RU2733692C1 - Syringe pen - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: claimed invention refers to medical equipment, namely to devices for drug delivery in the form of injections, and can be used for self-administered introduction of selectively measured doses of a drug preparation, mainly insulin. Said technical result is achieved by the fact that the syringe pen comprises a body with an internal thread providing a reciprocal interaction with the dispenser moved inside the body, connected to the drug cartridge holder, as well as a drive mechanism comprising a pusher with a rod, on the surface of which there is a thread, providing a relationship with the thread of the coupling, located in the housing, wherein dispenser is equipped with spring element installed with possibility of rotary and longitudinal movement between button and tube of rotation, in which there is a rotation transmission tube, wherein the spring member and the rotation transmission tube are provided with resilient elements, wherein along the entire length of the rod there are two symmetrical flats, and on its other sides - longitudinal slots for formation of splined connection with included therein and commensurate projections located inside rotation tube, at that, on external surface of rod there is a double-thread thread and on its one end there are projections, by means of which rod is fixed in connecting coupling, and on its other end there is connecting element, by means of which flange is fixed on stock by blind, wherein the spring element is provided with two resilient elements uniformly distributed around the circumference at distance of 180°, and the rotation transmission tube is made with three resilient elements located circumferentially at distance of 120° from each other.

EFFECT: technical result, achievement of which is claimed by the claimed invention, is reduction of pressing force during drug injection, increased dosing accuracy and provision of unobstructed back-and-forth movement of the rod.

1 cl, 2 tbl, 20 dwg

Description

The claimed invention relates to the field of medical technology, namely, to devices for the delivery of a drug in the form of injections and can be used for self-administered by a patient, selectively measured doses of a drug, mainly insulin.

From the prior art there is known a pen for injecting a medicament comprising a casing; a regulator for setting the dose, made with the possibility of rotation relative to the body when setting and adjusting the dose; and a drive capable of selectively engaging with the dose setting regulator and fixed in an angular position relative to the body when setting and adjusting the dose; moreover, the drive is designed to move in the longitudinal direction together with the dose setting regulator when setting and adjusting the dose, and the drive is made to rotate together with the dose setting regulator when performing an injection (patent RU No. 2676032 for the invention "Disposable syringe pen for several doses" , filing date 04.24.2018, published 12.25.2018, application US 61/457, 391).

Known is a drug delivery device comprising a housing, a drug reservoir mounted in the housing, a rod mounted in the housing with the ability to move with the possibility of displacing the drug from the specified reservoir, a trigger mechanism configured to create a driving force, a mechanism for setting dose, installed at least partially in the housing with the possibility of setting the dose of the drug and functionally connected to the trigger mechanism, the drive mechanism functionally connected in the housing with the mechanism for setting the dose and the rod with the possibility of transferring the specified driving force to the rod for its movement in depending on the prescribed dose of the drug, while the rod is also equipped with a number of teeth, and the specified device additionally contains an annular element equipped with a pawl and installed in the body in such a way that when the rod moves, it jumps from tanks on the teeth of the rod (patent RU No. 2700459 for the invention "Device for drug delivery", filing date 04/03/2019, published 09/17/2019).

In addition, a known syringe pen for injection includes a housing equipped with a push button, the body contains a dose setting regulator associated with the push button and installed with the ability to move in the longitudinal direction relative to the body, a cylindrical drive installed inside the dose setting regulator with the possibility of longitudinal movement relative to the body, while the drive is in engagement with the dose setting regulator, the rod installed in the cylindrical drive, the dose delivery screw installed inside the rod, and the adjusting ring in engagement with the dose setting regulator mounted on the rod with the possibility of rotation relative to it and containing protrusions on the inner side, and on the outer surface of the rod, recesses are formed, and the adjusting ring is installed on the rod in such a way that the projections of the adjusting ring together with the recesses of the rod form a ratchet engagement (patent No. 2696451 for the invention "Syringe-pen for injection ", Filing date 03/27/2019, published 08/01/2019).

The closest technical solution to the proposed protection of the invention is a pen containing a body, on the inner surface of which a thread is applied to ensure the movement of the dispenser with a core, at one end of which there are four elastic elements in the form of hooks; a cartridge holder adapted to be connected to the body; a dispensing mechanism that includes a button and a dispenser; a drive mechanism including a pusher with a rod on the surface of which a thread is made; a stem coupling rigidly fixed to the body and having an internal thread that coincides with the thread on the stem; and a protective cap made with the possibility of detachable connection with the cartridge holder, while the dispensing mechanism additionally includes a spring element located in the part of the dispenser with a large diameter between the button and the dispenser sleeve, having legs with four elastic petals and made in such a way that when increasing or decreasing the dose, the dispenser performs both a rotational movement and is displaced in the longitudinal direction, and the dispenser sleeve performs only a translational movement, and when the button is pressed to perform an injection, both the dispenser and the dispenser sleeve carry out both a rotary movement and a translational movement (patent RU No. 134431 on utility model "Syringe-pen", filing date 22.07.2013, published 20.11.2013).

It is known that the degree of freedom of a structure is understood as the mobility of the system under load. If this system has infinitely high rigidity, then it moves as an absolutely rigid body with mobility in one direction.

In the known technical solutions, including the one selected as a prototype, the degree of freedom constraints have basically two elements: a spring element (spring) and a dispenser core, which negatively affects the mobility of the device and ensures that the rod moves in only one direction.

The disadvantages of the known solutions are due to the fact that when using elastic elements with a stiffness higher than the stiffness of the elastic elements of the dispenser core, and in the case, for example, of an erroneous selection by the user of the dose of the drug and, accordingly, the need to rotate the dispenser in the opposite (opposite) direction, the protrusions, made on the sleeve of the dispenser do not come out of the mutual engagement formed with the protrusions of the dispenser, while the rotational movement of the dispenser is transmitted to all other elements (parts) of the device, which leads to the extension of the stem as in the case of standard injection of a dose of the drug. As a result, the drug leaks through the injection needle.

In addition, with the increased rigidity of the elastic elements of the dispenser core, a user needs a significant force to administer a dose of a drug, up to exceeding the maximum allowable 15 Nm. Moreover, the peaks of the increase in the force have a clearly identified periodicity, a multiple of the number of protrusions made on the inner surface of the body.

The technical result, which the claimed invention is aimed at, is to reduce the pressing force during injections of the medicinal product, to increase the dosing accuracy and to ensure the possibility of unhindered reciprocating movement of the rod.

The specified technical result is achieved in that a syringe pen containing a body with an internal thread, providing a reciprocal interaction with a dispenser moving inside the body, connected to the holder of a cartridge with a drug, as well as a drive mechanism, including a pusher with a rod, on the surface of which a thread is made, providing interconnection with the thread of the coupling located in the housing, while the dispenser is equipped with a spring element installed with the possibility of rotational and longitudinal movement between the button and the rotation tube, in which the rotation transfer tube is located, while the spring element and the rotation transfer tube are equipped with elastic elements , according to the invention, along the entire length of the rod, two symmetrical flats are made, and on its other sides there are longitudinal grooves to form a splined connection with protrusions entering them and commensurate with them, located inside the rotation transfer tube, while on the outer surface of the rod and a double-start thread is applied and at one end there are protrusions with the help of which the rod is fixed in the coupling, and at its other end there is a connecting element by means of which the blind flange is fixed on the rod, while the spring element is equipped with two elastic elements evenly distributed over circle at a distance of 180 °, and the tube for transferring rotation is made with three elastic elements located along the circumference at a distance of 120 ° from each other.

The invention is illustrated by drawings, where

fig. 1 - General view of the syringe pen assembly;

fig. 2 is a longitudinal section of the pen syringe taken along the line A-A in FIG. 1;

fig. 3 - a syringe pen in the form of a large disassembly;

fig. 4 - a pen in the form of a small disassembly;

fig. 5 - case;

fig. 6 - dispenser;

fig. 7 - cap;

fig. 8 - button;

fig. 9 - spring element;

fig. 10 - tube of rotation;

fig. 11 - tube for transmission of rotation;

fig. 12 - clutch;

fig. 13 stock;

fig. 14 - blind flange;

fig. 15 - gear wheel;

fig. 16 - cartridge holder;

fig. 17 is a graph of the pressing force of the samples of a syringe-pen selected as a prototype;

fig. 18 is a graph of the pressing force of samples of a syringe-pen according to the claimed invention;

fig. 19 is a summary histogram of data from a syringe pen selected as a prototype;

fig. 20 is a summary histogram of data from a pen in accordance with the claimed invention.

The pen contains a body 1 in the form of a hollow cylindrical element, the outer surface of which has a variable cross-section close to a truncated cone. The outer surface of the body is made rough for the convenience of using the device and preventing it from slipping out of the user's hands.

Inside, the body is divided into two unequal parts by means of a partition, in which a central through hole with two radial grooves located symmetrically with respect to the longitudinal axis is made: a large and a smaller one.

At one end of the housing, on the side of its most part, a through indicator window is made (position not assigned), which makes it possible to visualize the calibration scale on which the values of the measured value are indicated, namely, the number of dose units of the drug.

On the entire inner surface of most of the body, a screw thread is made, mainly with a large pitch.

On the inner surface of the smaller part of the body in the area adjacent to the partition, an annular belt is made with uniformly spaced protrusions. In addition, a groove is made inside the smaller part of the body in the area close to its end.

At the other end of the housing, an external thread is made, onto which the holder of the cartridge 3 with the drug, which is mainly used as insulin, is screwed. A cap 2 is put on and securely latched onto the cartridge holder, provided with a clip (not assigned) intended for fixing the pen, for example, on the user's clothing and closing the device when not in use.

The cartridge holder is made in the form of a hollow tube with through holes on one side of the side surface. On one end of the holder there is a thread for attaching an injection needle, on the other end there are annular belts of different diameters, gradually increasing towards the end of the holder, on the inner surface of which there is a thread for connection with the body. On the outer surface of the holder, on one side, a graduation scale is applied.

A dispenser 4 in the form of a hollow tube, one end of which is made with an annular thickening close to the sleeve, the outer surface of which is ribbed, is installed in the housing 1 from the side of its greater part. On the rest of the outer surface of the dispenser, a screw thread is applied, which reciprocally interacts with the screw thread of the body and provides the convenience of rotation (scrolling) of the dispenser by the user when choosing the dose of the drug required for administration. In the assembled state of the syringe pen, the annular thickening extends beyond the body and acts as a rotator pen. The dispenser is intended for the user to select the number of units of the dose of the drug required for administration, while the choice of the dose is determined using a graduation scale applied to the screw surface of the dispenser. An annular belt with radial protrusions is made inside the dispenser in the zone of transition of a tube with a smaller diameter into a thickening-sleeve, behind which a groove is made closer to the end zone.

Inside the dispenser 4 there is a tube of rotation 5, at one end of which a bead is made, and at the opposite end there are two symmetrical grooves, which form slots inside the tube in the form of longitudinal protrusions, ensuring the transmission of torque.

It is known from the prior art that the stiffness of the connection is many times less than the stiffness of the elements to be joined, and it is the stiffness of the connection that determines the rigidity of the system. In this case, it is important that the connection does not distort the shape of the product, does not introduce additional elements into its design. Bore-centered splines provide higher alignment, more accurate axial guidance and more even load distribution. In addition, such a connection ensures the strength of the connection during the operation of the device, and also, due to the large contact surface, allows the transmission of large torques and helps to reduce the number of connection parts.

The rotation tube installed in the dispenser is locked from the side of the shoulder by an elastic (springy) element 6, which is used, in particular, a spring containing an upper part in the form of a disk with a through central hole, from which four blades extend along the circumference at a distance of 90 ° in relation to each other and interconnected by bridges to form radial grooves. The disk is close to the turbine impeller, the blades of which create rotation. The blades are placed on legs in the form of lamellar protrusions, on which two elastic elements in the form of tongues are installed around the circumference at a distance of 180 °, forming the lower part of the spring, which, when assembling the syringe pen, the spring abuts against the collar of the rotation tube 5.

On the inner side of the disk along the perimeter of the through hole there are latches (not shown in the drawing) designed to fix the button 7 mounted in its through hole, in which the pressing platform is concave for ease of use.

The spring 6 is held against axial displacement by placing the disc in the groove of the dispenser 4, while the disc is mounted with the possibility of free rotation.

In the rotation tube 5, a rotation transmission tube 8 is placed, the flow section of which has a variable cross-section due to the conditional division into two sections, one of which has a diameter and length that coincide with the parameters of the rod 9 placed inside this section. On the inner surface of the same section, there are two symmetrical longitudinal protrusions designed to mate with the longitudinal grooves of the rod. At the end of the tube 8 from the side of the stem inlet, a bead is made with unidirectional elastic elements uniformly distributed around the circumference in the form of three hooks engaging with counter protrusions made on the inner surface of the body 1. At the other end of the tube 8 there are two symmetrical spline joints, which with the outer side responsively interact with the spline connection of the rotation tube 5, and on the inside of the tube 8 there are spline connections with the rod 9.

The rod 9 is a round bar with two symmetrical flat cuts - double-sided symmetric flats, made along its entire length and located equidistant from the longitudinal axis and parallel to each other. Longitudinal grooves are made on the other two sides of the rod, commensurate with the protrusions inside the rotation transfer tube, which enter the grooves when aligned. A double-start thread is applied to the outer surface of the stem. One end of the rod is equipped with protrusions that limit the stroke of the rod inside the tube for transferring rotation 8. At the other end of the rod, a connecting element is made, for example, in the form of a head, by means of which a blind flange 11 is fixed to the rod.

The sleeve 10 is installed on the side of the smaller part of the housing 1. On the outer surface of the sleeve 10 there is an annular protrusion that fits into a groove in the housing, thereby preventing its axial displacement. A double-start thread is made inside the coupling, corresponding to the thread on the stem. The double-start thread provides not only the movement of the stem together with the dispenser during the injection, but also the return of the stem to its original position before installing the cartridge due to the rotation of the sleeve at its toothed end. When assembling the body 1 with the holder of the cartridge 3 with the drug, the toothed end of the coupling is connected to the gear 12 soldered into the holder, and, accordingly, the coupling is fixed from rotation relative to the body when setting and adjusting the number of dosage units of the drug.

The syringe pen is made of polymeric materials, and polyethylene is used for the cap and body. Polyoxymethylene is used as the material for the dispenser, button, spring, rotation tube, rotation transfer tube, coupling and stem, and ABS plastic (high-impact technical thermoplastic resin based on copolymer of acrylonitrile with butadiene and styrene) for the gear wheel and holder of the drug cartridge (the name of the plastic is formed from the initial letters of the names of the monomers).

Up to 20 protrusions can be made in the body and dispenser. The invention is carried out as follows.

To select and set the dose of the administered drug, the dispenser is freely turned clockwise or counterclockwise until a graduation scale with an indicator of the required dose value appears in the indicator window of the housing. Rotation of the dispenser leads to its longitudinal movement relative to the housing with an indicator window, with the help of which the user visualizes the values of the selected number of units of the dose of the drug for administration in the form of injection. When rotating, the dispenser moves out of the body for a certain length.

When the rotary movement of the dispenser is carried out due to the elastic elements of the spring and the possibility of longitudinal movement, the transition (jumping) of the protrusions made on the annular belt of the rotation tube through the counter protrusions of the dispenser occurs. The transition is accompanied by audible clicks or tactile changes.

When moving, the rotation tube through the rotation transmission tube transfers the rotational motion to the rod, which interacts by means of a threaded connection with a coupling, which, on the one hand, is connected to the rotation transmission tube, and, on the other hand, is fixed in the holder of the drug cartridge through a gear wheel. Intermittent rotary motion is transmitted from the rotation transmission tube due to the presence of elastic elements on it. Free movement from the motion transmission tube is realized due to the increase in the degrees of freedom by uniformly placing elastic elements on it around the circumference at a distance of 120 °, which additionally makes it possible to reduce vibration, and, as a result, to increase the dosing accuracy. In this case, the rotational movement of the dispenser is transmitted to all other elements (parts) of the device, which leads to the extension of the stem, as in the case of standard injection of a dose of the drug. As a result, the drug leaks through the injection needle. In this case, the peaks of the increase in the force, having a clearly identified periodicity, a multiple of the number of protrusions made on the inner surface of the body, are reduced.

The stem, moving forward, through the blind flange, presses on the plunger of the drug cartridge, pushing it forward by a user-selected dose value for injection.

When the button is pressed, the stroke of the spring completely stops and due to its lamellar protrusions entering the spline connection, the position of the rotation tube is fixed inside the dispenser.

To inject a drug, mainly insulin, you must install a cartridge with a tool. To do this, remove the cap, unscrew the body from the cartridge holder and, after making sure that the stem is in its original position, insert the cartridge with the drug into the holder with the metal cap forward. Reconnect the cartridge holder to the body. Pre-remove the protective film from the new injection needle, attach the needle to the holder of the drug cartridge, while removing its protective cap and cap from the needle. All air is removed from the needle and a few drops of the drug are released. When the drug is injected, the button is pressed and held until the indicator of the number of dose units returns to the zero mark in the indicator window and is aligned with the indicator on the body. After the administration of the dose of the drug, the injection needle is removed together with its cap.

When developing the proposed technical solution, comparative studies were carried out to determine the accuracy of dosing and the degree of pressing force of the syringe-pen-prototype and the syringe-pen proposed for protection.

The studies were carried out according to the dosing accuracy method, which includes four stages:

- the first stage - to make 30 measurements in turn with the establishment of the dose of the injected drug with a step of 1 ME;

- the second stage - to make 10 measurements with the establishment of the dose of the injected drug with a step of 10 ME;

- the third stage - to perform 5 measurements, in each of which set the dose to 30 ME;

- the fourth stage - carrying out measurements of 1 ME until the contents of the cartridge with the medicinal product are completely consumed.

The results of studies on the accuracy of dosing of the syringe-pen-prototype are presented in Table 1.

The results of studies on the accuracy of dosing of the syringe pen offered for protection are presented in Table No. 2.

Tests on the pressing force were carried out on a bench for measuring the force, consisting of a power link and a reading device, while in the power link the measured force causes deformation, which is communicated to the reading device directly or through a transmission. The stand is designed for simultaneous measurement of forces in six test specimens.

Measurement range from 0 to 50 Nm.

Discreteness of interrogation of strain gauges - 50 ms.

The movement speed of the measuring rods is 1.25 mm / sec.

Supply voltage - 220 V.

The test pieces are placed in the formatting part so that their moving parts are under the measuring rods, after which the measurement process starts.

When taking a measurement, the platform with sensitive elements (load cells) begins to move smoothly downward. The stem of each strain gauge begins to press on the moving element of the test sample, as a result of which it also begins to move. The emerging forces are read from the load cells and recorded in the stand memory card.

The graphs of the pressing force of the samples of the syringe-pen, selected as a prototype, and the inventive device are presented in Fig. 6, 7, respectively.

The summary hisistragrams of the obtained data of the prototype and the proposed device are shown in Fig. 8, 9, respectively.

As can be seen from the data obtained, the claimed invention has a higher dosing accuracy compared to the known solution, while during its operation the user requires less pressing force.

Changes made to the design associated with an increase in the degrees of freedom by changing the design of the rod, adjusting the number of elastic elements with which the spring element and the rotation transmission tube are equipped, and the simultaneous use of spline joints in the device provide a different, higher, technical result, while realizing the possibility use a syringe pen as a reusable device.

Claims (1)

1. A syringe pen containing a body with an internal thread, which provides a reciprocal interaction with a dispenser moving inside the body, connected to the holder of a cartridge with a drug, as well as a drive mechanism, including a pusher with a rod, on the surface of which a thread is made, providing interconnection with the coupling thread placed in the housing, while the dispenser is equipped with a spring element installed for rotational and longitudinal movement between the button and the rotation tube, in which the rotation transfer tube is located, while the spring element and the rotation transfer tube are equipped with elastic elements, characterized in that by the entire length of the stem is made of two symmetrical flats, and on its other sides - longitudinal grooves to form a spline connection with protrusions entering them and commensurate with them, located inside the rotation transfer tube, while a two-start thread is applied to the outer surface of the stem and on one end there are protrusions with which the stem is fixed in the coupling, and at its other end there is a connecting element by means of which a blind flange is fixed on the stem, while the spring element is equipped with two elastic elements evenly distributed around the circumference at a distance of 180 °, and the tube rotation transmission is made with three elastic elements located along the circumference at a distance of 120 ° from each other.

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