Dose setting limiter

(12) PATENT DESCRIPTION (19) PL (11) 196742 (13) B1 (21) Application number: 354038 ⁽¹³⁾ (22) Date of notification: 04/09/2000 ^{(51) Int.Cl.}

A61M 5/315 (2006.01) (86) Date and number of the international application:

04.09.2000, PCT / DK00 / 00481 (87) Date and publication number of the international application:

2001-03-22, WO01 / 19434 PCT Gazette No. 12/01

<td colspan="2">(54) Injection device</td>

<td>(30) Priority: 1999-09-16, DK, PA199901309</td><td>(73) The right holder of the patent: NOVO NORDISK A / S, Bagsv «rd, DK (72) Inventor (s): Peter Christian Klitgaard, Sm0rum, DK</td>

<td>(43) Application was announced:</td><td>Steffen Hansen, Hiller0d, DK</td>

<td>15.12.2003 BUP 25/03</td><td>Bo Radmer, Hiller0d, DK Claus Schmidt M0ller, Fredensborg, DK</td>

<td>(45) The grant of the patent was announced:</td><td></td>

<td>31.01.2008 WUP 01/08</td><td>(74) Representative: Teresa Kuczyńska, POLSERVICE, Kancelaria Rzeczników Patentowych Sp. z o. o</td>

(57) 1. An injection device comprising a cartridge holding housing, an injection button for releasing a set dose, a plunger rod for advancing a plunger within the cartridge, and a restriction mechanism that prevents setting a dose exceeding the amount of liquid remaining in the cartridge irrespective of the amount of liquid remaining in the cartridge, said restriction mechanism comprises a dose setting member coupled to the injection button, and a drive member coupled to the piston rod, wherein the dose setting member and the drive member move relative to each other when the dose setting member is rotated to set the dose so that the injection button is moved away from the housing, and the dose setting member and the drive member move together upon releasing the set dose by returning the injection button, advancing the piston rod, characterized in that the drive member (9, 31) is provided with a track (20, 33) having an end wall (24) defining a length, which is related to the total amount of medicament in the cartridge (2), and the path (20, 33) cooperates with a pusher (21, 22, 32) connected to the dose setting member (6, 30) to follow the rotation of the member (6, 30). ) to set a dose, the pusher (21, 22, 32) and the dose setting member (6, 30) rotating together with respect to the drive member (9, 31) when a dose is set and when a dose is released the pusher (21, 22, 32) and segment (6, 30) the dose settings rotate simultaneously with the drive (9, 31).

<img file="PL196742B1_D0001.tif" />

PL 196 742 B1

Description of the invention

The subject of the invention is an injection device. In particular, the invention relates to injection devices in which the contents of the cartridge are injected as a plurality of individually adjustable doses.

These devices have a dose setting mechanism that sets the doses for subsequent injections when the injection button is actuated. This is done by moving the driver along the piston rod a distance proportional to the dose required, and then returning the driver to the starting position so that it lifts the piston rod with it, rather than moving along the piston rod.

A syringe is known according to EP 327 910 in which the dose is set by screwing the nut member along a threaded piston rod away from a stop in the housing. Injection of the set dose is effected by depressing the end of the cap member forming the injection button, thereby returning the cap member to the stopper. During the next movement of the nut member, the piston rod moves along the nut, which is stationary with respect to the piston rod during injection.

In setting the dose, it is convenient to use a restriction device that prevents the dose from being set in excess of the amount of drug remaining in the cartridge. In EP 327 910 this is achieved thanks to the selected length of the piston rod thread, at which the cartridge is emptied after twisting the nut to the end of the thread and reaching the stopper. By setting the dose, the nut can only be turned to the end of the thread, which limits the size of the last dose according to the amount remaining in the cartridge.

The distance traveled by the injection button corresponds to the distance traveled by the plunger in the cartridge to inject the set dose. This distance can be very small, especially with larger inserts with a large cross-sectional diameter. A type of gear may be used to obtain a greater displacement of the injection button whereby the distance of displacement of the injection button will be proportional to the dose injected, but many times the travel of the plunger in the cartridge.

EP 608 343 describes an example of such a gear ratio for a dose setting and injection mechanism.

In this device, the driver does not directly cooperate with the threaded piston rod, but with a drive element that can move the piston rod when injecting a set dose. In the device, the drive member comprises a nut secured against axial displacement in the injection device. The thread of the nut member cooperates with an external thread of the piston rod which is prevented from turning in the injection device. When setting the dose, the driver is rotated and moved away from the stop, to which it returns after actuation of the injection button. During the return movement, the driver rotates a drive member which advances the plunger further in the cartridge forcing it down such that a set amount of medication is pushed through the injection needle at the distal end of said cartridge. Since the cap member does not move with respect to the piston rod during dose setting, the dose limiting design described above cannot be used so as not to exceed the amount of liquid left in the injection device.

WO 91 / 14.467 describes a pen-shaped injection device having a restriction mechanism that prevents the setting of a dose exceeding the amount of liquid remaining in the cartridge. The limiting mechanism includes a dose limiting member coupled to the injection button and a piston rod having an integrated drive member or an upper thread that cooperates with the dose setting member such that the dose setting member and the upper thread move each other when rotating the dose setting member to set the dose and they move together to release a set dose. The dose setting member further has a plurality of detents, one of which will fall into a recess in the piston rod when the dose setting member is moved a predetermined distance from the piston rod. The specified distance was based on the total amount of liquid in the cartridge.

However, the solution described in WO 91 / 14.476 is inconvenient and inadequate for injection tools having a threaded piston rod with a circular cross-section as usually found in the piston rods of injection tools and is clearly useless for a bent piston rod.

An injection device comprising a cartridge holding housing, an injection button for releasing a set dose, a plunger rod for advancing a plunger within the cartridge, and a restriction mechanism that prevents setting a dose exceeding the amount of liquid remaining in the cartridge irrespective of the amount of liquid remaining in the cartridge, said restriction mechanism

The dose setting member comprises a dose setting member coupled to the injection button, and a drive member coupled to the piston rod, wherein the dose setting member and the drive member move relative to each other as the dose setting member is rotated to set the dose so that the injection button is moved away from the housing. and the dose setting member and the drive member move together to release the set dose by the return of the injection button, advancing the piston rod, according to the invention, characterized in that the drive member is provided with a track having a length defining end wall which is related to the total amount of medicament in the cartridge, and the track cooperates with a pusher connected to the dose setting member to follow rotation of the dose setting member, wherein the pusher and dose setting member rotate together with respect to the drive member when the dose is set, and when a dose is released the pusher and dose setting member are rotated simultaneously with the drive member.

The drive member is disc shaped and its path is spiral shaped and cooperates with a cam flexibly connected to the dose setting member such that the cam can move radially to follow the path of the drive member.

The drive member is cylindrical in shape and its path is helical in shape and cooperates with a cam connected to the dose setting member, which is a cylinder coaxial with the drive member.

The track is provided as a thread on the drive member, and the pusher is a nut-shaped member connected to the dose setting member and provided with a thread engaging the threads of the drive member.

The injection device according to the invention has a restriction mechanism which eliminates or improves on at least one of the drawbacks of the known devices and is suitable for simpler injection tools having a threaded piston rod with a circular cross-section that can rotate or having a bent-type piston rod.

The drive member has a path length related to the total amount of medication in the cartridge and the path cooperates with a pusher connected to the dose setting member to allow said dose setting member to be rotated. In setting the dose, a pusher moves in the path of the drive member depending on the set dose, and during dose setting, the setting member and the drive member rotate relative to each other. Since the driver follows the rotation of the dose setting member on injection, the dose setting member pin maintains its position in the track of the drive member during dose injection. The length of the track was chosen so that the pin reached the end of the track and prevented an increase in the set dose after setting the dose corresponding to the amount of liquid remaining in the cartridge.

In accordance with the invention, the drive member may be disc-shaped with a helical path cooperating with a cam on the member flexibly connected to the dose metering member such that the pin moves radially as it follows the path of the drive member.

In another embodiment of the invention, the drive member may be cylindrical in shape with a helical groove cooperating with a cam on the dose setting member, which is a cylinder coaxial with the drive member.

The path may be formed as a thread in the drive member, and the pusher may be a nut-shaped member connected to the dose setting member and having a thread engaging the threads of the drive member. When setting the dose, the setting member moves on the thread along the threads of the drive member. Limiting the dose setting is achieved by making an appropriate thread length.

The injection device is shown in the drawing in which Fig. 1 shows a syringe with a dose limiter according to the invention in an exploded view of its assembly; Fig. 2 shows the dose setting member and the syringe driver of Fig. 1 to an enlarged scale; Figure 3 shows a dose setting member, driver and plunger in another embodiment of the injection syringe.

The syringe in Fig. 1 has a housing 1 containing a cartridge 2, the contents of which are pressed into the piston rod during injection via gears 4 and 5 moved a distance corresponding to a setting by setting the dose. The dose setting member 6 is provided with a gear 7 surrounding a central opening through which a small gear 8 of the drive member 9 projects as shown in Fig. 2. The dose setting member 6 is operated by an adjusting member with an arrow 13 pointing to a scale 14 provided on the lid 15 forming part of the housing 1. Figure 1 further shows a cap 25 fitted to protect a needle, not shown.

It is fitted to a syringe and an injection button 16 is slidably mounted on the housing 1 and has a recess 17 which forms a rack 18 on one side surface.

In the assembled syringe, the gear 7 on the dose setting member 6 meshes with the rack 18 of the push member 16, while the small gear 8 on the drive member 9 meshes with the larger diameter portion of the gear 5, the smaller diameter portion of which engages with the rack 19 on the piston rod 3.

The drive member 9 has a pawl 26 which, with the not shown housing toothing, forms a one-way clutch enabling the drive member 9 to be rotated only in the direction in which the piston rod 3 engages the cartridge 2. The sawtooth pawl of the dose setting member 6 cooperates with a sawtooth 27 on the circumference of the drive member 9, the pawl allows the dose setting member 6 to be pivoted in one direction in which the drive member 9 can move, which is transferred from the dose setting member 6 to the drive member. 9. When the dose setting member 6 is rotated in the opposite direction, the teeth of the ratchet portions will jump one after the other.

To set a dose, the finger 11 on the actuator 10 is grasped and the actuator 10 is rotated clockwise until the arrow points to the desired dose on the scale 14. As mentioned, rotation will cause the ratchet portions of the dose setting member and the driver to jump towards each other. . If the dose setting member 6 is rotated clockwise to reduce the set dose, the ratchet will cause the rotation to be transmitted from the dose setting member 6 to the drive member 9, but when torque in this direction is transferred from the actuator via the driver 12 to the driver 12. 6, the dose setting member is deformed so that the protrusion on the dose setting member 6 is no longer in contact with the toothing 27 of the drive member 9, allowing the dose setting member to be rotated counterclockwise without transmitting this rotation to the drive member 9.

As a result of the meshing between the gear 7 on the dose setting member 6 and the rack 18 of the injection button 16, the button rises from the end of the housing 1 on dose setting and lowers on dose reduction.

When the injection button 16 of the set dose is depressed, the connection between the gear wheel 7 on the dose setting member 6 and the rack 18 of the injection button 16 will cause the dose setting member 6 to rotate counterclockwise. As the actuator 10 does not transmit torque to the dose setting member 6, the rack-and-pinion connection between the dose setting member 6 and the drive member 9 remains active and the drive member 9 will rotate with the dose setting member 6 counterclockwise and drive the piston rod. 3 put into the contribution.

As shown in Fig. 2, the disk drive member 9 has, on the side facing the dose setting member 6, a helical path 20 cooperating with a cam 21 at the end of the arm 22, which is connected to the dose setting member 6 by a flexible beam 23, whereby the arm 22 pivots and allows the movement of the cam 21 in the radial direction of the drive member 9. When the dose setting member 6 is rotated relative to the driving member 9 during dose setting, the cam moves along the path 20, while during injection the cam remains in its position on the dose setting path 20 due to the rotation of the dose setting member 6 and the drive member 9. In this way, the position of the cam on the track reflects the total amount of drug taken up. Once cam 21 has reached the end wall 24 of track 20, the set dose cannot be increased, and by adjusting the track length to the amount of drug in the cartridge it is ensured that no more drug remaining in the cartridge can be dispensed.

Fig. 3 shows a dose setting member 30 surrounding the drive member 31 in another embodiment of the dose setting limiter. The dose setting member 30 is cylindrical in shape and has, on its outer wall, a helical path 29 cooperating with the helical inner ridge of a housing, not shown, such that the dose setting member 30 twists out of said housing upon rotation during dose setting, and is screwed in. into said housing when rotated to reduce an oversized dose setting. When rotating for dose setting, the dose setting member 30 is freely rotated with respect to the drive member 31 surrounding it. Connected between the dose setting member 30 and the drive member 31 is a nut member 32 which, when rotated relative to the drive member 31, screws along the drive member which has a helical path 33 on its outer surface. On the outer wall, the nut member 32 has a recess 34 in an axial direction cooperating with a ridge 35 on

Inside the dose setting member 30. During dose setting, the nut member 32 rotates with the dose setting member 30 relative to the drive member 31 by the connection between the ridge 35 and the recess 34, whereby the position of the nut member on the drive member depends on the dose set. During dose injection by depressing a button, not shown, located in an end portion 36 of the dose setting member 30, the button presses a collar 37 at the end of the drive member 31 to engage the clutch teeth 38 at the bottom of the end portion 36 of the dose setting member 30. In the non-visible lower part, the flange 37 has clutch teeth corresponding to the clutch teeth 38 of the dose setting member 30, and when, due to the engagement between the track 29 in the dose setting member 30 and the ridge in the housing, the dose setting member 30 is forced to rotate with respect to the housing and at the same time. pushed against said housing, rotation will be transmitted to the drive element 31 which, by engagement of the gear clutch, rotates with the dose setting member, during rotation, the nut member 32 maintains its position on the drive member 31. Thus, the position of the cap member 32 on the drive member 31 will always indicate the total sum of the doses injected and the dose set. By adjusting the length of the helical path 33 on the drive member 31 to the amount of drug in the cartridge, the cap member 32 reaches the end of the path 33 and stops setting a dose greater than the amount remaining in the cartridge.