Syringe plunger rod, syringe barrel, and syringe

Abstract

A syringe plunger rod (100) extending along a longitudinal central axis (A) is provided. The syringe plunger rod (100) comprises a distal sealing plug (102) for sealing engagement with a syringe barrel (200), and a proximal elongated shaft (103) comprising a proximal end (104) adapted to receive an applied force along the longitudinal axis (A). The sealing plug (102) is made of an elastic material and a sealing plug distal surface (105).

Description

[0001] SYRINGE PLUNGER ROD, SYRINGE BARREL, AND SYRINGE

[0002] TECHNICAL FIELD

[0003] The present invention relates to a syringe plunger rod, a syringe barrel, and a syringe comprising a syringe plunger rod and a syringe barrel.

[0004] BACKGROUND

[0005] Injections are among the most common health care procedures, with as much as 22 billion injections administered globally each year. During 2021, the Covid- 19 mass vaccination will require even further vast amounts of syringes to conduct the injections.

[0006] Syringes known in the art may be pre-filled syringes, delivered already holding a medicament / vaccine, or conventional syringes, which are empty and filled on site with the drug to be administered to the patient. Pre-filled syringes are made from either glass or polymeric materials. Glass syringes still dominate the market. One of the reasons may be that the manufacturing process for manufacturing polymer syringes can generate scratches in the barrel. The probability for such scratches in glass barrels is extremely low. The market for pre-filled syringes is also heavily regulated by for example FDA and EMA, which represent the world’s two largest markets for biological medicaments. FDA and EMA set strict guidelines for filling and dispensing pre-filled syringes to enforce risk reduction. Pre-filled syringe glass is also more validated / verified than prefilled syringe polymer, i.e. there is a major difference in regulatory history. Also, the industry of biological medicament is associated with a very complicated manufacturing process, which means that it will be of increasing importance to find an efficient way to administer these expensive medicaments, i.e. with minimized medicament waste. Additionally, biological medicaments are often very viscous, which may additionally increase the risk of not satisfactory emptying the syringe. Glass syringes are thus very popular and of great future importance, due to the inertness of glass towards the medicament kept in the barrel. However, the barrel top, connected to the needle, is difficult to shape such that the barrel snuggly fits with the plunger top. Due to this, glass barrels are associated with a relatively large amount of medicament “trapped” in the barrel even after the plunger top has been pushed into its distal end position. However, there are also tolerances in relation to the void created in the top of the glass syringe barrel, which means that there is no exact standardized shape of the barrel top.

[0007] Hence, there is a need for an improved syringe, which is inexpensive to manufacture and which decreases the residual volume of the medicament in the barrel after injection, and especially syringes with glass barrels. Specifically, there is a need for an improved syringe that can empty the syringe better regardless of the nonstandardized shape of the barrel top of such glass syringe barrels.

[0008] SUMMARY OF THE INVENTION

[0009] 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 a syringe plunger rod extending along a longitudinal central axis comprising: a distal sealing plug for sealing engagement with a syringe barrel; a proximal elongated shaft comprising a proximal end adapted to receive an applied force along the longitudinal axis; wherein the sealing plug is made of an elastic material and wherein a sealing plug distal surface is substantially conical and is provided with a concave cone segment extending around the periphery of the sealing plug. A syringe comprising such a syringe plunger rod is also provided.

[0010] Further advantages will be apparent from the detailed description as well as the appended dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] These and other aspects, features and advantages of which the invention is capable, will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which

[0012] Fig. 1 shows a longitudinal section of a syringe;

[0013] Fig. 2 shows details of the syringe according to one embodiment of the present invention;

[0014] Fig. 3a shows details and sections of use positions of the syringe according to one embodiment of the present invention;

[0015] Fig. 3b shows details of a sealing plug according to one embodiment of the present invention; and

[0016] Figs. 4a to 4c shows sections of use positions of the syringe according to one embodiment of the present invention.

[0017] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] 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 invention, 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.

[0019] Referring to Figure 1, a syringe plunger rod 100 is disclosed. The syringe plunger rod 100 extends along a longitudinal central axis A. The syringe plunger rod 100 comprises a distal plunger top 101. The distal plunger top 101 comprises a sealing plug 102. The sealing plug 102 seals against a syringe barrel 200, upon use, to form a syringe 300. Proximally of the sealing plug 102 an elongated shaft 103 is provided. At the proximal end of the elongated shaft 103 there is provided a push plate 104. The push plate 104 extends substantially transversally to the longitudinal axis A. The push plate 104 is adapted to receive an applied force along the axis A, upon use, such that the syringe plunger rod 100 is displaced in relation to the barrel 200. The geometry of the sealing plug 102 is adapted after the specific dimensions of specific manufacturers of barrels, such as glass barrels.

[0020] In accordance with Fig. 2, a glass syringe barrel 200 is disclosed. The syringe barrel 200 extends along a longitudinal axis A. The syringe barrel 200 comprises a barrel cylinder 201 defining a volume V adapted to contain a drug. The barrel cylinder 201 has a distal plunger socket wall 202 and a tubular wall 203, extending proximally from said distal plunger socket wall 202. A needle hub 204 extends distally from the barrel cylinder 201. A hollow needle 205 extends distally from the needle hub 204. The distal plunger socket wall 202 comprises a convex cone segment 207. The convex cone segment 207 is arranged at the periphery of the plunger socket wall 202. This convex cone segment 207 is obtained through the manufacturing process of attaching the hollow needle 205 to the glass barrel cylinder 201. The plunger socket wall 202 may also be described along a longitudinal section as communication from a longitudinal needle channel 206 widening into two arcs of a circle, which than transitions into the tubular form of the barrel cylinder. The needle hub 204 is provided with the longitudinal needle channel 206. The channel 206 is preferably flush with the distal plunger socket wall 202, such that the channel 206 extends proximally to the volume V, such that the channel 206 falls out in volume V.

[0021] The sealing plug 102 is made of an elastic material. At the distal end of the sealing plug 102 a sealing plug distal surface 105 is arranged. The sealing plug distal surface 105 is substantially conical and is provided with a concave cone segment 106 extending around the periphery of the sealing plug 102. The concave cone segment 106 is thus arranged at the periphery of the sealing plug 102. In this context the periphery is intended to mean the outer most 50% in the central lateral direction. According to one embodiment of the present invention the sealing plug distal surface 105 is concavely conical also centrally of the concave cone segment 106, but the sealing plug distal surface 105 may also be more straight conical centrally of the concave cone segment 106. The concave cone segment 106 is configured to match and fit the convex cone segment 207 of the plunger socket wall 202. At the distal end the sealing plug distal surface 105 is provided with a transversal top surface 107, i.e. the substantially conical shape of the sealing plug distal surface 105 is truncated. The concave cone segment 106 may be described along a longitudinal section as widening into two arcs of a circle from the transversal top surface 107.

[0022] As can be seen in Fig. 3a, the sealing plug 102 has an internal void 108. The internal void 109 of the embodiment shown in Fig. 3a has a distal pointed tip, i.e. the distal tip of the internal void is conical. The internal void 108 of the sealing plug 102 realizes that outer shape of the sealing plug may be deformed to adapt to different shapes of the distal plunger socket wall 202. The wall thickness of the sealing plug 102, i.e. the distance from the sealing plug distal surface 105 and the void 108 may be substantially even, such that also the void 108 is defined by an inner sealing plug surface 109 that describes a substantially conical shape. The conical shape of the inner sealing plug surface 109 may have a convex conical segment adjacent the concave cone segment 106 of the sealing plug distal surface 105.

[0023] At the sealing plug distal surface 105 flow channels 111 are arranged. The flow channels 111 may be grooves or spaces between ridges. The flow channels 111 extend axially from the top surface 107 to the proximal end of the concave cone segment 106. The flow channels 111 may have different cross sectional shapes. In one embodiment, as disclosed in Fig. 3a, the flow channels 111 have a cross sectional shape in form of semi-circular with a radius transmission. The flow channels 111 may also be generally U or V shaped. It is preferred to have the cross sectional shape semi-circular with radius transitions or U shaped, since the risk of trapping liquid in the grooves 111 then is lower and to facilitate the possibility to apply coatings, such as barriers for avoiding reaction between medicament and the sealing plug, on the sealing plug 102, such that the coatings are applied on the entire surface. Sharp angles make it more difficult for coatings to be uniformly applied. The number of flow channels may vary from 2 to 10, preferably 2 to 8, such as 4 to 8. The flow channels may be arranged with substantially even radial distance between the grooves. For example, if the number of flow channels is 4, then they are preferably arranged with 90 degrees in between two flow channels 111 in a cross sectional plane from the central axis. If the number of flow channels 111 is 8, then the flow channels 111 are preferably arranged with 45 degrees in between two flow channels 111 in a cross sectional plane from the central axis. The flow channels 111 are also shown with references to Figs 3b and 4a-c.

[0024] As shown in Fig. 3a, when the syringe plunger rod 100 is displaced in relation to the barrel 200, eventually the sealing plug distal surface 105 will abut the distal plunger socket wall 202 of the barrel 200. Upon displacement of the syringe plunger rod 100 in relation to the barrel 200, the sealing plug 102 slides against the tubular wall 203 of the barrel 200. The sealing plug distal surface 105 then interacts with the distal plunger socket wall 202, and adapts to the distal plunger socket wall 202 to expel also the medicament in the distal volume of the barrel 200. When the distal plunger socket wall 202 is more stretched than the sealing plug distal surface 105, the sealing plug distal surface 105 will start interaction with the distal plunger socket wall at a lateral end of the sealing plug distal surface 105, squeezing the liquid towards the flow channels 111 to be injected centrally. The spaces between the grooves 111 or the ridges are compressed as the sealing plug distal surface 105 is pushed against the distal plunger socket wall 202. As the sealing plug distal surface 105 is compressed the cross sectional area of the flow channels 111 is decreased, such that flow of medicament centrally and distally is achieved. In this way the last portion of the medicament to be injected, such as vaccine or viscous medicament is pushed centrally from the periphery into the needle channel. Due to the elasticity of the sealing plug 102, the sealing plug 102 will deform, in accordance with above, upon additional force in the distal direction, whereby the central distal end of the sealing plug will be displaced in relation to the barrel 200 to abut the distal plunger socket wall 202. In this way the liquid to be injected is pushed further centrally. The amount of trapped liquid in the interface of the sealing plug 102 and the plunger socket wall 202 may thus be decreased.

[0025] Centrally, i.e. underneath the hollow needle 205, the sealing plug distal surface 105 may be provided with the central top surface 107. The top surface 107 is thus placed proximally directly underneath the hollow needle 205. In this way, the sealing plug distal surface 105 is configured such that a minimal amount of fluid to be injected is trapped in the barrel 200, since the top surface 107 may be arranged flush to the proximal end of the hollow needle 205.

[0026] The barrel 200 has a volume V configured to contain a drug, a vaccine or any other type of pharmaceutical liquid or solution to be administered to a patient. The drug may be in liquid form to be injected into a patient or user.

[0027] The plunger rod 100 in Fig. 1 is disposed within the barrel 200. The plunger rod 100 extends along the tubular wall 203 and the axis A. The sealing plug 102 is adapted to be in fluid-tight engagement with the tubular wall 203 of the barrel 200. By being in fluid-tight engagement with the tubular wall 203 of the barrel 200, the drug or liquid contained within the barrel 200 is prevented from leaking out of the syringe 300 in any other direction than through the hollow needle 205.

[0028] Fig. 3b shows details of the sealing plug 102. As shown in the two upper details of the two sealing plugs 102, the sealing plug 102 may be provided with varying number of flow channels 111. The uppermost sealing plug 102 is provided with 4 flow channels (only 2 are visible in Fig. 3b), and the lowermost sealing plug 102 has 8 flow channels 111 (only 3 are visible in Fig. 3b). Fig. 3b also shows a transversal cross section of the sealing plug 102 having 4 flow channels 111. As indicated in the enlarged view of the detail, the flow channel 111 has a semi-circular cross section with radial transitions.

[0029] In Figs. 4a to 4c, the operation of the syringe 300, comprising the plunger rod 100 and the barrel 200 of Fig. 1 is shown. The syringe 300 shown in Figs 4a to 4c further comprises the features as the syringe shown in Fig. 3a. However, the internal void 108 of the embodiment shown in Figs. 4a to 4c has a distal tip being more blunt than in the embodiment shown in Fig. 3. 1.e. the distal tip of the internal void 108 in Figs 4a to 4c rather has the shape of a truncated cone. Figs. 4a to 4c show sections of use positions of the syringe 100.

[0030] In Fig. 4a the plunger rod 100 is pushed distally. The sealing plug 102 is displaced along the tubular wall 203 of the barrel 200. The sealing plug distal surface 105 has not yet abutted the plunger socket wall 202. In Fig. 4b the periphery of the sealing plug distal surface 105 abuts the most lateral part of the plunger socket wall. Hence, the fluid / medicament contained in volume V of the syringe 100 is forced centrally. In this way there is a full closure for the medicament, such as a viscous medicament, and the medicament is squeezed through the flow channels 211 to the needle channel 206.

[0031] In Fig. 4c the plunger rod 100 is advanced yet further distally in comparison with the position in Fig. 4b, and due to the elastic characteristics of the sealing plug 102, the sealing plug 102 is further deformed to adapt to the shape of the plunger socket wall 202. Hence, the fluid / medicament contained in volume V of the syringe 100 is forced centrally. In this position the central top surface 107 closes the channel 206, such that the entire volume V of the barrel 200 has been emptied.

[0032] The sealing plug 102 is made from a resilient, flexible material, preferably a polymeric material, selected from a thermoplastic elastomer, or a natural or synthetic rubber material. As the sealing plug 102 is advanced further distally, the larger portion of the sealing plug distal surface 105 comes into contact with the plunger socket wall 202.

[0033] 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.

[0034] 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

CLAIMS1. A syringe plunger rod (100) extending along a longitudinal central axis (A) comprising: a distal sealing plug (102) for sealing engagement with a syringe barrel (200); a proximal elongated shaft (103) comprising a proximal end (104) adapted to receive an applied force along the longitudinal axis (A); wherein the sealing plug (102) is made of an elastic material and wherein a sealing plug distal surface (105) is substantially conical and is provided with a concave cone segment (106) extending around the periphery of the sealing plug (102).

2. The syringe plunger rod (100) according to claim 1, wherein the concave cone segment (106) is arranged at the periphery of the sealing plug (102).

3. The syringe plunger rod (100) according to claim 2, wherein the concave cone segment (106) is arranged at the outer most 50% in the central lateral direction of the distal sealing plug (102).

4. The syringe plunger rod (100) according to any one of the preceding claims, wherein the sealing plug distal surface (105) is concavely conical also centrally of the concave cone segment (106).

5. The syringe plunger rod (100) according to any one of the preceding claims, wherein a transversal top surface (107) is arranged at the distal end the sealing plug distal surface (105).

6. The syringe plunger rod (100) according to any one of the preceding claims, wherein the sealing plug (102) comprises an internal void (108).

7. The syringe plunger rod (100) according to any one of the preceding claims, wherein the wall thickness of the sealing plug (102) is substantially even, such that alsothe void (108) is defined by an inner sealing plug surface (109) that describes a substantially conical shape.

8. The syringe plunger rod (100) according to claim 7, wherein the conical shape of the inner sealing plug surface (109) has a convex conical segment adjacent the concave cone segment (106) of the sealing plug distal surface (105).

9. The syringe plunger rod (100) according to any one of the preceding claims, wherein the sealing plug distal surface (105) comprises flow channels (111).

10. The syringe plunger rod (100) according to claim 9, wherein the flow channels (111) extend axially.

11. The syringe plunger rod (100) according to claim 9 or 10, wherein the flow channels (111) are cross sectionally circular with radial transitions.

12. The syringe plunger rod (100) according to claim 9, 10 or 11, wherein the number of flow channels (111) is from 2 to 10, preferably 2 to 8, such as 4 to 8.

13. A syringe comprising a syringe plunger rod (100) according to any one of claims 1 to 12, and syringe barrel (200).

14. The syringe according to claim 13, wherein the barrel (200) is made of glass.

15. The syringe according to claim 13 or 14, wherein the syringe barrel (200) extends along a longitudinal axis (A) and comprises a barrel cylinder (201) defining a volume (V) adapted to contain a drug, wherein the barrel cylinder (201) has a distal plunger socket wall (202) and a tubular wall (203), extending proximally from said distal plunger socket wall (202).

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