the objective of the present invention is to achieve a simple method and arrangements for aseptic filling of an injection syringe , with no need for special fume cupboards or sterile rooms , and to eliminate the need for special sterile air containers . according to a first aspect of the invention , this objective is achieved with a method of the kind set forth in the preamble of claim 1 , employing the special measures set forth in the characterising part of the claim . since air can be sucked in directly from the atmosphere and passes an air filter arranged in connection to the injection syringe &# 39 ; s container , the filter removes bacteria and other contaminants from the admitted air . neither a sterile environment nor any special sterile air container is therefore necessary . thus , the invention method makes it possible to fill an injection syringe just about anywhere and at very low cost . the method can be used with a very simple , standard syringe . according to one preferred embodiment , a special filter unit can be arranged at the connection nozzle . the method can therefore be used with existing , standard syringes . according to an alternative embodiment , the method can be used with an injection syringe which is already equipped with a connection nozzle fitted with an air filter . this would eliminate the need for additional accessories . the communication between filter and container is suitably interrupted after the injection syringe has been charged with air , thereby facilitating subsequent stages in the process . this accordingly constitutes an additional , preferred embodiment of the invention method . in a preferred embodiment , the interruption is accomplished by detaching the filter . this allows the use of a very simple filter . in an alternative preferred embodiment , the interruption is accomplished by closing the communication between the container and the air filter and opening a communication between the container and a nozzle outlet . this simplifies the operation , since the filter need not to be detached before connecting the syringe to the vessel . according to an additional preferred embodiment of the invented method , an airtight connection is established between the connection nozzle and a vessel containing the injection agent . air in the injection syringe &# 39 ; s injection agent container is then forced into the vessel , and injection agent flows from the vessel into the injection agent container . this represents a particularly useful application of the invention method . according to one preferred embodiment , this connection is achieved with a separate coupling means . the use of such a coupling means reduces the risk of exposing preparation staff to injection agent leaking into atmosphere . this could be a serious problem in the preparation of cytostatics , i . e . drugs known to present an occupational hazard when released into atmosphere . antiviral agents , antibiotics and radioactive drugs are other items capable of causing problems in the occupational environment . according to another preferred embodiment of the invented method , a cannula on the coupling means is made to penetrate a membrane on the coupling means and a membrane on the vessel . this method establishes an airtight connection between the injection agent container and the vessel in a simple and reliable manner . according to another preferred embodiment of the invented method , the vessel is made to undergo a change in volume after connection to the injection syringe . this thereby equalises pressure in the vessel when air is introduced into it and / or injection agent is withdrawn from it . this facilitates these steps in the preparation process . according to another preferred embodiment of the invented method , a separate coupling means is attached to the connection nozzle such that during charging the container with air , air passes through the air filter into the coupling means and from the coupling means through the connection nozzle into the container , whereafter the coupling means is connected to a vessel containing the injection agent . this eliminates the need to exchange the unit that is attached to the connection nozzle and thereby further decreases the risk for contamination . the aforementioned embodiments of the invented method are set forth in the dependent claims of claim 1 . according to a second aspect of the invention , the objective is achieved when an injection syringe of the kind set forth in the preamble to claim 12 displays the features cited in the characterising part of this claim . since the injection syringe is accordingly provided with an air filter arranged at its connection nozzle , a means is obtained whereby the invention method can be implemented in an expedient manner . no other component , apart from the injection syringe itself , is required to fill the syringe with aseptic air . the invention injection syringe conveys advantages of the same kind as the invention method , and air - filling can therefore be carried out with no need for a fume cupboard , sterile room or special clean air containers . the invented syringe also has a very simple design , thereby reducing e . g . the risk of erroneous handling . according to a preferred embodiment of the syringe , the connection nozzle includes a valve , operable between a first position , in which communication is established between the container and the air filter , and a second position , in which said communication is closed , while communication between the container and a nozzle outlet is established . this embodiment allows connecting the syringe to a vessel without detaching the filter . this preferred embodiment is set forth in the dependent claim of claim 12 . according to a third aspect of the invention , the objective is achieved when a filter unit of the kind set forth in the preamble to claim 14 has the special features cited in the characterising part of this claim . since an air filter is equipped with a connection device for connection to the connection nozzle on an injection syringe , the invention method can be used with a syringe which does not have any such filter . according to a preferred embodiment , the filter unit &# 39 ; s connection device consists of the female part of a luer connector or luer - lok connector . since the injection syringe &# 39 ; s connection nozzle is usually devised with a corresponding male part , the filter can also be used with most syringes on the market . according to another preferred embodiment of the invented filter unit , the housing is provided with a valve , a first opening in the connection device , a second opening provided with the air filter and a third opening , the valve being operable between a first position , in which communication is established between the first and second openings , and a second position , in which said communication is closed and communication is established between the first and third openings . a filter unit according to this embodiment does not need to be detached before connecting the syringe to a vessel , which simplifies the operation . the preferred embodiment of the invented filter unit cited above is set forth in the dependent claims of claim 14 . according to a fourth aspect of the invention , the objective is achieved when a system of the kind set forth in the preamble to claim 17 has the special features cited in the characterising part of this claim . thus , the system primarily comprises an injection syringe and a filter unit with an air filter . since the filter unit has a coupling means , making it possible to establish an airtight connection to the injection syringe &# 39 ; s connection nozzle , components intended for direct connection with one another in performing the invention method in a simple and reliable fashion , become available . when these components are supplied as a complete system , the air filter and injection syringe are certain to fit together . according to a preferred embodiment of the system , the system also comprises a coupling means as a separate unit with which an airtight connection can be established with the injection syringe &# 39 ; s connection nozzle . this coupling means makes it possible to perform the invention method in a manner reducing the risk of leakage of injection agent into atmosphere . advantages of the kind corresponding to those cited above for the preferred embodiments of the invention method are thereby achieved . one such system could alternately comprise an injection syringe incorporating an integrated filter instead of a separate syringe and filter . according to an additional preferred embodiment of the invented system , the system also includes a coupling means , attachable to the invention syringe with an airtight connection . this results in a complete system with components which fit each other and which ensure the provision of both aseptic air and risk - free handling of injection agent . according to another preferred embodiment of the invented system , the injection agent vessel is provided with a pressure - equalisation device which facilitates the expelling of air and aspiration of injection agent . according to another preferred embodiment of the invented system , the injection agent vessel is equipped with a first membrane , coupling means with a second membrane and a cannula , the cannula being arranged to penetrate both membranes when the injection means vessel is connected to the coupling means . this version is a simple , safe and practical arrangement for ensuring that the air is not contaminated by atmosphere and that injection agent does not leak into atmosphere . according to another preferred embodiment of the invented system , the coupling means comprises a connection arrangement capable of airtight connection to the separate filter unit . this allows the air to be aspirated to the container without exchanging the unit that is attached to the connection nozzle and thereby further decreases the risk for contamination . the coupling means and the injection agent vessel connectable to same , as cited in the preceding embodiments , are components which are in themselves prior art . they are described in e . g . the aforementioned pct / se99 / 02144 . however , the advantages achieved with this application &# 39 ; s system for achieving aseptic air are particularly valuable when the system is employed in a system which also comprises the cited components , as a holistic solution , providing maximal safety in different respects in all the steps in the preparation process , is thereby achieved the aforementioned preferred embodiments of the invented system are set forth in the dependent claims of claim 17 . the invention will be explained in greater detail below in descriptions of the preferred embodiments and referring to attached drawings . [ 0042 ] fig1 is a lateral view of a system comprising an injection syringe and a filter unit according to a first embodiment of the invention ; [ 0043 ] fig1 a is a lateral view of a filter unit according to an alternative example ; [ 0044 ] fig2 is an enlarged section of the system in fig1 with the components interconnected ; [ 0045 ] fig3 is a lateral view of an injection syringe according to an alternative embodiment of the invention ; [ 0046 ] fig4 is a lateral view of a system according to a second embodiment of the invention , the said system comprising additional components ; [ 0047 ] fig5 is a cut - away view of a first component in the system in fig4 ; [ 0048 ] fig6 is a cut - away view of a detail in a second component in the system in fig5 ; [ 0049 ] fig7 - 13 illustrate different stages in use of the system shown in fig4 : [ 0050 ] fig1 is a cut - away view of a component shown in fig1 ; [ 0051 ] fig1 is a lateral view of a further embodiment of the invention ; [ 0052 ] fig1 is a lateral view of yet a further embodiment of the invention . [ 0053 ] fig1 shows a conventional injection syringe 1 with a piston rod 11 , piston 12 and injection agent container 13 and a connection nozzle 14 . a filter unit 2 , consisting of a housing 21 , a connection arrangement 22 and an air filter 23 , are also shown . the air filter 23 is suitably a hepa filter so even very tiny particles are filtered out in it . the injection syringe &# 39 ; s 1 connection nozzle 14 is devised as a luer connector and is therefore slightly tapered . in the corresponding manner , the filter unit &# 39 ; s 2 connection arrangement 22 is provided with an internally tapered channel and constitutes the female part of a luer connector . the filter unit 2 can thereby be connected to the injection syringe &# 39 ; s connection nozzle 14 . [ 0055 ] fig2 shows an enlarged view of the filter unit 22 connected to the injection syringe &# 39 ; s 1 connection nozzle 14 . [ 0056 ] fig1 a shows another example of the filer unit 2 a . the filter unit 2 a has a connection device 22 a for connection to the nozzle 14 of the syringe 1 shown in fig1 . the connection device 22 a has an opening 72 and is similar to that of the filter unit 2 shown in fig1 and 2 . the filter unit has also a connection arrangement 71 with an opening 74 provided for a connection to an injection agent vessel 4 of the type shown in fig4 . the filter unit also has a branch connection 75 to an air filter 23 a in a housing 21 a provided with an opening 73 . a valve 70 is provided in the filter unit 2 a . the valve 70 , in a first position , establishes communication between openings 72 and 73 , whereas the opening 74 is cut off from communication with the other openings . in a second position , the valve 70 establishes communication between the openings 72 and 74 , whereas the opening 73 is cut off from communication with the other openings . when using the filter unit according to fig1 a , the unit can be maintained connected to the syringe , when it is connected to the injection agent vessel 4 for performing the operation illustrated in fig7 - 13 . when an injection solution is prepared , the injection syringe is first charged with air . the piston 12 is then pressed to the bottom of the injection agent container 13 and then retracted . as it moves upward , air is drawn into the injection agent container 13 , filling this container with air when piston travel is completed . during air intake , the filter unit 2 is attached to the syringe &# 39 ; s connection nozzle 14 as shown in fig2 . admitted air is then forced through the air filter 23 in the filter unit 2 , causing the injection agent container 13 to fill with aseptic air . once the syringe &# 39 ; s injection agent container 13 is charged with air , the syringe is ready for filling with an injection agent . the filter unit 2 is then removed , and the syringe &# 39 ; s connection nozzle 14 is connected to a vessel containing the injection agent to be administered . aseptic air is forced into the vessel , whereupon injection agent is drawn into the syringe &# 39 ; s injection agent container . this is conventional procedure and does not require any detailed explanation . [ 0060 ] fig3 illustrates a second embodiment of an injection syringe 101 . in this embodiment , the syringe has a special design in which a filter 102 is pre - mounted on the syringe &# 39 ; s connection nozzle 114 . the same procedure as is described for fig1 is used for drawing in air . the syringe 101 shown in fig3 can alternatively have a nozzle provided with a filter of a construction corresponding to that of the filter unit shown in fig1 a . the components illustrated in fig1 and 2 , i . e . an injection syringe 1 and a filter unit 2 , can advantageously constitute a system of components provided in a single context . fig4 illustrates an embodiment in which the system comprises a coupling means 3 and an injection agent vessel 4 , in addition to the components shown in fig1 and 2 . the coupling means 3 is shown in greater detail in fig5 which is a cutaway view . the coupling means consists of a first part 31 , arranged for connection to the syringe 1 , and a second part 32 , arranged for connection to the injection agent vessel 4 . the second part 32 can be telescoped into the first part 31 . in the position shown in fig5 this is prevented by a detent 39 which slips into an opening in the first part 31 , thereby preventing the second part from rising . this locked position can be released with a handle 35 connected to the detent 39 and attached to the upper end of the first part 31 . the handle is pulled outward with a finger against the resilient force of its own resistance to bending . the first part 31 is equipped with the female part 37 of a luer connector with which the first part is connected to the injection syringe &# 39 ; s 1 connection nozzle 14 . the latter is guided into place by metal tongues 38 arranged next to the luer connector 37 . a cannula 33 , shown in the fig . with its tip pointing down , is arranged in the coupling means 3 . at the bottom of the fig ., the coupling means 3 is sealed with a membrane 34 and provided with flanges 36 for bayonet connection to the injection agent vessel 4 . in the depicted position , the cannula 33 is protected inside the coupling means 3 . pressing the first section 31 and the second section 32 of the coupling means 3 together forces the cannula 33 downward to penetrate the membrane 34 . the injection agent vessel shown in fig4 consists of a bottle 41 with a capping means 42 providing airtight sealing of the bottle . the capping means 42 has a collar 47 provided with slits 46 arranged to interact with the connection flanges 36 on the coupling means 3 . the capping means 42 is additionally provided with a pressure - equalisation chamber 43 whose volume can vary because one wall consists of an elastic film 44 . the capping means 42 also has a membrane 45 located inside the collar 47 . the capping means 42 is shown in greater detail in a cut - away view in fig6 . it is equipped with a lid section 48 . a channel 49 , extending to the membrane 45 and covered by it , passes through the lid section . the bottle ( not shown in fig6 ) is connected to the pressure equalisation chamber 43 , via a filter 52 , by means of an air channel 50 and a connecting channel 51 . changes in pressure are accommodated by the bulging or depression of the film 44 . the way in which the components cited in fig4 - 6 interact and the procedure for their handling will henceforth be described with reference to fig7 - 13 . the syringe is ready to be charged with injection agent from a vessel 4 once the injection syringe 1 is charged with aseptic air , as described in conjunction with fig1 - 3 , and the coupling means 3 has been attached to the injection syringe &# 39 ; s 1 connection nozzle 14 , as illustrated in fig4 . the lower end of the capping means 3 is then connected to the vessel &# 39 ; s capping means 42 by means of the luer connector &# 39 ; s bayonet mount 36 , 46 . [ 0069 ] fig8 illustrates the next step . the detent 39 is released from the locking position when the control handle 35 is moved outwards . both parts of the coupling means 31 , 32 are then pressed together as described for fig5 the position shown in fig8 then being assumed . the cannula 33 of the coupling means 3 then penetrates the membranes 34 , 35 on the coupling means 3 and vessel &# 39 ; s coupling means 42 respectively , thereby opening a connection between the injection syringe &# 39 ; s container 13 and the bottle 41 . in the next step , shown in fig9 the injection syringe &# 39 ; s 12 piston is depressed , leading to the expulsion of air from the container 13 through the coupling unit 3 and cannula 33 into the bottle 41 containing the injection agent . the rise in pressure is accommodated by the channel connection 50 , 51 and the pressure equalisation chamber 43 , described for fig6 the positive pressure causing the film 44 to bulge . the entire system is then turned upside down , as shown in fig1 , and injection agent is drawn into the injection syringe &# 39 ; s 1 container 13 when the piston 12 is retracted . the system is then returned to its original position . the parts 31 , 32 of the coupling means are separated , as shown in fig1 , and the detent 39 returns to the locked position . [ 0072 ] fig1 shows the way in which the injection agent vessel 4 is subsequently detached from the coupling means 3 by rotating the bayonet mount 36 , 46 . the injection syringe 1 has now been charged with injection agent and is ready for use . in those instances in which injection agent is to be administered to a patient through an injection line connected to the patient , the system also comprises an adapter unit 6 which is attached to the coupling unit 3 with a bayonet mount , as shown in fig1 . the adapter unit 6 is shown in greater detail in a cut - away view in fig1 . it is fitted with a collar 67 with slits 66 which , in the same way as the corresponding parts on the vessel &# 39 ; s 4 coupling means 42 , mates with the connection flanges on the coupling means 3 in connection . the adapter unit 6 has a membrane 65 which , when the unit is connected to the coupling means 3 , presses against the coupling means membrane 34 . the opposite end of the adapter means 6 is fitted with a luer - lok connector 61 for connection with a connection unit on the patient &# 39 ; s injection line . when the agent is to be injected , the parts 31 , 32 of the coupling means are pressed together in the same way as described above , causing the cannula 33 to penetrate the two membranes 34 and 65 and establishing a connection between the injection syringe &# 39 ; s container 13 and the injection line . a protective means 62 can be detachably attached to the adapter 6 during transportation etc . [ 0076 ] fig1 illustrates an alternative example how to perform the invented method . in this case the coupling means 3 illustrated in fig4 is attached to the connection nozzle 14 of the syringe 1 during the charging of air . the filter unit 2 is attached to the other end of the coupling means 3 , which is provided with a male - part 76 of a luer connector . when the charging of air is finished , the filter unit 2 is removed and the coupling means is connected to an injection agent vessel 4 as described in connection with fig4 . fig1 is intended to illustrate the principle of locating the filter at the lower end of the coupling means 3 . in practice it can be realized by providing an adapter unit that is similar to the adapter unit 6 of fig1 having a filter unit fixedly attached to its lower end , e . g . a unit corresponding to detail 62 of fig1 . a further alternative example is illustrated in fig1 . in this embodiment the coupling means 3 has a branch connection including an air filter 77 and a shut - off valve 78 . during charging with air , the valve 78 is open and air is aspired through the filter 77 into the coupling means 3 and further to the container 13 of the syringe 1 . when the charging is finished , the valve 78 is closed and the coupling means is connected to the injection agent vessel . for practical reasons it might be advantageous to attach the filter 77 at the end of the coupling means facing the syringe 1 .
a first aspect of the invention relates to a method for aseptic preparation with an injection syringe . the syringe comprises a container for injection agent and an immovable connection nozzle connected to the container . the method entails charging the container with air . according to the invention air is forced to pass through an air filter arranged on the connection nozzle . this enables the syringe container to be charged with aseptic air in a simple and reliable fashion . other aspects of the invention relate to devices for performing the method , viz . an injection syringe equipped with an air filter in the connection nozzle , a filter unit connectable to an injection syringe &# 39 ; s connection nozzle and a system comprising an injection syringe and a separate filter unit . the invention devices convey advantages of the same kind as the invention method .