Tail end cap for medical injection device
By designing an improved end cap including an elastomeric inner cap and a transparent rigid outer cap, the problem of twisting and compression of the end cap of the existing medical injection device during the twisting process is solved, sealing performance and removal ease, and lubricant contamination is avoided.
Patent Information
- Application Number
- CN202380066786.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-09-19
- Filing Date
- 2023-09-19
- Publication Date
- 2025-04-25
AI Technical Summary
The end cap of existing medical injection devices can easily cause the elastomer skirt to twist during the twisting process, resulting in poor sealing, increasing the risk of leakage and contamination of medical solutions. At the same time, a large pulling force is required when removing the end cap, which may lead to repeated strain and lubricant contamination.
An improved end cap is designed, including an inner cap made of elastomeric material and an outer cap made of transparent rigid plastic material. The skirt of the inner cap is aligned with the proximal edge of the outer cap, and the threaded portion of the outer cap engages with the threaded portion of the adapter, ensuring a tight connection between the end cap and the medical container and preventing the distribution of lubricant onto the rigid components.
By reducing the contact surface between the end cap and the medical container, the torsion and compression of the skirt during the twisting process is reduced, the sealing performance is improved, the pulling force required to remove the end cap is reduced, the risk of repetitive strain is reduced, and unnecessary distribution of lubricant is avoided.
Smart Images
Figure CN119894556A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a tip cap for a medical device, a tip cap assembly and a medical injection device comprising the tip cap assembly. Background Art
[0002] In the present text, with reference to an injection system intended to be used with the medical injection device, the distal end of the medical injection device must be understood as the end furthest from the user's hand, while the proximal end must be understood as the end closest to the user's hand. Thus, in the present text, the distal direction must be understood as referring to the injection direction of the injection system, while the proximal direction is the opposite direction, i.e. the direction towards the user's hand.
[0003] The medical injection device includes a container for safely storing a medical solution therein. Such a container typically includes an elongated hollow body and a distal end extending distally from the hollow body. The distal end of the container is provided with a fluid passage extending through the distal end to allow the medical solution in the container to be administered to the patient as required. In order to connect to a needle or a needle-free access device, the distal end may be provided with an adapter including an internal thread that allows a threaded connection.
[0004] Before use, the medical injection device can be pre-filled with a medical solution and equipped with an end cap for closing the channel, thereby ensuring the tightness of the medical container at its distal end, thereby avoiding leakage and / or contamination of the medical solution. To this end, a screw-on end cap can be mounted on an adapter at the distal end of the medical container.
[0005] Such screw-on tip caps generally comprise an inner cap having a skirt made of an elastomeric material to ensure a tight connection between the tip cap and the medical container once the tip cap is fastened onto the tip of the medical container. Figure 1 Such a tip cap is shown, comprising a rigid outer cap 200 and an elastomeric inner cap 100 comprising a skirt 110. The skirt 110 of the inner cap 100 is configured to enclose the tip of the medical device and protrudes proximally from the proximal end of the outer cap.
[0006] However, when sealing a medical device, the rotational motion during the screwing process often causes the elastomeric skirt 110 to twist, such as Figure 2 As shown by the arrow on the left in FIG. Therefore, the skirt 110 is twisted when the outer cap 200 is screwed onto the adapter during the sealing step, and after the end cap is screwed onto the end of the medical container, the skirt 110 can be rotated back in the opposite direction. Therefore, the screwing may be partially reversed, resulting in a leaky connection, and may cause contamination and / or loss of the medical solution.
[0007] In other cases, the skirt may be compressed during installation of the end cap, e.g. Figure 2 As shown by the arrow on the right. After the installation process, the skirt stretches in the proximal direction along the tip of the medical device to relax the constraint and / or torsion inside it. In other cases, due to the friction coefficient and contact surface between the glass tip of the syringe and the rubber inner cap, a sticking effect may occur, requiring a large pulling force to remove the tip cap before using the medical injection device. Therefore, it is difficult for users to remove the tip cap, especially for users who may have reduced strength in their fingers due to their medical conditions. For medical professionals, repeatedly performing the same posture that requires a large force on the tip cap may cause repetitive strain injuries.
[0008] Furthermore, the elastomeric skirt is often treated with a lubricant to facilitate the installation process. However, during storage of multiple end caps in a bag, the lubricant may contaminate the surface of the rigid part of the end cap, in particular the threads of the end cap to be screwed onto the adapter mounted on the medical container. This can lead to lubricant contamination of the threads of the adapter, which may mean a poor connection between the connector and the adapter when another needle or connector is screwed onto the adapter after the end cap has been removed. In fact, since the lubricant has been deposited on the threads, the end user may want to screw the connector more firmly, thereby accidentally damaging the connector or the adapter.
[0009] Therefore, there is a need for an improved tip cap that allows it to be tightly and securely screwed onto a medical container, that allows for easy removal of the tip cap prior to use, and that avoids unwanted distribution of lubricant. Summary of the invention
[0010] An object of the present disclosure is to provide an improved end cap for sealing an injection device, which has reduced adhesion and twisting characteristics to ensure a reliable connection between the end cap and the injection device.
[0011] To this end, the present disclosure is directed to a tip cap for closing a fluid passage extending through a distal tip of a medical container, the medical container comprising an adapter mounted on the distal tip and having a threaded interior portion, the tip cap comprising:
[0012] • an inner cap sealingly engageable with the tip, the inner cap being made of an elastomeric material and comprising a skirt extending in a proximal direction, the inner surface of the skirt being configured to sealingly engage the outer surface of the medical container tip along a contact surface,
[0013] • a rigid outer cap securely disposed about the inner cap, the outer cap comprising a threaded outer portion adapted to engage with a threaded inner portion of the adapter,
[0014] Therein, the proximal edge of the skirt of the inner cap is aligned with the proximal edge of the outer cap.
[0015] Furthermore, the provided end caps prevent the lubricant from being distributed on the rigid components during storage.
[0016] Advantageously, the alignment of the proximal end of the skirt of the inner cap and the proximal end of the outer cap has a mechanical tolerance equal to or less than + / - 0.3 mm.
[0017] Preferably, the proximal edge of the skirt of the inner cap and the proximal end of the rigid outer cap lie in the same plane perpendicular to the distal end.
[0018] The inner cap may be made of a thermoplastic elastomer or rubber.
[0019] The rigid outer cap may be made of a transparent rigid plastic material.
[0020] The transparent outer cap allows the user to inspect the cap to detect leaks.
[0021] Preferably, the rigid outer end cap is made of a rigid polymer selected from the list comprising polypropylene, polyethylene, polyvinyl chloride, polystyrene, polycarbonate, acrylonitrile butadiene styrene or styrene acrylonitrile.
[0022] Advantageously, the inner cap is assembled on the inner surface of the outer cap by friction engagement and / or clamping.
[0023] A second aspect of the present invention relates to an end cap assembly, comprising an end cap as described above, and an adapter adapted to engage with a distal end of a medical container such that the adapter concentrically surrounds the end of the medical container, the adapter comprising a threaded inner portion adapted to engage with a threaded outer portion of an outer cap.
[0024] A third aspect of the present invention relates to a medical injection system, the medical injection system comprising:
[0025] • a medical container comprising: a longitudinal barrel; a distal end extending distally from the barrel, the distal end being provided with a fluid passage extending therethrough; and an adapter having a threaded interior portion extending around the distal end, and
[0026] • End caps as above,
[0027] Therein, a threaded outer portion of the outer cap engages with a threaded inner portion of the adapter, and a skirt of the inner cap sealingly engages with the tip. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Other features and advantages will become apparent from the following detailed description based on the accompanying drawings, in which:
[0029] Figure 1Schematic diagram of a traditional end cap.
[0030] Figure 2 The forces acting on the skirt of the inner cap in a conventional tip cap are schematically shown.
[0031] Figure 3 is a schematic diagram of an end cap according to one embodiment of the present disclosure.
[0032] Figure 4 is a side view of a syringe with a tip cap assembly according to the present invention.
[0033] Figure 5 yes Figure 2 Schematic diagram of the elastomeric inner cap of the end cap shown in .
[0034] Figure 6 yes Figure 4 Magnified view of the end cap.
[0035] Figure 7 is a probability plot of pull-out force for a conventional end cap and an end cap according to one embodiment. DETAILED DESCRIPTION
[0036] Figure 3 An end cap 1 according to the invention is shown.
[0037] The tip cap 1 can be mounted on a medical injection device 40 (eg, a syringe), such as Figure 4 shown.
[0038] The medical injection device 40 comprises a container including an elongated hollow body 42 pre-filled with a medical solution. A distal end 41 extending from the hollow body 42 is provided with a fluid passage, thereby allowing the medical solution to flow through the distal end 41 for administration to a patient.
[0039] Typically, the medical container 40 comprises an adapter 30 mounted on the distal end of the syringe, at least partially surrounding the syringe's tip 41. Such an adapter 30 comprises an internal threaded portion 31 which may also allow the connection of a device for administering the medical solution to the patient's body, such as an injection needle, a device for performing intravenous infusion, or a needle-free injection device.
[0040] During storage of the injection device 40, after the container has been filled with a medical solution, the tip cap 1 is screwed onto the adapter 30. The tip cap seals the tip of the medical container to prevent leakage and contamination of the medical solution.
[0041] The medical injection device may further include a plunger rod 44 including a stopper 43 inserted into the open proximal end of the hollow body 42 and in fluid-tight engagement with the cylindrical wall of the hollow body 42. After the end cap 1 is removed, the distal sliding movement of the plunger rod 44 pushes the medical solution out of the hollow body 42 through the fluid channel in the end 41 of the medical injection device 40.
[0042] If you can Figure 3 As seen in FIG. 1 , the end cap 1 includes an outer cap 20 and an inner cap 10 .
[0043] The outer cap 20 is made of a transparent rigid material, preferably a rigid polymer. The outer cap can be manufactured by a molding process, such as by injection molding. The polymer can be selected from polypropylene, polyethylene, polyvinyl chloride, polystyrene, polycarbonate, acrylonitrile butadiene styrene, styrene acrylonitrile or similar polymers, or a combination thereof. The transparent material allows the correct assembly of the outer cap and the inner cap and the assembly of the end cap on the adapter of the medical container to be verified. In addition, when the end cap is installed on the medical container filled with the medical solution, the transparent outer cap allows the user to check the cap and check whether leakage occurs and whether the medical solution has penetrated into the space between the inner cap and the outer cap. Most preferably, the outer cap is made of polypropylene because it is a plastic material that is easy to mold, firm and lightweight. Polypropylene also has the advantages of being highly liquid-impermeable and inert to many chemicals, which prevents the outer cap from degrading when contacting the medical solution.
[0044] The outer cap 20 comprises an outer threaded surface 21 at its proximal end, which is adapted to be screwed to the inner thread 31 of the adapter 30 of the medical container 40 .
[0045] Furthermore, the outer cap 20 may include a rim 26 which provides a limit stop by contact between the rim 26 and the adapter 30 , or by contact between the inner cap 10 and the distal end of the medical container 40 , when the tip cap 1 is screwed onto the adapter 30 .
[0046] The outer cap 20 may also include a distal grip portion 25, which includes ribs, grooves, indentations or any other structure to allow the user to firmly grip the tip cap 1 when fastening the tip cap 1 to the syringe adapter 30, thereby preventing the tip cap from slipping in the user's hand. The grip portion 26 may also prevent the tip cap from rolling away when placed on a smooth surface, making it easier for the user to operate.
[0047] The outer cap 20 provides a rigid outer wall for the end cap 1 to protect the elastomeric skirt of the inner cap 10 from mechanical forces caused by the external environment, thereby preventing the inner cap from being deformed by compression or extrusion.
[0048] The outer cap 20 may include an opening on its distal end, which may be of any size less than or equal to the diameter of the outer cap 20. Such an opening does not affect the function of the outer cap, while simplifying the assembly of the outer cap 20 with the inner cap 10, because it avoids air compression between the inner cap and the outer cap, which would create resistance to the insertion of the inner cap 10 into the outer cap 20.
[0049] Figure 5 An inner cap 10 is depicted. The inner cap 10 is made of an elastomeric material, such as a rubber formulation such as a bromobutyl or chlorobutyl elastomer, or any other rubber formulation, or a thermoplastic elastomer that provides elasticity suitable for sealing the end of a medical container. A person skilled in the art will select a rubber formulation that is inert to the medical solution to be filled into the medical container, has sufficient heat resistance to withstand the necessary sterilization procedures, and has appropriate gripping and release characteristics so that the inner cap is slid onto the end of the medical container and released after use. The inner cap 10 can be manufactured by a molding process such as injection molding.
[0050] The inner cap 10 comprises a proximal skirt 11 having a hollow cylindrical shape. The inner wall of the hollow cylinder is straight, while the outer wall of the hollow cylinder is slightly tapered. The inner cap also comprises a distal solid sealing base 12, which may have a central protrusion 13 surrounded by the skirt 11, thereby forming an inner cavity having a circular shape, which is suitable for engaging with the distal edge of the end of the medical container. The central protrusion 13 may penetrate into the distal end of the end 41 of the medical container 40.
[0051] The diameter of the skirt 11 is selected so that the skirt stretches slightly radially when mounted on the end of the medical container. In this way, the inner wall of the skirt tightly wraps around the outer surface of the end 41 of the medical container 40. The tight cylindrical geometry and elastomeric material enable the inner cap to provide a liquid-tight seal to the end of the medical container, thereby avoiding any loss and / or contamination of the medical solution.
[0052] The inner cap 10 is usually fixed to the inner wall of the outer cap 20 by a clamping mechanism or any other connection based on the frictional engagement of the inner cap 10 and the outer cap 20. Both the inner cap and the outer cap may include ribs 28, grooves 18, or bumps suitable for providing such a connection of the inner cap and the outer cap. Alternatively, the inner cap may be bonded to the outer cap, for example by a suitable glue.
[0053] The inner cap 10 is in close contact with the outer cap 20 in the distal portion of the end cap. At the proximal end of the end cap, there is a radial gap 50 between the inner cap 10 and the outer cap 20. The radial gap allows the elastic inner cap to deform to adapt to the shape of the end of the medical device during assembly.
[0054] When the outer cap 20 and the inner cap 10 are assembled together, Figure 6As shown, the skirt 11 of the inner cap 10 is aligned in the proximal direction with the rigid outer cap 20. Alignment should be understood as that the proximal edge of the skirt of the inner cap and the proximal edge of the outer cap are located in the same plane perpendicular to the end of the medical device. The end cap brim contact surface engages with the end of the medical device.
[0055] The length of the outer cap has a mechanical tolerance of 0.1 mm and the length of the skirt of the inner cap has a mechanical tolerance of 0.2 mm. These tolerances are usually due to manufacturing reasons. Therefore, for alignment, a total mechanical tolerance of + / - 0.3 mm is acceptable. Therefore, the edge of the skirt of the inner cap and the end of the outer cap are aligned in the proximal direction after assembly by + / - 0.3 mm.
[0056] For example, in a 7025 type end cap, the total length of the skirt is 5.82 mm. A tolerance of + / - 0.3 mm results in a length variation of 5.2%. In an FM30 type end cap, the length of the entire cap is 5.77 mm. The length variation caused by a tolerance of + / - 0.3 mm is 5.2% of the total length of the end cap.
[0057] In a preferred embodiment, the proximal end of the outer cap is flush with the inner cap, ie, the proximal end of the outer cap and the proximal end of the skirt of the inner cap are located in exactly the same plane perpendicular to the distal end of the medical device.
[0058] When the end cap 1 is fixed to the prefilled medical container 40, the outer cap 20 is screwed into the inner thread 31 of the adapter 30 mounted on the distal end of the medical container 40 using the outer thread surface 21. This step is usually completed by a screw tightening machine. As a result, the inner cap 10 is pushed in the proximal direction, and the skirt 10 slides along the outer surface of the end 41 and tightly surrounds the end 41. When the end cap 1 is installed, the sealing base 12 seals the fluid channel on the end 41 of the medical container, and the central protrusion 13 is inserted into the end 41 of the medical container. The skirt 11 tightly surrounds the end 41 to provide a seal for the medical solution contained in the medical container 40.
[0059] During the screwing process, since the length of the skirt 11 of the inner cap 10 is relatively short, the skirt 11 of the inner cap 10 still maintains its original shape except for slight radial stretching. The skirt is neither squeezed nor twisted. Therefore, the skirt 11 immediately reaches its final shape and position at the end of the screwing, thereby tightly surrounding the end of the medical container. The end cap remains in place after being screwed on the syringe and does not move or relax to any different position after being fixed on the medical container.
[0060] Pull-out performance
[0061] The contact surface of the tip cap according to the present invention with the tip of the medical container is smaller than the contact surface of a conventional tip cap in which the skirt of the inner cap extends beyond the rigid outer cap. Preferably, the extension Lc of the contact surface in the proximal direction is equal to or smaller than the length Lc of the distal tip. T Two thirds of the length L of the distal end, more preferably equal to or less than the length L of the distal end T The length of the distal end is L T corresponds to the distance between the distal outer wall of the syringe barrel and the distal end of the tip, such as Figure 6 shown.
[0062] This results in a reduction in the pull-out force when removing the tip cap from the medical container.
[0063] The reduction in contact surface results in reduced friction between the tip cap and the tip of the medical container and thereby reduces the pull-out force that needs to be applied to remove the tip cap. The reduced pull-out force makes it easier for users to access the medical solution, especially for users with less strength in their fingers or medical professionals who repeatedly perform the same gesture.
[0064] The reduced pull-out force and ease of removal prevents accidental damage to the tip itself, or breaking the tip off the medical container, since the user needs to apply less force and less effort. In addition, when less effort is applied, the risk of the user accidentally twisting and bending the tip cap when removing it is reduced. This prevents the syringe tip from breaking, which would otherwise render the syringe and the medical solution contained therein ineffective.
[0065] A series of sample end caps from different syringe types have been tested for pull-off force. Figure 7 The distribution of the pull-out force (in N) of two batches of end caps, a batch of conventional end caps (represented by circles), and a batch of end caps according to the present invention (represented by squares) is shown. The pull-out force of the conventional end caps ranges from 1.6 N to 5.2 N, while the pull-out force of the end caps according to the present invention ranges from 0.8 N to 4.1 N. As can be seen from the probability plot, the pull-out force of the end caps according to the present invention is significantly lower.
[0066] In particular, the reduction in surface does not affect the integrity performance while providing reduced pull-out forces, the tightness of the connection being at the same level as that of conventional end caps.
[0067] Since sterilization and aging generally affect the pull-off force required to remove a tip cap, the pull-off performance of the tip caps according to the present invention was tested after a sterilization procedure and after applying an accelerated aging protocol.
[0068] Leak test
[0069] Several batches of end caps according to the invention have been tested for their sealing properties.
[0070] The first leak test procedure is a combined closure leak and pressure leak test, allowing the risk of loss of medical solutions contained in medical containers to be assessed. Therefore, a set of medical containers have been sterilized and filled with test solutions. A closure leak test was performed, applying a pressure of 1.1 bar for 5 seconds and measuring the leakage rate of the test solution. All samples met the specification requiring a leakage rate of less than 44Pa / sec.
[0071] After the closure leak test, a visual leak test was also performed. The medical container was then stoppered with a syringe stopper, leaving a 3mm to 4mm bubble, which is common in medical containers with stoppers. A pressure leak test was then implemented, during which pressure was applied to the piston of the syringe stopper and the leakage of the test liquid through the end of the medical container was observed with the applied mechanical pressure. The results were calibrated by subtracting the sliding force of the stopper measured separately on an empty injection device. All recorded pressure leak values were within the specification range of 1.1 bar.
[0072] The second leak test procedure is the dye immersion test, which allows testing the penetration of substances applied from the outside into the syringe and assessing the risk of contamination of the medical solution contained therein. For this type of test, a second set of medical containers are sterilized and plugged with syringe stoppers in an empty state. The stoppers are positioned in a position corresponding to the filling position of 1 ml of medical solution in the medical container. Subsequently, the end cap is mounted on the medical container. During the test, the end with the end cap mounted is immersed in a liquid dye, usually methylene blue dye. As a result, the medical container is not completely immersed. A vacuum of -350mbar is applied for 16 hours. The penetration of dye into the medical cylinder indicates the presence of a leak and there is a potential risk of contamination from the outside of the end cap. No leaks were found in all test samples.
[0073] Distribution of lubricants
[0074] The end caps for medical injection devices are usually treated with lubricants during or after manufacture and assembly. This lubricant is usually applied to the elastomeric inner cap to facilitate the end cap to slide on the end of the medical container. During storage, multiple end caps are usually stored in clean and dust-proof bags, such as sealed plastic bags. Since the elastomeric inner cap is completely surrounded by the outer cap, the lubricant usually remains in place and will not scratch the threaded portion of the outer cap, nor will it scratch the threaded portion of the adapter. Therefore, since there is no lubricant on the threaded portion of the adapter, after removing the cap, the needle or any other connector screwed on the adapter will be tightly fixed without the risk of loosening the threaded connection. This also prevents the user from being prompted to use more force to screw the connector, thereby reducing the risk of accidentally breaking the adapter or the needle or connector screwed on the medical container.
Claims
1. An end cap (1) for closing a fluid passage extending through a distal end of a medical container, the medical container comprising an adapter mounted on the distal end and having a threaded inner portion, the end cap (1) comprising: • an inner cap (10) capable of sealingly engaging the distal end, the inner cap (10) being made of an elastomeric material and comprising a skirt (11) extending in a proximal direction, the inner surface of the skirt (11) being configured to sealingly engage the outer surface of the distal end of the medical container along a contact surface, • a rigid outer cap (20) securely arranged around the inner cap, the outer cap comprising a threaded outer portion (21) adapted to engage with a threaded inner portion of the adapter, Wherein, the proximal edge of the skirt of the inner cap (10) is aligned with the proximal edge of the outer cap (20).
2. The end cap (1) according to claim 1, wherein: The alignment of the proximal end of the skirt (11) of the inner cap with the proximal end of the outer cap (20) has a mechanical tolerance equal to or less than + / - 0.3 mm.
3. The end cap (1) according to claim 1, wherein: The proximal edge of the skirt (11) of the inner cap (10) and the proximal end of the rigid outer cap (20) are located in the same plane perpendicular to the distal end.
4. The end cap (1) according to any one of the preceding claims, wherein: The inner cap (10) is made of thermoplastic elastomer or rubber.
5. The end cap (1) according to any one of the preceding claims, wherein: The rigid outer cap (20) is made of a transparent rigid plastic material.
6. The end cap (1) according to any one of the preceding claims, wherein: The rigid outer cap (20) is made of a rigid polymer selected from the following list: polypropylene, polyethylene, polyvinyl chloride, polystyrene, polycarbonate, acrylonitrile butadiene styrene or styrene acrylonitrile.
7. The end cap (1) according to any one of the preceding claims, wherein: The inner cap (10) is assembled on the inner surface of the outer cap (20) by friction engagement and / or clamping.
8. An end cap assembly, comprising an end cap (1) according to any one of the preceding claims and an adapter, the adapter being adapted to engage with the distal end of a medical container so that the adapter concentrically surrounds the end of the medical container, the adapter comprising a threaded inner portion adapted to engage with the threaded outer portion (21) of the outer cap (20).
9. A medical injection system, comprising: - a medical container comprising: a longitudinal barrel; a distal end extending distally from the barrel, the distal end being provided with a fluid passage extending through the distal end; and an adapter having a threaded inner portion extending around the distal end, and - an end cap (1) according to any one of claims 1 to 8, The threaded outer portion (21) of the outer cap (20) is engaged with the threaded inner portion of the adapter, and the skirt of the inner cap (10) is sealingly engaged with the end.