FR3010908A1 - INJECTOR PEN - Google Patents

Abstract

This pen injector (2) is used to inject an active ingredient into the body of a patient and comprises an electric motor (40), a storage cartridge of the active ingredient, a piston, adapted to slide inside the cartridge , a mechanism (52, 56) for thrusting the piston inside the cartridge, which is driven by the engine during an injection, a display screen (18) and control means (8) of the quantity of active ingredient to be injected. The motor (40), the thrust mechanism (52, 56) and the cartridge are aligned along a common longitudinal axis (X2).

Description

The invention relates to an injector pen, used to inject an active ingredient parenterally, that is to say, intravenously, subcutaneously or intramuscularly into the body of a patient. The invention is particularly applicable to patients with specific diseases such as diabetes or dwarfism. Indeed, the treatment of these patients requires at least one injection per day of insulin, in the case of diabetes, or growth hormones, in the case of dwarfism. For example, a diabetic usually has to inject at least a dose of insulin morning, noon and night. In view of the number of injections that patients must perform, they perform their injections themselves without calling a doctor or nurse. The most used means for parenteral administration is the syringe but the pen is more and more recommended in some cases. Indeed, the pen is easier to use compared to a conventional syringe because it uses cartridges. In addition, it is easily transportable by the patient as a classic pen. EP-A-0 293 958 discloses an injector pen adapted to be carried in the pocket of a patient. This pen has a housing that contains a cartridge containing an active ingredient and a driving electric motor of a mechanism for pushing a piston inside the cartridge. The electric motor is arranged parallel to the thrust mechanism, which requires a device for returning angle. In addition, placing the electric motor parallel to the push mechanism increases the width of the pen. Thus, it does not present the elongated shape of a writing pen.

This lack of aesthetics of the pen injects some patients because it takes up a lot of space and patients can not use it comfortably and discreetly. In practice, the pen injectors of this type have not been or have been marketed, because of their cost, weight or regulatory constraints. It is these drawbacks that the invention more particularly intends to remedy by proposing an injection pen which has a shape more like that of a pen and which can be manufactured industrially. For this purpose, the invention relates to a pen injector, used to inject an active ingredient into the body of a patient and which comprises an electric motor, a storage cartridge of the active ingredient, a piston, adapted to slide inside of the cartridge, a mechanism for pushing the piston inside the cartridge, which is driven by the engine during an injection, a display screen and means for controlling the amount of active ingredient to be injected. According to the invention, the motor, the thrust mechanism and the cartridge are aligned along a common longitudinal axis. Thanks to the invention, the injection pen has an elongated shape resembling that of a real pen. Thus, patients can use it discreetly and are able to carry it easily, for example in a pocket of their clothes. According to advantageous but not obligatory aspects of the invention, an injection pen may incorporate one or more of the following features taken in any technically permissible combination: The pen has a generally cylindrical shape, centered on the common longitudinal axis. - The piston push mechanism comprises a screw, which is rotated by the motor during injection, and a nut which is movable axially by rotation of the screw inside the nut so as to push the piston inside the cartridge. The pen comprises means for detecting the contact between the nut and the piston, which function in particular by detecting an overcurrent within the motor. - The pen further comprises an electronic control card, which is able to successively trigger an initial configuration sequence, to update the time and date from a gateway, a boot sequence, comprising a step of detecting the contact between the nut and the piston, and a step of generating vibrations within the cartridge and a communication sequence or, failing that, storing data relating to the injection. - During the priming sequence, the nut comes into contact with the piston and vibrations propagate within the cartridge for a predetermined duration. - The vibrations are generated by the motor, which is controlled by the electronic control board to perform an oscillatory rotation movement of small amplitude. - The electronic control board is able to trigger, after the priming sequence and prior to the communication sequence, an injection sequence, which adjusts the injection speed according to the amount of active ingredient to be injected and who manages the cartridge change. - During the communication sequence, the data relating to the injection is sent on a gateway, such as a smart mobile phone, while the data is sent in encrypted form, this encryption being performed in particular by a cryptographic chip equipping the pen. The pen comprises a thrust ball bearing adapted to support the axial forces that are transmitted to the engine during the injection sequence or during a validation test. - The display shows numbers, for reading the amount of active ingredient to be injected, having a height greater than 6mm. The pen comprises a battery for powering the motor and the control electronic card, and means for connecting the pen to the mains and / or to a computer. The pen comprises means for storing the data relating to each injection, before transfer to the gateway. The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of an embodiment of an injector pen according to its principle, given solely as an example. and with reference to the drawings in which: - Figure 1 is an exploded perspective view of an injector pen according to the invention; - Figure 2 is a perspective view of the injector pen of Figure 1 in assembled configuration, FIG. 3 is an enlarged perspective view of an electronic part belonging to the injection pen of FIGS. 1 and 2; FIG. 4 is an enlarged side view along the arrow IV in FIG. 2; FIG. 5 is a view on a larger scale of the box V of FIG. 4, FIG. 6 is a section along line VI-VI in FIG. 4, FIG. 7 is a section similar to FIG. 6 after activating a boot sequence of the pen i njector, - Figures 8 to 12 are views similar to Figure 4 but on a smaller scale, successively representing the steps leading to the priming of the injector pen, - Figure 13 is a section similar to Figures 6 and 7 in a FIG. 14 is a view on a larger scale of the box XIV of FIG. 13, and FIGS. 15 to 19 are views similar to FIGS. 8 to 12, illustrating successively the steps replacement of a pen cartridge injector.

In Figure 1 is shown an injector pen 2 in an exploded configuration. The injector pen 2 is generally cylindrical in geometry and extends along a longitudinal axis X2. The pen 2 has a length of about 170 mm and an equivalent diameter, or average of the order of 17.5 mm, which corresponds to the usual dimensions of a disposable pen. Moreover, the mass of the pen 2 does not exceed 60g. For clarity of the drawing, the constituent parts of the pen injector 2 are shown on three parallel axes. In fact, all the parts of the injector pen 2 are aligned along the longitudinal axis X2, which is why the three axes of FIG. 1 bear the same reference X2.

The injector pen 2 comprises an outer shell 4 formed by a body 4A and a cap 4B. The body 4A of the outer shell 4 is a plastic part which has a generally tubular geometry centered on the axis X2. This body 4A has two lateral orifices 14, only one of which is visible in FIG. 1. These orifices 14 are closed by buttons 8, of which a button 8A bears the sign "-" and a button 8B bears the sign "+" . The body 4A also comprises a cutout 16 of generally rectangular outline. This cutout 16 is provided to reveal a screen 18 for displaying data related to the injection. This screen 18 is connected to a printed circuit board, or electronic control board 20 whose dimensions are approximately 12 mm by 40 mm.

The control electronic card 20 is able to successively activate several sequences by following corresponding programs. Among these sequences, an initial configuration sequence of the injector is activated during the first use of the injector. This initial configuration sequence is intended to update the time and date of the injector from a gateway. In practice, this gateway is the mobile phone of the patient. This mobile phone is of the "Smartphone" type and has an application dedicated to the communication with the injector 2. The patient can therefore use the ergonomics of his mobile phone to update the time and date of the injector. To perform an injection, the electronic card 20 begins by following a boot sequence, an injection sequence and a communication sequence or, failing that, a storage sequence. These sequences are described below and are implemented by computer programs compiled by a microprocessor integrated in the card 20. Moreover, the electronic card 20 includes data storage means, namely a memory 67.

In the remainder of the description, the terms "axial" and "axially" designate a direction parallel to the axis X2 and the terms "radial" and "radially" must also be interpreted with respect to the axis X2. Finally, "the front" designates an axial direction oriented in the direction of the injection. For example, the cap 4B is at the front of the body 4A. The cap 4B is a conventional removable pen cap having a clip 12 which allows the pen 2 to be attached to a pocket of a pair of pants or a shirt. This cap 4B covers a cartridge holder 22 which serves as a receptacle for a cartridge 28 visible in an external view to Figure 17 and containing an active ingredient P. In practice, the cartridge holder 22 is removable and can contain several cartridge sizes. In the example, the active ingredient P is a dose of insulin. Furthermore, the cartridge holder 22 comprises windows 26 for displaying the quantity of active ingredient P remaining in the cartridge 28. In addition, the cartridge holder 22 comprises, at the front, a threaded front head 24 adapted to screw a needle 70. The needle 70 is not part of the pen 2 injector because it must be changed after each injection. The cartridge holder 22 also comprises an external thread 27 which is arranged at the rear, that is to say at the opposite end of the threaded front head 24 and which is adapted to cooperate with a tapping, not visible on the figures, of the body 4A. More specifically, one end 4A1 of the body 4A of the outer shell 4 cooperates with the thread 27 of the cartridge holder 22 and one end 4A2 of the body 4A is closed by a plug 6 provided with a cutout for receiving a rear button 10 Thus, the cartridge holder 22 can be unscrewed from the body 4A or screwed onto it, as desired. The button 10 and the buttons 8 are waterproof and flexible. They make it possible to act on an electronic part 17 of the injection pen 2 which is described below.

As can be seen in FIGS. 1 and 3, the electronic part 17 of the injection pen 2 comprises the screen 18 and the electronic card 20. The screen 18 is a liquid crystal screen comprising a print 58 forming digital characters for displaying the image. value of the dose of insulin to be injected or the blood glucose level. The imprint 58 makes it possible to display a number with a precision to the nearest tenth. The blood glucose level is displayed in grams per liter, as represented by the characters 82 and the amount of active ingredient is displayed in International Unit (IU), as represented by the characters 80. The screen 18 also has a fingerprint 60 forming digital time display characters and a fingerprint 62 forming numerical characters for displaying the date. A battery charge level icon 64 is also integrated in the screen 18 and makes it possible to indicate to the patients the level of autonomy of the injection pen 2. A bar 78 is disposed on the screen below the characters 58 to the FIG. 5 and shows the amount of active ingredient P present inside the cartridge 28. Below the screen 18 is disposed an electric motor 40 which is coupled to a planetary gear 42 having an output shaft 44. Alternatively, it is possible to use a geared motor. The motor 42 is powered by a lithium battery 30 whose charge level is illustrated by the icon 64. This battery can be recharged by means of a USB port 34 which protrudes externally to the body 4A of the outer shell 4. The USB port 34, allows to connect the pen 2, by means of a cable, to a computer or to the sector. In practice, the battery 30 allows the use of the pen 2 for about a month without recharging. As can be seen in FIG. 5, the digits 58 of the display 58 of the quantity of insulin to be injected have a height H which is greater than 6 mm so as to make clearly visible the quantity of insulin to be injected and thus avoid a possible error.

The electronic part 17 also comprises a contactor 35 which is activated when the button 10 is pressed and which is dedicated to the injection. In other words, the switch 35 makes it possible to trigger the rotation of the motor 40. Similarly, two contactors 31A and 31B activate when the buttons 8A and 8B are respectively pressed. These contactors 31A and 31B are dedicated to the adjustment of the value displayed at the imprint 58 of the screen 18. In addition, the electronic card 20 carries an encryption chip 69 whose function is described below and a module 66 communication using Bluetooth or Bluetooth Low Energy (BLE) technology. As can be seen in FIG. 6, the motor 40 is able to drive, via the gearbox 42, a mechanism for pushing a piston 68 inside the cartridge 28. This thrust mechanism is described below. and makes it possible to advance the piston 68 inside the cartridge 28 so as to force the active principle P contained in the cartridge 28 to exit through the needle 70. The thrust mechanism is arranged inside a 36 of plastic envelope which is generally tubular geometry centered on the axis X2 and which has lugs 38 for fixing inside the body 4A of the shell 4. In addition, this envelope 36 has an internal radial recess 37 which is better visible in Figure 14. The thrust mechanism comprises a screw 52 which is secured to the output shaft 44 of the gear 42 by coupling means 45 disposed at the rear of the recess 37. This screw 52 comprises a threaded portion 52A and a screw head 52B disposed at the rear of the threaded portion 52A. The screw head 52B is hollow to receive the output shaft 44. In addition, the screw head 52B includes radial bores 54. The coupling means 45 of the screw 52 with the output shaft 44 comprise a ring 46 and two screws 48. The ring 46 comprises two threads which are not visible in the figures but which are adapted to receive the screws 48. The ring 46 is arranged around the screw head 52B so that these threads are aligned with the holes 54 of the screw head 52B. Thus, the screws 48 pass radially through the ring 46 and the screw head 52B and bear against the output shaft 44. The output shaft 44 is thus caught in a vice between the two screws 48, so that the shaft 44 is integral in rotation with the screws 48. The screw head 52B is secured to the ring 46 by the screws 48, it is also rotated about the axis X2. The rotation of the screw 52 about the axis X2 drives a nut 56 in translation along the axis X2. Indeed, the nut 56 comprises an internal thread which is not visible in the figures, but which has a screw thread complementary to that of the thread 52A of the screw 52. Thus, depending on the direction of rotation of the screw 52, the nut 56 is moved in translation along the axis X2 forwards or backwards. Furthermore, the nut 56 is made of plastic, including polytetrafluoroethylene (PTFE), while the screw 52 is made of steel. Thus, the coefficient of friction between the screw 52 and the nut 56 is very low and the torque to be supplied by the motor 40 to cause the displacement of the nut is light, which allows to equip the injection pen 2 d a 40 engine of low power, so small diameter. Alternatively, the nut 56 is made of steel and the screw 52 is made of plastic. As best seen in FIG. 14, a thrust bearing 50 is supported rearwardly against the internal recess 37 of the casing 36 and is formed by two disks 502 and 504 which are arranged axially opposite one another. and between which are interposed several balls 506. A bearing washer 53 is interposed between the thrust bearing 50 and the threaded portion 52A of the screw 52 to increase the bearing surface to better transmit the force of the screw. 52 to the thrust bearing 50 and prevents a degradation of the thread of the screw 52. Similarly, a sliding washer 47 is interposed between the recess 37 and the coupling means 45 to limit the friction between the coupling means 45 and the recess 37 of the casing 36 during the retreat of the nut 56. During an injection, the patient begins by informing the electronic control board 20 of the pen 2 of his blood glucose. Then, the patient enters the instructions, the amount of insulin to inject. The two operations mentioned above are carried out by alternately pressing the buttons 8A and 8B until the desired quantity is displayed at the level of the digits 68. The fact that the patient gives his blood sugar level makes it possible, on the one hand, to facilitate the use of data related to the injection and, secondly, to invite the patient to check the consistency between the blood glucose level and the amount of insulin to be injected.

Once the data has been validated, the patient can perform the injection by pressing the rear button 10. A pressing force on the rear button 10 causes the electronic control board 20 to trigger the priming sequence of the pen. Injector 2. For clarity of the drawings, the pen 2 is shown horizontally in Figures 6, 7 and 13. However, it is convenient in practice to hold the pen 2 vertically during the boot sequence. The boot sequence is implemented at each cartridge change 28. This boot sequence includes an initial step of defining an initial mark for the nut 56. Specifically, the nut 56 is moved back to the end. in abutment against the washer 53. This position is an initial position along the axis X2. The washer 53 is in contact with the thrust bearing 50 which is pressed against the recess 37 of the casing 36. Thus, when the nut 56 contacts the washer 53, the motor 40 provides an overtorque because the casing 36 opposes the recoil of the nut 56. This overtorque corresponds to an overcurrent which is detected by measuring the voltage across a resistor, or "shunt" integrated into the electronic control board 20. In fact, this resistance is traversed by the power supply of the motor 40. The measurement of an overvoltage across the resistor thus testifies to an overcurrent consumed by the motor 40. In a second step of this boot sequence, the motor 40 drives the screw 52 in rotation until the nut 56 comes into contact with the piston 68, as represented by the arrow F1 in FIG. 6. When the nut 56 and the piston 68 come into contact with each other, the presence of the active ingredient P inside the cartridge 28 opposes a resistance to the advance of the nut 56, which requires overtorque from the motor 40. This overtorque corresponds to an overcurrent which is measured in the same way as in the initial step, that is to say that is to say by measuring the voltage across a resistance traversed by the motor supply current 40. This advantageously makes it possible to dispense with a proximity sensor, or an optical sensor that would add thickness , that is to say, the size of the pen 2. Moreover, a Hall effect sensor integrated in the motor 40 makes it possible to know the number of revolutions made by the motor 40 between the initial position and the position of contact with the piston 68. The electronic control board 20 can therefore deduce the stroke made by the nut 56 from the initial position to the piston 68. However, the position of the piston 68 for a solid cartridge is known. Therefore, it is possible to deduce a possible advance of the piston 68 relative to the position it occupies in a full cartridge. In this way, the electronic card 20 knows, via the position of the piston 68 inside the cartridge 28, the remaining dose of active ingredient inside the cartridge 28, this dose being displayed at the of the bar 78. From the moment when the nut 56 comes into contact with the piston 68, the movement of the nut 56 is stopped, which brings the pen 2 into the configuration of FIG. 7. In FIG. the needle 70 is not mounted on the injector pen 2. Alternatively, it is possible to mount the needle 70 on the threaded head 24 of the pen 2 before launching the detection of the position of the piston 68. Indeed, the measurement made by detecting an overcurrent across a resistor of the motor supply circuit 40 is sufficiently sensitive to detect the position of the piston 68 even when the cartridge 28 is pierced. Then, it is convenient for the patient to remove the cap 4A of the injection pen 2, as shown by the arrow F2 in FIG. 8, to install the needle 70. This needle 70 comprises a protective cover 76 and a tapping 72. Thus, it can be screwed, as represented by the moment M1 in FIG. 9, onto the threaded portion 24 of the cartridge 22. When the needle 70 is screwed onto the cartridge 22, it pierces the cartridge 22, so that the principle active P can escape from the cartridge 22 if the piston 68 is advanced. Finally, it is necessary to remove the cover 76 as represented by the arrow F3 in FIG. 10. This brings the injection pen 2 into the configuration of FIG. 11.

In this configuration, the patient triggers, by pressing the rear button 10 again, the rest of the boot sequence, concretized by the formation of F4 vibrations within the cartridge 22. These F4 vibrations are intended to take off from any air bubbles present within the cartridge 22. Indeed, it may happen that, during the introduction of the cartridge 22 inside the pen 2 or during the perforation of the cartridge 22 by the needle 70, air infiltrates in the form of bubbles in the active principle P. It is essential to eliminate these air bubbles on the surface of the active ingredient P to prevent them being injected into the patient's body . With the current pen injectors, the patient is obliged to tap the cartridge slightly to raise these bubbles to the surface. The injector pen 2 according to the invention makes it possible to overcome this operation by vibrating the cartridge 22 at a certain frequency and for a predetermined duration. In practice, this frequency is chosen between 5 Hz and 20 Hz, in particular of the order of 12 Hz and the F4 vibrations last for about 5 seconds. Including an automatic boot sequence allows you to remove a manual step for the patient and thus avoid oversights. The vibrations are generated by the electronic control board 20 which drives the motor 40 so that it provides oscillatory rotation and low amplitude. In other words, the output shaft 44 rotates alternately in one direction and the other with a constant angular amplitude. This oscillatory movement causes vibrations within the pen 2 injector through a slight displacement of the nut 52 in contact with the piston 68. In practice, this displacement is of the order of 30 micrometers. When the vibrations F4 stop, that is to say after about 5 seconds, the priming sequence continues by a displacement of the nut 52 in contact with the piston 68 forward. This displacement is greater than that caused for F4 vibrations. It is in practice of the order of 300 micrometers, which causes the appearance of a first drop G, which is visible in Figure 12 and which shows that all the air bubbles were removed. The injector pen 2 is then ready for use. By pressing the back button 10 again, the patient activates the injection sequence. If the amount of insulin requested by the patient is available within the cartridge 28, the injection can continue. Otherwise, the injector pen 2 alerts the patient that there is not enough active ingredient in the cartridge to perform the injection. The patient may then choose to inject the remaining amount of insulin into the cartridge and then change the cartridge to inject the supplement or change cartridge directly to inject the entire dose into a single injection. The injection sequence thus manages these end-of-cartridge situations where it is necessary to change the cartridge to perform the injection. Once the check on the amount of available insulin has been performed, the injection sequence continues with the injection step itself, which consists of driving the screw 52 in rotation around the axis X2 in order to move the nut 56 and the piston 68. The piston 68 is pushed axially forwardly by the nut 56 until it reaches the configuration of FIG. 13 in which the piston 68 has arrived at the end of stroke of the cartridge 22. In this case, the entire active ingredient P has been injected. However, some cartridges are expected to last about a month. In this case, the displacement of the piston 68 is in each case proportional to the quantity of active ingredient to be injected. In general, the stroke to be performed by the piston 68 to inject the appropriate dose of active principle is calculated by the electronic control board 20 and this stroke results in a number of laps to be made for the engine 40. This number of turns is measured by the Hall effect sensor so that the electronic board 20 can adapt the advance of the piston 68 inside the cartridge 28 depending on the dose to be injected. For clarity of the drawing, the needle 70 is not shown in Figure 13 while it is, in fact, mounted on the cartridge holder 22 during the entire injection. During the injection sequence, the electronic control board 20 adapts the speed of rotation of the motor 40. Thus, the injection speed, which is proportional to the rotational speed of the motor 40, is adapted, depending on the dose of insulin to administer. In its displacement, the piston 68 is subjected to F5 efforts from the thrust of the piston 68 inside the cartridge 28. These efforts F5 are resistant efforts that come from the resistance of the liquid, or active ingredient P contained in the inside of the cartridge 28, the advance of the piston 68. As such, the F5 efforts are axial forces directed towards the rear of the pen injector 2. These efforts F5 are transmitted through the intermediary of the nut 56, to the screw 52. They then apply to the bearing washer 53 and to the thrust bearing 50. The thrust bearing 50 makes it possible to support the entirety of the axial forces F5 of resistance to the advance of the Piston 68 in the cartridge 22. By supporting all the resistant forces F5, the thrust ball bearing 50 avoids oversizing of the geared motor assembly, formed by the motor 40 and the gear 42, which prevents excessive consumption of energy. The pen injector 2 has, therefore, a better autonomy.

In addition, a security routine is embedded in the injection sequence. This safety routine makes it possible, among other things, to block the buttons 8A and 8B during the injection to avoid a double injection. The electronic control board 20 also activates a non-visible light signal in the figures which guides the patient in the various phases of the injection so that he respects the instructions of good practice of use of the pen 2. For example, this indicator light light emits a first light signal with a first color at the end of the priming sequence and a second light signal with a second color at the end of the injection, this second color illuminating about 5 seconds after the injection, so that the patient waits before removing the pen 2.

In the case of a single-use cartridge, it is necessary to change the cartridge at each injection. The cartridge changing steps 28 are shown in Figures 15 to 19. First, the patient removes the cap 4B and unscrews the cartridge holder 22 of the body 4A of the shell 4 by applying a moment M2. It is then possible to remove the cartridge 28 from the cartridge holder 22 and replace it with a new cartridge, as represented by the arrow F6. Finally, it is necessary to screw the cartridge holder 22 again onto the body 4A of the shell 4, as represented by the moment M3. In addition, the injector pen 2 is communicating, that is to say that the electronic control board 20 activates, after each injection, the communication sequence. This communication sequence aims to transfer, via the gateway, the data relating to the injection to a database. This database is secure and the information sent by the pen 2 is encrypted by the cryptographic chip 69. The data related to the injection are in practice the blood glucose level of the patient, the amount of insulin injected, the date and the time of the injection. The patient's Smartphone hosts an application that manages this data transfer. The pen 2 communicates with the patient's smartphone by short-range waves, including using Bluetooth or Bluetooth Low Energy (BLE) technology. In the case where the smartphone of the patient is not within the scope range of the Bluetooth system, which is of the order of 12m, the data related to the injection are stored in memory in the memory 67 of the pen 2 until to the next injection, which forms the storage sequence. Thus, during the next injection, the injector pen 2 sends the data stored in memory that could not be transmitted during the previous injection. The fact that the pen 2 is communicating facilitates its first configuration and updates. Indeed, during the first use of the pen 2, it is necessary to perform a complementary configuration operation of the update of the date and time of the pen 2. This step is to associate the patient with his injector pen 2 to then be able to check that the pen 2 belongs to the right patient. For this, a first identification number is assigned to the patient and a second identification number is assigned to the injector pen 2. The first identification number and the second identification number are associated and stored in memory in the mobile phone of the patient. Thus, before an injection, the application retrieves the second identification number and verifies that it corresponds to that stored in memory during the first use. In a variant not shown, the vibrations F4 created by the priming sequence are produced by an electromagnet which vibrates axially against the cartridge 22.

Alternatively, the same pen 2 can be used for injections of growth hormones or for any other type of active ingredients. Alternatively, the USB port 34 of the injection pen 2 can be used to transfer the data related to the injection directly to a computer. The variants and embodiments mentioned above can be combined with one another to give new embodiments of the invention.

Claims (12)

CLAIMS1.- Injector pen (2), used to inject an active ingredient (P) into the body of a patient and comprising: an electric motor (40), a cartridge (28) for storing the active ingredient, piston (68), adapted to slide inside the cartridge, -a mechanism (52, 56) for pushing the piston inside the cartridge, which is driven by the engine during an injection, -un display screen (18) and control means (8) for the quantity of active ingredient to be injected, characterized in that the motor (40), the push mechanism (52, 56) and the cartridge (26) are aligned along a common longitudinal axis (X2). 2. Pen according to claim 1, characterized in that it has a generally cylindrical shape, centered on the common longitudinal axis (X2). 3. Pen according to one of claims 1 and 2, characterized in that the piston of the thrust mechanism comprises a screw (52), which is rotated by the motor (40) during injection, and a nut (56) which is axially displaceable by rotation of the screw within the nut so as to urge the piston (68) into the interior of the cartridge (28). 4. Pen according to claim 3, characterized in that it comprises means for detecting the contact between the nut (56) and the piston (68), which operate in particular by detecting an overcurrent within the motor. 5. Pen according to claim 4, characterized in that it further comprises an electronic control card (20), which is able to trigger successively: an initial configuration sequence, to update the time and the date from a gateway, a boot sequence, including a step of detecting the contact between the nut (56) and the piston (68), and a step of generating vibrations (F4) within the cartridge (28), anda communication sequence or, failing that, storage of data relating to the injection. 6. Pen according to claim 5, characterized in that, the electronic control board (20) is arranged to actuate the motor (40), to perform a small amplitude oscillatory rotation and generate vibrations (F4). 7. Pen according to one of claims 5 or 6, characterized in that the electronic control board is arranged to trigger, after the priming sequence and prior to the communication sequence, an injection sequence, which adapts the injection speed according to the amount of active ingredient to be injected and which manages the cartridge change (28). 8. Pen according to one of claims 5 to 7, characterized in that the electronic control board (20) comprises means (66, 69) for sending, in encrypted form, the data relating to the injection to a gateway, such as a smart mobile phone, the data encryption being in particular carried out by a cryptographic chip (69) equipping the pen (2). 9. Pen according to claim 7, characterized in that it comprises a thrust bearing (50) adapted to support the axial forces which are transmitted to the motor (40) during the injection sequence or during a test of confirmation. 10. Pen according to one of the preceding claims, characterized in that the display screen (18) comprises numbers (58) for displaying the amount of active ingredient (P) to be injected, which have a height (H) greater than 6mm. 11. Pen according to one of the preceding claims, characterized in that it comprises: a battery (30) for supplying the motor (40) and the electronic control board (20), and means (34) connecting the pen to the mains and / or a computer, 12. Pen according to claim 8, characterized in that it comprises means for storing (67) data relating to each injection, before transfer to the gateway.