WO2024175400A1

WO2024175400A1 - A power unit of a medicament delivery device

Info

Publication number: WO2024175400A1
Application number: PCT/EP2024/053472
Authority: WO
Inventors: Ola HALLSTRÖM; Daniel SÄLL; Mattias Myrman; Daniel Carlsson; Plamen BALKANDJIEV
Original assignee: Shl Medical Ag
Priority date: 2023-02-24
Filing date: 2024-02-12
Publication date: 2024-08-29

Abstract

A power unit (2) of a medicament delivery device (1) is provided, comprising a pusher element (241) for pushing a plunger (32), a drive unit (23) with a drive nut (234) and a stepper motor (231), a controller (222) for controlling the stepper motor (231), and an encoder (25) for determining a displacement position of the pusher element (241). The drive nut (234) is adapted to transfer a rotational movement of a rotor (233) of the stepper motor (231) into a proximal displacement of the pusher element (241). The drive unit (23) is configured as a direct drive, i.e. the drive nut (234) rotates in accordance and at the same speed as a rotor (233) and the rotational movement of the drive nut (234) is transferred directly into a displacement of the pusher element. The controller (222) is configured to monitor a back electromotive force of the stepper motor (231).

Description

A POWER UNIT OF A MEDICAMENT DELIVERY DEVICE

TECHNICAL FIELD

The present invention generally relates to a power unit of a medicament delivery device. The medicament delivery device can particularly be an electromechanical injector having a power unit to which a medicament unit with a medicament container and an injection needle can releasably be attached. The invention also relates to a medicament unit and to a medicament delivery device with such a power unit and such a medicament unit.

BACKGROUND

Medicament delivery devices in the form of auto-injectors have several advantages over manual injectors. Not only do they make drug administration much easier for patients, but they are also safer in terms of operating errors. For example, the insertion of the needle into the patient's skin and the administration of the drug can be automated, so that underdosing in particular can be avoided. In some of these devices, the energy to deliver the fluid medicament is provided by a spring. Another category relates to electromechanical injectors, in which the energy for expelling the medicament is provided by a motor, usually an electric motor.

Medicament delivery devices in the form of electromechanical injector devices typically comprise a power unit to which a medicament unit releasably attached. The medicament unit comprises a medicament container for storing a medicament as well as a medicament delivery element, such as a needle, through which the medicament can be injected into the patient. For expelling the medicament from the medicament container and through the needle, a pusher element of the power unit is displaced proximally into the medicament container of the medicament unit, where it engages and pushes a plunger in a proximal direction towards the needle. For displacing the pusher element, an electric motor is usually used in these devices.

In most state-of-the-art electromechanical medicament injectors, the entire content of the medicament container is expelled upon triggering the injection. Thus, the pusher element is advanced by the motor until the plunger reaches the proximal end of the medicament container, meaning that the container has been emptied. In these devices, the displacement distance of the pusher element to empty the entire medicament container is for example controlled by a mechanical switch, which stops the motor when the pusher element has been displaced over a certain distance. Such empty-all devices have the inherent drawback that the injected dosage is given and cannot be adjusted. Furthermore, since the entire or almost the entire medicament content of the medicament unit is expelled with an empty-all device, the medicament unit usually cannot be re-used and needs to be disposed after a single use.

Other electromechanical injectors are known, which allow the administration of a dose of a fluid medicament, i.e. only a part, but not the entire content of the medicament container is administered per injection. For this purpose, the steps carried out by a stepper motor during injection can be counted, in order to stop the motor after a predetermined dose of the medicament has been expelled. Thus, the injector can be re-used for a certain number of injections, where each time only a certain amount (dose) of the medicament is injected.

The problem of counting the steps of a stepper motor for determining the administered amount of the medicament is, that steps might be missed, if e.g. a blockage in the fluid path of the device occurs.

A re-usable auto-injector for administering a dose of a fluid medicament is for example disclosed by EP 2 654 843 B1. The device comprises an encoder sensor for determining the initial position of the plunger of a re-usable medicament unit. The encoder sensor is also used to detect stall of the motor.

US 2022/0257864 A1 discloses an auto-injector delivery device configured with a stall and endpoint detection algorithm based on an encoder coupled to the motor.

US 2013/0253420 A1 relates to an infusion pump with pulse width modulation (PWM) motor control. Displacement of the plunger is measured by means of a rotary encoder, in order to determine the number of missed motor steps. In this way, an occlusion in the fluid path of the device can be detected.

Another prior art document, which discloses a medicament delivery device with an encoder for detecting stall of the motor, is US 2014/0114277 A1. In this device, detection of motor stall is further used to detect the initial position of the plunger.

US 9,216,249 B2 discloses plunger contact detection using an encoder for an infusion pump. For this purpose, a stepper motor is operated with limited power, so that the motor pushes against the plunger with as little force as possible. Contact with the plunger is detected based on motor stall detection by means of the encoder.

EP 4 059 547 A1 discloses an injection device, in which an instantaneous motor value is compared with a reference motor value, in order to detect contact of a dispensing member that is forwarded by the motor via a gear with a reservoir element. For the instantaneous motor value, it is proposed to either use a position value of a movable drive member or to use a back electromotive force value. Detection of the initial plunger position based on a detection of motor stall by means of an encoder has the drawback that the motor power needs to be considerably reduced, in order to not push the plunger excessively forward. Even then, a certain displacement of the plunger can hardly be avoided. As a consequence, accuracy of dose administration is impaired.

SUMMARY

It is an object of the present invention to provide a power unit of an electromechanical medicament delivery device that allows the administration of a predetermined dose with particular accuracy and reliability.

This object is solved by a power unit as claimed in claim 1. A medicament unit adapted to be used with such a power unit is indicated in claim 14. In claim 15, a medicament delivery device comprising such a power unit is claimed. Further and preferred embodiments are provided in the dependent claims.

The present invention thus relates to a power unit of a medicament delivery device, in particular of an auto-injector, for delivering a medicament from a medicament container to a human or animal patient, the power unit comprising:

- a pusher element adapted to engage and push a plunger in a proximal direction, in order to expel the medicament from the medicament delivery device;

- a drive unit comprising a drive nut and a stepper motor with a rotor and a stator, wherein the drive nut is adapted to transfer a rotational movement of the rotor into a proximal displacement of the pusher element;

- a controller for controlling the stepper motor; and

- an encoder for determining a displacement position of the pusher element.

The drive unit is configured as a direct drive in such a way that the drive nut rotates in accordance and at the same speed as the rotor of the stepper motor and that the rotational movement of the drive nut is transferred directly into a displacement of the pusher element. The controller is configured to monitor a back electromotive force of the stepper motor.

By combining the determination of the displacement position of the pusher element using an encoder with the monitoring of the back electromotive force of the stepper motor, a particularly reliable and accurate dosing can be achieved. By monitoring of the back electromotive force, the controller has the capability of sensing force applied to the stepper motor, which cannot only be used to detect the position of the plunger and, thus, the starting point for dosing prior to the injection, but also to measure the counter-pressure acting on the plunger during the injection. Using the back electromotive force, detection of plunger position can be achieved with minimal displacement of the plunger. If a certain plunger displacement nevertheless occurs, this can be detected by the encoder, in order to still enable accurate dosing. The counter-pressure occurring during the injection can be an important indicator for e.g. the viscosity of the medicament, a partial or full blockage of the fluid path or an inappropriate insertion of the needle at the injection site. The use of an encoder allows obtaining direct information concerning the position and displacement of the plunger, instead of only knowing the current state of the motor. Thus, the correct administration of a certain dose can be verified in a particular reliable and consistent way. By combining the use of an encoder with the monitoring of the back electromotive force, it is also possible to detect stall of the stepper motor during injection and to recover from the latter. Due to this capability to recover from stall or lost steps and still inject a correct dose, it is also possible to operate the stepper motor at a comparable high load. As a consequence, the current invention is not only well suited for auto-injectors with dosing capabilities, but for electromechanical medicament delivery devices in general, i.e. also for empty-all devices.

The use of a drive unit in the form of a direct drive, i.e. without a gear, further increases the significance of the measured data, such as of the back electromotive force, of the count of steps carried out by the motor and of the data measured by the encoder, with regard to their combined usability by the controller for achieving an accurate and reliable dosing. Due to the provision of the direct drive, the steps of the motor as counted, the data as measured by the encoder and the measured back electromotive force are more closely related to each other, since no backlash of a gear unit needs to be taken into account.

By providing a stepper motor, a particular precise displacement of the pusher element over a predetermined distance is possible. The use of a stepper motor also allows to count the steps during the displacement of the pusher element when finding the starting point for dosing or during the injection and to relate the counted steps to the measurement of the encoder, in order to e.g. detect stall of the motor.

In the present disclosure, when the term “distal direction” is used, this refers to the direction pointing away from the dose delivery site during use of the medicament delivery device. When the term “distal part/end” is used, this refers to the part/end of the delivery device, or the parts/ends of the members thereof, which during use of the medicament delivery device is/are located furthest away from the dose or medicament delivery site. Correspondingly, when the term “proximal direction” is used, this refers to the direction pointing towards the dose delivery site during use of the medicament delivery device. When the term “proximal part/end” is used, this refers to the part/end of the delivery device, or the parts/ends of the members thereof, which during use of the medicament delivery device is/are located closest to the dose delivery site.

Further, unless otherwise indicated, the terms “longitudinal”, “longitudinally”, “axially” and “axial” refer, to a direction extending from the proximal end to the distal end and along the device or components thereof, typically in the direction of the longest extension of the device and/or component.

Similarly, the terms “transverse”, “transversal” and “transversally” refer to a direction generally perpendicular to the longitudinal direction.

Preferably, the power unit form a re-usable component of the medicament delivery device, which is used for the administration of the medicament in combination with a medicament unit that comprises a medicament container for storing the medicament to be injected and a medicament delivery element, such as a needle, through which the medicament can be injected into the patient's body. The medicament unit, which is typically attachable to the power unit in a releasable manner, can be designed for single use only or for being re-used, in particular for the administration of multiple doses. The plunger is usually arranged within the medicament container, in order to be engaged by the pusher element after attaching the medicament unit to the power unit.

The medicament delivery device can for example be an autoinjector, a pen injector or an on- body device. The medicament delivery element is usually a cannula or hollow needle, also abbreviated as a needle. The medicament delivery device is preferably adapted to be inserted into the skin of the patient with its proximal end first, in order to subcutaneously inject the medicament to the desired place inside of the patient's body. The medicament is usually delivered from the medicament container to the patient, by means of forwarding a plunger inside of the container along the proximal direction. The forwarding of the plunger is effected by the stepper motor.

The medicament delivery devices described herein can be used for the treatment and/or prophylaxis of one or more of many different types of disorders.

Exemplary disorders include, but are not limited to: rheumatoid arthritis, inflammatory bowel diseases (e.g. Crohn’s disease and ulcerative colitis), hypercholesterolaemia, diabetes (e.g. type 2 diabetes), psoriasis, migraines, multiple sclerosis, anaemia, lupus, atopic dermatitis, asthma, nasal polyps, acute hypoglycaemia, obesity, anaphylaxis and allergies. Exemplary types of medicaments that could be included in the medicament delivery devices described herein include, but are not limited to, antibodies, proteins, fusion proteins, peptibodies, polypeptides, pegylated proteins, protein fragments, protein analogues, protein variants, protein precursors, and/or protein derivatives. Exemplary medicaments that could be included in the medicaments delivery devices described herein include, but are not limited to (with non-limiting examples of relevant disorders in brackets): etanercept (rheumatoid arthritis, inflammatory bowel diseases (e.g. Crohn’s disease and ulcerative colitis)), evolocumab (hypercholesterolaemia), exenatide (type 2 diabetes), secukinumab (psoriasis), erenumab (migraines), alirocumab (rheumatoid arthritis), methotrexate (amethopterin) (rheumatoid arthritis), tocilizumab (rheumatoid arthritis), interferon beta-1 a (multiple sclerosis), sumatriptan (migraines), adalimumab (rheumatoid arthritis), darbepoetin alfa (anaemia), belimumab (lupus), peginterferon beta-1 a' (multiple sclerosis), sarilumab (rheumatoid arthritis), semaglutide (type 2 diabetes, obesity), dupilumab (atopic dermatis, asthma, nasal polyps, allergies), glucagon (acute hypoglycaemia), epinephrine (anaphylaxis), insulin (diabetes), atropine and vedolizumab (inflammatory bowel diseases (e.g. Crohn’s disease and ulcerative colitis)). Pharmaceutical formulations including, but not limited to, any medicament described herein are also contemplated for use in the medicament delivery devices described herein, for example pharmaceutical formulations comprising a medicament as listed herein (or a pharmaceutically acceptable salt of the medicament) and a pharmaceutically acceptable carrier. Pharmaceutical formulations comprising a medicament as listed herein (or a pharmaceutically acceptable salt of the medicament) may include one or more other active ingredients, or may be the only active ingredient present.

Further exemplary disorders include, but are not limited to: dyslipidemia, cardiovascular disease, diabetes (e.g. type 1 or 2 diabetes), psoriasis, psoriatic arthritis, spondyloarthritis, hidradenitis suppurativa, Sjogren's syndrome, migraine, cluster headache, multiple sclerosis, neuromyelitis optica spectrum disorder, anaemia, thalassemia, paroxysmal nocturnal hemoglobinuria, hemolytic anaemia, hereditary angioedema, systemic lupus erythematosus, lupus nephritis, myasthenia gravis, Behpet's disease, hemophagocytic lymphohistiocytosis, atopic dermatitis, retinal diseases (e.g., age-related macular degeneration, diabetic macular edema), uveitis, infectious diseases, bone diseases (e.g., osteoporosis, osteopenia), asthma, chronic obstructive pulmonary disease, thyroid eye disease, nasal polyps, transplant, acute hypoglycaemia, obesity, anaphylaxis, allergies, sickle cell disease, Alzheimer’s disease, Parkinson’s disease, dementia with Lewy bodies, systemic infusion reactions, immunoglobulin E (IgE)-mediated hypersensitivity reactions, cytokine release syndrome, immune deficiencies (e.g., primary immunodeficiency, chronic inflammatory demyelinating polyneuropathy), enzyme deficiencies (e.g., Pompe disease, Fabry disease, Gaucher disease), growth factor deficiencies, hormone deficiencies, coagulation disorders (e.g., hemophilia, von Willebrand disease, Factor V Leiden), and cancer.

For supplying power to the stepper motor and advantageously also to the controller, the power unit preferably comprises at least one primary energy source, such as a battery, in particular a researchable battery. In addition to the energy source as mentioned, the power unit preferably comprises at least one secondary energy source, such as a coin cell battery, in order to supply energy to a real-time clock (RTC), even if the primary energy source is discharged or is being replaced.

The power unit preferably comprises one or several signal elements for providing the user information concerning the state of the device. The signal elements preferably include a vibrator for providing haptic feedback. Signal elements that can be provided alternatively or in addition are for example one or several light-emitting diodes (LEDs) and a sound generator. The LEDs can be arranged to form a progress bar, in order to e.g. indicate the progress of the administration of the currently injected dose and/or of the entire treatment including a plurality of doses to be injected.

The pusher element preferably has the form of a rod that is arranged on a longitudinal main axis of the power unit extending from the distal to the proximal end of the power unit. The pusher element can have an outer thread for being engaged by an inner thread of the drive nut. The inner thread of the drive nut, if provided, preferably serves to transfer the rotational movement of the rotor into a displacement of the pusher element. In order to prevent the pusher element to rotate with the drive nut, an anti-rotation guidance is preferably provided that allows the pusher element to be displaced, but not rotated relative to the drive nut.

The stepper motor preferably comprises a hollow motor shaft, through which the pusher element extends. The drive nut is preferably fixedly attached to the hollow shaft or even made in one piece with the latter.

The controller preferably has the form of one or several microchips that are part of a printed circuit board (PCB) which is advantageously arranged within a housing of the power unit. The one or several microchips preferably comprise at least a calculation unit and a memory unit, in which instructions are stored that are executed by the calculation unit during use of the device. The controller is considered to be configured in particular in accordance with the instructions stored in the memory unit.

In a particularly preferred embodiment, the controller is configured to detect contact of the plunger with the pusher element based on the monitoring of the back electromotive force.

As long as the pusher element is freely displaceable and no blockage of the drive unit occurs, the back-electromotive force (back-EMF) is typically proportional to the rotational speed of the rotor of the stepper motor, which means that the motor speed can be indirectly measured via the back-EMF. Basically, the back-EMF is determined by measuring the electrical energy flowing into the stepper motor and the electrical energy flowing out of the motor. The difference between both energies, i.e. the back-EMF, gives an indication of the mechanical load taken from the motor. In other words, it is measured which part of the energy fed to the stepper motor goes back to the power supply (or energy source). This spare energy is a measure for the mechanical load applied to the stepper motor. If it goes to zero, no spare energy will be left and the motor may stall.

In order to determine a counter-force that is acting on the pusher element during proximal (or distal) displacement in a reliable manner, the controller is preferably configured to detect a change in the relationship between the back-EMF and a first reference value. The first reference value preferably has the form of a threshold value, and the controller is configured to detect whether the back-EMF falls below or exceeds the threshold value. Thus, the controller is particularly configured to detect a change of the back-EMF while the threshold value remains constant. The detected change in the back-EMF can particularly be used by the controller to determine that the pusher element has been brought into contact with the plunger. A second reference value can be used by the controller, in order to detect a stall of the stepper motor, i.e. when the measured back-EMA exceeds the second reference value. The second reference value, which can also be regarded as a threshold value, can be the same or lower or higher than the first reference value.

The controller is preferably configured to carry out a device calibration, in order to set the first reference value and/or the second reference value. The calibration is preferably triggered by the attachment of a medicament unit to the power unit. The reference value(s) are preferably adjusted in dependence on the amount of electric current supplied to the stepper motor for displacing the pusher element, on the rotational frequency of the rotor of the stepper motor and/or on the displacement speed of the pusher element. The calibration can for example be achieved by carrying out a test displacement of the pusher element at a safe distance from the plunger and taking into account the electric energy supplied to the stepper motor and the respectively measured back-EMF. In addition or alternatively, predetermined values can be set for the reference values during calibration, which can for example be chosen based on an information of the attached medicament unit. The information can for example be taken from a detection of the type of medicament unit that has been attached or from a user input, e.g. by means of a separate wired or wireless device. The reference value(s) can then for example be set by the controller with the help of a lookup-table stored in the memory unit.

In a particularly preferred embodiment, the controller is configured to relate the monitored back electromotive force to an electrical current supplied to the stepper motor. In this way, a contact of the pusher element with the plunger or a stall of the motor can be detected in a particularly reliable way. The controller is preferably configured to relate the monitored back electromotive force to a displacement position of the pusher element as determined by the encoder. For example, the information obtained from the encoder concerning the displacement position of the pusher element can be used by the controller to determine whether a sudden change in den back-EMF is due to a contact of the pusher element with the plunger or rather due to a stall of the stepper motor. By relating the monitored back-EMF to the displacement information of the encoder, it is also possible to determine accurately the position of the plunger before and after contact by the pusher element. Furthermore, during injection, it is possible in this way to determine exactly the position of the plunger immediately before stall of the stepper motor. A recovery from the stall thus becomes possible.

For determining the displacement position of the pusher element, the encoder preferably measures a rotational position of the drive nut and/or the displacement position of the pusher element. While a measurement of the displacement position of the pusher element along the main longitudinal axis of the device provides a more direct and thus particularly reliable information of the state of the pusher element, a measurement of the rotational position of the drive nut is usually simpler to implement and still sufficiently reliable.

The encoder preferably comprises an optical sensor, in particular a photoelectric sensor. The photoelectric sensor is preferably in the form of a photointerrupter. While a displacement measurement using a photointerrupter usually only allows the measurement of discrete values, it is highly accurate and reliable.

In order to achieve a direct measurement of the rotational state of the drive nut, the encoder preferably comprises a disk attached to or made in one piece with the drive nut. The disk advantageously comprises portions, which are discernible by an optical sensor of the encoder.

The controller is preferably configured to stop the stepper motor in particular during medicament injection, when a predetermined displacement position of the pusher element as determined by the encoder is reached. By measuring the displacement position of the pusher element by means of the encoder, a very reliable and accurate dosing can be achieved.

In a preferred embodiment, the controller is configured to receive a dosing instruction, preferably from a medicament unit of the medicament delivery device or from a user, and to control the stepper motor in such a way, that the pusher element is brought into a displacement position corresponding to the received dosing instructions and/or that the pusher element is proximally displaced by a displacement distance corresponding to the received dosing instruction. The power unit preferably comprises a radio-frequency identification (RFID) unit and/or a wireless receiver unit for receiving the dosing instruction. The RFID-unit can for example be adapted to read an RFID-tag of the medicament unit that provides information concerning the dosing of the medicament stored in the medicament unit. The dosing instruction usually comprises information relating to the amount of medicament that is to be injected. The dosing instruction can also comprise information concerning the state of the medicament unit, e.g. relating to the actual position of the plunger in the light of previous dose administrations. By using the information of the plunger position, an even faster and more accurate contacting of the plunger by the pusher element can be achieved. Alternatively or in addition, the radio-frequency identification (RFID) unit can serve to verify e.g. the medicament stored in the medicament unit and/or the supplier of the medicament unit.

The controller is preferably configured to detect removal of a closure cap of a medicament unit of the medicament delivery device. The closure cap usually serves to close, in particular seal, an injection needle of the medicament unit. By removing the closure cap, the medicament delivery device is made ready for injection by the user. The controller is preferably configured, upon detection of removal of the closure cap, to enter a pre-delay phase, during which the stepper motor remains idle. Thus during the pre-delay phase, which can e.g. last for 1 to 10 seconds, the pusher element is not displaced by the stepper motor, but remains in its position. The pre-delay serves to allow the pressure in the medicament container to even out after the plunger has been contacted and engaged by the pusher element. In this way, dose accuracy can considerably be improved. The user can be informed when the pre-delay period expires by means of e.g. visual, audible and/or haptic signals. Injection can then be started.

Preferably, the controller is configured to enter a post-delay phase upon completed proximal displacement of the pusher element, i.e. after completed dose administration. During the post-delay phase, the stepper motor remains idle, meaning that the pusher element is not displaced. By providing the pre-delay phase, which can e.g. last for 1 to 10 seconds, the pressure in the medicament container is allowed to even out, what allows dose accuracy to be considerably improved with regard to further dose injections later on.

In a particularly preferred embodiment, the power unit is adapted to receive a medicament unit of the medicament delivery device by means of a releasable attachment, the medicament unit comprising a medicament container for storing the medicament to be injected as well as a medicament delivery element with a proximal end, through which the medicament can be delivered to the patient.

The current invention also relates to a medicament unit, which is adapted to be received by the power unit comprising an RFID-unit as described further above. The medicament unit comprises a radio-frequency identification (RFID) tag that is adapted to store a dosing instruction, which can be read by the RFID-unit of the power unit. The controller of the power unit is preferably configured to cause the medicament delivery device to expel an amount of medicament from the medicament unit in accordance to the dosing instruction received from the RFID-tag.

Furthermore, the present invention relates to a medicament delivery device comprising the power unit as described and a medicament unit, preferably the medicament unit as described.

Exemplary types of drugs or medicaments that could be included in the delivery devices described herein include, but are not limited to, small molecules, hormones, cytokines, blood products, enzymes, vaccines, anticoagulants, immunosuppressants, antibodies, antibodydrug conjugates, neutralizing antibodies, reversal agents, radioligand therapies, radioisotopes and/or nuclear medicines, diagnostic agents, bispecific antibodies, proteins, fusion proteins, peptibodies, polypeptides, pegylated proteins, protein fragments, nucleotides, protein analogues, protein variants, protein precursors, protein derivatives, chimeric antigen receptor T cell therapies, cell or gene therapies, oncolytic viruses, or immunotherapies.

Exemplary drugs that could be included in the delivery devices described herein include, but are not limited to, immuno-oncology or bio-oncology medications such as immune checkpoints, cytokines, chemokines, clusters of differentiation, interleukins, integrins, growth factors, coagulation factors, enzymes, enzyme inhibitors, retinoids, steroids, signaling proteins, pro-apoptotic proteins, anti-apoptotic proteins, T-cell receptors, EB-cell receptors, or costimulatory proteins.

Exemplary drugs that could be included in the delivery devices described herein include, but are not limited to, those exhibiting a proposed mechanism of action, such as human epidermal growth factor receptor 2 (HER-2) receptor modulators, interleukin (IL) modulators, interferon (IFN) modulators, complement modulators, glucagon-like peptide-1 (GLP-1 ) modulators, glucose-dependent insulinotropic polypeptide (GIP) modulators, cluster of differentiation 38 (CD38) modulators, cluster of differentiation 22 (CD22) modulators, C1 esterase modulators, bradykinin modulators, C-C chemokine receptor type 4 (CCR4) modulators, vascular endothelial growth factor (VEGF) modulators, EB-cell activating factor (BAFF), P-selectin modulators, neonatal Fc receptor (FcRn) modulators, calcitonin gene- related peptide (CGRP) modulators, epidermal growth factor receptor (EGFR) modulators, cluster of differentiation 79B (CD79B) modulators, tumor-associated calcium signal transducer 2 (Trop-2) modulators, cluster of differentiation 52 (CD52) modulators, B-cell maturation antigen (BCMA) modulators, enzyme modulators, platelet-derived growth factor receptor A (PDGFRA) modulators, cluster of differentiation 319 (CD319 or SLAMF7) modulators, programmed cell death protein 1 and programmed death-ligand 1 (PD-1/PD-L1) inhibitors/modulators, B-lymphocyte antigen cluster of differentiation 19 (CD19) inhibitors, B- lymphocyte antigen cluster of differentiation 20 (CD20) modulators, cluster of differentiation 3 (CD3) modulators, cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors, T-cell immunoglobulin and mucin-domain containing-3 (TIM-3) modulators, T cell immunoreceptor with Ig and ITIM domains (TIGIT) modulators, V-domain Ig suppressor of T cell activation (VISTA) modulators, indoleamine 2,3-dioxygenase (IDO or INDO) modulators, poliovirus receptor-related immunoglobulin domain-containing protein (PVRIG) modulators, lymphocyte-activation gene 3 (LAG3; also known as cluster of differentiation 223 or CD223) antagonists, cluster of differentiation 276 (CD276 or B7-H3) antigen modulators, cluster of differentiation 47 (CD47) antagonists, cluster of differentiation 30 (CD30) modulators, cluster of differentiation 73 (CD73) modulators, cluster of differentiation 66 (CD66) modulators, cluster of differentiation w137 (CDw137) agonists, cluster of differentiation 158 (CD158) modulators, cluster of differentiation 27 (CD27) modulators, cluster of differentiation 58 (CD58) modulators, cluster of differentiation 80 (CD80) modulators, cluster of differentiation 33 (CD33) modulators, cluster of differentiation 159 (CD159 or NKG2) modulators, glucocorticoid-induced TNFR-related (GITR) protein modulators, Killer Ig-like receptor (KIR) modulators, growth arrest-specific protein 6 (GAS6)/AXL pathway modulators, A proliferation-inducing ligand (APRIL) receptor modulators, human leukocyte antigen (HLA) modulators, epidermal growth factor receptor (EGFR) modulators, B-lymphocyte cell adhesion molecule modulators, cluster of differentiation w123 (CDw123) modulators, Erbb2 tyrosine kinase receptor modulators, endoglin modulators, mucin modulators, mesothelin modulators, hepatitis A virus cellular receptor 2 (HAVCR2) antagonists, cancer-testis antigen (OTA) modulators, tumor necrosis factor receptor superfamily, member 4 (TNFRSF4 or 0X40) modulators, adenosine receptor modulators, inducible T cell co-stimulator (ICOS) modulators, cluster of differentiation 40 (CD40) modulators, tumor-infiltrating lymphocytes (TIL) therapies, or T-cell receptor (TOR) therapies.

Exemplary drugs that could be included in the delivery devices described herein include, but are not limited to: etanercept, abatacept, adalimumab, evolocumab, exenatide, secukinumab, erenumab, galcanezumab, fremanezumab-vfrm, alirocumab, methotrexate (amethopterin), tocilizumab, interferon beta-1 a, interferon beta-1 b, peginterferon beta-1 a, sumatriptan, darbepoetin alfa, belimumab, sarilumab, semaglutide, dupilumab, reslizumab, omalizumab, glucagon, epinephrine, naloxone, insulin, amylin, vedolizumab, eculizumab, ravulizumab, crizanlizumab-tmca, certolizumab pegol, satralizumab, denosumab, romosozumab, benralizumab, emicizumab, tildrakizumab, ocrelizumab, ofatumumab, natalizumab, mepolizumab, risankizumab-rzaa, ixekizumab, and immune globulins. Exemplary drugs that could be included in the delivery devices described herein may also include, but are not limited to, oncology treatments such as ipilimumab, nivolumab, pembrolizumab, atezolizumab, durvalumab, avelumab, cemiplimab, rituximab, trastuzumab, ado-trastuzumab emtansine, fam-trastuzumab deruxtecan-nxki, pertuzumab, transtuzumab- pertuzumab, alemtuzumab, belantamab mafodotin-blmf, bevacizumab, blinatumomab, brentuximab vedotin, cetuximab, daratumumab, elotuzumab, gemtuzumab ozogamicin, 90- Yttrium-ibritumomab tiuxetan, isatuximab, mogamulizumab, moxetumomab pasudotox, obinutuzumab, ofatumumab, olaratumab, panitumumab, polatuzumab vedotin, ramucirumab, sacituzumab govitecan, tafasitamab, or margetuximab.

Exemplary drugs that could be included in the delivery devices described herein include “generic” or biosimilar equivalents of any of the foregoing, and the foregoing molecular names should not be construed as limiting to the “innovator” or “branded” version of each, as in the non-limiting example of innovator medicament adalimumab and biosimilars such as adalimumab-afzb, adalimumab-atto, adalimumab-adbm, and adalimumab-adaz.

Exemplary drugs that could be included in the delivery devices described herein also include, but are not limited to, those used for adjuvant or neoadjuvant chemotherapy, such as an alkylating agent, plant alkaloid, antitumor antibiotic, antimetabolite, or topoisomerase inhibitor, enzyme, retinoid, or corticosteroid. Exemplary chemotherapy drugs include, by way of example but not limitation, 5-fluorouracil, cisplatin, carboplatin, oxaliplatin, doxorubicin, daunorubicin, idarubicin, epirubicin, paclitaxel, docetaxel, cyclophosphamide, ifosfamide, azacitidine, decitabine, bendamustine, bleomycin, bortezomib, busulfan, cabazitaxel, carmustine, cladribine, cytarabine, dacarbazine, etoposide, fludarabine, gemcitabine, irinotecan, leucovorin, melphalan, methotrexate, pemetrexed, mitomycin, mitoxantrone, temsirolimus, topotecan, valrubicin, vincristine, vinblastine, or vinorelbine.

Exemplary drugs that could be included in the delivery devices described herein also include, but are not limited to, analgesics (e.g., acetaminophen), antipyretics, corticosteroids (e.g. hydrocortisone, dexamethasone, or methylprednisolone), antihistamines (e.g., diphenhydramine or famotidine), antiemetics (e.g., ondansetron), antibiotics, antiseptics, anticoagulants, fibrinolytics (e.g., recombinant tissue plasminogen activator [r-TPA]), antithrombolytics, or diluents such as sterile water for injection (SWFI), 0.9% Normal Saline, 0.45% normal saline, 5% dextrose in water, 5% dextrose in 0.45% normal saline, Lactated Ringer’s solution, Heparin Lock Flush solution, 100 U/mL Heparin Lock Flush Solution, or 5000 U/mL Heparin Lock Flush Solution.

Pharmaceutical formulations including, but not limited to, any drug described herein are also contemplated for use in the delivery devices described herein, for example pharmaceutical formulations comprising a drug as listed herein (or a pharmaceutically acceptable salt of the drug) and a pharmaceutically acceptable carrier. Such formulations may include one or more other active ingredients (e.g., as a combination of one or more active drugs), or may be the only active ingredient present, and may also include separately administered or coformulated dispersion enhancers (e.g. an animal-derived, human-derived, or recombinant hyaluronidase enzyme), concentration modifiers or enhancers, stabilizers, buffers, or other excipients.

Exemplary drugs that could be included in the delivery devices described herein include, but are not limited to, a multi-medication treatment regimen such as AC, Dose-Dense AC, TCH, GT, EC, TAG, TC, TCHP, CMF, FOLFOX, mFOLFOX6, mFOLFOX7, FOLFCIS, CapeOx, FLOT, DCF, FOLFIRI, FOLFIRINOX, FOLFOXIRI, IROX, CHOP, R-CHOP, RCHOP-21, Mini-CHOP, Maxi-CHOP, VR-CAP, Dose-Dense CHOP, EPOCH, Dose-Adjusted EPOCH, R-EPOCH, CODOX-M, IVAC, HyperCVAD, R-HyperCVAD, SC-EPOCH-RR, DHAP, ESHAP, GDP, ICE, MINE, CEPP, CDOP, GemOx, CEOP, CEPP, CHOEP, CHP, GCVP, DHAX, CALGB 8811, HIDAC, MOpAD, 7 + 3, 5 +2, 7 + 4, MEC, CVP, RBAC500, DHA-Cis, DHA-Ca, DHA-Ox, RCVP, RCEPP, RCEOP, CMV, DDMVAC, GemFLP, ITP, VIDE, VDC, VAI, VDC-IE, MAP, PCV, FCR, FR, PCR, HDMP, OFAR, EMA/CO, EMA/EP, EP/EMA, TP/TE, BEP, TIP, VIP, TPEx, ABVD, BEACOPP, AVD, Mini-BEAM, IGEV, C-MOPP, GCD, GEMOX, CAV, DT-PACE, VTD-PACE, DCEP, ATG, VAC, VelP, OFF, GTX, CAV, AD, MAID, AIM, VAC-IE, ADOC, or PE.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to a/an/the element, apparatus, member, component, means, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, member component, means, etc., unless explicitly stated otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will now be described by way of example only and with reference to the following accompanying drawings.

Figure 1 shows a perspective view of a preferred embodiment of an inventive power unit of a medicament delivery device;

Figure 2 shows a perspective view of the power unit of Fig. 1 from another viewing direction;

Figure 3 shows the power unit of Fig. 1 , without front and back cover; Figure 4 shows the power unit of Fig. 3, additionally without chassis and front frame;

Figure 5 shows the power unit of Fig. 4, additionally without RFID-antenna, interface element, switch activator, vibrator, battery cells, rear cap and screws;

Figure 6A shows the power unit of Fig. 5, of which only the drive unit, the pusher unit and the encoder are shown;

Figure 6B shows a side view of the drive unit, the pusher unit and the encoder as shown in Fig. 6A; and

Figure 7 shows a schematic view of a preferred embodiment of a medicament delivery device.

DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplifying embodiments are shown. The inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Elements, components and parts of different examples, embodiments or variants, but having the same or a similar function are designated by the same reference numerals in the figures.

Figures 1 to 6B show a possible embodiment of an inventive power unit 2 of a medicament delivery device in a perspective view from a distal lateral viewing point. The power unit 2 is adapted to be coupled with a medicament unit 3 not shown in figures 1 to 6B, but schematically depicted in figure 7. For administering a medicament to a patient, the medicament unit 3 is adapted to be inserted, with a medicament delivery element, into a patient's body and the power unit 2 is adapted to expel a medicament contained in the medicament unit 3 through the medicament delivery element. The power unit 2 as shown here is particularly adapted to administer a certain dose of the medicament, meaning that only a part of the medicament contained in the medicament unit 3 is administered.

The medicament delivery device 1 comprises both the power unit 2 and the medicament unit 3. As can be seen in figure 7, the distal end of the power unit 2 coincides with a distal end 12 of the medicament delivery device 1. A proximal end 11 of the medicament delivery device 1 is formed by the medicament unit 3. A longitudinal main axis 13 of the medicament delivery device 1 extends along an injection direction from the distal end 12 to the proximal end 11. As shown in figures 1 and 2, the power unit 2 comprises an outer housing 20 with a front cover 201 and a back cover 202. A front frame 203 is attached to the proximal end of the front cover 201 . The front frame 203 forms the proximal end of the power unit 2.

At the proximal end of the power unit 2, an opening is provided for receiving the medicament unit 1. The opening is at least partially surrounded by an interface element 211 , which serves to releasably attach the medicament unit 1 to the power unit 2 by means of a bayonet connection.

Within the housing 20, a chassis 212 is arranged (figure 3), which forms the main structural component of the power unit 2. The interface element 211 is attached to the chassis 212 by means of screws.

The power unit 2 comprises an electronic unit 22, which can be seen best in figures 4 and 5. The electronic unit 22 comprises a printed circuit board (PCB) 221 , on which a controller 222 is arranged. The controller 222, which is provided as an integrated circuit in the form of a microchip, serves to control the various functional components of the power unit 2, in particular a stepper motor 231 . The electronic unit 22 further comprises an RFID-antenna 223, which surrounds the interface element 211 and is connected to the controller 222. For supplying the electronic unit 22, the stepper motor 231 and an encoder 25 with electric energy, two rechargeable battery cells 224 are provided in the distal region of the power unit 2.

Also arranged within the housing 20 of the power unit 2 is a vibrator 213, which serves for providing haptic signals to the user. Further signal elements, such as in particular LEDs, are provided, in order to provide visual and/or acoustic information to the user concerning the state of the device.

A holding plate 214 serves to hold a variety of electronic components and to connect them to the PCB 221 and to the controller 222 in particular.

A drive unit 23 of the power unit 2 is shown particularly well in figures 6A and 6B. The drive unit 23 serves to proximally displace a rod-like pusher element 241 of a pusher unit 24, in order to expel the medicament from the medicament container of the medicament unit 3. For this purpose, the drive unit 23 comprises a stepper motor 231 which has an outer stator 232 and an inner rotor 233. Fixedly attached to the rotor 233 is a hollow motor shaft, which is not visible in the figures. The stepper motor 231 is connected to the controller 222 by means of lead wires 235, in order to be controlled and supplied with electrical energy.

Fixedly attached to the hollow motor shaft is a drive nut 234, which thus rotates with the rotor 233, without any gear unit coupled in-between. The drive nut 234 serves to transfer the rotational movement of the rotor 233 into a proximal (or distal) displacement of the pusher element 241. For this purpose, the drive nut 234 comprises an inner thread, which is engaged by an outer thread of the pusher element 241 . Due to the mutual thread engagement, rotation of the drive nut 234 and thus of the rotor 233 is directly coupled to a longitudinal displacement of the pusher element 24.

The pusher element 241 is part of a pusher unit 24, which further comprises a front adapter 242 and an anti-rotation element 243. The front adapter 242 forms the proximal end of the pusher element 241 and is adapted to contact and engage a plunger of the medicament unit 3. The anti-rotation element 243 is attached to the distal end of the pusher element 241 in a torque-proof manner and prevents the pusher element 241 to be rotated together and by the drive nut 234. For this purpose, the anti-rotation element 243 is guided by longitudinally extending guide grooves provided on an inner surface of the chassis 212.

Thus, the pusher element 241 extends along the main longitudinal axis 13 through the drive nut 234 and through the hollow motor shaft attached to the rotor 233.

Fixedly attached to or even made in one piece with the drive nut 234 is an encoder disk 251 of an encoder 25. The circular encoder disk 251 has a plurality of through-openings that are arranged at regular distances along the circumference of the disk. The through-openings serve to detect the rotational state of the encoder disk 251 and thus of the drive nut 23 by means of an optical sensor in the form of a photointerrupter 252 (see figures 6A and 6B). The number of through-openings of the encoder disk 251 is preferably the same or an integral multiple of the number of steps that are required by the stepper motor 231 for a single full rotation of the rotor 233. The stepper motor 231 can e.g. be a 7.5° stepper type motor having a full-step length of for example 12.7pm. The photointerrupter 252 is connected to the controller 222, in which the signals generated by the photointerrupter 252 are further processed and used for controlling the stepper motor 231.

For monitoring the back-EMF of the stepper motor 231 , a respective back-EMF monitoring device is provided, preferably on the PCB 221. The back-EMF monitoring device basically serves to measure the electrical energy flowing into the stepper motor 231 and the electrical energy flowing out of the stepper motor 231. A particularly well suited device for monitoring the back-EMF is the commercially available product StallGuard2™ of the company TRINAMIC Motion Control GmbH & Co. KG, Hamburg, Germany.

For detecting the coupling of the power unit 2 with a medicament unit 3, a switch activator 261 is provided. The switch activator 261 , of which only the distal part is visible in figure 4, extends into the proximal opening of the power unit 2, which serves to receive the medicament unit 3. When inserting the medicament unit 3 into the proximal opening, the switch activator 261 is displaced, against the biasing force of an activation spring 262, in the distal direction by the medicament unit 3, in order to actuate a switch not shown in the figures. The switch is connected to the controller 222, which is thus informed by the coupling of the medicament unit 3.

Figure 7 shows a schematic view of an inventive medicament delivery device 1 having a power unit 2, designed for example in accordance with the embodiment of figures 1 to 6B. Coupled to the power unit 2 is a medicament unit 2. The medicament unit 2 comprises an outer housing 30, which surrounds a medicament container 31 that serves to store a medicament to be injected. The medicament is expelled from the medicament container 31 and trough a needle 33 by proximally displacing the pusher element 241 of the power unit 2 until the front adapter 242 gets into contact with and proximally pushes a plunger 32 arranged within the medicament container 31. Before and after the injection, the needle 33 is laterally covered by a needle cover 34. The injection is triggered by placing the medicament delivery device 1 on an injection site. In doing so, the needle cover 34 is distally displaced, i.e. retracted, against the biasing force of a spring and thus triggers the injection. Via a respective mechanism, the retraction of the needle cover 34 is indicated to the controller 222, which effects the injection by means of activating the stepper motor 231. A closure cap 35 serves to seal the needle 33 prior to the use of the medicament unit 3.

In the following, use of the medicament delivery device 1 is described with reference to figure 7, with the assumption that the power unit 2 of the device of figure 7 is designed in accordance with the embodiment of figures 1 to 6B:

Between injections, the power unit 2 is in sleep mode. The crystal in a RTC watch of the PCB 221 is kept running by a coin cell battery to prevent the power 2 unit from losing track of time. The RTC watch is calibrated by connecting the power unit 2 to, for example, a patient smartphone or other relay device wirelessly or via an electrical connector 225, which transmit information and are connected to a network. The electrical connector 225 serves for recharging the battery cells 224 and/or for data connection.

Connection with the smartphone or other smart device can be achieved, for example, by a Bluetooth Low Energy (BLE) module. Data such as time of injection, dose, expiry date, amount of medicament in the medicament container 31 , medicament type, medicament amount injected and/or injection speed preference is transmitted before and/or after a successful or unsuccessful injection attempt.

When the power unit 2 is turned on or reset by the user, a homing sequence is triggered, in which the controller 222 causes the pusher element 241 to be displaced distally until an end limit switch inside of the power unit 2 is hit and actuated. The controller 222 then displaces the pusher element 241 in the proximal direction until the pusher element 241 reaches a "home position" HP as shown in figure 7.

When the medicament unit 3 is mounted to the power unit 2 using a bayonet motion, the power unit 2 is activated by means of the switch activator 26, meaning that the system is woken up. The RFID antenna 223 is used to read out the information on the RFID tag of the medicament unit 3. If all information is correct, the user is prompted with e.g. a green light on a progress bar on the power unit 2 as well as with tactile feedback from the vibrator 213 and/or sound by a buzzer.

If any information received from the RFID tag of the medicament unit 3 is considered incorrect, such as that the time for injection has not yet come or that the medicament has expired, e.g. an orange light and/or a tactile feedback will be presented to the user by the power unit 2.

If the battery cells 224 run low and there is no power left to complete an injection, the user will be prompted via e.g. a battery indication LED on the power unit 2. Battery status can also be transmitted wirelessly, such that e.g. a smartphone app will prompt the user, if the power unit 2 is suspected to run out of battery power. Battery status is preferably indicated by a progress bar when the user charges or picks up the power unit 2 after it has been stationary over a pre-set time limit. The power unit 2 is then activated by an accelerometer (G-sensor) that is preferably provided in the power unit 2, which is triggered by the patient lifting the device.

If the information received from the RFID tag is considered to be correct, meaning that a respective injection is possible, the controller 222 starts an initial calibration and positioning procedure, before prompting the user with the green light. In a first step of this calibration and positioning procedure, the threshold(s) for the motor control based on the sensing of the back-EMF are set. The threshold(s) relate e.g. to the detection of the contact of the pusher element 241 with the plunger 32 and to the detection of a stall of the stepper motor 231 . For this purpose, the threshold(s) (or reference value(s)) are adjusted in dependence on the amount of electric current supplied to the stepper motor 231 for displacing the pusher element 241, on the rotational frequency of the rotor 233 and/or on the displacement speed of the pusher element 241. The calibration procedure preferably also takes into account a possible compensation for unknown influences such as motor coil temperature. The calibration can e.g. be achieved by carrying out a test displacement of the pusher element 241 without contacting the plunger 32 and taking into account the electric energy supplied to the stepper motor 231 and the respectively measured back-EMF. In addition or alternatively, reference value(s) can also be applied, which have been received from the RFID tag of the medicament unit. In a second step of the calibration and positioning procedure, the pusher element 241 is proximally displaced by the controller until it contacts the plunger 32 at a plunger position PP (figure 7), which is detected by comparing the measured back-EMF with the previously set threshold. In doing so, the encoder 25 is used to detect possible lost steps of the stepper motor 231 . Such lost steps due to stall can particularly occur when the pusher element 241 , with the plunger adapter 242, hits the plunger 32 and displaces the plunger 32 proximally by a short distance from the plunger position PP to a dosing start position DSP until the stepper motor 231 comes to a stop.

If the patient receives a green light after mounting the medicament unit 3 to the power unit 2, he or she can proceed by removing the closure cap 35, which has been unlocked by the bayonet attachment of the medicament unit 3 to the power unit 2. As the closure cap 35 is removed, the needle cover 34 is exposed to the patient. This allows the needle cover 34 to be retracted.

The removal of the closure cap 35 is preferably detected by the controller 222 by appropriate means. When the removal of the closure cap 35 is detected, the controller 222 preferably starts a pre-delay phase during which the stepper motor 231 remains idle, in order to allow pressure inside the medicament container 31 and the fluid path to even out. An increased pressure can particularly be caused due to the practically inevitable short proximal displacement of the plunger 32 from the plunger position PP to the dosing start position DSP. Due to the pre-delay phase, a particularly accurate dosing can be achieved. The user can be informed by means of visual, audible and/or haptic signals, when the pre-delay phase is over and the device is ready for injection.

To start an injection, the patient pushes the device with the needle cover 34 against the injection site. In doing so, the needle cover 34 is retracted into the housing 20 of the power unit 2 until the needle 33 is close to the final injection depth. As the needle cover 34 is retracted, it actuates a mechanical start switch inside of the medicament unit 3, which is registered by the controller 222. As a result, the controller 222 triggers an injection procedure of the stepper motor 231. In the injection procedure, the drive nut 234 is rotated by the stepper motor 231. Since the anti-rotation element 243 prevents a rotation of the rodlike pusher element 241 , the rotation of the drive nut 234 is transferred into an axial displacement of the pusher element 241 from the dosing start position DSP towards a dosing end position DEP. During the displacement, the stepper motor 231 is controlled by monitoring the back-EMF generated by the stepper motor 231. If a pre-set threshold close to motor stall is reached, the motor speed is reduced by the controller 222, in order to lower the required force for the injection. If the threshold is nevertheless met or exceeded, the stepper motor 231 is reversed by the controller 222 and injection is aborted. Thus, by monitoring the back-EMF, stalling is effectively prevented. The exact position of the pusher element 241 at the time of stalling is known due to the measurement by the encoder 25. The stroke required for the complete injection of a dose is known based on the information received from the medicament unit 3 by the RFID antenna 223 and is compared to the actual movement of the drive nut 234 as measured by the encoder 25. When the pusher element 241 has reached a dose end position DEP as detected by the encoder 25, the entire dose has been injected and the displacement of the pusher element 241 is stopped by the stepper motor 231 .

Upon completion of the injection, the controller 222 triggers a post-delay phase, during which the stepper motor 231 again remains idle, in order to allow pressure inside the medicament container 31 and the fluid path to even out after the injection. Due to the post-delay phase, a particularly accurate dosing can be achieved, also with regard to further dose injections. The user can be informed by means of visual, audible and/or haptic signals, when the post-delay phase is over and the device is ready for removal from the injection site.

When the post delay-phase is over, the controller 222 causes the stepper motor to return the pusher element 241 to the "home position" HP as quickly as possible.

When the user lifts the device from the injection site, the mechanical start switch inside the medicament unit 3 is de-activated and the controller 222 causes the stepper motor 231 to stop. To continue the injection, the patient simply presses the needle cover 34 against the injection site again, so that the start switch is activated again and the injection is continued by the controller 222. If, however, the user lifts the device further, the needle cover 34 is rotated about the longitudinal main axis 13 due to a respective guide path inside of the medicament unit 3, which brings the needle cover 34 in a lock out-position, in which it is prevented from being retracted into the housing 30 again. Thus, a further injection is prevented and the needle 33 is covered by the needle cover 34, so as not to injure the patient.

T o remove the medicament unit 3 from the power unit 2, the user turns the medicament unit 3 by 90 degrees in the opposite direction as during the mounting procedure. The disconnection of the bayonet coupling is registered by the controller via the switch activator 261. As a result, the power unit 2, via the controller 222, starts transmitting information of the injection via wireless means or via the electrical connector 225 to the patient’s smartphone or to another device and then returns to sleep mode.

Furthermore, a supplementary sensor can be used to facilitate the detection of the position of the plunger. For example, a mouse sensor, e.g., an optical navigator, can be used.

The inventive concept has mainly been described above with reference to a few examples.

However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended claims. It is particularly to be noted that the combinations of elements, components and parts as shown in the figures are merely to be understood as non-limiting examples. The individual elements, components and parts of the various embodiments as described and/or shown in the figures can basically be interchanged with each other as desired and supplemented, for example, with further elements. Various modifications to the embodiments described are possible and will occur to those skilled in the art without departing from the invention which is defined by the following claims.

Claims

1 . A power unit (2) of a medicament delivery device (1 ) for delivering a medicament from a medicament container (31 ) to a human or animal patient, the power unit (2) comprising a pusher element (241 ) adapted to engage and push a plunger (32) in a proximal direction, in order to expel the medicament from the medicament delivery device (1 ); a drive unit (23) comprising a drive nut (234) and a stepper motor (231 ) with a rotor (233) and a stator (232), wherein the drive nut (234) is adapted to transfer a rotational movement of the rotor (233) into a proximal displacement of the pusher element (241 ); a controller (222) for controlling the stepper motor (231 ); and an encoder (25) for determining a displacement position of the pusher element (241 ); wherein the drive unit (23) is configured as a direct drive in such a way that the drive nut (234) rotates in accordance and at the same speed as the rotor (233) of the stepper motor (231 ) and that the rotational movement of the drive nut (234) is transferred directly into a displacement of the pusher element (241 ); and wherein the controller (222) is configured to monitor a back electromotive force of the stepper motor (231 ).

2. The power unit (2) of claim 1, wherein the controller (222) is configured to detect contact of the plunger (32) with the pusher element (241) based on the monitoring of the back electromotive force.

3. The power unit (2) of claim 1 or 2, wherein the controller (222) is configured to relate the monitored back electromotive force to an electrical current supplied to the stepper motor (231 ).

4. The power unit (2) of one of the preceding claims, wherein the controller (222) is configured to relate the monitored back electromotive force to a displacement position of the pusher element (241 ) as determined by the encoder (25).

5. The power unit (2) of one of the preceding claims, wherein for determining the displacement position of the pusher element (241 ), the encoder (25) measures a rotational position of the drive nut (234) and/or the displacement position of the pusher element (241 ).

6. The power unit (2) of one of the preceding claims, wherein the encoder (25) comprises an optical sensor, in particular a photoelectric sensor (252).

7. The power unit (2) of one of the preceding claims, wherein the encoder (25) comprises a disk (251 ) attached to or made in one piece with the drive nut (234).

8. The power unit (2) of one of the preceding claims, wherein the controller (222) is configured to stop the stepper motor (231 ), when a predetermined displacement position of the pusher element (241 ) determined by the encoder (25) is reached.

9. The power unit (2) of one of the preceding claims, wherein the controller (222) is configured to receive a dosing instruction, preferably from a medicament unit (3) of the medicament delivery device (1) or from a user, and to control the stepper motor (231 ) in such a way, that the pusher element (241 ) is brought into a displacement position corresponding to the received dosing instructions and/or that the pusher element (241 ) is proximally displaced by a displacement distance corresponding to the received dosing instruction.

10. The power unit (2) of claim 9, additionally comprising a radio-frequency identification (RFID) unit (223) and/or a wireless receiver unit for receiving the dosing instruction.

11. The power unit (2) of one of the preceding claims, wherein the controller (222) is configured to detect removal of a closure cap (35) of a medicament unit (3) of the medicament delivery device (1) and, upon detection of removal of the closure cap (35), to enter a pre-delay phase, during which the stepper motor (231 ) remains idle.

12. The power unit (2) of one of the preceding claims, wherein the controller (222) is configured to enter a post-delay phase upon completed proximal displacement of the pusher element (241 ), during which the stepper motor (231 ) remains idle.

13. The power unit (2) of one of the preceding claims, wherein the power unit (2) is adapted to receive a medicament unit (3) of the medicament delivery device (1) by means of a releasable attachment, the medicament unit (3) comprising a medicament container (31 ) for storing the medicament as well as a medicament delivery element (33) with a proximal end, through which the medicament can be delivered to the patient.

14. A medicament unit (3), which is adapted to be received by the power unit (2) comprising an RFID-unit (223) as claimed in claim 10, and which comprises a radiofrequency identification (RFID) tag for storing a dosing instruction that can be read by the RFID-unit (223) of the power unit (2).

15. A medicament delivery device (1 ) comprising the power unit (2) as claimed in one of claims 1 to 13 and a medicament unit (3).