Usage counting system

Abstract

1. A dose counting system for an injection device or a module configured for use with or applied to an injection device, the dose counting system comprising: a sensor arrangement including a first sensor configured to output a first signal and a second sensor configured to output a second signal, the first sensor and the second sensor having an angular offset with respect to each other, the sensor arrangement configured to detect movement of a rotary encoder system relative to the sensor arrangement during administration of a medicament; and a processor, the processor: detecting an angular offset of the first signal and the second signal. calculating numerical derivatives; detecting a peak in the derivative of the first signal and a peak in the derivative of the second signal when the first and second derivative signal values ​​exceed a predetermined threshold; determining that a unit of drug has been administered when the peaks in the derivative of the first signal and the derivative of the second signal are simultaneous, the peak in the derivative of the first signal has a different sign from the peak in the derivative of the second signal, and the peak in the derivative of the first signal has a different sign relative to a previous peak in the derivative of the first signal; and configured to determine a drug dose administered by the injection device by counting the units of drug administered.

Description

Technical Field

[0001] The present disclosure relates to a dosing counting system for an injection device or a module configured to be used with or applied to an injection device, and a method of operating the dosing counting system.

Background Art

[0002] There are various diseases that require regular treatment by injection of a drug. Such injections can be performed by using an injection device applied by a healthcare provider or the patient themselves. As an example, type 1 and type 2 diabetes can be treated by the patient themselves, for example, by injecting insulin doses once or several times a day. For example, a pre-filled disposable insulin pen can be used as an injection device. Alternatively, a reusable pen can also be used. With a reusable pen, it is possible to replace an empty drug cartridge with a new one. A set of disposable needles is associated with both pens, and this needle is replaced each time before use. Then, for example, by turning a dose knob and observing the actual dose from a dose window or display of the insulin pen, the insulin dose to be injected can be manually selected by the insulin pen. Then, the dose is injected by inserting the needle into a suitable skin portion and pressing an injection button of the insulin pen. It is desirable to measure information related to the state and / or use of the injection device, such as information regarding the injected insulin dose, so as to be able to monitor insulin injections, for example, to prevent incorrect handling of the insulin pen or to track the doses already applied.

[0003] Patent Document 1 describes an injection device including a movable dosage program component including a rotary encoder system having a predetermined angular periodicity and a sensor device. The sensor device includes a first optical sensor configured to detect the movement of the movable dosage program component relative to the sensor device during drug administration, and a second optical sensor configured to detect the movement of the rotary encoder system relative to the second optical sensor. The first optical sensor is configured to operate in a stroboscopic sampling mode at a first frequency, and the second optical sensor is configured to operate in a stroboscopic sampling mode at a second frequency lower than the first frequency. The injection device also includes a processor device configured to determine the drug dosage administered by the injection device based on the detected movement. Patent Document 1 further describes a method of processing signals generated by a sensor device in which two optical sensors are arranged with a 180° shift such that the signals of the first sensor of the two sensors and the signals of the second sensor of the two sensors are in antiphase. This method includes the steps of setting a high threshold and a low threshold for the signals of the first sensor and the second sensor, respectively, and counting the units of the dosage selected by the movable dosage program component when the signal of the second sensor exceeds the high threshold, then exceeds the low threshold, then the signal of the first sensor exceeds the low threshold, and then exceeds the high threshold.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Means for Solving the Problems

[0005] The first aspect disclosed herein requires a dosage counting system for an injection device or a module configured to be used with or applied to an injection device, the dosage counting system comprising: A sensor device including a first sensor configured to output a first signal and a second sensor configured to output a second signal, wherein the first sensor and the second sensor have an angular offset relative to each other, and the sensor device is configured to detect the movement of a rotational encoder system relative to each sensor device during administration of a drug; A processor, wherein the processor: Calculates numerical derivatives of the first signal and the second signal; Detects peaks in the derivative value of the first signal and peaks in the derivative value of the second signal when the first and second derivative signal values exceed a predetermined threshold; Determines that a unit of drug has been administered when the peaks in the derivative value of the first signal and the derivative value of the second signal are simultaneous, the peak in the derivative value of the first signal has a different sign from the peak in the derivative value of the second signal, and the peak in the derivative value of the first signal has a different sign from the previous peak in the derivative value of the first signal; Is configured to determine the drug dosage administered by an injection device by counting the units of drug administered.

[0006] The processor can be further configured to calculate a moving average value of a series of values of the first signal and the second signal.

[0007] The moving average value can include a value obtained by subtracting the average value of a second set of values from the average value of a first set of values of the same sensor, and the first and second sets include the same number of values. The first and second sets can overlap.

[0008] Alternatively, the processor can be further configured to calculate a moving median value of a series of values of the first signal and the second signal. The moving median value can include a value obtained by subtracting the median value of a second set of values from the median value of a first set of values, and the first and second sets include the same number of values. The first and second sets can overlap.

[0009] The injection device can include an injection button configured to be depressed to administer a dose of a medicament from the injection device. The processor can be further configured to determine that the injection button has been depressed or released when peaks in the first signal and the second signal have the same sign.

[0010] In response to determining that the injection button has been depressed, the processor can be further configured to initiate communication pairing with an external device or to perform data synchronization with an external device. The communication pairing can be Bluetooth pairing.

[0011] In response to determining that the injection button has been released, the processor can be further configured to initiate manual data synchronization.

[0012] In response to determining that the injection button has been released, the processor can be further configured to output a dose end indication.

[0013] The rotary encoder system can include an encoder encoding that includes a plurality of substantially light-reflective flags circumferentially disposed around the encoder encoding according to a predetermined angular periodicity.

[0014] A second aspect disclosed herein requires a method of operating a dose counting system of an injection device or a module configured to be used with or applied to an injection device, the dose counting system comprising: A sensor device including a first sensor configured to output a first signal and a second sensor configured to output a second signal, the first sensor and the second sensor having an angular offset relative to each other, the sensor device being configured to detect movement of a rotary encoder system relative to each sensor device during administration of a medicament; And a processor; Wherein the method comprises: Calculating the numerical derivatives of the first and second signals; When the first and second differential signal values exceed a predetermined threshold, detecting peaks in the derivative value of the first signal and peaks in the derivative value of the second signal; Determining that a unit of the drug has been administered when the peaks in the derivative value of the first signal and the derivative value of the second signal are simultaneous, the peak in the derivative value of the first signal has a different sign from the peak in the derivative value of the second signal, and the peak in the derivative value of the first signal has a different sign from the previous peak in the derivative value of the first signal; Determining the drug dosage administered by the injection device by counting the units of the drug administered.

[0015] The method of the second aspect can further include calculating a moving average value of a series of values of the first signal and the second signal.

[0016] To more fully understand the general concepts described in the previous section, embodiments thereof will be described with reference to the accompanying drawings.

Brief Description of the Drawings

[0017]

Figure 1

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Figure 3B

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Figure 4B

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Figure 5B

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Figure 9

Best Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments will be described with reference to an insulin injection device. However, the present disclosure is not limited to such application examples and can be equally suitably deployed in injection devices that discharge other drugs.

[0019] Embodiments related to an injection device that records and / or tracks data regarding the dosage delivered thereby, particularly a variable - dosage injection device, are provided. These data can include the size of the selected dosage, the date and time of administration, the duration of administration, and the like. The configurations described herein include the arrangement of sensing elements, power - management techniques (to facilitate small batteries), and the arrangement of trigger switches in order to enable efficient power use.

[0020] Certain embodiments herein are shown with respect to Sanofi's injection device in which an injection button and a grip are combined. The mechanical structure of such an injection device is described in detail in International Patent Application WO2014 / 033195A1, which is incorporated herein by reference. Other injection devices having the same kinematic behavior of the dial extension and the trigger button during the dose setting and dose expelling modes of operation are also known, for example, as the Kwikpen® device marketed by Eli Lilly and the Novopen® device marketed by Novo Nordisk. Thus, the application of the general principles to these devices is considered to be straightforward and further description is omitted. However, the general principles of the present disclosure are not limited to their kinematic behavior. It is also possible to consider certain other embodiments with separate injection button and grip components as application examples to injection devices, such as the device described in WO2004078239. The embodiments described herein can in particular be based on the embodiments described in WO2019 / 101962A1, which is incorporated herein by reference.

[0021] In the following discussion, the terms "distal", "distally", and "distal end" refer to the end of the injection device where the needle is provided. The terms "proximal", "proximally", and "proximal end" refer to the opposite end of the injection device where the injection button or the dose knob is provided.

[0022] Figure 1 from WO2019 / 101962A1 is an exploded view of a drug delivery device. In this example, the drug delivery device is an injection device 1 such as an injection pen described in WO2014 / 033195A1.

[0023] The injection device 1 of FIG. 1 is a pre-filled disposable injection pen, including a housing 10 and an insulin container 14, and a needle 15 can be attached to the insulin container 14. The needle is protected by an inner needle cap 16 and an outer needle cap 17 or other cap 18. The insulin dose scheduled to be discharged from the injection device 1 can be programmed or "dial-set" by turning the dose knob 12, and then the currently programmed dose is displayed, for example, in multiples of units, through the dose window 13. For example, if the injection device 1 is configured to administer human insulin, the dose can be displayed in so-called international units (IU), and 1 IU is biologically equivalent to about 45.5 micrograms (1 / 22 mg) of pure crystalline insulin. Other units can also be used in injection devices for delivering analog insulin or other drugs. Note that the selected dose can be equally appropriately displayed in a manner different from that shown in the dose window 13 of FIG. 1.

[0024] The dose window 13 can be in the form of an aperture within the housing 10 and is configured to move as the dose knob 12 is turned to enable the user to view a restricted portion of a dial sleeve 70 that provides a visual indication of the currently programmed dose. The dose knob 12 is rotated on a helical path relative to the housing 10 when turned during programming.

[0025] In this example, the dose knob 12 includes one or more formations 71a, 71b, 71c to facilitate attachment of a data collection device.

[0026] The injection device 1 can be configured to produce a mechanical click sound by turning the dose knob 12 and provide acoustic feedback to the user. The dial sleeve 70 interacts mechanically with the piston within the insulin container 14. In this embodiment, the dose knob 12 also acts as an injection button. The dose knob can accommodate a separate pushable button or can be a single component that the user presses to perform the administration process. When the needle 15 pierces the patient's skin portion and then the dose knob 12 is axially pushed, the insulin dose displayed in the display window 13 is discharged from the injection device 1. If the needle 15 of the injection device 1 remains in the skin portion for a specific time after the dose knob 12 is pushed, most of the dose is actually injected into the patient's body. The discharge of the insulin dose can also cause a mechanical click sound, which is different from the sound generated when the dose knob 12 is rotated during the dial setting of the dose.

[0027] In this embodiment, during the delivery of the insulin dose, the dose knob 12 is returned to its initial position by an axial movement rather than rotation, and the dial sleeve 70 rotates back to its initial position, displaying, for example, a zero-unit dose.

[0028] The injection device 1 can be used for several injection processes until the insulin container 14 is empty or until the expiration date of the drug within the injection device 1 (e.g., 28 days after the first use) is reached.

[0029] Furthermore, before first use of the injection device 1, it may be necessary to perform a so-called "prime shot" by, for example, selecting 2 units of insulin and depressing the dose knob 12 while holding the injection device 1 with the needle 15 pointing upward, in order to remove air from the insulin container 14 and the needle 15. To simplify the presentation, hereinafter it is assumed that the amount discharged substantially corresponds to the dose injected, and thus for example the amount of drug discharged from the injection device 1 is equal to the dose received by the user. Nevertheless, it may be necessary to take into account the difference (e.g., loss) between the amount discharged and the dose injected.

[0030] As described above, the dose knob 12 also functions as an injection button, and thus the same component is used for both dial setting and dosing.

[0031] Figures 3A and 3B show an encoder system 500 according to a particular embodiment. The encoder system can be configured to be used with the injection device 1 described above. As shown in Figures 3A and 3B, the primary sensor 215a and the secondary sensor 215b are configured to target a specially adapted area at the proximal end of the dial sleeve 70. In this embodiment, the primary sensor 215a and the secondary sensor 215b are infrared (IR) reflection sensors. Accordingly, the specially adapted proximal area of the dial sleeve 70 is divided into a reflective area 70a and a non-reflective (or absorptive) area 70b. The portion of the dial sleeve 70 that includes the reflective area 70a and the non-reflective (or absorptive) area 70b can be referred to as the encoder encoding.

[0032] Having two sensors facilitates the power management techniques described below. The primary sensor 215a is arranged to target a series of alternating reflective regions 70a and non-reflective regions 70b located at a frequency corresponding to the resolution required for a specific drug or administration method, for example, a dose history requirement corresponding to 1 IU. The secondary sensor 215b is arranged to target a series of alternating reflective regions 70a and non-reflective regions 70b at a reduced frequency compared to the primary sensor 215a. It should be understood that the encoder system 500 can function with only the primary sensor 215a to measure the administered dose. The secondary sensor 215b facilitates the power management techniques described below.

[0033] Two sets of encoded regions 70a, 70b are shown concentrically in FIGS. 3A and 3B, with one located on the outside and the other on the inside. However, any suitable arrangement of the two encoded regions 70a, 70b is possible. Note that the regions 70a, 70b are shown as a castellated region, but other shapes and configurations are also possible.

[0034] A dose counting system 700 is schematically shown in FIG. 2. The dose counting system 700 can be an integral member of the injection device 1 or a member of a module configured to be attached to the injection device 1. The dose counting system 700 includes a processor device 23 including one or more processors such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc., and a memory unit 24, 25 including a program memory 24 and a main memory 25 capable of storing software for execution by the processor device 23.

[0035] The dose counting system 700 controls a sensor device 215 including one or more sensors 215a, 215b.

[0036] Output 27 is provided, and the output 27 can be a wireless communication interface for communicating with another device via a wireless network such as Wi-Fi or Bluetooth (registered trademark), or can be an interface for a wired communication link such as a socket for receiving a Universal Serial Bus (USB), mini-USB, or micro-USB connector. For example, data can be output to a data collection device attached to Device 1.

[0037] The power switch 28 is also provided together with the battery 29.

[0038] Power management It is advantageous that the power consumption of the dose counting system 700 can be minimized so that the size of the battery 29 that needs to be accommodated within the device 1 can be minimized. The sensors 215a, 215b used in this embodiment require a certain amount of power to operate. This embodiment is arranged such that the sensors 215a, 215b can be intermittently switched on and off at a controlled frequency (i.e., stroboscopic sampling mode). In essence, there is a limit to the maximum rotational speed that can be counted by the encoder system before aliasing occurs. Aliasing is a phenomenon where the sampling speed is less than the speed at which the sensing region passes through the sensor, which means that counting errors are likely to occur when the region change is missed. The secondary sensor 215b, which has a frequency reduced compared to the primary frequency 215a, can withstand a higher rotational speed before aliasing becomes too large. The secondary sensor 215b cannot resolve the dosed amount to the same resolution as the primary sensor 215a, but the output of the secondary sensor 215b maintains high reliability even at higher speeds. Therefore, by using both sensors 215a, 215b in combination, it becomes possible to accurately determine the amount of dose delivered up to the first threshold rotational (dosing) speed. Subsequently, the sensors 215a, 215b can be used to determine an approximate dose delivered up to the second (higher) threshold dosing speed. When the speed exceeds the second threshold speed, the sensors 215a, 215b can no longer accurately or approximately determine the dose delivered, and thus the second threshold is set to exceed the speed that is physically impossible for the injection device 1.

[0039] The first speed threshold is determined by the sampling speed of the primary sensor 215a and the frequency of the encoder region transition, and the frequency of the encoder region transition is fixed by the resolution required by the intended drug or administration method (e.g., 1 transition per 1 IU). The second speed threshold is determined by the sampling speed of the secondary sensor 215b and the frequency of the encoder region transition. The first threshold is set so that the system can cover the maximum dosing speed range for accurate reporting of the dosed amount.

[0040] The exemplary embodiment shown in FIG. 3B has a primary sensor 215a that targets region transitions at 1 transition per 1 IU of the delivered dose and a secondary sensor 215b that targets region transitions at 1 transition per 6 IU of the delivered dose. Other options including 1 transition per 2 IU, 1 transition per 4 IU, 1 transition per 8 IU, and 1 transition per IU unit are also possible. These options are each possible because there are 24 distinct regions 70a, 70b per revolution within the encoder system 500 shown in FIG. 3B. Generally, if the number of distinct regions 70a, 70b per revolution is n units, there should be an option of 1 region transition per m units, where m is any integer factor of n greater than 1 and less than n.

[0041] The slower the sampling frequencies of both sensors 215a, 215b, the lower the required power consumption, and thus the smaller the required size of the battery 29. Therefore, by design, it is optimal to minimize the sampling frequency as much as realistically possible.

[0042] The following embodiments relate to alternative sensing techniques for determining the number of drug units dosed from the device 1.

[0043] Similar to the above-described embodiments, two sensors 215 are attached within the injection button 12 and are configured to sense the relative rotational position of the dial sleeve 70 with respect to the injection button during dosing. This relative rotation can be considered equal to the size of the dosed dose and can be used for the purpose of generating and storing or displaying dose history information.

[0044] As shown in FIG. 4A, the two sensors 215 from this embodiment are configured to target specially adapted regions 70a, 70b of the dial sleeve 70. In this embodiment, IR reflection sensors are used, and thus the regions of the dial sleeve 70 are divided into reflection and absorption sections 70a, 70b. In this specification, the sections 70a, 70b may also be referred to as flags.

[0045] Unlike the encoder system 500 described above in connection with FIGS. 3A and 3B, both encoder systems 900 shown in FIGS. 4A and 4B have IR sensors 215 that target the same type of regions 70a, 70b. In other words, these sensors 215 are arranged such that both face the reflection region 70a or both face the absorption region 70b at the same time. During dosing, the dial sleeve 70 rotates counterclockwise 15° with respect to the injection button 12 each time a drug unit is dosed. The alternately positioned flag elements are 30° (or 2 units) sections. The sensors 215 are arranged such that they are out of phase with each other, and thus the angle between the sensors 215 is equal to an odd number of units (e.g., 15°, 45°, 75°, etc.), as shown in FIG. 4B.

[0046] The encoder system 900 shown in FIG. 4B has 12 units per rotation, i.e., 12 alternately positioned regions 70a, 70b. Generally, the embodiments function in any multiple of 4 units per rotation. The angle α between the sensors 215 can be represented by Equation 1, where m and n are both arbitrary integers and 4m units are dosed per rotation. α=(2n - 1)360 4m Equation 1 - Angle between sensors

[0047] Figure 10 shows how the outputs for sensors A and B change when the dial sleeve 70 rotates counterclockwise during drug dosing.

[0048] Combined, the two sensors A and B produce a 2-bit Gray code output (11, 01, 00, 10). The 2-bit code sequence repeats every time 4 units are dosed. This coded output facilitates the detection of positive (counterclockwise) and negative (clockwise) rotations. For example, when the sensor reads "11", a change to "01" should be a positive rotation and a change to "10" should be a negative rotation. This direction sensing system has the advantage that, compared to a pure incremental system, it is possible to accurately determine the true dosed volume when negative rotations can occur. For example, when the user releases the injection button 12, there is a mechanism that rotates too far at the end of the dose stopper and then "backs off".

[0049] Next, an encoder system according to a further embodiment will be described with reference to FIGS. 5A and 5B. This encoder system can be used to record the dose delivered from an injection device. The concept of this encoder system is based on an optical waveguide used to convey the state of an indicator flag to a reflective sensor located physically remote from the flag. The embodiments shown in FIGS. 5A and 5B use an optical add-on module configured to be attached to an injection device. For simplicity, the housing of the add-on module is omitted, and only the sensor and optical components are shown in FIGS. 5A and 5B. The add-on module also includes a dose counting system 700 such as that shown in FIG. 2. Such an add-on module can be configured to be added to a suitably configured pen injection device for the purpose of recording the dial settings and doses delivered from the device. The add-on module can be configured to replace the dial setting knob / injection button of the injection pen, or alternatively, can be adapted to an existing dial setting knob / injection button. In these embodiments, the indicator flag is formed by the relative rotation of a digital sleeve or dial sleeve and the add-on module, and the add-on module includes at least one optical sensor. This functionality can be useful to a wide variety of device users, either as a memory aid or to support detailed logging of the dosing history. The add-on module can be configured to be connectable to an external device such as a smartphone or tablet PC to enable the dosing history to be periodically downloaded from the module. However, the concept of the encoder system is applicable to any device involving separation of the indicator flag and sensor, such as the injection device 1 of FIG. 1, and the module can be implemented within the dose knob 12, which can be made removable.

[0050] According to the concept of the encoder system, a collimating optical system is arranged between the active surface of at least one optical sensor, which can be an IR reflection sensor, and the movable dosage program component. The collimating optical system can include one or more individual collimating lenses and one or more light conductors. The geometry of the lens can be selected to collimate ( "collimate") the divergent radiation emitted by at least one optical sensor before transmission between the at least one sensor and the target, i.e., the indicator flag, through the light conductor.

[0051] Figure 5A shows the essential components of one embodiment of module 1000 implementing this encoder concept: the relative rotation of the digital sleeve 1006 around the rotation axis 1010 can form an indicator flag 1008, which in the illustrated embodiment is implemented, for example, by radially protruding teeth formed at the top of the digital sleeve or dial sleeve 70 of the injection device 1; an optical sensor 215c and a collimating optical system are included, and the collimating optical system includes two collimating lenses 1004a, 1004b and a light guiding part in the form of a light conductor 1002 for transmitting the state of the indicator flag 1008 to the sensor 215c located away from the flag. The collimating optical system 1002, 1004a, 1004b and the optical sensor 215c can be positioned relative to the peripheral components within the injection device and can be particularly associated with an add-on module. As can be seen, the collimating optical system including the lenses 1004a, 1004b and the light conductor 1002 is arranged between the active side of the optical sensor 215c, i.e., the IR emission and reception side, and the indicator flag 1008 formed by the digital sleeve 1006.

[0052] Figure 5B shows a chassis 1012 that houses two optical sensors 215c (represented by their locations within the chassis 1012 shown by the thick-lined rectangles) and respective collimating lenses 1004a, 1004b, according to one embodiment of module 1000. The collimating lenses 1004a, 1004b are here implemented by individual lenses and are assumed to be held with respect to the proximal surfaces of the optical sensor 215c and the light conductor by a cradle or other positioning geometry that exists as a function within the chassis 1012.

[0053] Fundamentally, all of the above points relate to a more robust encoder machine system where the optical (reflective) sensors form the active elements within the optical encoder. If the movement of the digital sleeve relative to the dose button is captured more efficiently, the reduced emitter power of the optical sensors and the use of algorithms that require less microcontroller operation can be utilized, reducing energy consumption and extending battery life. The encoder systems described herein are equally applicable to inclusion in disposable or reusable injection devices, or any device that includes an optical encoder arrangement having a similar light conductor architecture.

[0054] FIG. 6 shows a partial view of the digital sleeve 400 and the arrangement of teeth or flags 402 on the digital sleeve. The flags 402 are substantially light-reflective. For example, the flags 402 can be made of a reflective material, or can be coated with a reflective material, or a reflective material can be printed on the surface of the flags 402. The flags 402 are spaced at an angle of 30 degrees from each other, and thus twelve flags 402 are evenly spaced around the circumference of the digital sleeve 400. FIG. 6 also shows the exemplary positions of two light conductors associated with respective light sensors indicated by the ellipses numbered 1 and 2. The light conductors are separated at an angle of 45 degrees, and thus the difference between the angular spacing of the light conductors and the angular spacing of the flags 402 is 15 degrees, and the signals from the two sensors are out of phase with each other. In some embodiments of the injection device, the digital sleeve 400 is configured to rotate 15 degrees each time a unit of the drug is dialed or delivered. Thus, with the arrangement shown in FIG. 6, it is possible to use the signals from the two sensors to measure the number of units of the drug dialed or delivered. This embodiment has been described in terms of optical sensing and reflective flags, but in some other embodiments, induction, capacitance, or magnetic sensing can also be used. For example, the flags 402 can include conductive or magnetic regions that pass under an induction, capacitance, or magnetic sensor to determine the amount of rotation of the digital sleeve 400.

[0055] Next, an embodiment of an algorithm for processing the signals, particularly the signal voltage, generated by the light sensors of the sensor device described above in relation to the injection device and the module will be described. The algorithm is implemented as a computer program for execution by one or more processors of a processor device 23 included in, for example, the dose counting system 700 shown in FIG. 2.

[0056] The algorithm is implemented to process signals delivered by one or more optical sensors 215a, 215b, 215c, i.e., to decode a selected drug dosage scheduled or already delivered by the injection device. The algorithm is preferably applicable to devices involving separation of indicator flags and sensors by a light conductor, such as the modules described above.

[0057] The relative rotation between the dose button and the digital sleeve can be optically encoded using an incremental encoder, such as an orthogonal encoder, and two or more optical sensors, particularly reflective IR sensors, look axially at the castellations or radially protruding teeth or flags formed on the top surface of the digital sleeve. The encoder system can be implemented as an add-on module, which means that even after calibrating the module, due to variations in the manufacturing process of the injection device to which the module is fitted, the detected position of the castellations or teeth can vary from device to device with respect to the position of the optical sensors. Thus, there is a high likelihood of signal variations between devices during typical use. In addition, during the time the dose button is depressed and released, the axial position of the optical sensors can also vary with respect to the castellations.

[0058] The algorithm described below can be implemented within the injection device or an add-on module, particularly for the purpose of recording the dosage delivered from the injection device. This function can be useful to a wide variety of injection device users, either as a memory aid or to support detailed logging of the dosage history. It is envisioned that the electronic device implementing the algorithm can be configured to be connectable to a mobile device, such as a smartphone, in order to enable the dosage history to be periodically downloaded from the electronic device.

[0059] The algorithm is configured to detect the castellation or relative rotation of teeth on a digital sleeve with respect to non-rotating components such as a dose button. The presence of castellation or tooth function, etc., provides a binary code, and this binary code can be used to count the number of units dosed from the injection device. The voltage output of the optical sensor can typically approximate a sine curve. The algorithm is capable of detecting the presence of castellation or tooth function, etc., across all devices, and such devices may have any combination of geometric tolerances of physical functions.

[0060] In addition, when the dose button moves axially towards or away from the castellation or tooth function at the start and end of dose expulsion, the change in the signal generated by the optical sensor should not be misinterpreted as rotation of the castellation or tooth function. Thus, the algorithm can accommodate significant amplitude modulation of the signal generated by the optical sensor.

[0061] The algorithm relates to a system in which two optical sensors are arranged with a 180° phase shift, and thus the signal voltages generated by both sensors are in antiphase.

[0062] One embodiment of the algorithm provides improved noise immunity and false positive reduction and is not affected by offset drift (amplitude modulation) and sensor amplitude fluctuations.

[0063] The first image of FIG. 7 shows a typical transition of the signal voltages generated by two optical sensors when a dose is being administered. The signal voltage of the first sensor is shown by the thick line, and the signal voltage of the second sensor is shown by the thin line. The two optical sensors can have different gain profiles from each other. The signal voltages are amplitude modulated. Due to the different gain profiles, significantly different signal voltages are generated by the two optical sensors and sent to a processor for processing the signal voltages. The different gain profiles can occur, for example, due to tolerances associated with electronic components. In this system, the two optical sensors are arranged with a 180° phase shift, and thus the signal voltages generated by both sensors are in opposite phases.

[0064] The second image of FIG. 7 shows the numerical derivative values of the signal transitions of the first image. If simultaneous peaks (positive and negative) exist within the derivative values of the first and second signal voltages, detection of the unit of the administered drug is performed by an algorithm. The small series of peaks at the beginning of the derivative value graph (only within the first sensor signal) are caused by the pressing of the injection button and the accompanying axial movement. Since there are no corresponding peaks of the opposite sign within the second sensor signal, this is not counted as an administered drug unit. The peaks within the derivative values of both the first and second sensors at the end of the derivative value graph are caused by the release of the injection button. Also in this case, since the peaks in the two sensors do not have opposite signs, these peaks are not counted as administered drug units.

[0065] The first image of FIG. 8 shows a typical transition of the signal voltages generated by two optical sensors when the injection button is pressed when the dose is not dialed in to the injection device. The first sensor signal voltage is shown by the thick line, and the second sensor signal voltage is shown by the thin line.

[0066] The second image of FIG. 8 shows the derivative values of the signal transitions of the first image. A series of positive peaks in both the first and second sensor signals at the beginning of the derivative value graph are caused by pressing the injection button. Thus, pressing the injection button is detected by the algorithm but not counted as an administration of a unit of the drug. A series of negative peaks in both the first and second sensor signals at the end of the derivative value graph are caused by releasing the injection button. Thus, releasing the injection button is detected by the algorithm but not counted as an administration of a unit of the drug. Thus, signals caused by pressing and releasing the injection button are not misidentified as administration events.

[0067] To determine the amount of drug administered by the injection device, the algorithm calculates the numerical derivatives of the first and second signals. The algorithm then identifies the maximum and minimum values within the derivative values of the two sensor signals. The algorithm defines a differential peak threshold that determines when the size of the differential peak value needs to be confirmed as a peak. The differential peak threshold can be set during calibration of the sensor during manufacturing. The algorithm can define different differential peak thresholds for the first and second sensors due to differences in the gain profiles. The algorithm detects peaks in the derivative value of the first signal and peaks in the derivative value of the second signal when the first and second differential signal values exceed the differential peak threshold or their respective differential peak thresholds.

[0068] The algorithm determines that a unit of the drug has been administered when the following three criteria are met: (a) The detected peaks in the derivative value of the first signal and the derivative value of the second signal are simultaneous. The range within which the detected peaks in the two derivative signals must be simultaneous can be predefined by the algorithm. For example, it can be expected that these peaks do not occur exactly simultaneously due to the manufacturing tolerances of the dosimeter system. Therefore, the algorithm can define a simultaneity threshold, and if the peaks in the derivative value of the first signal and the derivative value of the second signal occur within this threshold range, these peaks are considered to be simultaneous; (b) The peak in the derivative value of the first signal has a different sign from the peak in the derivative value of the second signal. The two sensors are arranged such that their signals are out of phase. Therefore, as the signal from the second sensor increases, the signal from the first sensor should decrease, and vice versa, resulting in opposite signs for the respective derivative values; (c) The peak in the derivative value of the first signal has a different sign from the previous peak in the derivative value of the first signal. This criterion contributes to ensuring that the peak in the derivative value represents the passage of the previous flag of the sensor rather than the pressing or releasing of the button.

[0069] The algorithm then determines the drug dosage administered by the injection device by counting the number of units of the drug administered.

[0070] To further improve the robustness of the peak detection process, the algorithm can calculate the moving average value or the moving median value of a series of values of the first and second signals.

[0071] When a moving average value is used, the moving average value can include a value obtained by subtracting the average value of a second set of sensor values from the average value of a first set of sensor values, where the first and second sets contain the same number of values and can overlap. In a simple example, a moving average value of 8 values, such as average value =..., average value(1 - 8), average value(2 - 9), average value(3 - 10), etc., can be calculated. The first 7 samples and the last 7 samples of each sensor can be used without averaging, or can be averaged depending on the available information, such as average value = 1, average value(1 - 2), average value(1 - 3), average value(1 - 4),..., average value(1 - 7), average value(1 - 8), average value(2 - 9), average value(3 - 10). Alternatively, the first 7 values can be completely ignored. The sample rate of the sensor is in the kHz range, and as a result, the delay should be less than 1 / 100 of a second, and thus no dosage should be missed. In another example, a larger overlap is used in the calculation of the average value. The average value can be calculated as the value obtained by subtracting the average value of sensor values 2 - 9 from the average value of sensor values 6 - 13. This average value can be considered to have an average of 8 and a distance (or overlap) of 4. After the average value is calculated as described above, the derivative of the average signal is calculated.

[0072] When a moving median value is used, the moving median value can include a value obtained by subtracting the median value of a second set of sensor values from the median value of a first set of sensor values, where the first and second sets contain the same number of values and overlap. For example, the average value can be calculated as the value obtained by subtracting the median value of peaks 3 - 9 from the median value of peaks 6 - 12. This average value can be considered to have an average of 7 and a distance (or overlap) of 3. After the average value is calculated as described above, the derivative of the average signal is calculated.

[0073] The algorithms discussed above are not affected by offset drift (amplitude modulation) and sensor amplitude variations because the raw sensor data is first averaged and then differentiation is applied.

[0074] As already discussed, the injection device includes an injection button configured to be depressed by a user to administer a dose of the medicament from the injection device. The algorithm is configured such that depression and release of the injection button are not misidentified as the administration of a dose of the medicament. The algorithm achieves this by determining that the injection button has been depressed or released when the peaks in the first signal and the second signal have the same sign, as can be seen in the second images of FIGS. 7 and 8.

[0075] The processor of the dose counting system can be configured to cause further action to be taken in response to detecting that the injection button has been depressed or released. For example, in response to determining that the injection button has been depressed, the processor can initiate communication pairing with an external device using a wireless transceiver unit (not shown) of the injection device or module. The communication pairing can be a Bluetooth pairing.

[0076] In response to determining that the injection button has been released, the processor can initiate manual data synchronization. Typically, at the end of each administration event, the dose data is automatically synchronized. If the algorithm detects button depression and release while a dose has not been delivered, the data is also synchronized at this time.

[0077] As a further example, in response to determining that the injection button has been released, the processor can cause a dose end indication to be output. This can take the form of an audible alert or a visual display of information on the display of the injection device or module. Prior to the dose end indication, detection of button release can trigger a countdown of the dwell time, which indicates the time the user should hold the injection needle in the skin after the injection device has reached zero units.

[0078] As already discussed, a rotary encoder system can include an encoder ring having a plurality of substantially light-reflective flags arranged circumferentially. Each of these flags can have a concave or convex shape. Such a shape increases the signal gradient of the signals received by the first and second sensors, and thus increases the amplitude of the derivative of these signals.

[0079] Regarding the above embodiment, it has been described in relation to collecting data from an insulin injection pen, but it should be noted that the embodiments of the present invention can also be used for other purposes such as monitoring the injection of other drugs.

[0080] The terms "drug" or "medication" are used synonymously herein and describe a pharmaceutical formulation comprising one or more active pharmaceutical ingredients or pharmaceutically acceptable salts or solvates thereof, and optionally a pharmaceutically acceptable carrier. An active pharmaceutical ingredient ("API") is, in the broadest sense, a chemical structure that has a biological effect on a human or animal. In pharmacology, a drug or medicine is used for the treatment, cure, prevention, or diagnosis of a disease, or otherwise to improve physical or mental well-being. Drugs or medications can be used for a limited duration or, in the case of chronic disorders, periodically.

[0081] As described below, a drug or agent can include at least one API or a combination thereof in various types of formulations for the treatment of one or more diseases. Examples of APIs include small molecules having a molecular weight of 500 Da or less, polypeptides, peptides, and proteins (e.g., hormones, growth factors, antibodies, antibody fragments, and enzymes), carbohydrates and polysaccharides, and nucleic acids, double-stranded or single-stranded DNA (including naked and cDNA), RNA, antisense nucleic acids such as antisense DNA and RNA, small interfering RNA (siRNA), ribozymes, genes, and oligonucleotides. Nucleic acids can be incorporated into molecular delivery systems such as vectors, plasmids, or liposomes. Mixtures of one or more drugs are also contemplated.

[0082] A drug or medicament can be contained in a primary package or “drug container” adapted for use in a drug delivery device. The drug container can be, for example, a cartridge, syringe, reservoir, or other rigid or flexible vessel configured to provide a chamber suitable for containing one or more drugs (e.g., short-term or long-term containment). For example, in some cases, the chamber can be designed to contain a drug for at least one day (e.g., one day to at least 30 days). In some cases, the chamber can be designed to contain a drug for about one month to about two years. The containment can be carried out at room temperature (e.g., about 20°C) or refrigerated temperature (e.g., about -4°C to about 4°C). In some cases, the drug container can be or include a dual-chamber cartridge configured to separately contain in each chamber two or more components of a pharmaceutical formulation to be administered (e.g., an API and a diluent, or two different drugs). In such cases, the two chambers of the dual-chamber cartridge can be configured to allow mixing between the two or more components before and / or during dosing into a human or animal body. For example, the two chambers can be configured to be in fluid communication with each other (e.g., via a conduit between the two chambers) and, optionally, allow mixing of the two components by the user before dosing. Alternatively or additionally, the two chambers can be configured to allow mixing upon dosing of the components into a human or animal body.

[0083] The drugs or agents included in the drug delivery devices described herein can be used for the treatment and / or prevention of many different types of medical disorders. Examples of disorders include, for example, diabetes or complications associated with diabetes such as diabetic retinopathy, thromboembolic disorders such as deep vein thrombosis or pulmonary embolism. Further examples of disorders are acute coronary syndrome (ACS), angina, myocardial infarction, cancer, macular degeneration, inflammation, hay fever, atherosclerosis and / or rheumatoid arthritis. Examples of APIs and drugs are those described in handbooks such as the Rote Liste 2014 (for example, but not limited to, main group 12 (antidiabetic agents) or 86 (oncological agents)) or the Merck Index, 15th edition.

[0084] Examples of APIs for the treatment and / or prevention of type 1 or type 2 diabetes or complications associated with type 1 or type 2 diabetes include insulin, such as human insulin, or a human insulin analog or derivative, glucagon-like peptide (GLP-1), a GLP-1 analog or GLP-1 receptor agonist, and its analog or derivative, dipeptidyl peptidase-4 (DPP4) inhibitor, or a pharmaceutically acceptable salt or solvate thereof, or a mixture of any of them. As used herein, the terms “analog” and “derivative” refer to a polypeptide having a molecular structure formally derivable from the structure of a naturally occurring peptide, such as the structure of human insulin, by deletion and / or exchange of at least one amino acid residue present in the naturally occurring peptide and / or by addition of at least one amino acid residue. The added and / or exchanged amino acid residues can be any of the codable amino acid residues or other naturally occurring residues or purely synthetic amino acid residues. Insulin analogs are also referred to as “insulin receptor ligands”. In particular, the term “derivative” refers to a polypeptide having a molecular structure formally derivable from the structure of a naturally occurring peptide, for example, a molecular structure of human insulin in which one or more organic substituents (such as fatty acids) are attached to one or more of the amino acids. Optionally, one or more amino acids present in the naturally occurring peptide are deleted and / or replaced by other amino acids including non-codable amino acids, or amino acids are added including those non-codable for the naturally occurring peptide.

[0085] Examples of insulin analogs are Gly(A21), Arg(B31), Arg(B32) human insulin (insulin glargine); Lys(B3), Glu(B29) human insulin (insulin glulisine); Lys(B28), Pro(B29) human insulin (insulin lispro); Asp(B28) human insulin (insulin aspart); human insulin in which the proline at position B28 may be replaced by Asp, Lys, Leu, Val or Ala and the Lys at position B29 may be replaced by Pro; Ala(B26) human insulin; Des(B28 - B30) human insulin; Des(B27) human insulin and Des(B30) human insulin.

[0086] Examples of insulin derivatives are, for example, B29 - N - myristoyl - des(B30) human insulin, Lys(B29)(N - tetradecanoyl) - des(B30) human insulin (insulin detemir, Levemir (registered trademark)); 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 - gamma - glutamyl) - des(B30) human insulin, B29 - N - omega - carboxypentadecanoyl - gamma - L - glutamyl - des(B30) human insulin (insulin degludec, Tresiba (registered trademark)); B29 - N - (N - lithocholyl - gamma - glutamyl) - des(B30) human insulin; B29 - N - (ω - carboxyheptadecanoyl) - des(B30) human insulin and B29 - N - (ω - carboxyheptadecanoyl) human insulin.

[0087] Examples of GLP-1, GLP-1 analogs, and GLP-1 receptor agonists include, for example, lixisenatide (Lyxumia®), exenatide (exendin-4, Byetta®, Bydureon®, a 39-amino acid peptide produced by the salivary gland of the Gila monster), liraglutide (Victoza®), semaglutide, taspoglutide, albiglutide (Syncria®), dulaglutide (Trulicity®), r exendin-4, CJC-1134-PC, PB-1023, TTP-054, langlenatide / HM-11260C, CM-3, GLP-1 eligogene, ORMD-0901, NN-9924, NN-9926, NN-9927, nodexen, viadorl-GLP-1, CVX-096, ZYOG-1, ZYD-1, GSK-2374697, DA-3091, MAR-701, MAR709, ZP-2929, ZP-3022, TT-401, BHM-034, MOD-6030, CAM-2036, DA-15864, ARI-2651, ARI-2255, exenatide-XTEN, and glucagon-Xten.

[0088] An example of an oligonucleotide is, for example, mipomersen sodium (Kynamro®), a cholesterol-lowering antisense therapeutic agent for the treatment of familial hypercholesterolemia.

[0089] Examples of DPP4 inhibitors are vildagliptin, sitagliptin, denagliptin, saxagliptin, and berberine.

[0090] Examples of hormones include pituitary hormones or hypothalamic hormones or regulatory active peptides and their antagonists, for example, gonadotropins (folitropin, lutropin, chorionic gonadotropin, menotropin), somatropin (Somatropine) (Somatropin), desmopressin, terlipressin, gonadorelin, tryptorelin, leuprorelin, buserelin, nafarelin, and goserelin.

[0091] Examples of polysaccharides include glucosaminoglycans, hyaluronic acid, heparin, low molecular weight heparin or ultra-low molecular weight heparin or their derivatives, or sulfated polysaccharides such as the polysaccharides described above in polysulfated form, and / or their pharmaceutically acceptable salts. An example of a pharmaceutically acceptable salt of polysulfated low molecular weight heparin is enoxaparin sodium. Examples of hyaluronic acid derivatives are hylan G-F20 (Synvisc (registered trademark)), sodium hyaluronate.

[0092] As used herein, the term "antibody" refers to an immunoglobulin molecule or an antigen-binding portion thereof. Examples of antigen-binding portions of immunoglobulin molecules include F(ab) and F(ab’)2 fragments that retain the ability to bind to an antigen. Antibodies can be polyclonal antibodies, monoclonal antibodies, recombinant antibodies, chimeric antibodies, deimmunized or humanized antibodies, fully human antibodies, non-human (e.g., murine) antibodies, or single-chain antibodies. In some embodiments, the antibody has effector functions and is capable of fixing complement. In some embodiments, the antibody has a reduced or no ability to bind to an Fc receptor. For example, the antibody can be an isotype or subtype, antibody fragment or mutant having a mutation or deletion in the Fc receptor-binding region that does not assist in binding to the Fc receptor. The term antibody also includes antigen-binding molecules based on tetravalent bispecific tandem immunoglobulins (TBTIs) and / or dual variable domain antibody-like binding proteins having a crossover binding region orientation (CODV).

[0093] The term "fragment" or "antibody fragment" refers to a polypeptide (e.g., an antibody heavy chain and / or light chain polypeptide) derived from an antibody polypeptide molecule that does not include a full-length antibody polypeptide but still includes at least a portion of the full-length antibody polypeptide capable of binding to an antigen. An antibody fragment may include a cleaved portion of the full-length antibody polypeptide, but the term is not limited to such cleaved fragments. Antibody fragments useful in the present invention include, for example, Fab fragments, F(ab’)2 fragments, scFv (single-chain Fv) fragments, linear antibodies, single-specific or multispecific antibody fragments, such as bispecific, trispecific, tetra-specific and multispecific antibodies (e.g., diabodies, triabodies, tetra-bodies), monovalent or polyvalent antibody fragments, such as divalent, trivalent, tetravalent and polyvalent antibodies, minibodies, chelated recombinant antibodies, tribodies or bibodies, intrabodies, nanobodies, small modular immunopharmaceuticals (SMIPs), binding domain immunoglobulin fusion proteins, camelized antibodies, and VHH-containing antibodies. Additional examples of antigen-binding antibody fragments are known in the art.

[0094] The term "complementary determining region" or "CDR" refers to short polypeptide sequences within the variable regions of both the heavy and light chain polypeptides that mainly play a role in mediating specific antigen recognition. The term "framework region" refers to the amino acid sequences within the variable regions of both the heavy and light chain polypeptides that are not CDR sequences and mainly play a role in maintaining the proper arrangement of the CDR sequences to enable antigen binding. The framework region itself is typically not directly involved in antigen binding, but as is known in the art, certain residues within the framework region of a particular antibody may be directly involved in antigen binding or may affect the ability of one or more amino acids within the CDR to interact with the antigen.

[0095] Examples of antibodies are anti-PCSK-9 mAb (e.g., alirocumab), anti-IL-6 mAb (e.g., sarilumab), and anti-IL-4 mAb (e.g., dupilumab).

[0096] Any pharmaceutically acceptable salts of the APIs described herein are contemplated for use in a drug or agent in a drug delivery device. Pharmaceutically acceptable salts are, for example, acid addition salts and basic salts.

[0097] Without departing from the full scope and spirit of the invention, various components of the APIs, manufacturing methods, devices, methods, systems, and embodiments described herein can be modified (added and / or deleted), and it will be understood by those skilled in the art that the invention encompasses such modifications and any equivalents thereof.

Claims

Claim 1 A dose counting system (700) for an injection device (1) or a module configured to be used with or applied to an injection device, comprising: A sensor device (215) including a first sensor (215a) configured to output a first signal and a second sensor (215b) configured to output a second signal, wherein the first sensor (215a) and the second sensor (215b) have an angular offset with respect to each other, and the sensor device (215) is configured to detect the movement of a rotary encoder system (500, 900) with respect to the sensor device (215) during administration of a drug; A processor (23), wherein the processor (23) is configured to: Calculate numerical derivatives of the first signal and the second signal; Detect peaks in the derivative value of the first signal and peaks in the derivative value of the second signal when the first and second derivative signal values exceed a predetermined threshold; Determine that a unit of drug has been administered when the peaks in the derivative value of the first signal and the peaks in the derivative value of the second signal are simultaneous, the peaks in the derivative value of the first signal have a different sign from the peaks in the derivative value of the second signal, and the peaks in the derivative value of the first signal have a different sign from the previous peaks in the derivative value of the first signal; The dose counting system configured to determine the drug dose administered by the injection device by counting the units of drug administered. Claim 2 The dose counting system (700) according to claim 1, wherein the processor (23) is further configured to calculate a moving average value of a series of values of the first signal and the second signal. Claim 3 The dose counting system (700) according to claim 2, wherein the moving average value includes a value obtained by subtracting the average value of a second set of values from the average value of a first set of values of the same sensor, and the first and second sets include the same number of values. Claim 4 The dose counting system (700) according to claim 3, wherein the first and second sets overlap. Claim 5 The dose counting system (700) according to claim 2, wherein the processor (23) is further configured to calculate a moving median value of a series of values of the first signal and the second signal. Claim 6 The dose counting system (700) according to claim 5, wherein the moving median value includes a value obtained by subtracting the median value of a second set of values from the median value of a first set of values, and the first and second sets include the same number of values.

7. The dosage counting system (700) according to any one of claims 1 to 6, wherein the injection device (1) includes an injection button (12) configured to be pressed to administer a dosage of a medicament from the injection device.

8. The dosage counting system (700) according to claim 7, wherein the processor (23) is further configured to determine that the injection button (12) has been pressed or released when peaks in the first signal and the second signal have the same sign.

9. The dosage counting system (700) according to claim 8, wherein the processor (23) is further configured to initiate communication pairing with an external device or perform data synchronization with an external device in response to determining that the injection button (12) has been pressed.

10. The dosage counting system (700) according to claim 9, wherein the communication pairing is Bluetooth pairing.

11. The dosage counting system (700) according to any one of claims 7 to 10, wherein the processor (23) is further configured to initiate manual data synchronization in response to determining that the injection button (12) has been released.

12. The dosage counting system (700) according to any one of claims 7 to 11, wherein the processor (23) is further configured to output a dosage end indication in response to determining that the injection button (12) has been released.

13. The dosage counting system (700) according to any one of claims 1 to 12, wherein the rotary encoder system (500, 900) includes an encoder encoding (700, 400, 1006), the encoder encoding (700, 400, 1006) including a plurality of substantially light-reflective flags (70a) circumferentially arranged around the encoder encoding according to a predetermined angular periodicity.

14. A method of operating a dosage counting system (700) of an injection device (1) or a module configured to be used with or applied to the injection device, the dosage counting system comprising: A sensor device (215) including a first sensor (215a) configured to output a first signal and a second sensor (215b) configured to output a second signal, wherein the first sensor (215a) and the second sensor (215b) have an angular offset relative to each other, and the sensor device (215) is configured to detect the movement of a rotary encoder system (500, 900) relative to the sensor device during administration of a drug; including a processor (23); wherein the method comprises: calculating numerical derivatives of the first signal and the second signal; detecting peaks in the derivative value of the first signal and peaks in the derivative value of the second signal when the first and second derivative signal values exceed a predetermined threshold; determining that a unit of the drug has been administered when the peaks in the derivative value of the first signal and the derivative value of the second signal are simultaneous, the peak in the derivative value of the first signal has a different sign from the peak in the derivative value of the second signal, and the peak in the derivative value of the first signal has a different sign from the previous peak in the derivative value of the first signal; determining the amount of drug administered by the injection device by counting the units of drug administered. **Claim 15** A method of operating a dose counting system (700) of an injection device (1) or a module configured to be used with or applied to an injection device, the method further comprising calculating a moving average value of a series of values of the first signal and the second signal, as recited in claim 14.

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