JP2008525070A - Segmented piston rod - Google Patents

Abstract

  The present invention relates to a piston rod of a syringe, the piston rod comprising a plurality of axially arranged segments (1), the plurality of segments (1) forming a stack of segments having a basic length. And are rotatable relative to each other. In the segment stack, at least two of the plurality of segments (1) are each provided with an inclined surface (5) that is inclined with respect to the axial direction of the piston rod, so that the relative rotation between these two segments Changes the length of the stack of segments.

Description

The present invention relates to segmented piston rods. Specifically, the present invention relates to a segmented piston rod for use in a syringe such as a drug or infusate delivery device.

Background of the invention US 5514097 discloses a drug infusion device for subcutaneous or intramuscular delivery of drugs. In this device, the needle is hidden behind the needle shroud. When the device is in operation, the needle is pushed forward and the tip of the needle is pushed out of the needle shroud with sufficient force to penetrate the skin. Thus, the needle is automatically introduced into the tissue in the appropriate direction relative to the skin. In the same operation, the device dispenses an exact preset dose of drug. This dose can be set by a manual variable dosing assembly or by an automatic dosing assembly.
US2002 / 0016571 relates to a device for administering a dose of injectable drug. The device according to US 2002/0016571 comprises in particular a reservoir of medicament and a piston that forcibly releases the medicament from the reservoir when moved in the supply direction towards the outlet of the reservoir.

In both US5514097 and US2002 / 0016571, the piston for forcibly releasing the drug from the reservoir is a rigid and rigid element having a constant or non-variable length.
US Pat. No. 6,508,788 discloses a drug delivery device comprising a container for containing a fluid drug. The drug is released by moving the elastic piston in the cartridge forward. The piston is moved forward by a telescopic piston rod. The piston rod can be located in the center of the container or eccentric. One end of the telescopic piston rod is in contact with the elastic piston by itself or through another plate. It can be seen that such contact provides a sufficient amount of friction to prevent rotation of the lower portion of the telescopic piston rod. In order to prevent the elastic piston from rotating in the container, a second telescopic piston rod is provided in parallel with the first telescopic piston rod.

Other references such as WO 03/062672 and WO 01/78811 also disclose telescopic piston rods.
However, in a telescoping system, it is difficult to maintain full control of the outermost element of the telescoping piston rod, thereby losing precise control over, for example, the dose to be ejected from the syringe. This lack of controllability is a major drawback of such telescopic syringes.

Accordingly, one object of the present invention is to provide a piston rod configuration in which each element constituting the piston rod can be completely controlled.
Another object of the present invention is to provide an expandable piston rod configuration that has as little private space as possible in the unexpanded state. By reducing the space required for the unexpanded piston rod, the overall size of the syringe containing the piston rod can be reduced.

SUMMARY OF THE INVENTION The above object is achieved in a first aspect by providing a syringe piston rod comprising a plurality of axially arranged segments. In this piston rod, these segments form a stack of segments having a basic length and are rotatable relative to each other. At least two of the plurality of segments each have at least one inclined surface that is inclined with respect to the axial direction of the piston rod, so that the length of the stack of segments as a result of the two segments rotating relative to each other. Is prevented from changing.
One or more segments can rotate between an initial position and a final position. In principle, the rotation angle between the initial position and the final position can be several degrees to 360 degrees.

A first locking arrangement can be provided to maintain control of multiple segments. The mechanism of the first lock configuration can fix any segment of the plurality of segments at one place between the initial position and the final position of one segment, thereby enabling an infinitely expandable piston rod. can get. The first locking mechanism is applied while the length of the segment stack is extended. This first locking mechanism can be implemented as a key / keyway connection between the segment and the associated inner surface portion of the syringe.
A second locking configuration can be provided. This second locking mechanism is implemented as a mechanism that acts directly between two adjacent segments when one segment is moved to the farthest opposite side to the segment that touches it. The second locking mechanism can be implemented by various methods such as a ripple formed as a microstructure on the surface portion of the segment, an edge or a dent formed on the surface portion of the segment.

Each segment is constituted by at least two substantially identical parts in a plane substantially perpendicular to the axial direction of the piston rod. In one embodiment, each segment is constituted by two substantially identical portions, each having at least one inclined surface. In another embodiment, each segment has a helically inclined surface in a plane generally perpendicular to the axial direction of the piston rod.
The stack of segments comprises 5-30 segments, for example 10-20 segments. Each or part of the segment is made of a polymer-based material such as metal or plastic. If multiple segments are made from metal, the segments can be manufactured using a stamping process or, alternatively, can be manufactured by sintering from metal powder.
The diameter of each segment can be adapted within the cartridge of the associated syringe, which means that the diameter of each segment can be 5-15 mm, for example about 10 mm.

In a second aspect, the invention relates to a syringe comprising a piston rod according to the first aspect. The syringe can be a drug delivery device or some other type of infusion device.
In a third aspect, the invention relates to a segment of a segmented piston rod of a syringe, the segment comprising a surface that is inclined with respect to the axial direction of the piston rod so that the segment is relative to another segment. And thus changing the length of the segmented piston rod is prevented.

The present invention will now be described in more detail with reference to the accompanying drawings.
While the invention is susceptible to various modifications and alternatives, specific embodiments are shown by way of example in the drawings and will be described in detail. However, the invention is not limited to the specific forms disclosed. On the contrary, the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims.

DETAILED DESCRIPTION OF THE INVENTION In the most general aspect of the invention, a piston is formed by a plurality of segments arranged to form a stack of segments. The segments forming the stack are rotatable with respect to each other so that, for example, one or more segments are maintained in a fixed direction while one or more other segments are fixed in the one or more Can rotate with respect to the segment. In order for the stack of segments to be expandable, at least two of the segments have inclined surfaces so that the relative rotation of the two segments causes the segment stack to form a piston rod. It is necessary to configure so that the total length is expanded. A stack of segments can be formed by the same segment or can be formed by multiple sets of segments, each set being formed by a base segment and a rotating segment. Alternatively, the stack of segments can be formed by a combination of one or more segment sets and the same segment.
When extending the length of a stack of segments, the following procedure is generally taken. The segment to be separated from the stack of unseparated segments, i.e. the segment pushed forward, is kept fixed with respect to the piston plate in contact with the cartridge containing the drug released from the syringe. Thus, it is the segment or segments that are not in contact with the piston plate that rotate when pushing the segment forward. This or rotation of these segments pushes and moves the segment in the direction of the cartridge through one or more inclined surfaces so that a dose of drug is released from the cartridge.

1 and 2 show various examples of segments suitable for the practice of the present invention. As shown, the segments can take a variety of forms and shapes, but in order to extend the length of the stack by rotation, at least two segments need to have at least one inclined surface.
The diameter of the segments forming the stack is in principle arbitrary. However, in order to use a stack of segments as a piston rod in a drug delivery device, the diameter of the segments must fit within a cartridge that holds the drug released from the drug delivery device. The diameter of the segment according to the invention is preferably 5-15 mm, for example about 10 mm.

FIG. 1 shows an embodiment of the present invention. FIG. 1a shows the isolated segment of this embodiment, FIG. 1b shows the stack of segments in the unexpanded state, and FIG. 1c shows the segment stack in the expanded state.
As shown in FIG. 1 a, the segment 1 according to this embodiment is constituted by two identical halves 2 and 3. Each half comprises a mechanical stop mechanism 4 and two oppositely inclined surfaces 5 and 6. These inclined surfaces are inclined over an angle of more than 180 degrees and terminate in a mechanical stop mechanism 4. The inclination angle is determined according to the number of segments forming the stack. If 15 segments form a stack and the stack must be expandable by 50 mm, the contribution of each segment to expansion is within 3.3 mm.

FIG. 1 b shows a stack formed by three segments 7, 8 and 9. By placing two adjacent segments in opposite directions, they can be perfectly matched. Such a perfect match is seen in FIG. 1b between segments 7 and 8 and between segments 8 and 9. It can also be seen that the mechanical stop mechanism 4 defines the minimum length of the entire stack. That is, when the stop mechanism 4 of the segment 7 comes into contact with the corresponding stop mechanism of the segment 8, the minimum length of the stack formed by the segment 7 and the segment 8 is obtained. The same is true for segment 8 and segment 9.
To increase the overall length of the segment stack, two of the segments, for example 8 and 9, need to be rotated relative to the third segment 7. During this rotation, segments 8 and 9 are maintained in a fixed relationship with respect to each other. The relative rotation of segments 8 and 9 and segment 7 increases the length of segments 7 and 8, thereby increasing the overall length of the stack.

  When the segments 7 and 8 reach the position farthest from each other, the segments 7 and 8 are fixed to each other by some kind of fixing means. Such fixation may include a click sound mechanism in the form of an uneven portion of the inclined surface, a protrusion or the like. In such a position where the segments 7 and 8 are farthest away, no further expansion due to the relative movement of the segments 7 and 8 is obtained. However, if segment 9 is rotated relative to segments 7 and 8 (segments 7 and 8 are now fixed together), the stack can be further expanded. FIG. 1c shows an example in which all three of these segments (7, 8, and 9) are rotating with respect to each other. However, none of the segments shown in FIG. 1c has reached the farthest position. This means that the overall length of the segment stack shown in FIG. 1c can be further expanded.

FIG. 2 shows another embodiment of the present invention. Fig. 2a shows a single segment, Fig. 2b shows the unexpanded state of a stack composed of three segments, and Fig. 2c shows the expanded state of a stack composed of two segments.
Again, each segment 10 is constituted by two identical halves 11 and 12 (see FIG. 2a). Each half comprises a stop mechanism in the form of a stop surface 13 and an inclined surface 14. FIG. 2b shows the three segments forming the unexpanded state of the stack. Figure 2c shows the expanded state of the stack formed by two segments. As shown, as the two segments 15 and 16 rotate relative to each other, the overall length of the stack increases significantly. As shown in FIG. 2c, the segments 15 and 16 are near their furthest positions so that when the segment 16 is further rotated counterclockwise with respect to the segment 15, the two segments are locked together by the securing means Is done.

FIG. 3 shows a segmented piston rod according to the present invention disposed within the drug delivery device 26. The segmented piston rod operates as follows.
The released dose is set by rotating the scale drum 17 upward along the inner housing thread 18. A rosette 19 between the scale drum and the connecting pipe 20 pushes the connecting pipe 20 upward. The rotation of the connecting tube 20 is prevented by the dose cup 21. The dose cup 21 is locked to the housing of the drug delivery device by a one-way ratchet (not shown).

When delivering a dose from the drug delivery device, the button 22 must be depressed. When the button 22 is depressed, the dose cup 21 is rotated by the scale drum 17 and the connecting tube 20. As the dose cup 21 rotates, the idling segment 23 (the segment closest to the dose cup 21) rotates with the dose cup 21. The rotation of the segment 24 pushed forward (toward the cartridge) is prevented. In order to prevent rotation of the segment 24 in contact with the cartridge, this segment 24 can have a key / keyway connection (not shown) with the housing of the drug delivery device. By maintaining the segment 24 secured to the housing of the drug delivery device, the plurality of segments 23 and the one segment 24 rotate relative to each other, thereby pushing the segment 24 toward the cartridge.
When segment 24 reaches its end position, it is released from the key / keyway connection (or other type of locking configuration). If another segment has already been pushed in the direction of the cartridge, the segment just released from the locking configuration is locked to that segment. In fact, this is shown in FIG. 3, where the segment 25 has already been pushed towards the cartridge.

  When segment 24 is released, the next segment (the segment of the plurality of segments 23 closest to the cartridge) is locked to the housing and one or more segments between the locked segment and the dose cup 21 rotate. This locked segment is then pushed toward the cartridge.

1 shows a first embodiment of a piston rod according to the invention. 2 shows a second embodiment of a piston rod according to the invention. Fig. 3 shows an embodiment of a piston rod according to the invention attached to a drug delivery device.

Claims (18)

  A piston rod of a syringe comprising a plurality of axially arranged segments (1), wherein the plurality of segments (1) form a stack of segments having a basic length and are rotatable with respect to each other And at least two of the plurality of segments (1) each comprise at least one inclined surface (5) inclined with respect to the axial direction of the piston rod, so that the relative rotation between the two segments A piston rod that changes the length of the stack.   The piston rod of claim 1, wherein the one or more segments rotate between an initial position and a final position.   The piston rod according to claim 2, further comprising a first locking configuration that secures any of the plurality of segments to a position between an initial position and a final position of one segment, thereby providing an infinitely expandable piston rod. Piston rod.   4. A piston rod according to claim 3, wherein the first locking arrangement is provided on an inner surface portion of the associated syringe.   The piston rod according to any one of claims 1 to 4, further comprising a second lock configuration that fixes any of the plurality of segments at a position farthest from the contacting segment.   The piston rod according to claim 5, wherein the second locking configuration is provided on a surface portion of some of the plurality of segments.   The piston rod according to any one of claims 1 to 6, wherein each segment is constituted by at least two substantially identical portions in a plane substantially perpendicular to the axial direction of the piston rod.   8. A piston rod according to claim 7, wherein each segment is constituted by two substantially identical parts.   The piston rod according to claim 8, wherein each of the two substantially identical portions comprises at least one inclined surface.   The piston rod according to any one of claims 1 to 6, wherein each segment has a helically inclined surface in a plane substantially perpendicular to the axial direction of the piston rod.   11. A piston rod according to any one of the preceding claims, wherein the segment stack comprises at least five segments.   The piston rod of claim 11, wherein the stack of segments comprises 5 to 30 segments, for example 10 to 20 segments.   The piston rod according to any one of claims 1 to 12, wherein each segment is made of a material made of a polymer such as metal or plastic.   14. A piston rod according to any one of the preceding claims, wherein the diameter of each segment fits within an associated syringe cartridge.   The piston rod according to claim 14, wherein the diameter of each segment is 5 to 15 mm, for example about 10 mm.   A syringe comprising the piston rod according to any one of claims 1 to 15.   The syringe of claim 16, which is a drug delivery device.   A segment of a segmented piston rod of a syringe, comprising an inclined surface that is inclined with respect to the axial direction of the piston rod so that the relative rotation between the segment and another segment is the length of the segmented piston rod A segment that changes its height.

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