WO2019009778A1

WO2019009778A1 - Syringe

Info

Publication number: WO2019009778A1
Application number: PCT/SE2018/050602
Authority: WO
Inventors: Per Knutsson
Original assignee: Krui Ab
Priority date: 2017-07-05
Filing date: 2018-06-11
Publication date: 2019-01-10
Also published as: SE1750881A1

Abstract

The present invention discloses a syringe 100. The syringe 100 comprises a barrel 102 with a needle 101 arranged at a distal end 1 10 of the barrel 102. The barrel 102 is adapted to contain a drug and the barrel 102 has a tubular wall extending proximaily from the distal end 110. The barrel 102 extends along an axis 1000. The syringe 100 further comprises a plunger stopper 103 disposed within the barrel 102, wherem the plunger stopper 103 is adapted to be in fluid-tight engagement with the tubular wall of the barrel 102. The plunger stopper 103 has a thread profile 105b. The syringe 100 also comprises a plunger rod 104 extending along the axis 1000, wherem said plunger rod 104 has a thread profile 105a that engaging with the thread profile 105b of the plunger stopper 103. The engaged plunger stopper 103 and plunger rod 104 are being displaceable along the axis 1000 within the barrel 102. The engagement of the thread profiles 105a, 105b is configured such that the axial separation force B between the plunger stopper 103 and the plunger rod 104 in a proximal directing is being less than a liquid suction force A through the needle 101.

Description

SYRINGE

TECHNICAL FIELD

The present invention relates to a syringe with a construction that prevents re- usage of the syringe and wherein the syringe may be manufactured at a cost similar to a conventional syringe.

BACKGROUND

The business area of prefilled syringes is undergoing strong expansion. There are several reasons for this, but one of the main reasons is that the prefilled syringes are "ready for use". Therefore, the need for the users to fill the syringes and the handling of the drugs and syringes before use is minimized. This will accordingly reduce the risk of infections and assure the quantity and the quality of the drug contained within the syringe.

Prefilled syringes are usually made of glass with highest quality. The reason for this is that the drug contained within the syringe carries the highest cost. The syringes are constructed such that they have a minimal dead space, which will assure that almost all drug or medicine contained within the syringe will be released. However, these positive characteristics of the syringes will make it tempting for users to reuse them, as conventional syringes, by refilling the syringes with drugs again. Misusage of syringes is a common issue; over 2 million users each year are infected with severe blood transmittable deceases, such as HIV, Hepatitis B and C. By current constructions and designs of prefilled syringes, this problem is not complete solved, and the attempts to solve the problem are done at a very high cost.

Hence, there is a need to provide a syringe which addresses the disadvantages and shortcomings described above and to provide a non-reusable syringe. SUMMARY

Accordingly, the present invention preferably seeks to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solves at least the above mentioned problems by proposing a solution according to the appended independent claims. Advantageous embodiments are defined in the appended dependent claims.

In a first of its aspects, this disclosure therefore presents a syringe. The syringe comprises a barrel with a needle arranged at a distal end of the barrel. The barrel is adapted to contain a drug and the barrel has a tubular wall extending proximally from the distal end. The barrel extends along an axis. The syringe further comprises a plunger stopper disposed within the barrel, wherein the plunger stopper is adapted to be in fluid- tight engagement with the tubular wall of the barrel. The plunger stopper has a thread profile. The syringe also comprises a plunger rod extending along the axis, wherein said plunger rod has a thread profile that engaging with the thread profile of the plunger stopper. The engaged plunger stopper and plunger rod are being displaceable along the axis within the barrel. The engagement of the thread profiles is configured such that the axial separation force between the plunger stopper and the plunger rod in a proximal directing is being less than a liquid suction force through the needle.

In some embodiments, the syringe contains the drug.

In some embodiments, the pitch of the thread profiles of the syringe is 1,6 mm.

In some embodiments, the plunger stopper is made of an elastomer having a Young's modulus within the interval 25 MPato 200 MPa. In some embodiments, the plunger rod is made of a thermoplastic polymer having a Young's modulus within the interval 900 MPa to 2000 MPa.

In some embodiments, a thread angle of the thread profile for the plunger rod is larger than 30°. In some embodiments, a separation angle of the thread profile for the plunger rod is larger than a threaded drive angle of the thread profile for the plunger rod. For example, the separation angle may be within the interval 45 °± 25 °. In one embodiment the threaded drive angle of the thread profile for the plunger rod is 15 °. In some embodiments, the separation angle of the thread profile for the plunger rod is different from the separation angle of the thread profile for the plunger stopper.

In some embodiments, the depth of the thread is 0.5 mm

In some embodiments, the form of the thread is hemispherical. In some embodiments the depth of the thread is 0.5 mm

The inventor of the present invention has realized, after inventive and insightful reasoning, that by constructing thread profiles of plunger stoppers and plunger rods for syringes in a clever way with certain angles, dimensions and/or forms, a prefilled non-reusable syringe which can be manufactured in a similar way as a conventional syringe, without additional costs, is provided.

Further advantages will be apparent from the detailed description as well as the appended dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which the invention is capable, will be apparent and elucidated from the following description of non-limiting embodiments of the present invention, reference being made to the accompanying drawings, in which

Fig. 1 is a longitudinal section view of an existing syringe;

Fig. 2 is a longitudinal section view of a syringe according to one example;

Fig. 3 shows a longitudinal section view of a syringe according to one example;

Fig. 4 shows a longitudinal section view of a syringe according to one example.

DETAILED DESCRIPTION OF THE EMBODIMENTS Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in order for those skilled in the art to be able to carry out the invention. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The embodiments do not limit the i vention, but the invention is only limited by the appended patent claims. Furthermore, the terminology used in the detailed description of the particular embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention.

Referring to Figure 1, an existing syringe 100 is shown. The syringe 100 comprises a barrel 102 with a needle 101 attached to a distal end 110 of the barrel 102. The needle 101 is mechanically and hermetically attached to the syringe as known in the art, such as molded or glued, around the rear end of a hollow needle, whereby liquid passage is allowed in both directions, from the rear end of the needle unit to and through a needle tip of the hollow needle. The needle 101 is usually very thin, with a surface diameter of 0.3 - 0.6 mm

With reference to Figure 2, one example of a syringe 100 according to the teaching herein is shown. The barrel 102 of the syringe 100 may be made of any material suitable for containing a drug, but is preferably made of glass. The glass is preferably transparent. The barrel 102 is adapted to contain a drug. The drug may be in liquid form to be injected into a patient or user. The barrel 102 has a distal end 110, to which the needle 101 is attached, and a tubular wall extending proximally from the distal end. The syringe 100 extends along an axis 1000 which defines the direction in which the barrel 102 extends, e.g. the barrel 102 extends along the axis 1000.

A plunger stopper 103 is disposed within the barrel 102. The plunger stopper 103 is adapted to be in fluid-tight engagement with the tubular wall of the barrel 102. By being in fluid-tight engagement with the tubular wall of the barrel 102, the drug contained within the barrel 102 is prevented from leaking out of the syringe 100 in any other direction than through the needle 101 at the distal end 110 of the barrel 102. The plunger stopper 103 is disposed within the barrel 103 after the syringe 100 has been filled with the drug.

The plunger stopper 103 has a thread profile 105b which is adapted to receive a piece with a thread profile that engages with the thread profile 105b of the plunger stopper 103. A thread is a helical structure used to convert between rotational and linear movement or force, and the thread is a ridge wrapped around a cylinder or cone in the form of a helix. The plunger stopper 103 according to the teachings herein is thus adapted to receive such a cone or cylinder with a thread profile configured to engage with the thread profile 105b of the plunger stopper 103. The thread profile may have some characteristics, such as for example the cross-sectional shape of the thread, often called its form or threadform, the angle characteristic of the cross-sectional shape, often called the thread angle and the distance from the crest of one thread to the next, also called pitch.

The syringe 100 according to one embodiment herein, as illustrated in Figure 2, furthermore comprises a plunger rod 104. The plunger rod 104 extends along the axis 1000 and has a thread profile 105a that engages with the thread profile 105b of the plunger stopper 103. Because the plunger stopper 103 and the plunger rod 104 have engaging thread profiles 105b, 105a, the two parts may be effectively attached to each other. The plunger stopper 103 represent an external thread and the plunger rod 104 represent an internal thread. The engaging thread profiles 105b, 105a of the plunger stopper 103 and the plunger rod 104 work as a screw with a matching bolt. By using a fastening element such as engaging thread profiles 105a, 105b, the fastening element is relatively easy and cheap to produce, without the need to add any additional materials or components except the plunger stopper 103 and the plunger rod 104.

By engaging, and thereby attaching, the plunger stopper 103 and the plunger rod 104 with each other by the engaging thread profiles 105b, 105a, the two parts may be displaceable together along the axis 1000 within said barrel 102. By displacing the plunger stopper 103 and the plunger rod 104 along the axis 1000 in a direction within the barrel 102 towards the distal end 110 with the attached needle 101, injection of the drug is achieved. When the plunger stopper 103 and the plunger rod 104 have been moved as far as possible towards the distal end 110 of the barrel 102, almost all drug contained within the syringe 100 have been released and injected to the user. Since the syringe 100 is constructed such that dead space is minimized, almost all of the valuable drug will be released. In one embodiment according to the teachings herein, the syringe 100 contains the drug.

The syringe 100 according to the teachings herein is manufactured in a similar way as a conventional syringe. The syringe 100 is manufactured by mechanically and hermetically fixing the needle 101 to the syringe as known in the art, by gluing the needle 101 around the rear end of the needle 101 and attaching it to the barrel 102. The drug is filled into the syringe with a pipe, wherein H e pipe starts at the bottom of the syringe 100 and extends upwardly in order to avoid air inclusions within the syringe 100. Only after the drug has been filled into the syringe 100, the plunger stopper 103 is disposed and put in to place within the barrel 102. Thereafter the plunger rod 104 may be integrated, by the engagement of the thread profiles 105a, 105b, with the plunger stopper 103. The plunger rod 104 and the plunger stopper 103 may have corresponding thread profiles 105a, 105b and the two thread profiles 105a, 105b may accordingly be engageable. The plunger rod 104 and the plunger stopper 103 may in another embodiment have thread profiles 105a, 105b that are different, as long as the two thread profiles 105a, 105b are engageable. In order for the thread profiles 105a, 105b to be engageable, some dimensions, angles and/or forms have to correspond to each other between the two thread profiles 105a, 105b.

It is of importance that the plunger stopper 103 does not move in an axial direction when the plunger rod 104 is integrated, through the thread profiles 105a, 105b, with the plunger stopper 103 by the rotational movement or force which is converted to the linear movement or force. By not moving the plunger stopper 103 avoidance of creating a positive or negative pressure within the section containing the drug is achieved. The plunger rod 104 may be symmetrically moved due to the pitch and the rotation speed of the rotational movement.

The engagement of the thread profiles 105b, 105a of the plunger stopper 103 and the plunger rod 104 is configured such that the axial separation force B between the plunger stopper 103 and the plunger rod 104 in a proximal direction being less than a liquid suction force A through the needle 101. Due to the current design and construction of existing prefilled syringes, reuse of them are possible. This, despite the fact that a higher negative pressure is created when the drug is received within the syringe, due to the smaller inner diameter and length of the needle. However, the proposed syringe 100 according to the teachings herein solves the problem with reusable syringes. The syringe 100 may still be manufactured at a cost similar to a conventional syringe.

As illustrated in Figures 2, the pitch p of the thread profiles 105a, 105b is 1.6 mm This distance is the same as for a conventional syringe 100, as illustrated in Figure 1. The pitch p may be varied, but in order for ihe syringe 100 to be manufactured by Ihe existing assembly process, which has to be given the same conditions, this distance is preferably maintained at 1.6 mm. With the same pitch p as conventional syringes, the rotational movement of the plunger rod 104 will be transformed with the same speed to a given linear position. The plunger stopper 103 will not be moved during the assembly process.

Another dimension of the thread profiles 105b, 105a that may affect the characteristics of the plunger stopper 103 and the plunger rod 104 may be an angle called the thread angle a. The thread angle a is the angle characteristic of the cross- sectional shape and is the angle between the threads. In a conventional syringe 100, the thread angle a of the thread profiles commonly is 30° as illustrated in Figure 1. An angle of 30 ° is common when the thread profile has a trapezoidal thread form In some embodiments according to the teachings herein, the thread angle a of the plunger rod 104 is preferably larger than 30°.

Another important dimension of the thread profiles 105a, 105b is a threaded drive angle γ. The threaded drive angle γ is the flank angle measured between a transverse plane C and the flank of the thread facing the distal end 110 of the barrel 102. In a symmetrical thread, where the flanks of the thread have the same inclination, the threaded drive angle γ is the thread angle a divided by two.

The threaded drive angle γ according to the teachings herein may be varied, but in a preferred embodiment the threaded drive angle γ is 15 °. A threaded drive angle γ of 15 ° is the same threaded drive angle γ as used in conventional syringes and is proven to be effective when the plunger stopper 103 and the plunger rod 104 are to be engaged with, and attached to, each other. The thread profiles 105a, 105b are then easily integrated with each other when the plunger rod 104 is to be inserted and fixed to the plunger stopper 103. Furthermore, a threaded drive angle γ of 15 "is also proven to be suitable when moving the two engaged part 103, 104 in the direction towards the distal end 110 with the needle 101 for inj ecting the drug into the user.

Another important dimension of the thread profiles 105a, 105b is an angle called the separation angle β. The separation angle β is the flank angle measured between a transverse plane C and the flank of the thread facing the head 107 of the plunger rod 104. In a symmetrical thread, the separation angle β is the same as the threaded drive angle γ and accordingly half the thread angle a.

In the embodiments when the thread angle a is larger than 30°, the separation angle β may be increased. Accordingly, the threaded drive angle γ may be maintained at 15 °, while the separation angle β is increased in order to increase the thread angle a. The separation angle β may accordingly be larger than the threaded drive angle γ, as also illustrated in Figures 2 and 3. In one embodiment, the separation angle β is 45 °± 25 ° and accordingly the separation angle β may be set to any angle within the interval from 20°to 70°.

By making the separation angle β larger than the threaded drive angle γ, and preferably larger than 15 ° it may be assured that the syringe 100 may only be used once. Because of the large negative pressure that is created when a viscous drug is drawn into a syringe 100, the construction of the thread profiles 105b, 105a of the plunger stopper 103 and the plunger rod 104 will make it impossible to use the syringe 100 again. It will not be possible to pull the plunger rod 104 backwards, in a direction away from the distal end 110 with the needle 101, in order to refill the syringe 100 with drugs again because the axial separation force B between the plunger stopper 103 and the plunger rod 104 in a proximal direction will be less than the liquid suction force A through the needle 101. The engagement of the thread profiles 105a, 105b is configured to not support a displacement in the axial direction away from the distal end of the barrel 102, and the plunger stopper 103 and the plunger rod 104 will be separated from each other. Accordingly, by increasing the separation angle β to be larger than in a conventional syringe, a prefilled syringe 100 which is not possible to reuse and which is manufactured at a similar cost as a conventional syringe is provided.

The threadform of the thread profiles 105a, 105b according to the teachings herein may differ between different embodiments. The cross-sectional shape of the threads of the plunger rod 104 and the plunger stopper 103 may be of any threadform, for example trapezoidal, square or triangular. The threadform may be symmetrical or unsymmetrical, i.e. with the same inclinations of the flanks or with different inclinations of the flanks.

In one embodiment, as illustrated in Figure 2, the threaded drive angle γ is 15 ° the thread angle a is larger than 30 "and the threadform of the plunger rod 104 is unsymmetrical. The thread profile 105a of the plunger rod 104 tightly follows the form of the engageable thread profile 105b of the plunger stopper 103. Advantages with this embodiment is that the construction is suitable for threading and suitable for moving in an axial direction towards a distal end 110 in order to inject a drug, while still making it impossible to refill the syringe 100 and to use it multiple times.

In another embodiment, as illustrated in Figure 3, the thread angle a and the threaded drive angle γ may be the same, or similar, as in the described embodiment with reference to Figure 2, while the threadform may be different. The thread profile 105a of the plunger rod 104 is engageable with the thread profile 105b of the plunger stopper 103, but the thread profile 105a does not follow the thread profile 105b as tightly as in the previous described embodiment. The pitch p of the plunger stopper 103 and the plunger rod 104 are the same, otherwise they would not be engageable, but the form of the tread profile 105b of the plunger stop 103 is not the same as the form of the thread profile 105a of the plunger rod 104. The upper flank of the plunger rod 104, i.e. the flank of the thread that faces the distal end 0 of the barrow 102, tightly follows the flank of the plunger stopper 103. The lower flank of the plunger rod 104 however does not tightly follow the flank of the plunger stopper 103. The lower flank of the plunger rod 104 may in these embodiments preferably have an inclination that differs from the inclination of the flank of the plunger stopper 103, but may in some embodiments, have the same inclination between the lower flank of the plunger rod 104 and the flank of the plunger stopper 103. The thread profiles 105a, 105b do not tightly follow each other because the crest width 108 of the plunger rod 104 thread is noticeably smaller than the root width 109 of the plunger stopper 103 thread. These embodiments also has the advantage that the construction of the thread profiles 105b, 105a of the plunger stopper 103 and the plunger rod 104 of the syringe 100 will prevent the syringe 1.00 to be reused.

The thread depths d of both the previously described embodiments, where the separation angle β is larger than the threaded drive angle γ, as illustrated in Figures 2 and 3, may be varied. In some preferred embodiments, the thread depth d may be 0.5 mm

The cross-sectional shape of the threads of the plunger rod 104 and the plunger stopper 103 may be of any form, for example trapezoidal as described above, square, triangular, or any other shape. In one embodiment, the form of the threads of the plunger rod 104 and the plunger stopper 103 may be spherical with rounded crests and roots, as illustrated in Figure 4. In one embodiment the thread form is hemispherical. The spherical thread profile may be optimized by adjusting the thread depth d and/or by press fit. Dependent on the proportion of the sphere that the thread comprises, the thread angle a, and accordingly the separation angle β and threaded drive angle γ, may be varied. However, a true hemispherical threadform will lack a thread angle, in a similar way as a square thread form. A hemispherical threadform of the thread profile 105b, 105a of the plunger stopper 103 and the plunger rod 104, may prevent the syringe 100 to be reused by its form. The hemispherical threadform will make it impossible to displace the plunger rod 104 and the plunger stopper 103 in an axial direction away from the distal end of the barrel in order to once again fill the syringe 100 with drugs.

The thread depth d of the hemispherical thread profile 105a, 105b may be varied. In one embodiment, the thread depth d may be 0.5 mm.

It is important that the plunger rod 104 is not slipping during the assembly process when the plunger rod 104 is threaded with the plunger stopper 103, especially when the plunger stopper 103 is made of an elastomer. The plunger stopper 103 may be made of any material having good sealing properties, preferable an elastomer. The elastomer may have a Young's modulus within the interval 25 MPa to 200 MP a. The plunger rod 104 may preferably be made of a stiffer material than the plunger stopper 103, with a higher Young's modulus. Compared to a more elastic material the stiffer material does not deform as much as the elastic material while being exposed to the same force. The plunger rod may be made of a thermoplastic polymer, preferably Polypropylene. The material may have a relatively high Young's modulus within the interval 900 MPa to 2000 MPa.

The advantage of the described embodiments is that the costs for the manufacturing methods used to produce the syringes according to the teachings herein will not be increased, while still assuring that the syringes are not possible to re-use.

Further, the invention has mainly been described with reference to a few embodiments. However, as is readily understood by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended claims.

In the claims, the term "comprises/comprising" does not exclude the presence of other elements or steps. Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly advantageously be combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. The terms "a", "an", "first", "second" etc do not preclude a plurality. Reference signs in the claims are provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.

Claims

1. A syringe (100) comprising a barrel (102) with a needle (101) arranged at a distal end (110) of the barrel (102), said barrel (102) being adapted to contain a drug, the barrel (102) having a tubular wall extending proximally from said distal end (110), whereby the barrel (102) extends along an axis (1000), the syringe (100) further comprising:

a plunger stopper (103) disposed within the barrel (102), said plunger stopper (103) being adapted to be in fluid-tight engagement with the tubular wall of the barrel (102), wherein said plunger stopper (103) having a thread profile (105b); and

a plunger rod (104) extending along the axis (1000), wherein said plunger rod (104) having a thread profile (105a) engaging with the thread profile (105b) of the plunger stopper (103);

whereby said engaged plunger stopper (103) and plunger rod (104) are being displaceable along the axis (1000) within said barrel (102), whereby said engagement of the thread profiles (105a, 105b) is configured such that the axial separation force (B) between the plunger stopper (103) and the plunger rod (104) in a proximal direction being less than a liquid suction force (A) through the needle (101).

2. The syringe (100) according to claim 1 , wherein the syringe (100) contains the drug.

3. The syringe (100) according to claim 1 or 2, wherein the pitch (p) of the thread profiles (105a, 105b) is 1,6 mm.

4. The syringe (100) according to any of claims 1 to 3, wherein the plunger stopper (103) is made of an elastomer having a Young's modulus within the interval 25 MPa to 200 MP a.

5. The syringe (100) according to any of the preceding claims, wherein the plunger rod (104) is made of a ihermoplastic polymer having a Young's modulus within the interval 900 MPa to 2000 MPa.

6. The syringe (100) according to any of the preceding claims, wherein a thread angle (a) of the thread profile (105a) for the plunger rod (104) is larger than 30°.

7. The syringe (100) according to any of the preceding claims, wherein a separation angle (β) of the thread profile (105a) for the plunger rod (104) is larger than a threaded drive angle (γ) of the thread profile (105a) for the plunger rod (104).

8. The syringe (100) according to claim 7, wherein the separation angle (β) is within the interval 45 "± 25 °.

9. The syringe (100) according to any of claims 5 to 8, wherein the threaded drive angle (γ) of the thread profile (105a) for the plunger rod (104) is 15 °.

10. The syringe (100) according to any of claims 5 to 9, wherein the separation angle (β) of the thread profile (105a) for the plunger rod (104) is different from the separation angle (β) of the thread profile (105b) for the plunger stopper (103).

11. The syringe (100) according to any of claims 5 to 10, wherein the depth (d) of the thread is 0.5 mm.

12. The syringe (100) according to any of claims 1 to 4, wherein the form of the thread is hemispherical.

13. The syringe (100) according to claim 12, wherein the depth (d) of the thread is 0.S mm.