Device for fluid dispensing from a prefilled vessel

Abstract

A syringe comprising a barrel 3 and a two part plunger rod 2 5. The short first section of the plunger rod 5 is pushed by a second section 2 which is inserted into the back of the syringe to then engage with the first. This second section of the plunger rod also acts as the rigid needle shield (RNS) on a staked needle syringe to protect the needle. The plunger seal 4 of the first section of the plunger rod may have an integrated valve 7 (also Figure 6a / 6b) which opens when the contents of the syringe have been administered. This creates an air path from the needle all the way through the syringe to prevent the first section of the plunger from being removed by pressurising the syringe through the needle.

Description

The present disclosure relates to a device for a fluid dispensing vessel such as a medical pre-filled fixed needle syringe or cartridge for an autoinjector.. Background Pre-filled syringes are becoming more popular in their use as drug companies are moving towards combination devices i.e. devices for packaging a drug which can also deliver the drug. Moreover many of these pre-filled syringes used a fixed needle as this is convenient for self-administration at home as well as preventing the removal and re-use of the needle. In this case the combination device is a fixed needle syringe pre-filled with a liquid drug ready for delivery via injection, whether the type of injection is intravenous (IV), intramuscular (IM), intradermal (ID) or subcutaneous. These devices are often supplied to the end user by the healthcare community for selfadministration use at home. The length of the needle of these pre-filled syringes have will be determined by the intended type of injection the drug is formulated for. The integrated (fixed) needle is bonded into the nozzle of the syringe and cannot be removed. These types of syringes are also referred to as staked needle syringes and are seen in both polymer and glass syringes. As the needles are permanently attached, these pre-filled syringes are always fitted with a rigid needle shield (RNS) over the needle which remains in place until just before the injection of the drug. For safety reasons (potential for needle stick injury) the RNS is not replaced and the empty syringe and RNS are immediately discarded into a sharp's disposal box. As these syringes are prefilled with the liquid drug the syringe plunger will be protruding from the back of the syringe ready for the user to push the plunger in order to inject the drug. This protruding plunger therefore makes the prefilled syringe vulnerable to incidental plunging during packaging and transportation. In some instances, the device manufacturer provides some sort of lock to prevent incidental plunging of the prefilled syringe which therefore requires the end user to unlock the plunger before use. Another concern with these devices is that they are designed for single use only and should not be re-used. However, in some demographics such as low- and middle-income countries (LMICs), the practice of re-using syringes is known to be taking place and as such the World Health Organization (WHO) has determined that in order to reduce the risks associated with reuse, auto disable (AD) functionality is a critical feature and must be included in the design of immunization syringes. There is a current standard to which these syringes must perform (ISO 7886-3) which requires that the plunger cannot be removed via applying a pressure via the fixed needle. Some syringe designs employing an auto-disable function lock the plunger when the plunger rod reaches its final position i.e. in contact with the bottom of the syringe barrel. Therefore the ISO standard specifies an applied pressure of 300kPa which the locking mechanism must resist. Currently there is only one compact, prefilled, and autodisable (CPAD) device that is market-available and meets the needs of the WHO. This is the BD Uniject™ injection system. The present disclosure seeks to address both the incidental plunging of pre-filled syringes and also provide an auto disable (AD) function. These features are achieved with the same simple design which involves minor modification of the RNS and the plunger of the syringe and the use of a valve as the plunger seal (stopper). This valve has a patent granted to the current applicant under references US2017030592A1 and EP2596245B1. The design exploits the fact that the plunger of a prefilled syringe is only ever pushed and never pulled as is necessary with a standard disposable syringe when drawing up the drug. The valve also serves to open up a pathway from the fixed needle through to the rear of the syringe barrel once the plunger rod reaches its final position i.e. in contact with the bottom of the syringe barrel. This therefore prevents the application of a pressure through the fixed needle as in this final position the syringe barrel is not sealed and therefore cannot be pressurised in an attempt to eject the plunger. A syringe for an auto-injector (usually referred to as a cartridge) which is a device into which the syringe (or cartridge) is loaded for the device to undertake the plunging action is also an applicable application for the arrangement. For this application it may not be necessary to install the second part of the plunger rod (also acting as the RNS) depending on the design of the autoinjector. Summary of Invention 1. An arrangement wherein the first section of the plunger rod does not protrude from the back of the pre-filled syringe; and a rigid needle shield (RNS) used as a second section of the plunger rod for plunging the syringe (or cartridge); wherein the RNS is a slidable fit within the syringe barrel, and which has an annular feature at the lower end shaped to emulate the end of a standard syringe plunger rod. 2. An arrangement according to paragraph 1 where the plunger seal of the first section of the plunger rod has a conduit and a slidable valve which opens once the valve comes into contact with the end of the syringe barrel to provide a passageway between the needle and the rear of the syringe barrel. 3. An arrangement according to paragraph 1 &2 which uses a staked needle glass pre-filled syringe. 4. An arrangement according to paragraph 1 &2 which uses a staked needle polymer pre-filled syringe. 5. An arrangement according to paragraphs 1 to 4 which has a capacity between 1ml and 10ml. 6. An arrangement according to paragraphs 1 to 4 where the end of the first section of the plunger rod (opposite to the seal attachment end) is conical in geometry. 7. An arrangement according to paragraphs 1 to 6 where the second section of the plunger rod slidably engages with the syringe barrel to contact the first section of the plunger rod. 8. An arrangement according to paragraphs 1 to 7 wherein the pre-filled syringe contains two or more chambers created by the installation of one or more additional valves in the syringe barrel. 9. An arrangement according to paragraphs 1 to 8 wherein the second section of the plunger rod is easily removed after being used to dispense the contents of the syringe. 10. An arrangement according claims 1 to 9 wherein the end of the RNS has a feature which locates with the conical geometry of the end of the first section of the plunger rod. 11. An arrangement according to all previous claims wherein the syringe is used in an autoinjector. 12. A fluid dispensing device substantially described or as shown herein. 13. A rigid needle shield (RNS) which is used as the second section of the plunger rod. 14. A short first section of the plunger rod which is tubular and contains an airway and does not protrude from the syringe barrel. 15. A valve fixed to the tubular plunger rod which opens the airway in the tubular plunger rod once it contacts the end of the syringe barrel. Detailed Description Most prefilled syringes, aside from those containing flushes such as saline solution, are between 1ml and 3ml as typically the amount of liquid drug to be injected is 0.5ml to 3ml. Also, many prefilled syringes will have a permanently attached staked needle, whether glass or polymer and as such always have a shield over the staked needle. This type of protective syringe cap is referred to as a rigid needle shield (RNS). Although the diameter of the RNS can be varied the existing size and shape of a RNS for a 2.25ml staked needle prefilled syringe such as the 2.25ml Becton Dickenson Neopak glass syringe has a RNS with a diameter slightly less than the internal diameter of the syringe barrel which makes it suitable for inserting into the end of the syringe to act as the second section of the plunger rod. Although the RNS can be designed to be any length longer than the staked needle by keeping it the same length as it is currently will keep the overall length of the device to a minimum. The diameter of the RNS can always be configured to fit within the barrel of a syringe, the smallest diameter being around 4mm which is for a 1ml long syringe. The RNS in the arrangement presented here will form the second section of the plunger rod and the first section, attached to the plunger seal with a conduit and an integrated valve will not protrude from the barrel of the syringe. The operation of the fixed needle prefilled syringe is herein described with reference to the drawings. Figure 1 shows the device comprising a staked needle 1 permanently attached to a syringe barrel 3, the fixed needle shielded by a rigid needle shield (RNS) 2. Within the upper section of the syringe barrel 3 and sealed by the plunger seal 4 with integrated valve 7 is the prefilled liquid drug 6. Attached to the plunger seal 4 is the first section of the plunger rod 5. The first section of the plunger rod 5 has an open circular conduit 5a from where the plunger rod seal 4 attaches aligned with the conduit 4a in the plunger seal 4. The conduit 5a is connected to a second circular conduit 5b, where the two conduits 5a and 5b meet at right angles to each other. (See figure 5 which shows an exploded view of the first section of the plunger rod). The conical end 5c of the first section of the plunger rod 5 has a small annular clearance with the syringe barrel 3 in order to form part of the passageway such that the syringe barrel 3 is not airtight when the valve 7 is open. The small annular clearance although providing an air passage is small enough so as not to provide any opportunity to mechanically hook the first section of the plunger rod in attempt to remove it by an applied force. Additionally, the conical shape is functional in that it does not provide any opportunity for a small suction cup to be used to try and attach a device to mechanically remove the first section of the plunger rod 5 (with the plunger seal 4 and valve 7). This conical shape will also serve to thwart any attempt to drill into the back of the first section of the plunger rod 5 to make any other sort of attachment e.g. using a self-tapping screw. The user will remove the RNS 2 to expose the needle and place the RNS 2 into the end of the syringe barrel 3 to engage with the first plunger section 5- see figure 2. This will now allow for the prefilled liquid drug 6 to be injected via the staked needle 1 by pushing on the RNS 2, the first section of the plunger 5 and the RNS 2 acting together in the same manner as a more traditional syringe plunger rod. Once the liquid drug 6 has been fully dispensed (figure 3) the valve 7 will engage with the end of the syringe barrel 3 at the base of the syringe nozzle, the force being applied by the user to the first section of the syringe plunger (comprising parts 7, 4 and 5) via the RNS 2 will slidably move the valve 7 in the conduit 4a of plunger seal 4 to open a passageway from the fixed needle to the rear of the syringe barrel. Figures 6a and 6b show the valve in the closed and open positions respectively, one view in each figure being isometric, the other view being a sectional view of the assembly of the valve 7 slidably engaged with the conduit 4a of the plunger seal 4. The RNS 2 used as the second section of the plunger rod can be removed (figure 4). The RNS 2 and the complete syringe comprising the staked needle 1, the syringe barrel 3, the plunger seal 4, the valve 7 and the first section of the plunger rod 5 can now be disposed of. In an additional embodiment the device serves to provide an auto-disable function to a dual chamber syringe created by fitting an additional plunger seal 4 with a conduit and a valve 7 to create two chambers above the plunger rod 5 using the same plunger seal 4 with a conduit and a valve 7. Both valves 7 in this arrangement are in a position which seal the conduit in plunger seal 4. Figure 7a shows this arrangement where the plunger rod 5 is shorter than in a single chamber prefilled syringe to accommodate the second chamber prefilled with a second liquid 8. As in the previous example the steps are exactly the same in terms of how the user dispenses the prefilled contents of the syringe, the difference being that in this arrangement there are two prefilled liquids 6 and 8 in the front and rear chambers respectively which are sequentially dispensed. Figure 7b shows, as before, that The user will remove the RNS 2 to expose the needle and place the RNS 2 into the end of the syringe barrel 3 to engage with the first plunger section 5. This will now allow for the prefilled liquid drug 6 to be injected via the staked needle 1 by pushing on the RNS 2, the first section of the plunger 5 and the RNS 2 acting together in the same manner as a more traditional syringe plunger rod. Once the first liquid drug 6 has been fully dispensed (figure 7c) valve 7 of plunger seal 4 which is separating the two chambers the will engage with the end of the syringe barrel 3 at the base of the syringe nozzle, the force being applied by the user to the first section of the shorter syringe plunger (comprising parts 7,4 and 5) via the RNS 2 will slidably move the valve 7 in the conduit 4a of plunger seal 4 to open the conduit in this first valve arrangement (comprising parts 4 and 7). The user continues to push on the RNS 2 (the second section of the plunger rod) - see figure 7c to dispense the second liquid 8. After this second liquid 8 has been fully dispensed (figure 7d) the second valve 7 will engage with the plunger seal 4 of the first valve at end of the syringe barrel 3, the force being applied by the user to the first section of the syringe plunger (comprising parts 7, 4 and 5) via the RNS 2 will slidably move the valve 7 in the conduit 4a of plunger seal 4 to open a passageway from the fixed needle to the rear of the syringe barrel through both open valves 7. The RNS 2 used as the second section of the plunger rod can be removed (figure 7d). The RNS 2 and the complete syringe comprising the staked needle 1, the syringe barrel 3, the two plunger seals 4, and valves 7 and the first section of the plunger rod 5 can now be disposed of.

Claims

1. A fluid dispensing vessel, such as a fixed needle prefilled medical syringe where the plunger rod is in two parts.

2. A fluid dispensing vessel, such as a fixed needle prefilled medical syringe according to claim 1 where the first section of the plunger rod does not protrude from the syringe barrel.

3. A fluid dispensing vessel, such as a fixed needle prefilled medical syringe according to claims 1 &2 where the plunger seal of the first section of the plunger rod has a conduit and a slidable valve which opens once the valve comes into contact with the end of the syringe barrel to provide a passageway between the bore of the needle and the rear of the syringe barrel.

4. A fluid dispensing vessel, such as a fixed needle prefilled medical syringe according to claims 1 to 3 where the second section of the plunger rod is also the rigid needle shield (RNS) fitted to the prefilled syringe to shield the fixed needle.

5. A fluid dispensing vessel, such as a fixed needle prefilled medical syringe according to claims 1 to 4 where the second section of the plunger rod slidably engages with the syringe barrel and makes contact with the first section of the plunger rod.

6. A fluid dispensing vessel, such as a fixed needle prefilled medical syringe according to claims 1 to 5 which has an annular feature at the lower end of the RNS shaped to emulate the flange at the end of a standard syringe plunger rod.

7. A fluid dispensing vessel, such as a fixed needle prefilled medical syringe according to claims 1 to 6 which uses a fixed needle glass pre-filled syringe.

8. A fluid dispensing vessel, such as a fixed needle prefilled medical syringe according to claims 1 to 7 which uses a fixed needle polymer pre-filled syringe.

9. A fluid dispensing vessel, such as a fixed needle prefilled medical syringe according to claims 1 to 8 which has a capacity between 1ml and 10ml.

10. A fluid dispensing vessel, such as a fixed needle prefilled medical syringe according to claims 1 to 9 where the end of the first section of the plunger rod (opposite to the plunger seal attachment end) is conical.

11. A fluid dispensing vessel, such as a fixed needle prefilled medical syringe according to all previous claims wherein the second section of the plunger rod (also the RNS) is easily removed after being used to dispense the contents of the syringe.

12. A fluid dispensing device substantially described or as shown herein.

13. A rigid needle shield (RNS) substantially described or as shown herein.

14. A short first section of the plunger rod substantially described or as shown herein.

15. A valve fixed to the tubular plunger rod substantially described or as shown herein.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS:-Claims04 11 24a. A syringe with a barrel containing a plunger seal and first section of a plunger, and a needle shield which is removable and attachable to the first section in use to make a functional plunger.b. A syringe with a barrel, plunger and a plunger seal, the plunger seal comprising a conduit with a slidable valve which opens when the valve contacts the end of the syringe.

2. A syringe according to claim 1 where the first section of the plunger is tubular and has an air passage from the valve to the rear of the syringe barrel.

3. A syringe according to claim 1 &2 where the first section of the plunger does not protrude from the syringe barrel.

4. A syringe according to claims 1 to 3 where the syringe has a fixed needle and is prefilled with liquid medication.

5. A syringe according to claims 1 to 4 where the needle shield is rigid - a rigid needle shield (RNS) and fitted to the prefilled syringe to shield the fixed needle.

6. A syringe according to claims 1 to 5 where the RNS acts as a second section of the plunger rod and slidably engages with the syringe barrel to make contact with the first section of the plunger.

7. A syringe according to claims 1 to 6 which has an annular feature at the lower end of the RNS shaped to emulate the flange at the end of a standard syringe plunger.

8. A syringe according to claims 1 to 7 which uses a glass syringe barrel with a fixed needle.

9. A syringe according to claims 1 to 8 which uses a polymer syringe barrel with a fixed needle.

10. A syringe according to claims 1 to 9 which has a capacity between 1ml and 10ml.

11. A syringe according to claims 1 to 10 where the end of the first section of the plunger,opposite to the plunger seal attachment end, is conical.

12. A syringe according to all previous claims wherein the second section of the plunger, which is also the RNS, is removable after being used to dispense the contents of the syringe.

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