Reconstituting device for injectable medication

Abstract: A device (140) for placing a first and a second vessel (3,7) in liquid communication is provided, the device comprising: a hollow double-ended needle (10) having first and second needle ends; a support (141) for the needle; and a housing for the needle and the support, wherein the housing surrounds the support and the needle before, during and after use of the device so as to shield a user from injury by the needle ends, characterised in that an axially slidable bung (145, 146) is arranged in an open end of the housing to maintain the first needle end in a sterile environment.

Description: The present invention relates to a device for reconstituting a liquid for medical use, such as a parenteral or pharmaceutical liquid. It is common practice for people requiring frequent parenteral administration of drugs to be provided with home-use kits containing autoinjectors which may be used for the purposes of self-administration. Liquid formulations of drugs are however seldom stable over prolonged periods of time and it is common for the drug itself to be provided in a solid form eg. a lyophilised (i.e. freeze dried), dehydrated or crystalline form. Typically, a user might be provided with a two weeks' supply of a lyophilised drug in sealed vials together with a supply of cartridges containing diluent. However, one problem associated with conventional autoinjector devices is the lengthy procedure (in excess of 40 steps) needed to reconstitute the solid drug into a liquid formulation prior to administration. A known drug reconstitution device is illustrated in Figure 1 of the accompanying drawings. In normal use, a plunger pin 1 is screwed into a plunger 2 in a cartridge 3 which contains a diluent for the drug. The cartridge 3 is placed into a barrel 4 of a dismantled autoinjector and a collar 5 is screwed onto a thread 11 thereby holding the cartridge inside the barrel 4, with the plunger pin projecting outwardly of the barrel. A vial 7 containing a drug in solid form has a flip-off plastic seal 7b on a bung 7a. The seal 7b is removed and the exposed portion of the bung is sterilised with an alcohol swab. The drug vial 7 is slid into the end of an adapter 8. A needle 10 is screwed onto a thread 6a of the barrel 4 and an outer needle cover 12 and an inner needle cover 13 are removed. The adapter 8 is then screwed onto a thread 6 of the barrel 4, at which time the needle 10 penetrates the bung 7a of the drug vial 7. To effect reconstitution of the drug formulation, the complete assembly is held vertically with the needle pointing upwards and the plunger pin 1 is gently depressed thereby injecting the contents of the cartridge 3 into the vial 7. The whole assembly is inverted and typically left to stand for 5 minutes to ensure complete dissolution of the drug. After ensuring that the plunger pin 1 is fully depressed the complete assembly is held vertically with the needle pointing upwards and the plunger pin 1 is gently pulled out thus drawing the constituted drug formulation into the cartridge. The vial adapter 8 is then unscrewed from thread 6 and discarded along with the empty vial 7. With the needle pointing vertically upwards, the plunger pin 1 is gently depressed until a few droplets of liquid appear at the end of the needle to ensure that any air trapped within the cartridge is removed. The inner needle cover 13 and the outer needle cover 12 are replaced onto the needle prior to the needle 10 being unscrewed from thread 6a and discarded. The plunger pin 1 is unscrewed from the plunger 2 and the collar 5 from thread 11 and both may be discarded. The reconstitution process is now complete and the charged cartridge may be loaded into an autoinjector which may be re-assembled and primed ready for use. Added to the problem of the lengthy reconstitution procedure, it has also been observed with devices of this type that foaming may occur when the cartridge contents are introduced to the vial. This undesirable effect is limited to a certain degree provided that the user follows the recommended procedure and holds the assembly with the needle pointing upwards before gently depressing the plunger and injecting the liquid vertically upwards into the drug vial. However the lack of control which the user is generally able to exert over the transmission of the liquid diluent onto the drug means there is still a considerable risk of foaming and associated unwanted effects, especially if the diluent is injected into the vial too rapidly. It is difficult for the user to be able reliably to control the rate at which diluent passes into the vial to avoid foaming on each occasion that the device is used. A problem with the known system shown in Figure 1 is that the needle covers 12 and 13 have to be removed prior to penetration of the bung 7a of the drug vial 7 by the needle, so that the needle is exposed to a non-sterile environment. The potential for contamination is even worse if the sharp end of the needle is actually handled by a user. Viewed from a first aspect, the present invention provides a device for placing a first and a second vessel in liquid communication, the device comprising: a hollow double-ended needle having first and second needle ends; a support for the needle; and a housing for the needle and the support, wherein the housing surrounds the support and the needle before, during and after use of the device so as to shield a user from injury by the needle ends, characterised in that an axially slidable bung is arranged in an open end of the housing to maintain the first needle end in a sterile environment. Since the needle can be disposed of with the device whilst in a shielded condition, there is improved safety over the known system shown in Figure 1 in which the needle itself had to be screwed onto and unscrewed from the barrel 4. There is thus increased safety in that the discarded components cannot cause needle-stick injury, because the needle is enclosed within the housing. Preferably the housing is a cylinder having open ends. Preferably a second axially slidable bung is arranged in an opposite open end of the housing. Preferably beads are provided on the interior wall of the housing to locate the bung or bungs and to vent air when the bungs are slid axially. Preferably the needle support comprises a web extending substantially perpendicular to the walls of the housing to form upper and lower needle chambers in the housing. Preferably the web is formed with apertures which communicate the upper and lower needle chambers. The device of the invention may be used in a kit for reconstituting a liquid for medical use by bringing together a first liquid medium contained in a first vessel and a second medium contained in a second vessel, the kit comprising a pack for holding the first and second vessels, and a device in which the pack is removably insertable, the kit being operable to bring the first liquid medium and the second medium together. In a convenient form of construction of pack including a device according to the invention, the needle may be arranged in a tubular housing for receiving the first vessel at one end and the second vessel at the opposite end. The second vessel is preferably removably held by the pack. This enables more than one second vessel to be used with the first vessel, which is useful for example to produce different concentrations of drug in a diluent. It will be appreciated that the sterility of the first needle end can be maintained even if the second vessel is supplied separately of the pack for user assembly therewith. This may be advantageous in that the pack can be manufactured independently of the second vessel. In the device according to the invention the liquid transfer means is a double ended needle. Such an arrangement may be useful if the first vessel is a cartridge closed at one end by a penetratable seal. The arrangement may be such that the sterility of the second needle end is maintained at all times prior to penetration of the first vessel closure, as with the first mentioned needle end. This may be achieved by a protective member such as a sheath or a bung, even if the first vessel is supplied separately of the pack. The device according to the invention is most convenient for reconstituting solid drugs (e.g. lyophilised drugs in the form of powders or pastes and the like) into a liquid solution or suspension using appropriate solvents, diluents, carriers, etc. However, the device is equally useful for contacting a first liquid (or a first mixture of liquids) with a second liquid or suspension or a mixture of liquids and/or suspensions. Particular examples of drugs which may be provided in a lyophilised form include growth hormone, fertility drugs, antibiotics (eg. cephalosporins) and renitidine. Although the first and second vessels may take various forms, in one preferred form of the invention the device is suitable for use with a first vessel in the form of a cartridge with a movable plunger and a second vessel in the form of a vial. It is envisaged that the device according to the invention in its various aspects will be used by doctors, dentists and the like but particularly by home-users. Thus the device as hereinbefore defined may be used for reconstituting a pharmaceutical liquid formulation, preferably a parenteral liquid formulation comprising a drug and a diluent or carrier. Certain preferred embodiments of the invention will now be further described by way of example and with reference to Figures 2 to 13 of the accompanying drawings, in which: Figures 2a and 2b show a fully assembled reconstitution device according to one embodiment which does not fall within the scope of the invention; Figures 3a to 3d show a pack which does not fall within the scope of the invention in various stages of assembly; Figures 4a to 4e show the assembled pack loaded into a reconstitution device at various stages of the constitution process; Figure 5 shows an alternative form of a reconstitution device which does not fall within the scope of the invention for receiving a pack, in a neutral condition; Figure 6 shows the reconstitution device of Figure 5 in a condition primed for delivery; Figure 7 shows the reconstitution device of Figure 5 in a condition after liquid has been delivered from a first vessel to a second vessel; Figure 8 shows the reconstitution device of Figure 5 in a condition primed for delivery of the liquid back to the first vessel; Figure 9a to 9i show various stages of the liquid reconstitution procedure using the reconstitution device of Figure 5; Figure 10 shows a further alternative form of pack including a device according to the invention; Figure 11 shows a sectional view of part of the pack of Figure 10; Figure 12 shows a sectional view on the lines A-A of Figure 11; and Figure 13 shows a syringe formed using the cartridge shown in Figure 10. A unitary pack 70 which does not fall within the scope of the invention is shown in Figures 3b-3d. This pack comprises a first vessel, in the form of a diluent cartridge 3, and a sterile needle 10 carried by a needle hub 10a in a sleeve-shaped housing 17. The cartridge 3 has a plunger 21 at one end and a seal 23 at the other end, adjacent the needle. The end of the needle hub 10a nearest to the cartridge may conveniently be covered with any conventional seal 15, such as a paper seal, for example a Tyvek (registered trade mark) seal, to retain its sterility and its other end 16 may be protected by for example a rubber sheath (not shown) to retain sterility. A tamper evident cap 18 closes the end of the housing 17 adjacent the cartridge 3. At the other end of the housing there is disposed a second vessel, in the form of a vial 7 sealed by a bung 24, containing a drug in solid form. Figures 2a, 2b and 4a-4e show a reconstitution device 19 which does not fall within the scope of the invention into which the pack 70 is removably insertable. The device 19 has a housing 62 having a screw fitted lid 40 provided with a recess 41 in which the portion of the pack holding the vial 7 engages. Internally of the housing 62 there is provided control means comprising an operating member in the form of a plunger rod 50 and a tubular weight 20 arranged coaxially therewith. The plunger rod 50 has a threaded end for screwing into the plunger 21. An externally projecting member 60 projects from the tubular weight 20 through a slot 61 in the housing 62 of the device 19. In use, the operator removes a flip-off cover (not shown) from the top of a bung 24 of the drug vial 7 and the seal 30 from the end of pack housing 17 and, after ensuring the sterility of the bung 24 in the vial, clips the vial into the end of the pack 70. The tamper evident cap 18 is removed from the pack and the pack is inserted into the reconstitution device 19 shown in Figures 4a-4e. It is screwed into position, so that the plunger rod 50 screws into the plunger 21. In the arrangement illustrated in Figures 4a-4e, the reconstitution device is arranged to compress the pack, from its initial length to the length "L" shown in Figure 3d. This forces the end 16 of the needle through its rubber sheath and then through the bung 24 on the top of vial 7. The seal 23 of the cartridge is forced through the seal 15 of the needle hub and is then penetrated by the needle 10. The compression is achieved by the lid 40 as it is screwed into place. The situation after the needle 10 has penetrated through the bung 24 and the seal 23 is shown in Figure 4a (and Figure 2a). The further steps in the process will be described with reference to Figures 4b-4e. the reconstitution device 19 is inverted to adopt the position shown in Figure 4b and this causes the tubular weight 20 to move under the effect of gravity, depressing plunger 21 in the cartridge and thereby forcing diluent 22 into the vial 7. The device adopts the position shown in Figure 4c (and 2b). The weight 20 is arranged to cause the smooth, gentle movement of plunger 21. The weight therefore provides the drive of the control means. The drive is thus effected in a controlled manner, substantially automatically and independently of the user, who simply has to invert the device to initiate the process. The reconstitution device is left to stand for several minutes in the position shown in Figure 4c to ensure the complete dissolution of the drug and then inverted once more to the position shown in Figure 4d. This results in weight 20 again moving under the effect of gravity, withdrawing plunger 21 and thereby drawing the constituted drug back into the cartridge 22, as shown in Figure 4e. Disassembly of device 19 allows the pack 70 to be removed therefrom and the cartridge 22 from pack 70, leaving needle 10 and vial 7 in pack 70 for safe disposal. Cartridge 22 is then placed in the autoinjector which is re-assembled and primed for use. The device is also usefully provided with an externally viewable indicator for indicating the position of the weight so that the user is made aware of when to re-invert the device. This is provided by the member 60 projecting through the slot 61. Alternatively, a timing device such as an hour-glass may be incorporated which is independent of the movement of the control means. The embodiment described above has the advantage of allowing constitution in a significantly reduced number of steps to that possible with prior art devices. Thus the process of reconstitution in this embodiment is as follows: 1. Open the pack; 2. Remove the flip-off from the drug vial; 3. Insert the drug vial into the pack after ensuring the sterility of the seal on the vial; 4. Insert the pack into the device; 5. Invert the device and leave to stand; 6. Invert the device; 7. Remove the pack; and 8. Remove the cartridge from the pack and use as directed by the physician. It will be noted that the device is reusable and portable. Figure 5 shows an alternative form of a reconstitution device 19 which again does not fall within the scope of the invention, for receiving a pack 70, in a neutral condition and before a pack has been added. The principal difference between this device and the one shown in Figures 2a, 2b and 4a-4e is that the Figure 5 device is driven by a spring 80, rather than by a weight. This enables the overall device to be lighter and hence particularly convenient to use. The device 19 has a housing 62 having a lid 40 provided with an external thread 41a in which the portion of a pack holding a vial 7 is to engage (e.g. thread 131 shown in Figure 10). Internally of the housing 62 there is provided a plunger rod assembly including a plunger rod 50 secured by a screw fitting 81 to a plunger hub 82. An air flow path 83 passes through the plunger hub so as to vent a plunger chamber 84 to atmosphere. The air flow path 83 is provided with a pair of paper filters 85,86 which provide a resistance to air flow across the filters and also maintain the cleanliness of plunger chamber 84. The top end of the plunger rod 50 (as seen in Figure 5) passes through an opening 87 formed at the lower end of an inner guide tube 88, which is fixed to the external housing 62. The opening 87 is provided with a plunger rod seal 89. The top of the plunger rod is formed with a male thread 110. An outer guide tube 90 extends upwardly from and is fixed to the plunger hub 82 so as to be movable therewith. The outer guide tube 90 is arranged to be guided on inner guide tube 88. A shoulder 93 is provided at the top of outer guide tube 90 and extending upwardly of the shoulder 93 the plunger rod assembly has an indicator flag 96. A collar 91 is arranged outwardly of outer guide tube 90 so as to be axially movable relative thereto. The spring 80 engages a lower flange of the collar at its lower end and at its upper end it engages both the shoulder 93 of the plunger rod assembly and a shoulder 94 of an actuating assembly 95. The collar 91 is slidably supported on the actuating assembly 95 so as to be movable between a lower limit position as seen in Figures 5, 6 and 7 and an upper limit position as seen in Figure 8. The actuating assembly further comprises an inner portion 97 on which the shoulder 94 is formed and which is movable axially inside the housing 62, and an outer sleeve 98 axially movable with the inner portion but situated outwardly of the housing 62. A lower latch 100 and an upper latch 101 are disposed on the outer sleeve 98 of the actuating assembly. A leaf spring 102 is arranged to urge an upper end of the lower latch 100 and a lower end of the upper latch 101 radially inwardly. The lower latch 100 is arranged to rock about a horizontal axis on a pivot 103, whilst a corresponding pivot 104 is provided for the upper latch 101. Each latch is provided with a respective operating knob 105,106. Detents 120,121 are provided on the housing for engagement by the respective latches 100,101. Figures 9a-9i show various stages of the liquid reconstitution procedure using the reconstitution device of Figure 5. The procedure will now be described with reference to Figures 5-8 and 9a-9i. The device in its initial condition, without a pack, is shown in Figure 9a. The lid 40 is unscrewed, as shown in Figure 9b, and a pack is screwed into place, with a female thread 130 in a plunger 21 (see Figure 10) receiving the male thread 110 at the top of the plunger rod 50. The lid 40 is screwed onto the exposed end of the pack, to adopt the position shown in Figure 9c. The device is inverted to adopt the position shown in Figure 9d and operating knob 105 of latch 100 is depressed to cause disengagement of the latch from detent 120. This releases the actuating assembly so that it can be slid downwardly to the position shown in Figure 9e. The device is then in the condition primed for delivery shown in Figure 6, with latch 101 engaged on detent 121. It will be seen from Figure 6 that in this primed condition spring 80 is compressed. Since collar 91 is in its lower limit position it cannot move and thus as spring 80 expands it pushes the plunger rod assembly downwardly (upwardly as viewed in Figure 6) so as to push liquid from the cartridge 22 into the vial 7. The rate at which the plunger rod assembly moves is determined by the rate of air venting from plunger chamber 84 via the air flow path 83 provided with air filters 85,86. The smaller the pore size of these filters the slower the rate of movement of the plunger rod assembly and a typical target time for the total movement is about 2-3 minutes. As the plunger rod assembly moves downwardly the indicator flag 96 moves downwardly through a slot in the housing 62 so as to be visible through a transparent portion of the lid 40. Use of appropriate graphics on the indicator flag shows when liquid transfer from the cartridge to the vial is complete. This condition is shown in Figures 9f and 7. It will be seen that latch 101 engages detent 121. In the next step the reconstitution device is inverted to adopt the position shown in Figure 9g. The user depresses operating knob 106 to release latch 101 from detent 121 and slides the actuating assembly downwardly until latch 102 engages detent 120, as shown in Figures 9h and 8. Again this compresses spring 80 which then expands and pushes the plunger rod assembly downwardly, so that the reconstituted liquid is sucked from the vial back into the cartridge. When the indicator flag 96 disappears, liquid transfer back to the cartridge is complete, as shown in Figure 9i. The time taken for return liquid transfer is typically 1-3 minutes. The lid 40 is unscrewed from the device and the pack is unscrewed from the device. The cartridge, now containing the dissolved drug, is removed from the pack and the rest of the pack is discarded. The lid 40 may be screwed back onto the device ready for future use. A form of pack suitable for use in the device of Figure 5 is shown in Figure 10. The pack 70 holds a first vessel, in the form of a diluent cartridge 3, and a second vessel in the form of a drug vial 7. The cartridge 3 has a plunger 21 formed with a female screw thread 130 (for engagement with male screw thread 110 of plunger rod 50 shown in Figure 5). At the other end the cartridge 3 has a seal 23. The pack 70 has a sleeve shaped housing 17 formed at its end for receiving the drug vial 7 with a thread 131 suitable for engagement with thread 41a shown in Figure 5. Prior to installation of the vial 7, the end of the housing is sealed by a film or paper seal 30. At its other end the pack has a cap 18 which closes the end of the housing 17 adjacent the cartridge 3. When the pack is to be inserted in a device 19 the cap 18 is removed whereby the cartridge 3 protrudes from the housing 17. A needle assembly 140 according to the invention is located at a fixed position within housing 17. Referring to Figures 11 and 12, the needle assembly 140 comprises a needle hub which is generally "H" shaped in longitudinal cross-section, supporting a double-ended needled 10. A web 141 supports the needle 10 and is formed with apertures 142 which communicate upper and lower sterile needle chambers 143,144. The upper end of upper needle chamber 143 is closed by an axially slidable bung 145, whilst the lower end of lower needle chamber 144 is closed by an axially slidable bung 146. Beads 147 are provided on the inner wall of the needle hub serving both to locate the bungs 145,146 in the positions shown in Figure 11 and also to vent air from the needle chambers 143,144 when the bungs are pushed onto the needle 10. Figure 12 shows the condition of the pack when vial 7 has been pushed into housing 17 such that it pushes bung 145 downwardly to cause penetration by needle 10 of both the bung 145 and the bung 24 which forms the vial closure. It will be appreciated that during the penetration action the sharp end of needle 10 pierces through the two bungs sequentially and is thus maintained in sterile conditions at all times. Lower bung 146 is shown in Figure 10 prior to axial upward movement thereof. This will be effected by pushing of the cartridge 3 upwardly (after cap 18 has been removed) to cause the needle 10 to penetrate first through bung 146 and then through seal 23 of the cartridge. It will be appreciated that whilst the pack 70 shown in Figure 10 is suitable for use with a constitution device such as that shown in Figure 5, it may also be used to reconstitute a drug formulation without such a device. Thus a plunger rod 150 (see Figure 13) may be screwed into thread 130 of plunger 21 and then used manually to push plunger 21 into the cartridge 3. A patient may be supplied with the pack 70 with or without a cartridge 3 and vial 7 already in place. It will generally be preferred for the vial and the cartridge to be preassembled in the pack. The plunger rod 150 may be supplied ready assembled or separately so that the user has to screw it to the plunger 21. The drug vial 7 is first pushed inwardly onto the needle, followed by the cartridge. Plunger rod 150 is used manually to transfer the contents of the cartridge to the vial, the pack is inverted and the reconstituted drug is pulled back into the cartridge. The cartridge is removed from the pack and the pack is thrown away. A moulded housing 151 for the cartridge is shown in Figure 13. The cartridge 3 is clipped into the housing 151, where it is held by a lip 152. A standard injection needle 153 is attached to the end of the cartridge 3 and the drug is injected. The syringe and needle are then discarded. Alternatively, the cartridge could be inserted into an autoinjector.

Claims: A device (140) for placing a first and a second vessel (3,7) in liquid communication, the device comprising: a hollow double-ended needle (10) having first and second needle ends; a support (141) for the needle; and a housing for the needle and the support, wherein the housing surrounds the support and the needle before, during and after use of the device so as to shield a user from injury by the needle ends, characterised in that an axially slidable bung (145, 146) is arranged in an open end of the housing to maintain the first needle end in a sterile environment. A device as claimed in claim 1, wherein the housing is a cylinder having open ends. A device as claimed in claim 1 or 2, wherein a second axially slidable bung (145,146) is arranged in an opposite open end of the housing. A device as claimed in any preceding claim, wherein beads (147) are provided on the interior wall of the housing to locate the bung or bungs (145,146) and to vent air when the bungs are slid axially. A device as claimed in any preceding claim, wherein the needle support (141) comprises a web extending substantially perpendicular to the walls of the housing to form upper and lower needle chambers (143,144) in the housing. A device as claimed in claim 5, wherein the web is formed with apertures (142) which communicate the upper and lower needle chambers (143,144).

Inventors: CALVERT JOHN RICHARD, HOBBS MICHAEL ANTHONY, ROBINSON GRENVILLE ARTHUR, ROWLANDS MARTYN OMAR, CALVERT, JOHN RICHARD, HOBBS, MICHAEL ANTHONY, ROBINSON, GRENVILLE ARTHUR, ROWLANDS, MARTYN OMAR
Applicants: APPLIED RESEARCH SYSTEMS, APPLIED RESEARCH SYSTEMS ARS HOLDING N.V.
Application year: 1997
Main classification: A61J1
IPC codes: A61J1, A61J3, A61M5