SYRINGE

Abstract: A pre-filled disposable syringe comprises a cartridge (1) containing the injectable liquid, a plunger (2) adapted to be pushed into the cartridge by a plunger barrel (3), and a needle hub (4) fitted tightly over the head (11) of the cartridge. Finger grips (46) for manipulation of the syringe are fixed on and extend outwardly from the needle hub.

Description: Syringe The invention relates to syringes and m particular to pre-filled and disposable syringes. In a first known type of pre-filled disposable syringe, the container for the injectable liquid is formed with a needle glued into a narrow passage at one end of the container. The container is filled from its other end and then closed by a plunger There are several disadvantages to this type of syringe Firstly, the liquid is permanently m contact with that part of the needle which is inside the container and also with the glue. This can lead to contamination. Secondly, the container has to be filled under vacuum conditions so that the plunger can be inserted. Thirdly, the presence of the needle extending from the container makes filling of the container more awkward. Another known type of pre-filled and disposable syringe overcomes some of the above drawbacks by providing the miectable liquid m a standard cartridge having a head at one end closed by a crimped cap and a penetrable seal and having its other end closed by a plunger In this case, the cartridge is filled through the head end with the plunger m place and then closed by the crimped cap and seal . It is not necessary to carry out this operation under vacuum, nor is there any needle handling problem involved. The needle s held in a separate needle hub which is fitted in sterile conditions over the head end of a filled glass cartridge and located thereon m a first inoperative position in which the needle does not penetrate the seal. Prior to use it is necessary to push the needle hub further onto the cartridge to penetrate the seal. This operation is difficult due to the presence of the needle which makes the needle hub awkward to handle. To reduce the difficulty, the fit between the needle hub and the cartridge is made fairly loose. This, however, gives rise to the fact that the needle void between the needle hub and the cartridge will not remain sterile. Finger grips used in this known syringe are fitted onto the glass cartridge at its end opposite the head, that is, at the end through which the plunger is inserted. The finger grips are normally made of glass or of moulded plastics and are snap-fitted onto the end of the cartridge after it has been fitted. There remain several disadvantages of this known type of syringe . Since the finger grips are remote from the needle, control of the needle is poor. This also leads to the finger grips being very close to the handle end of the plunger barrel at the end of the injection operation. Again, control of the needle is compromised. Because the finger grips are snap-fitted onto the glass cartridge, there is always a risk that they will come off or break during an injection. Also, they form an additional component which requires an assembly operation to be fitted to the cartridge. The invention sets out to provide an improved syringe of the second type mentioned above. Accordingly, the present invention provides a syringe comprising a cartridge arranged to contain an injectable liquid, a needle hub which supports a needle, and a plunger barrel; and in which: the cartridge is closed at a first end by a plunger, and is closed at a second dispensing end by a penetrable seal; the needle hub has outwardly extending finger grips arranged to be gripped by the fingers of a user; and in which the plunger barrel is arranged to be connected to the plunger i-n order to dispense the liquid through the needle; characterised in that the needle hub is located over the dispensing end of the cartridge to define a sterile internal space within the needle hub adjacent the penetrable seal, the rear end of the needle extending into the sterile space; and the needle hub is movable relative to the cartridge between a first inoperative position and a second primed position whereby movement from the first position to the second position causes the rear end of the needle to penetrate the penetrable seal while maintaining a sterile condition within the sterile space. It will be appreciated that with this arrangement, the needle hub and cartridge may be fitted together in the first position under sterile conditions, so that they constitute a sterile sub-assembly. Location of the finger grips on the needle hub means that they are well spaced from the open end of the cartridge into which the plunger is pushed. This increases the spacing between the handle end of the plunger and the finger grips and this gives much better control, especially towards the later stages of the injection. Further, this location of the finger grips means that they are substantially nearer to the needle and this again improves control of the syringe during use. Location of the finger grips on the needle hub is also very helpful during movement of the hub from the inoperative transport position to the operative position in which the needle penetrates the seal . Because the user is able to place the plunger end of the cartridge against the root of his thumb and grasps the finger grips with his first and second fingers, he is able to apply a substantial controlled force without having to put any part of his hand close to the needle. As a result, it is possible to have a very tight fit between the needle hub and the cartridge to maintain sterility in the void or space defined by the needle hub and the end of the cartridge, into which the rear end of the needle protrudes. It will also be appreciated that since pressure is being applied between the finger grips and the end of the cartridge (rather than a member acting on the plunger) , the liquid in the cartridge is not subjected to any pressure when the needle penetrates the seal. Thus, even though there is a very tight fit between the hub and the cartridge to maintain sterility, there is no danger of liquid ejection on penetration of the seal. In an alternative embodiment, the syringe may be provided with a needle retraction mechanism. This would be arranged to withdraw the needle into the body of the syringe after injection had been completed. The system may operate by manual withdrawal of the needle or it may be spring loaded. The advantage of a retraction mechanism is that a used syringe can be made safe with minimal danger to the user. The invention may be carried into practice in various ways and some embodiments will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic longitudinal cross- section through a syringe according to the present invention; Figure 2 is a transverse cross-section through the plunger barrel of the syringe taken on the line A-A in Figure 1; Figure 3 is a longitudinal cross-section through a needle shroud; and Figure 4 is a longitudinal cross-section through an alternative form of needle hub. The assembled syringe shown in Figure 1 consists of a cylindrical cartridge 1 adapted to contain an injectable liquid, a plunger 2 fitted into and closing one end of the cartridge, a plunger barrel 3 fitted to the plunger, a needle hub 4 fitted over the dispensing end of the cartridge, and a needle shroud 5, which fits over the needle 6 when the syringe is not m use. The cartridge 1 is of conventional type and comprises a head 11 closed by a crimped cap 12 incorporating a penetrable seal 13, a neck 14 and a body portion 15 connected to the neck by a shoulder 16. The cartridge has an open end 17 which is closed by the plunger 2 The cartridge is filled with the plunger m place and is then closed by fitting on the cap 12. The plunger 2 has a screw threaded blind bore formed m it for connection to the plunger barrel 3. (In an alternative design (not shown) the plunger may simply have a barbed socket for connection to a suitable element on the barrel) The mam part of the barrel is of cruciform section and is formed by four radial vanes 22. The radial outer surfaces 23 of the vanes are curved to fit into and match the internal surface of the body portion 15 of the cartridge This prevents lateral play of the plunger barrel inside the cartridge At the end of the barrel remote from the plunger, a sealing ring 24 holding O-rmg seals 25 may be formed. This ring 24 is dimensioned to fit closely inside the body portion 15 A handle ring 26 is connected to the sealing ring 24 by a plurality of circumferentially spaced bars 30 As described below, the handle ring 26 can be snapped off the ring 24 by breaking the bars 30 The longer barrel is adapted for use as a needle shroud and is therefore formed centrally with an elongate bore 27. Rings 24 and 26 are formed with flared bell shaped entrances 28 and 29 leading to the bore 27. The needle hub 4 or activator is generally cup- shaped. At its closed end it carries a hollow needle 6 in a known manner. The front part 61 of the needle projects from a nib 62 on the hub while the rear part 63 is floated within the hub. The hub is mainly formed from a cylindrical nose 41 which is a tight fit over the head of the cartridge and a sleeve portion 42 which fits over the body portion 15 of the cartridge. The axial length of the sleeve portion 42 is substantially smaller than the axial length of the body portion 15 of the cartridge. It will generally be less than half the length and in the embodiment shown, it is about one third the length. Within the nose 41 are two spaced circular ribs 43,44. These ribs can selectively engage a circumferential groove 45 formed on the cap 12 as described below. A pair of outwardly extending finger grips 46 are fixed to the sleeve portion 42 of the needle hub 4. In the position shown in Figure 1, the grips 46 are located adjacent the shoulder 16 of the cartridge 1, towards the dispensing end of the cartridge. The grips 46 are thus well spaced from the handle ring 26 at the remote end of the plunger barrel 3. The needle shroud 5 fits over the needle and grips the rib 62 so that it is held in place. The fit may be sufficiently tight to form a hermetic seal. The shroud is formed with a bell shaped end 51 to assist in (re-) locating the shroud over the needle. Assembly and operation of the syringe is as follows. Firstly, and under conditions so as to render the filled and assembled syringe sterile, the needle hub 4 with the needle shroud attached, is fitted onto the dispensing end of a filled cartridge 1 to the point shown in Figure 1 where the rib 43 locates in the groove 45 on the cap 12. This is an inoperative position, and for transport the plunger barrel can be located over the needle instead of using the shroud 5. In another embodiment (not shown) the plunger barrel is formed to fit over both the needle 6 and the shroud 5. In order to move to the operative position, the user pushes the cartridge further into the needle hub 4 to the position in which rib 44 locates in the groove 45. The finger grips 46 are used to hold the needle hub 4 during this operation. The provision of the grips 46 on the needle hub 4 enables this operation to be relatively easily carried out even when the nose 41 is a very tight fit over the head of the cartridge; such a tight fit being advantageous since it helps maintain the sterility of the needle void 60. As the cartridge is moved into the operative position, the rear part 43 of the needle 6 penetrates the seal 13 and comes into contact with the injectable liquid in the cartridge. To use the syringe, the plunger barrel 3 is then fitted to the plunger 2 and lastly the needle shroud is removed. The user then places the handle ring 26 against the root of his thumb and holds the finger grips 46 with his first and second fingers. After use, the syringe can be made safe for disposal in several ways. If the plunger barrel has moved sufficiently for the ring 24 to enter the cartridge, the ring 26 can be snapped off to make removal of the plunger barrel from the cartridge for re-use, very difficult. Alternatively the plunger barrel, with the ring 26 attached or detached, can be unscrewed from the plunger 2 and used as a needle shroud. The flared entrances 28 and 29 assist in safely locating the plunger barrel over the needle. The shroud 5 can also, of course, be relocated over the needle . Figure 4 shows an alternative version of the needle shroud in which an ultra thin disc seal 7 is fitted adjacent rib 44 to maintain the sterility of the needle void. The seal 7 may be sealed in place ultrasonically or moulded with the hub. The seal is ruptured when the head of the cartridge is moved into the operative position. Alternatively, the rear part of the needle may be covered by a rupturable rubber sleeve in order to enhance the sterility. Although not shown, a needle retraction system may be incorporated into the design in order to retract the needle into the body of the syringe, for reasons of safety.

Claims: Claims : 1. A syringe comprising a cartridge (1) arranged to contain an injectable liquid, a needle hub (4) which supports a needle (6) , and a plunger barrel (3) ; and in which: the cartridge (1) is closed at a first end by a plunger (2) , and is closed at a second dispensing end by a penetrable seal (13) ; the needle hub (4) has outwardly extending finger grips (46) arranged to be gripped by the fingers of a user; and in which the plunger barrel (3) is arranged to be connected to the plunger (2) in order to dispense the liquid through the needle (6) ; characterised in that the needle hub (4) is located over the dispensing end of the cartridge (1) to define a sterile internal space (60) within the needle hub (4) adjacent the penetrable seal (13) , the rear end (63) of the needle (6) extending into the sterile space (60) ; and the needle hub (4) is movable relative to the cartridge (1) between a first inoperative position and a second primed position whereby movement from the first position to the second position causes the rear end (63) of the needle (6) to penetrate the penetrable seal (13) while maintaining a sterile condition within the sterile space (60) . 2. A syringe as claimed in Claim 1, characterised in that the penetrable seal (13) is held in position over the end of the cartridge by means of a crimped metal cap (12) . 3. A syringe as claimed in Claim 2, characterised in that the cap (12) and the needle hub (4) are formed with engagement features (43,44,45) which define the operative and primed positions. 4. A syringe as claimed in Claim 3 , characterised in that the engagement features comprise a groove (45) on the cap (12) and two ribs (43,44) on the inside surface of the needle hub (4) . 5. A syringe as claimed in any preceding Claim, characterised in that a needle shroud (5) is provided for fitting over the needle (6) and has a flared bell shaped end (51) for guiding the needle (6) into it. 6. A syringe as claimed in Claim 1 or Claim 2, wherein the needle hub (4) has a nose portion (41) dimensioned to engage over the head of the cartridge (1) and a sleeve portion (42) dimensioned to fit over the body of the cartridge (1) , the finger grips (46) being located on the sleeve portion (42) . 7. A syringe as claimed in Claim 6, characterised in that the axial length of the sleeve portion (42) is substantially smaller than that of the body portion of the cartridge (1) . 8. A syringe as claimed in any preceding Claim, characterised in that the plunger barrel (3) is adapted at one end to be screwed into the plunger (2) and has a handle (26) at its other end which can be snapped off. 9. A syringe as claimed in Claim 8, characterised in that the plunger barrel (3) is formed with an elongate blind bore (27) having a flared entrance such that the plunger barrel (3) can be used as a needle shroud. 10. A syringe as claimed in Claim 8 or Claim 9, characterised in that a main part of the plunger barrel (3) is of cruciform section and is formed on a plurality of radial vanes (27) having curved outer surfaces matched to the internal surface of the cartridge (1) . 11. A syringe as claimed in any preceding Claim, characterised by a mechanism arranged to retract the needle (6) into the cartridge (1) .

Inventors: KATZ RICHARD ANTHONY ERIC, KATZ, RICHARD, ANTHONY, ERIC
Applicants: EPSOM GLASS IND LTD, KATZ RICHARD ANTHONY ERIC, EPSOM GLASS INDUSTRIES LIMITED, KATZ, RICHARD, ANTHONY, ERIC
Application year: 1996
Main classification: A61M5
IPC codes: A61M5