MXPA99000240A - Device for fixing a do - Google Patents

Abstract

In a device for releasing an active ingredient a dose to be dispensed from a cartridge is fixed by changing the relative position of cooperating elements to fix the dose (3, 5) and is injected by pressing a button (5) until this button makes contact with a stop (6). Through the operation of up counting buttons (7) or downward counting (8) the dose is set and read in an electronic circuit (9) comprising a microprocessor and the movement to set the dose of the elements to set the dose in relation mutual is effected by a motor (11) controlled by the circuit according to the dose read. The fixed dose is shown on a visual representation device (10). The motor (11) is further controlled to effect certain movements of the piston rod (3), so that the retraction of this rod when a cartridge (1) is advancing to be changed and the advance of the piston rod to enter contact with the piston (2) after the cartridge has been changed and in addition to make advance this piston to expel the air from the cartridge

Description

DEVICE FOR FIXING A DOSE DESCRIPTION OF THE INVENTION The invention relates to systems for the release of active ingredients by means of which a fixed dose of a cartridge can be distributed and released, the fixation of the dose is done by changing the relative position of the cooperating elements to fix the dose and the release is done by pressing a button until it comes into contact with a stop. The release can take place as an aerosol spray, an injection, or a high-pressure jet, which penetrates the skin, so that the released material can be precipitated in the tissue under the skin. The elements for setting the dose can be a threaded rod or a nut as in EP 327 910, wherein the threaded rod is a piston rod that acts on a piston, which presses out liquid from a cartridge according to the distance the piston moves. By setting the dose a nut on the end of a hollow button surrounding a threaded piston rod is threaded along the piston rod away from a stop and therefore raises the button above the proximal end of the piston rod. injection device. The injection is made by pressing the button to move the nut backwards, towards the stop, REF. 29212 movement by which the piston rod and the piston are pressed towards the cartridge a distance corresponding to the distance that the nut was pink away from the stop. In another mechanism for setting the dose as described in WO 90/0038 a carrier, which can carry the piston rod only in a distal direction, is therefore the fixation of a dose that moves away from a stop and It can subsequently by pressing an injection button be moved back until it comes into contact with the stop. In a further injection device as described in EP 0 245 312, a button with a push rod can be operated to oscillate over a fixed distance. During part of this oscillating movement, the push rod drives a piston towards a cartridge. Such part corresponds to a fixed dose, which is set by varying a free space between the piston rod and the piston when the push button and the push rod are in their non-operated position. The size of the fixed doses is indicated mainly by an indicator or through a window, which is coupled to one of the elements to fix the dose and indicates the number corresponding to the fixed dose on a scale coupled to the other element for To fix the dose, the size of the dose is proportional to the distance of the two elements that have moved in mutual relation. This fact sets a limit for the size of the figures to scale although different initiatives have been taken to expand the space available for these figures. The dose is fixed by rotating a screw or a wheel or by rotating two parts of the injection device in mutual relation and concurrently verifying the size of the fixed dose. For some constructions of the mechanism to fix the dose it is not possible to reduce the fixed dose if the two elements to fix the dose that has moved away in mutual relation, that is to say if a very large dose has been fixed. For other constructions it is necessary to ensure that the device is readjusted before a dose can be set. A device which is very simple to use is the one that is aspired to. The simplest form of the device should only show a device for setting the very simple dose and an injection button. The object of the invention is to provide a user-friendly injection device by which most of the known disadvantages are avoided. This is obtained by means of a device, injection as described at the beginning of this specification, device which is characterized in that the dose setting is read in an electronic circuit and the movement to set the dose of the elements to fix the dose in mutual relation is effected by an electromechanical device, for example an engine, controlled by the electronic circuit according to the reading to set the dose. According to the invention, the electronic circuit may appropriately comprise a microprocessor. The use of an electric motor in an injection device is known but in such known devices the engine is used to effect the injection. However, it has apparently been preferable to do the injection manually since it gives the user the possibility of adjusting the injection speed in accordance with the absorption of the liquid injected into the tissue. In addition, the energy consumption is greater to carry out the injection movement and consequently the batteries, which must have small physical dimensions, will be exhausted very quickly. The combination of electronic control and electromechanical fixation of a dose allows the device to actively intervene if anomalous or unintended conditions are detected during a sequence to fix a dose or if an unauthorized manipulation of the device is detected, such as • opening the cartridge holder during fixation of a dose. The active intervention can include a readjustment of the dose setting to a starting point corresponding to the dose = 0 and then report a malfunction until the error has been corrected, for example by closing the cartridge holder. In this way, the risk of erroneous doses and doubts about whether or not a correct dose was released can be overcome. When the error has been corrected or the unintended manipulation of the device has stopped, the dose setting can be reset from the starting position of the device. An electronic fixation of the dose can be carried out using one or two buttons by means of which an ascending count or a downward count can be ordered to an electronic circuit. The fixed dose may be concurrently displayed on an electronic display device and the count may be performed in ascending as well as descending fashion. The use of an electronic visual representation device offers the advantage that the size of the figures in the visual representation device depends solely on the size of the visual representation device. Other display devices than the visual display device may also be used, for example a speech frequency synthesizer circuit which commonly pronounces the number corresponding to the fixed dose. The fixation can be obtained by reading the desired dose in the electronic circuit which presents the reading of the dose in the visual representation device and controls the motor to run in a direction to fix the mechanical parts of the mechanism to set the dose accordingly. When a signal from a position reader indicates that the mechanical parts have reached a position corresponding to the fixed dose, the electronic circuit will cause the motor to stop. The motor may be capable of effecting mechanical fastening at approximately the same speed as the ascending or descending count on the visual display device. If the mechanical fixation is not obtained or delayed in an unbearable manner in relation to that shown by the visual representation device, it is taken as an indicator of exhausted batteries and an error is reported to the user, for example turning off the visual representation device. Alternatively, reading the visual representation device can be feedback from a position reader that reads the size of the mutual movement of the elements to set the dose. In this way it is ensured that the fixation of the dose is in accordance with the reading on the visual representation device when this reading is an expression of the real relative position of the parts to fix the dose. In this mode, an exhausted battery will result in a very slow or failed count in the visual display device. In known motor-driven release systems, a fixed dose can be displayed on a visual display device and a downward count can be shown concomitant with the motor driven injection. Nevertheless, except as shown by the visual representation device, the fixed dose is not visually recognizable. In contrast to this, the electromechanical fixation according to the invention will ensure that the fixation is also physically recognizable since the physical position of the parts to fix the dose in mutual relation can be visually inspected. A switch can be provided, which is operated when the injection button is pressed. The operation of the switch ensures that the injection button is in its zero position before the setting of a new dose. An additional advantage of the device according to the invention is that limits can be set as information read in the electronic circuit. If not, exceed a maximum dose the circuit can be programmed so that it can not be read a number higher than the maximum number of units of the active principle to be released in the electronic circuit.

The circuit can also be programmed to set a predetermined dose each time the dose setting is operated. This may be important for people who are themselves unable to effect fixation. The movement of the elements to fix the dose is recorded in the electronic circuit and is translated into a number that indicates the fixed dose in units defined for the type of medication that is administered by the injection device. Since a drug can be found at different concentrations and from one type of medicine to another, different volumes can correspond to one unit, it is advantageous that the translation of the movement in units is done electronically, so that the same mechanical device can be used for different types and concentrations of medications only by programming the circuit. Circuit programming can cooperate with a code on the cartridge, so that the program is automatically adapted to the drug in the cartridge and the correct amount is released when a dose is set for this number of units. In the following the invention will be described with reference to the drawing which schematically shows an electronic device for setting the dose according to the invention.

A cartridge 1 is accommodated in a housing not shown. By using the device a piston 2 is pressed on the cartridge 1 to press out some of the contents of this cartridge through a needle not shown, which can be mounted on a distal end of the cartridge. The piston is moved by a piston rod 3 which is shown as a threaded rod and forms a first element to fix the dose. A second element for setting the dose is a nut 4 with an internal thread cooperating with the external thread of the piston rod 3. A button with a hole accommodating an outer end of the piston rod 3 forms an integral part of the piston rod 3. nut and forms an injection button 5. The injection button 5 can be pressed to move the piston 2 towards the cartridge until the nut 4 comes into contact with a stop 6 which forms part of the housing not shown. A bolt 17 in the housing engages an axial rail in the piston rod to lock this piston rod against rotation relative to the housing. When a dose is to be set, the device is in an initial position with the nut 4 in contact with the stop 6. The dose is set by activating one of a couple of buttons to set the dose 7 and 8, one 7 the forward or upward count and another 8 for the backward or downward count. The fixed dose is stored in an electronic circuit 9 and deployed on a visual display device 10. As the ascending count button 7 is pressed the fixed dose is increased and the dose size can be followed concurrently on the Visual representation device 10. If the ascending count runs too far, the count down button 8 must be activated until the fixed dose decreases to the desired size. The mechanical fixation of the elements for setting the dose according to the electronically fixed dose is effected by an electric motor 11 having an output shaft provided with an elongated gear 12, meshing which engages the teeth 13 on the periphery of the nut 4. The motor 11 which can be controlled to run both clockwise and counterclockwise is controlled by the electrical circuit to rotate the nut according to the fixed dose. The rotation is measured by a position reader 16 which counts the number and direction of the passing teeth. Fixed to ensure that the electronically fixed dose is also mechanically fixed. The visual display device can be operated so that it does not display the value until the feedback signal from the position reader 16 confirms that the mechanical fixation has taken place. In other words, when the up counting button 7 is activated the circuit 9 controls the motor 11 to rotate in a direction of increasing the dose and the visual display device will then show concurrently as the nut rotated in a direction corresponding to an increasing value . When the descending count button 8 is activated, a reduction of the mechanically fixed dose is obtained and recorded in the same manner. Alternatively, a number is counted ascending in the visual representation device by activating the rising count button 7, and the motor is then controlled to set the parts that fix the dose in relation to the position corresponding to the number of devices of visual representation. The motor and the battery must have enough power to ensure that the mechanical fixation of the parts that fix the dose follow the ascending or descending count in the visualization device very closely, ie without any or only a very small delay. When the delay exceeds a pre-set time, the electronic circuit may indicate an error, for example by turning off the device, visual representation or by activating a "low battery" indicator. If the "count down button 8 is activated when the display device shows zero, reading which corresponds to the position of the nut 4 when it is in contact with the stop 6, it will not be possible to set a negative dose. avoided either by the fact that the nut 4 operates a switch 15 mounted on the stop 6 operation by which a signal is sent to the circuit 9 to stop further operation of the motor 11 in the direction of dose reduction. alternatively the circuit 9 can concurrently verify the power consumption of the motor 11 and stop this motor when an increase in power consumption indicates that the nut 4 is in contact with the stop 6. The corresponding setting of a dose exceeding the amount of drug remaining in the cartridge can be avoided by providing a stop 14 at the outer end of the piston rod, the position of this stop is such that the cartridge is emptied only when the nut 4 is threaded up to this stop and pressed to come into contact with the stop 6. When the motor during the setting of a dose is operated in the direction of increasing the dose to move the nut 4 towards the end The external piston rod increases suddenly its energy consumption, due to the fact that the nut 4 has reached the stop 14 on the piston rod 3, which the circuit takes as an indication of the fact that the fixed dose can not further increase and the motor will stop and the size of the fixed dose corresponding to the drug remaining in the cartridge can be read on the visual representation device 10. By activating the mechanical fixation by the motor the realization of the stops is it becomes very simple since the energy of the motor is limited and the stops only have an influence on the power consumption of the motor in a recognizable manner while the d manually operated devices can be exposed to heavy forces, the elements of which in the device will be able to resist without breaking at the same time as the elements that will be miniaturized if the devices are not inconveniently bulky. In fact, the stops can be made purely electronic. In the electronic circuit can be stored how many units of an active ingredient contains the cartridge and the number of units released can be accumulated so that the circuit can calculate the number of units left in the cartridge and set this number as an upper limit for the dose that It can be fixed. The switch 15 on the stop can serve for the function of indicating when the injection button is pressed, to the bottom and an injection is completed. When the injection is pressed to the bottom it can also be blocked in this position until a new dose is set. When a signal indicating an injection is completed, it is sent to circuit 9, the newly completed injection size is stored and can be displayed on the visual display device as required until the next dose is set. This demand can be signaled in different ways, for example by briefly pressing one of the buttons to set the dose, by means of a switch activated when a protection cover is removed from the housing, or by operating a button that releases the injection button of its Pressed position to the bottom. When the injection button is pressed to its initial position the motor can be used to automatically perform other functions to make the use of the device less complicated. When a cartridge is to be changed the cartridge holder is opened, the piston rod must move back to a retracted position to make room for a new cartridge, the new cartridge must be inserted, the cartridge holder must be closed, and the piston rod it should move towards the piston to raise this piston again and then move further forward to move the piston towards the cartridge until the air in this cartridge is pressed out through an injection needle. A switch that detects the opening of the cartridge carrier sends a signal to the circuit to obtain the operation of the motor in a direction of decreasing the dose. By this operation the nut can come into contact with the stop 6 and slide and pull the piston rod backwards. When an increase in motor power consumption indicates that the piston rod can not be pulled further back, the motor stops and the empty cartridge can be removed and replaced by a new full one. When the carriage holder is closed the motor can be controlled to rotate in the opposite direction and the nut is somehow blocked against movement along the piston rod, the piston rod will move its place towards the cartridge and in contact with the piston. This contact is indicated by an increase in energy consumption. The piston rod can move the piston further towards the cartridge to direct air out of the cartridge with the condition that a needle is mounted and the device is held with the needle in place. When the air is pressed out of the cartridge a new rise in power consumption indicates that the air is pressed out and now the liquid is pressed out. This pattern of energy consumption can be stored in the circuit so that the motor can stop when it detects that it is starting to be pressed. outward a liquid. Later the device is ready to be used. This ability to discriminate between the outward pressure of the air and the liquid can be used for an automatic air firing function which can be activated before each use of the injection device. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the one conventional for the manufacture of the objects to which it relates. Having described the invention as above, property is claimed as contained in the following:

Claims (4)

RESIGNATIONS

1. A device for releasing the active ingredient by which fixed doses of a cartridge are distributed and released, comprising elements that cooperate to set the dose, the relative position of which can be changed to set a dose mechanically and a release button, which rises from the device for mechanical fixation of a dose and is pressed back to inject the fixed dose, characterized in that the device further comprises an electronic circuit, in which a value defining the fixed dose is read and stored, and an electromechanical device, for example, a motor, which can move the elements to fix the dose in mutual relation, and which is controlled by a mechanical circuit according to the value read and stored, so that a corresponding movement is made at the fixed dose. The device according to claim 1, characterized in that the electronic circuit comprises a microprocessor. 3, The device according to claim 1 or 2, characterized in that the switches for setting the dose are coupled to the electronic circuit, so that the reading in the value can be increased or decreased gradually by the operation of such switches. The device according to claim 1, 2 or 3, characterized in that the electronic circuit has means for calculating the number of active ingredient units left in the cartridge, and for setting this number with an upper limit for the value that can be be read in the circuit to set a dose. The device according to claim 1, 2, 3 or 4, characterized in that the electronic circuit has an output in which the size of the dose represented by the value read in, and stored is communicated with an electronic signal to a electronic visual representation device or a speech synthesizer, which presents the size of the dose to the user. The device according to claim 5, characterized in that the electronic circuit has means which continuously compare the dose represented by the relative position of the elements to fix the dose with the dose communicated to the user and controls the electromechanical device to move the . elements to balance a possible difference. The device according to claim 5, characterized in that the electronic circuit controls the motor according to the dose setting and the display of the visual representation device is controlled by signals from a position reader that reads the mechanical movements of the device. the elements that fix the dose. The device according to any of the preceding claims, characterized in that the button is coupled to an element for setting the dose, so that a distance corresponding to the fixed dose rises from the device. The device according to any of the preceding claims, characterized in that a switch is provided and positioned so that it is operated when the button is pressed to its initial position. The device according to any of the preceding claims, characterized in that a switch (not shown) coupled to the electronic circuit detects whether a cartridge holder is open or closed. The device according to claim 10, characterized in that the switch (not shown) is coupled to the electronic circuit, which is programmed to activate the motor to run in one. direction in which the piston rod retracts until the piston rod is fully retracted, when the signal of the switch indicates the opening of the cartridge holder when the injection button is in a pressed position to its initial position. 1

2. The device according to claim 11, characterized in that the electronic circuit is programmed, so that it activates the motor to run in a forward direction of the piston rod until an increase in motor power consumption indicates that the piston rod is in contact with the piston in a cartridge, when a signal of the switch indicates the closing of the cartridge holder when the injection button is in its initial position pressed. The device according to claim 11 and 12, characterized in that an air release button (not shown) is provided and which, when pressed, when the injection button is in its initial pressed position, causes the electrical circuit activates the motor to run in its direction of advance of the piston rod until its power consumption when compared to a value stored in the electronic circuit indicates that the liquid is not being pressed the air out through of an injection needle. The device according to any of the preceding claims, characterized in that the electronic circuit verifies the signals it handles and alerts the user if a permitted signal was not observed.