
which are not explicitly shown in Figure 1. The drive mechanism is preferably
configured
to not move the piston rod 12 with respect to the housing 13 when the dose
part is
moved in the proximal direction with respect to the housing for setting of the
dose.
Embodiments of a drive mechanism which are suitable to be provided in the
medication
delivery device 1 as it was described above are described in more detail
below.
An embodiment of a drive mechanism which is suitable for being implemented in
the
medication delivery device 1 as described above is described in connection
with the
following figures.
The drive mechanism comprises a housing part 17. The housing part 17 has a
proximal
end 18 and a distal end 19. The housing part 17 may be (outer) housing 13 of
Figure 1,
a part thereof or an insert within housing 13, this insert is preferably
secured against
rotational and axial movement with respect to housing 13. The housing part 17
may be
an insert sleeve, for example. The insert sleeve may be snap-fitted or glued
to housing
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13, for example. The housing part 17 may have a tubular shape. Housing part 17
may
comprise outer fixing elements, for example snap-fit elements, for fixing
housing part 17
to housing 13.
The piston rod 12 is retained in the housing 13, preferably within housing
part 17. The
piston rod 12 is driven in the distal direction with respect to the housing
part 17 during
dose delivery.
The drive mechanism furthermore comprises a drive member 20. Drive member 20
is
retained within the housing part 17. Drive member 20 is configured to transfer
force,
preferably torque, to the piston rod 12. The transferred force may cause the
piston rod
12 to be displaced in the distal direction with respect to the housing part 17
for dose
delivery.
Drive member 20 is rotatable with respect to housing part 17. The drive member
20 may
engage the piston rod 12. Rotational movement of the drive member, for example
rotational movement in a second direction may be converted into distal
movement of the
piston rod 12 with respect to the housing part 17. This is explained in more
detail below.
The drive mechanism furthermore comprises a rotation member 21. The rotation
member 21 is rotatable with respect to the housing part 17 in a first
direction, in
particular for setting of a dose of the medication, and in a second direction,
in particular
for delivering the set dose. The second direction is opposite to the first
direction. The
first direction may be counter-clockwise and the second direction may be
clockwise as
seen from the proximal end of the device, for example.
Drive member, rotation member and/or piston rod are preferably configured to
be
rotatable about a (common) rotation axis. The rotation axis may extend through
drive
member, rotation member and/or piston rod. The rotation axis may be the main
longitudinal axis of the piston rod. The rotation axis may run between the
proximal end
and the distal end of the housing part 17.
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The rotation member 21 is coupled to the drive member 20 by a uni-directional
clutch
mechanism, in particular a friction clutch mechanism. This clutch mechanism
permits
rotational movement of the rotation member 21 with respect to the drive member
20
when the rotation member rotates in the first direction with respect to the
housing part
17. The clutch mechanism prevents rotational movement of the rotation member
21 with
respect to the drive member 20, when the rotation member rotates in the second
direction with respect to the housing part 17. The drive member 20 may thus
follow
rotational movement of the rotation member 21 in the second direction with
respect to
the housing part 17.
The drive member 20 is arranged to abut and/or engage the rotation member and,
in
particular, engages rotation member 21. The drive member 20 comprises a
toothing 22.
Toothing 22 may be provided at one end of the drive member, e.g. its proximal
end. The
rotation member comprises a toothing 23. Toothings 22 and 23 face one another.
Toothing 23 may be provided at one end of the rotation member which end faces
the
drive member 20, e.g. at the distal end of the rotation member. Toothing 22
comprises a
plurality of teeth 24. Toothing 23 comprises a plurality of teeth 25. Teeth 24
and/or 25
may extend and preferably may be oriented along the rotation axis. Toothings
22 and
23 may be configured to mate with one another. The rotation member and the
drive
member may engage each other by toothings 22 and 23 being in engagement.
A respective tooth of teeth 24 and/or teeth 25 may be ramp-shaped, in
particular along
the azimuthal (angular) direction as seen from the rotation axis. The ramp of
the
respective tooth is limited (in the angular direction) by a steep end face of
that tooth, i.e.
a face of the tooth that runs parallel to the rotation axis or includes a
smaller angle with
the rotation axis when projected on this axis than the ramp when projected on
this axis.
The steep end face is followed by the ramp of the next tooth.
The teeth 24 may be circumferentially disposed on the drive member 20,
particularly at
the end of the drive member 20 which faces the rotation member 21. The teeth
25 may
be circumferentially disposed on the rotation member 21, particularly at the
end of the
rotation member 21 which faces the drive member 20.
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When the steep end faces of two teeth abut and the rotation member is rotated
further
on in the second direction, the steep sides stay in abutment and drive member
20
follows the rotation of rotation member 21. When the rotation member rotates
in the first
direction, the ramp of the teeth - which ramps, in particular, run obliquely
with respect to
the rotation axis - slide along each other and, in consequence, the rotation
member 21
may rotate with respect to the drive member 20.
The drive mechanism furthermore comprises a stop member 26. The drive member
may be arranged between the stop member 26 and the rotation member 21. The
stop
member 26 is configured for preventing rotational movement of the drive member
20 in
the first direction with respect to the housing part 17 during setting of a
dose, i.e. when
the rotation member rotates in the first direction. Thus, the rotation member
21 may
rotate in the first direction with respect to the housing part 17, whereas the
drive
member 20 and the stop member 26 do not rotate.
The stop member 26 is coupled to the drive member 20 by another uni-
directional clutch
mechanism, in particular a friction clutch mechanism. This clutch mechanism
prevents
rotational movement of the drive member 20 with respect to the stop member 26
when
the rotation member 21 rotates in the first direction with respect to the
housing part 17.
The clutch mechanism permits rotational movement of the drive member 20 with
respect to the stop member 26, when the rotation member 21 rotates in the
second
direction with respect to the housing part 17.
Thus, the rotation member 21 may rotate with respect to the drive member 20
and the
stop member 26 in the first direction during setting of the dose, with
rotation of the drive
member 20 being prevented by its interaction with the stop member 26, and
rotation
member 21 as well as drive member 20 may rotate with respect to the stop
member 26
in the second direction during delivery of the dose.
The stop member 26 may be arranged to abut and/or engage the drive member 20
during setting of the dose and, preferably, during delivery of the dose. The
stop member
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26 has a toothing 27. Toothing 27 may be provided at one end of the stop
member
which faces the drive member, e.g. its proximal end. The teeth may be ramp-
shaped
with a steep side and a less steep ramp. The teeth may be azimuthally disposed
along
the stop member, in particular on the perimeter of the stop member.
Drive member 20 has a toothing 28. Toothing 28 may be provided at one end of
the
drive member which faces the stop member, e.g. the distal end of the drive
member.
The teeth of toothing 28 may extend and preferably may be oriented along the
rotation
axis. Toothings 22 and 28 of the drive member 20 are oppositely disposed.
Toothing 28
may be configured in accordance with toothing 21 of the rotation member.
Toothing 22
may be configured in accordance with toothing 27 of the stop member. Toothings
27
and 28 may face one another. Toothings 27 and 28 may mate with one another.
Toothings 27 and 28, in particular the steep sides of the teeth, do cooperate,
e.g. abut,
for preventing rotation of the drive member 20 with respect to the housing
part 17 and,
in particular, with respect to the stop member 26 in the first direction.
Stop member 26 is preferably secured against rotational movement, particularly
preferably permanently secured against rotational movement, with respect to
the
housing part 17. Stop member 26 may be fixed to the housing or integrated into
the
housing. Stop member 26 may be fixed against displacement with respect to the
housing part 17 or displacement with respect to the housing part 17 may be
allowed.
As it is illustrated in the present embodiment, stop member 26 is displaceable
with
respect to the housing but non-rotatable with respect to the housing part 17.
For that
purpose, one or a plurality of, preferably oppositely disposed, guide
features, for
example guide lugs 29, are provided in the stop member 26. The respective
guide
feature 29 engages a corresponding guide slot 30 which may be provided in the
housing, e.g. in housing part 17. This can be seen in Figures 2 to 3. A guide
feature 29
cooperates with a guide slot 30 to prevent rotational movement of the stop
member with
respect to the housing part 17, with axial movement of the stop member 26 with
respect
to the housing being allowed. The axial movement of the stop member 26 may
compensate for play between components of the drive mechanism during
operation.
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From the group comprising drive member 20, stop member 26 and rotation member
21
one or more members, preferably two members or three members, may be axially
displaceable with respect to the housing part 17 and, preferably, with respect
to the
piston rod 12. Therein, the drive member and another one of the recited
members may
be axially displaceable with respect to the housing. The remaining member may
be
secured against axial displacement or may also be axially displaceable during
operation
of the drive mechanism for medication delivery. Accordingly, if the drive
member and
the stop member are axially displaceable, the rotation member may be axially
secured
or axially displaceable and so on. Play between the components caused by
relative
(axial) movement of components of the clutch mechanism with respect to the
housing
can be compensated for in this way. The distance by which the respective
components
may be axially displaced with respect to the housing may correspond to the
(maximum)
depth of a tooth of the respective toothing 22 or 28 of the drive member.
Alternatively,
the distance may be greater than the (maximum) depth of a tooth of the
respective
toothing.
Furthermore, the drive mechanism comprises a resilient member 31, preferably a
spring
member. The resilient member 31 may be biased during medication delivery
operation
of the drive mechanism. The resilient member may provide for a force that
tends to
keep the drive member 20 in engagement with the stop member 26 and/or the
rotation
member 21. The force may be exerted along the rotation axis. In the situation
shown in
Figures 2 to 3, this force may be exerted in the proximal direction. The
resilient member
31 may be a helical (coil) spring. The resilient member 31 may be a
compression
spring.
The resilient member 31 may keep the drive member 20 and the stop member 26 in
(permanent) mechanical contact, e.g. in abutment, with each other during
setting and
delivery of a dose of the medication. Alternatively or additionally, the
resilient member
31 may keep the drive member 20 and the rotation member 26 in (permanent)
mechanical contact, preferably abutment, with each other during setting and
delivery of
a dose of the medication.
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The resilient member 31 may be integrated within stop member 26 or a separate
component. The resilient member 31 may be arranged on the distal end side of
the stop
member 26.
The drive mechanism furthermore comprises a support member 32. Support member
32 is expediently fixed against axial and rotational movement with respect to
the
housing part 17 or integrated into housing part 17. Support member 32 is
arranged on
that side of the drive member 20 which is remote from the stop member 26.
Support
member 32 may be a protrusion, for example a ring-like protrusion. Rotation
member 21
may extend through an opening in support member 32. The support member 32 may
provide for a counter force to the force which is exerted by the resilient
member 31.
Permanent abutment of the rotation member with the drive member and of the
drive
member with the stop member during setting and delivery of medication is
facilitated in
this way.
The rotation member 21 has an (radially) outwardly protruding member 33, for
example
a flange portion. The protruding member 33 is expediently provided for
abutting support
member 32, in particular the distal end side of support member 32.
The drive mechanism furthermore comprises a dose member 34. Dose member 34 may
be dose part 16 or may be a part of the dose part 16 of Figure 1. Dose member
34 is
movable with respect to the housing in the proximal direction for setting of a
dose and
for delivery of the dose. For example, the dose member 34 may be moved in the
proximal direction with respect to the housing part 17 during dose setting and
in the
distal direction with respect to the housing part 17 during dose delivery. The
dose
member 34 may engage the housing part 17 or, alternatively, another part of
housing 13
(not explicitly shown). Dose member 34 is preferably secured against
rotational
movement with respect to the housing part 17. The dose member 34 may comprise
a
guide feature 35, for example a guide lug or a guide slot, that engages
another guide
feature, for example a guide slot or a guide lug, respectively, that is
provided in the
housing part 17 or the housing 13. The dose member 34 may be displaced with
respect
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to housing part 17 preferably only axially along and/or rotationally around
the rotation
axis.
Dose member 34 may be moved in the proximal direction and in the distal
direction with
respect to rotation member 21. Dose member 34 is arranged to be coupleable and
is
preferably (permanently) coupled to rotation member 21 such that movement of
the
dose member, e.g. in the proximal direction with respect to the housing part
17, for
setting a dose of the medication is converted into rotational movement of the
rotation
member in the first direction and movement of the dose member, e.g. in the
distal
direction with respect to the housing part 17, for delivering the dose is
converted into
rotational movement of the rotation member 21 in the second direction opposite
to the
first direction.
The rotation member 21 may be provided with an (outer) thread 36. Thread 36
may be
engaged with one of or a plurality of engagement members 42 of dose member 34.
The
respective engagement member may be arranged on the inside of the dose member.
The respective engagement member may be a thread or a part of a thread, for
example.
Thus, dose member 34 and rotation member 21 may be threadedly coupled, in
particularly threadedly engaged. The rotation member 21 may be arranged inside
the
dose member 21.
The rotation member 21, the drive member 20, the stop member 26 and/or the
dose
member 34 may be or may comprise a respective sleeve. The piston rod 12 may be
arranged to be driven and, in particular, may be driven through one of, more
of or all of
those sleeves. The piston rod 12 may run through one of, more of or all of
those
sleeves.
The drive member 20 and the piston rod 12 are configured for rotational
movement of
the drive member 20 with respect to the housing being converted into
rotational
movement of the piston rod with respect to the housing. The drive member 20
may
engage the piston rod 12. The piston rod 12 is displaceable with respect to
the drive
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member 20 along a displacement axis. Presently, the displacement axis runs
along the
rotation axis. The drive member 20 may be splined to the piston rod 12, for
example.
The piston rod 12 is threadedly coupled to the housing 13 and comprises an
engagement track 37, preferably two oppositely disposed engagement tracks, on
the
outside. The (respective) engagement track 37 may interrupt the thread. The
(respective) engagement track 37 preferably extends along the axis along which
the
piston rod is displaceable with respect to the housing and, in particular,
with respect to
the drive member.
Rotational movement of the drive member 20 with respect to the housing may
thus be
converted into rotational movement of the piston rod 12 with respect to the
housing and
the rotational movement of the piston rod 12 is, on account of the threaded
engagement
of the piston rod and the housing (part), converted into movement of the
piston rod with
respect to the housing in the distal direction.
The dose part 16 may comprise a dose knob which may be configured to be
gripped by
a user. Dose knob 41 may be arranged and connected to the dose member 34 at
the
proximal end. Dose knob and dose member may be unitary.
In the following, operation of the present drive mechanism for delivering drug
from the
cartridge 4 of Figure 1 is described.
To set a dose, a user may manually move dose member 34 in the proximal
direction
(arrow 43) with respect to the housing part 17. To do so, the user may grip
dose knob
and pull it in the proximal direction. Dose member 34 moves proximally also
with
respect to the rotation member 21. Proximal movement of the rotation member is
prevented by support member 32 which abuts protruding member 33 of rotation
member 21. Consequently, the proximal movement of dose member 34 with respect
to
the housing part 17 is converted into rotational movement of the rotation
member 21 in
the first direction (arrow 44) with respect to the housing part 17, in
particular on account
of the threaded engagement of dose member 34 and rotation member 21. Thus, the
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rotation member 21 rotates in the first direction - counter-clockwise as seen
from the
proximal end of the rotation member - with respect to the housing. Rotation
member 21
also rotates with respect to the drive member 20 and to the stop member 26.
The drive
member 20 is prevented from rotating in the first direction by interaction
with the stop
member 26, e.g. by interlocking of toothings 27 and 28. As the piston rod 12
is coupled
to the drive member 20 and rotation in the first direction of the drive member
would
cause the piston rod to travel in the proximal direction, the piston rod 12 is
prevented
from being driven in the proximal direction by interaction of stop member 26
and drive
member 20. By preventing the piston rod 12 from moving during dose setting
dose
accuracy can be increased.
When the rotation member 21 rotates in the first direction, the ramps of the
teeth of
toothing 23 of rotation member 21 slide along the ramps of the teeth of
toothing 22.
Thus, a tooth of the rotation member may index around the rotation axis until
the tooth
engages one of the next teeth of toothing 22 of drive member 20. The teeth of
rotation
member 21 slide along the ramps of the teeth of drive member 20. During this
movement, drive member 20 and, in particular, stop member 26 are displaced
along the
rotation axis with respect to piston rod 12 and housing by a distance
determined by,
preferably equal to, the depth of a tooth of toothing 22, before a tooth of
toothing 23
(totally) disengages that tooth of toothing 22. Afterwards, the tooth of the
rotation
member 21 engages the next tooth of toothing 22 and the force provided by
resilient
member 31 moves drive member 20 and, in particular, stop member 26 back along
the
rotation axis into the axial start position. An according movement of stop
member and
drive member in the distal direction and back into the proximal direction is
indicated by
double arrow 45 in Figures 2 and 3.
A tooth of the rotation member which engages the next tooth of the drive
member may
cause an audible and/or tactile feedback to the user.
The drive mechanism is suitable for a fixed dose device or a user settable
dose device.
The size of the fixed dose of medication which is to be delivered or the
increments in
which a user-settable dose may be varied by a user are preferably determined
by the
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distribution of the teeth of the respective toothings in the drive member,
rotation
member and stop member. The rotation member may be rotated over more than one
teeth (dose increment) of the drive member for a user-settable dose device and
over
one tooth (only) for a fixed dose device. The number of teeth in the drive
member 20
over which the rotation member 21 rotates during dose setting determines the
size of
the dose which is actually delivered.
After the dose has been set, the dose part 16 and with it the dose member 34
is moved
(pushed) by the user in the distal direction with respect to housing part 17.
Thus, the
dose member 34 is moved in the distal direction with respect to the housing
part 17.
The rotation member 21 accordingly rotates in the second direction, which is
opposite to
the first direction, with respect to the housing. Drive member 20 follows
rotational
movement of the rotation member in the second direction. Rotational movement
of the
drive member 20 in the second direction is converted into rotational movement
of the
piston rod 12 in the second direction, which movement, in turn, is converted
into
movement of the piston rod 12 in the distal direction. Accordingly, the piston
10 of
Figure 1 may be displaced in the distal direction with respect to the
cartridge 4 and a
dose of medication 5 is dispensed from the cartridge the amount of which
corresponds
to the previously set dose.
During dose delivery, toothings 22 and 23 interlock and ramps of the teeth of
toothing
28 of the drive member 20 slide along ramps of the teeth of toothing 27 of
stop member
26. This movement is similar to that as described above for the relative
rotational
movement of rotation member and drive member with opposite rotation direction.
The
stop member 26 is thereby displaced in the distal direction with respect to
the drive
member 20 by a distance corresponding to the depth of a tooth of toothing 27
in stop
member 26. Resilient member 31 forces the stop member 26 back into the axial
starting
position, when the next tooth of toothing 28 is engaged by the respective
tooth of
toothing 27.
A tooth of the drive member which engages the next tooth of the stop member
may
cause an audible and/or tactile feedback to the user.
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In a normal operation mode the drive member 20 is rotationally locked with the
piston
rod 12 by means of splines, which enables only axial movement between the
drive
member 20 and the piston rod 12.
To reset the drive mechanism the piston rod 12 must be returned in the
proximal
direction back into the housing. This is impossible when the drive mechanism
is
engaged. The piston rod 12 has to rotate through the threaded engagement to
the
housing. The drive member 20 is splined to the piston rod 12 and would also
rotate. The
stop member 26 stops the drive member 20 from rotating. During reset the drive
member 20 is decoupled from the piston rod 12, so that the piston rod 12 can
rotate
back to an initial start position.
Figure 4 shows the device and in particular the position of the piston rod 12
after
delivery of the last dose. Figure 5 shows this device after detaching the
cartridge holder
11. When the cartridge holder 11 is detached, the piston rod 12 is decoupled
from the
drive member (not shown in figures 4 to 6). Figure 6 shows the device after
returning
the piston rod 12 to its initial start position and attaching a new cartridge.
In this mode
the drive member is splined to the piston rod again.
Figure 7 shows a sectional view along line AN in figure 6 of one embodiment of
a part
of a drive mechanism in the reset mode. Only the drive member 20, the piston
rod 12
and a spring 70 which is suitable to spline the drive member 20 to the piston
rod 12 is
shown. In the reset mode the drive member 20 and the piston rod 12 are
decoupled.
The piston rod 12 comprises a first track 71 which extends in the axial
direction. The
track may be the engagement track 37 shown in figure 3. The drive member 20
comprises a second track 72 formed as a hole. The spring 70 runs partly
circumferentially around the drive member 20. The spring 70 has a protruding
part 73
which is suitable to be pushed through the second track 72 of the drive member
20 into
the first track 71 of the piston rod 12 so that the drive member 20 and the
piston rod 12
cannot rotate with respect to each other. In other words, the protruding
element 73 may
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serve as a spline. However, axial movement is still possible. The protruding
part 73 may
slide along the first track 71. In the reset mode the spring 70 is relaxed so
that
protruding element 73 is pulled out off at least the first track 71, thereby
the piston rod
12 being rotatable with respect to the drive member 20, which enables to reset
the
device. The protruding element 73 may be integrally formed with the spring,
e.g. as v-
shaped or u-shaped part of the spring 70. Alternatively the protruding element
73 may
be a pin-like element attached to the spring 70.
The spring 70 relaxes so that the protruding element 73 is moved radially
outwards,
when the cartridge holder (not shown in figure 7) is detached. The
disengagement
enables to rotationally move the piston rod 12 in the proximal direction,
while the drive
member 20 does not rotate with respect to the housing 17.
Figure 8 shows a sectional view of the embodiment shown in figure 7 in the
normal
operation mode, in which the protruding element 73 extends through the second
track
72 of the drive member 20 into the first track 71 of the piston rod 12,
thereby coupling
the drive member 20 and the piston rod 12 so that they cannot rotate with
respect to
each other.
The spring 70 is deformed so that the protruding element 73 is pushed radially
inwards
when the cartridge holder is attached. The cartridge holder may be formed so
that the
spring 70 is deformed and couples the drive member 20 and the piston rod 12
when the
cartridge holder is attached. In one embodiment the cartridge holder comprises
a
radially inwards extending protrusion 74 serving as a push member which pushes
the
protruding element radially inwards when the cartridge holder is attached. In
another
embodiment the cartridge holder pushes an element of the device so that the
spring 70
is deformed. Alternatively, the drive member 20 slides away from the push
member
which may be part of the housing 17, when the cartridge holder is detached.
This
movement may be caused by a relaxing spring element.
Figures 9 and 10 show a further embodiment wherein a spring 70 is running
partly
circumferentially around the drive member 20, the spring 70 comprising
protruding
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elements 73. In this embodiment the protruding elements 73 are formed as
inwardly
extending ends of the spring 70. The piston rod 12 comprises axially running
first tracks
71 which are arranged on opposite sides of the piston rod 12. The drive member
20
comprising second tracks formed as holes on opposite sides of the drive member
20,
the first and second tracks are aligned. Push means 75 are provided which are
suitable
to deform the spring 70 so that the protruding elements 73 engage with the
tracks in the
drive member 20 and the piston rod 12. The push members 75 may be parts of the
cartridge holder, which slides along the spring 70 so that it deforms during
attachment,
as shown on the right hand side of figure 9. During the detachment of the
cartridge
holder the push members 75 are moved away from the spring 70 so that it
relaxes and
the protruding elements disengage, as shown on the left hand side of figure 8.
The
distal parts of the push elements 75 may be sloped which avoids blocking
during
attachment and enables sliding of the push elements 75 over the spring 75
during
attachment. The left hand side of figure 10 shows a protruding element 73
which is
disengaged from the first track 71 in the piston rod 12. The right hand side
of figure 10
shows a protruding element 73 which is engaged with the first track 71.
Figure 11 shows an exploded view of a further embodiment, comprising a housing
17, a
piston rod 12, a stop member 26 and a drive member 20. Figures 12A and 13A
show
the embodiment in sectional views in the normal operation mode and the reset
mode,
respectively.
The drive member 20 is positioned inside the housing 17 which comprises a part
formed
as a sleeve 96 and is suitable for guiding the drive member 20, the sleeve 96
having a
circumferential trench 99.
The piston rod 12 comprises at least one axially extending track 71,
preferably more
than one. Pegs 91 are provided for releasably coupling the drive member 20 and
the
piston rod 12 by means of a splined connection. The peg 91 comprises a
coupling part
92 which is suitable for engaging with the track 71 and a shaft 97 having a
head 93,
wherein the diameter of the shaft 97 is less than the one of the head 93. The
shaft 93 is
put through a hole 94 in the drive member 20. The hole 94 has a size and form
that
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corresponds with the section of the shaft 97 but avoids movement of the head
93 and
the coupling part 92 through the wall of the drive member 20. The radial
movement of
the peg 91 with respect to the drive member 20 is limited by the head 93 which
is
located outside the drive member 20 and the coupling part 92 which is located
inside
the drive member 20. A leaf spring 95 is located on the outer side of the
drive member
20; the leaf spring 95 having a hole 98. The leaf spring 95 is positioned in a
cavity 89 of
the drive member 20. The leaf spring 95 is curved in a relaxed state. The
contour of the
cavity 89 corresponds with the even form of the leaf spring 95 under
compression. The
hole 94 of the drive member 20 and the hole 98 of the leaf spring 95 are
aligned. The
shaft 97 of the peg 91 extends through the holes 94, 98 so that the coupling
part 92 is
located inside the drive member 20 while the head 93 is located outside. When
the leaf
spring 95 is relaxed the peg 91 is biased outwardly, so that the head 93 and
the
coupling part 92 are pushed radially outwards. When the head 93 is pushed
inwards the
leaf spring 98 is deformed by the underside of the head 93 which pushes onto
the leaf
spring 95; thereby moving the coupling part 92 radially inwards so that it
engages with
the track 71. The position of the pegs 91 is aligned with the position of the
tracks 71.
Figure 12A shows the embodiment of figure 10 in a sectional view. Figure 12B
is a
detailed view of a marked part of figure 12A. Figure 12C shows the arrangement
of the
peg 91 in detail. Figures 12A, 12B and 12C show the drive mechanism in the
normal
operation mode, which means that the drive member 20 and the piston rod 12 are
coupled.
In the normal operation mode there is a gap 85 between the housing 17 and the
stop
member 26 which is held apart from the housing 17 by a spring member (not
shown).
The spring member pushes the stop member 26 proximally when the cartridge
holder is
attached. The stop member 26 forces the drive member 20 to a position in which
the
heads 93 of the pegs 91 are not aligned with the trench 99. In other words,
the sleeve
96 which serves as push means 75 pushes the pegs 91 radially inwards, so that
the
coupling parts 92 engage with the tracks 71 in the piston rod 12. The heads 93
are
positioned in the cavities 89 and do not or only slightly protrude from the
outer side of
the drive member 20.
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Figure 13A shows the embodiment of figure 11 in a sectional view. Figure 13B
is a
detailed view of a marked part of figure 13A. Figure 13C shows the arrangement
of the
peg 91 in detail. Figures 13A, 13B and 13C show the drive mechanism in the
reset
mode, which means that the cartridge holder is detached. After detachment the
stop
member 26 and the drive member 20 move distally with respect to the housing
17.
When the heads 93 of the pegs 91 reaches the trench 99, the leaf spring 95
relaxes so
that the heads 93 protrude from the drive member 20 into the trench 99,
thereby moving
the coupling parts 92 towards the inner side of the drive member 20. When the
pegs 91
move radially outwards, the coupling parts 92 disengage from the tracks 71 in
the piston
rod 12 so that the drive member 20 and the piston rod 12 can rotate with
respect to
each other which enables resetting the device.
Figures 14A, 14B, 14C show another embodiment of a drive member 20 having pegs
91. Figure 14A shows a three-dimensional view. Figure 14B shows a sectional
view.
Figure 14C shows an exploded sectional view.
The pegs 91 are u-shaped. Each peg 91 has a coupling part 92 and two shafts 97
with
heads 93 protruding at the ends of the coupling part 92. An alternative
embodiment of
the peg (not shown) comprises more than two shafts. The shafts 97 extend
through
holes 94 in the drive member 20. A resilient member biases the peg 91
outwardly. A
spring coil 88 runs around each shaft 97 between the outer side of the drive
member 20
and the head 93. The holes 94 are located in a cavity 89 so that the heads 93
do not
protrude from the outer side of the drive member 20 if the heads 93 are pushed
radially
inwards.
Figures 15A and 15B, which is more detailed, show a sectional view of the
drive
member 20 of figures 14A, 14B, 14C in the normal operation mode. When the
cartridge
holder is attached, the sleeve 96 serving as push means 75 pushes onto the
heads 93
of the pegs 91 so that coupling part 92 engages with the track 71 in the
piston rod 12.
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Figures 16 A and 16B, which is more detailed, show a sectional view of the
drive
member 20 of figures 14A, 14B, 14C in the reset state. After detaching the
cartridge
holder the drive member 20 moves axially with respect to the sleeve 96 so that
the
heads 93 reach the trench 99 in the sleeve 96. Then the spring coils 88 relax,
thereby
pushing the heads 93 radially outwards into the trench 99. This movement
causes
disengagement of the coupling parts 92 from the track 71 in the piston rod 12
which
enables rotational movement of the piston rod 12 with respect to the drive
member 20
for the purpose of resetting the piston rod 12.
It should be mentioned that the features of the embodiments can be combined.
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Reference numerals
1 drug delivery device
2 cartridge unit
3 drive unit
4 cartridge
5 drug
6 outlet
7 distal end of the device
8 proximal end of the device
9 membrane
10 piston
11 cartridge retaining member
12 piston rod
13 housing
14 proximal end side of the cartridge unit
15 distal end side of the housing
16 dose part
17 housing part
18 proximal end of housing part
19 distal end of housing part
20 drive member
21 rotation member
22 toothing
23 toothing
24 tooth
25 tooth
26 stop member
27 toothing
28 toothing
29 guide feature
30 guide slot
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31 resilient member
32 support member
33 protruding member
34 dose member
35 guide feature
36 thread
37 engagement track
41 dose knob
42 engagement member
43,44,45 arrow
70 spring
71 first track
72 second track
73 protruding part
74 extending protrusion
75 push means
85 gap
88 spring coil
89 cavity
91 peg
92 coupling part
93 head
94 hole
95 leaf spring
96 sleeve
97 shaft
98 hole
99 trench
AN line
