Abstract:
The present invention relates to a medical device ( 1, 100 ) comprising a first container ( 10, 110 ) holding a first medium and defining a general axis, a second container ( 20, 120 ) holding a second medium, and fluid connection means ( 50, 150 ) for establishing fluid connection between the first container ( 10, 110 ) and the second container ( 20, 120 ), the fluid connection means ( 50, 150 ) being arranged at least partially between the first container ( 10, 110 ) and the second container ( 20, 120 ). The device further comprises a cover receiving portion ( 42, 42 ) and a cover ( 4, 104 ) removably mounted thereon to shield at least an operable portion of the first container ( 10, 110 ). The cover ( 4, 104 ) is operatively coupled with the fluid connection means ( 50, 150 ) and configured to cause a relative converging motion between at least one of the first container ( 10, 110 ) and the fluid connection means ( 50, 150 ) and the second container ( 20, 120 ) and the fluid connection means ( 50, 150 ) in response to a dismounting of the cover ( 4, 104 ) from the cover receiving portion ( 42, 142 ).

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to medical devices and more specifically to devices for transferring one or more substances between separate containers. 
       BACKGROUND OF THE INVENTION 
       [0002]    Within drug delivery it may be of vital importance to maintain purity of a product to be administered from its production to its administration. Many drug substances are therefore supplied in sealed containers having penetrable access means, such as rubber septa, which are adapted to be pierced by a suitable tool, e.g. a hollow needle. 
         [0003]    For example, people with IDDM frequently attach an injection needle to their insulin pen to thereby penetrate a self-sealing rubber septum of an insulin containing cartridge and establish a delivery line for subcutaneous administration. The needle and the insulin are stored in respective sterile environments until the point of connection. 
         [0004]    Some pharmaceutical drugs adapted for parenteral administration are only stable in the administrable form a relatively short period of time. For convenience reasons, and in order to extend the shelf life of such a drug, it is sometimes preferred to store individual constituents of the drug separately and to mix them only just before a dose is needed. 
         [0005]    Traditionally, a mixing of two substances stored in separate vials is performed using a syringe with a needle to withdraw the substance from the one vial and inject it into the other vial. The syringe with the attached needle is then used to withdraw from this vial the desired amount of drug to be injected into the patient. Oftentimes, the needle used for transferring the substances must be replaced by another needle for the actual administration of the drug. 
         [0006]    This kind of manual operation may be cumbersome and may bring about some uncertainty as to the exact concentration of the resulting drug, because it can be difficult to completely empty a vial by such an approach. Moreover, since the first substance is withdrawn from one vial and transported to another vial via a syringe with a needle, typically including a penetration of two rubber septa in order to establish fluid connection to the respective vial interiors, both sterility and safety (in terms of e.g. risk of needle stick injuries) may be compromised. To reduce the risk of contamination of the administrable substance it is customary to clean the respective rubber septa with an alcohol swab before needle penetration. This, however, is often considered a hassle by the user, especially if she/he needs to mix the substances and administer the resulting drug quickly to avert a serious situation. 
         [0007]    U.S. Pat. No. 5,466,220 (Bioject, Inc.) discloses different examples of drug vial mixing and transfer devices comprising one or two vials and a syringe pre-aligned and packaged in sealed sterile packages to eliminate the need for swabbing the vials before piercing and to avoid sharp needle exposures. While overcoming some of the drawbacks of the traditional way of mixing substances, the solutions comprising two vials appear bulky and operationally cumbersome, and the solutions including a single vial introduce a risk of carrying out the individual operational steps in a wrong order, because the syringe plunger is operable before connection of the vial and the syringe, thereby enabling unintended delivery of some of the syringe contents to the exterior of the vial. 
         [0008]    WO 97/46203 (Applied Research Systems ARS Holding N.V.) discloses a pre-assembled pack for a drug reconstituting device, which pack comprises a vial co-axially aligned with a cartridge and separated therefrom by a double-ended needle element. In the pre-use state of the device the needle element is shielded at each end by a slidable bung, providing for closed, sterile needle chambers. Like the above mentioned prior art solutions including a single vial, this pack also lacks a mechanism which prevents it from being manipulated erroneously to e.g. expel the contents of the cartridge before fluid connection to the vial has been established. 
         [0009]    EP 0 565 103 A1 (Nissho Corporation) discloses a bedside mixing arrangement comprising a drug vial, a solvent bag, a double-pointed hollow needle, and a guide capsule with a cap rotatably mounted thereon. The cap serves as a means for driving the drug vial towards the solvent bag for establishment of fluid connection between the two via the double-pointed hollow needle. To mix the drug and the solvent, firstly the cap is operated to cause the fluid connection to be established, then the entire arrangement is turned upside down allowing the solvent to flow into the drug vial to mix with the drug, and finally the entire arrangement is turned upside down again to transfer the drug solution to the solvent bag. This mixing procedure is slow and cumbersome given the size and flexibility of the solvent bag. Furthermore, the dimensions of this arrangement make it ill-suited for being carried about in connection with regular ambulatory use. 
         [0010]    WO 2011/088471 (Bayer Healthcare LLC) discloses a device comprising a receptacle, a spike assembly having a perforating shaft and a connector element for receiving a syringe, and an actuating mechanism for automatically causing the shaft to perforate a closure of the receptacle upon rotation of an outer cover surrounding the spike assembly. While this device ensures that fluid communication between the spike assembly and the receptacle is established before a syringe is even capable of being attached to the spike assembly, it does not overcome the problems of potential premature activation of the syringe piston. Moreover, in principle the connector element needs to be swabbed before attachment of the syringe to secure a reasonable level of cleanliness during the mixing procedure. This requires additional operational steps to be performed by the user, prolonging the time needed to prepare a drug product for administration. 
         [0011]    Especially for people who must administer a therapeutic agent several times during the day it is of importance that a portable delivery device is compact such that it takes up as little space as possible in e.g. a bag or a pocket. If the delivery device is a syringe type device comprising a piston which is slidable in a tubular reservoir in response to an operation of a piston rod, and if the device is prefilled with the therapeutic agent, or with a component therefore such as a solvent or a diluent, the axial dimension of the device must be at least twice the axial dimension of the reservoir in order to enable complete emptying thereof, because the piston rod has to extend beyond the reservoir a distance corresponding to the full stroke of the piston in the pre-use state of the device. 
         [0012]    WO 2009/108847 (Becton, Dickinson and Company) discloses a prefilled syringe with a two piece piston rod comprising a first piece slidably mounted to a second piece, allowing the piston rod to be extended from a compressed length to an extended length by application of an axial force in the proximal direction. 
         [0013]    While such a solution may reduce the overall dimension of the syringe in the storage condition, it adds to the number of operational steps a user must perform in order to prepare the syringe for administration of its contents. Whereas an ordinary prefilled syringe may be operated to expel its contents immediately upon removal from its packaging the preparation steps for the syringe disclosed in WO 2009/108847 include 1) removing the syringe from the packaging, 2) applying an initial axial force to one of the piston rod pieces in the proximal direction to cause disengagement of the locking elements interlocking the two piston rod pieces, and 3) applying a continuous axial force to the piston rod in the proximal direction so a locking element of the first piston rod piece engages with a locking element of the second piston rod piece. 
         [0014]    It is therefore desirable to provide a solution of the type disclosed in WO 2009/108847 which does not entail any additional operational steps for a user. 
       SUMMARY OF THE INVENTION 
       [0015]    In view of the above, it is an object of the invention to provide an arrangement for securing safe and clean (e.g. sterile) fluid access to a medical container. Further, it is an object of the invention to provide an arrangement for safe and clean (e.g. sterile) transfer of media between containers. In particular, it is an object of the invention to provide a simple, intuitive and easy to use handheld arrangement for mixing substances contained in separate containers, which arrangement reduces or eliminates the risk of erroneous handling and ensures that purity (e.g. sterility) of the substances is maintained throughout the mixing procedure. 
         [0016]    It is a further object of the invention to provide a handheld medical device for mixing substances that requires a minimum number of operational steps and optionally includes an integrated automatic sequence controller, ensuring correct establishment of fluid connection between the individual elements. 
         [0017]    It is an even further object of the invention to provide a handheld medical device for transferring media between separate containers, where the configuration of the device ensures that a user cannot accidentally operate, e.g. pressurise, any of the containers until a fluid connection between the containers has been properly established. 
         [0018]    It is an even further object of the invention to provide a medical mixing device which is easily transportable and which fits into e.g. a small handbag, thereby increasing opportunities for a flexible lifestyle. 
         [0019]    In the disclosure of the present invention, aspects and embodiments will be described which will address one or more of the above objects and/or which will address objects apparent from the below disclosure as well as from the description of exemplary embodiments. 
         [0020]    In an aspect of the invention a medical arrangement, in particular a handheld medical device, is provided comprising a first container comprising a variable volume chamber holding a first medium, a second container holding a second medium, fluid connection means (e.g. a fluid connection structure) for establishing a fluid connection between the first container and the second container, a cover receiving portion, and a cover removably mounted on the cover receiving portion to shield at least an operable portion of the first container. The cover is operatively coupled with the fluid connection means and configured to cause a relative converging motion between at least one of a) the first container and the fluid connection means and b) the second container and the fluid connection means in response to a dismounting of the cover from the cover receiving portion. 
         [0021]    In another aspect of the invention, a medical device is provided comprising a first container comprising a variable volume chamber holding a first medium, a second container holding a second medium, fluid connection means (e.g. a fluid connection structure) for establishing a fluid connection between the first container and the second container, a cover receiving portion, a cover removably mounted on the cover receiving portion to shield at least an operable portion of the first container, the cover being operatively coupled with the first container so that a displacement of the cover in a first axial direction relative to the cover receiving portion activates the first container, and guide means structured to displace an activated first container in a second direction, the second direction being opposite to the first direction and towards the fluid connection means. 
         [0022]    In a further aspect of the invention a medical device is provided comprising a first container holding a first medium and defining a general axis, a second container holding a second medium, and fluid connection means (e.g. a fluid connection structure) for establishing fluid connection between the first container and the second container, the fluid connection means being arranged at least partially between the first container and the second container. The device further comprises a cover receiving portion and a cover removably mounted thereon to shield at least an operable portion of the first container. Guide means are also provided for guiding a relative motion between the first container and the second container from a first relative position in which the first container and the second container are fluidly unconnected and spaced apart a first axial distance to a second relative position in which the first container and the second container are spaced apart a second axial distance, which is smaller than the first axial distance. The cover is operatively coupled with the first container, the operative coupling being configured to cause a relative motion between the first container and the second container from the first relative position to the second relative position in response to a dismounting of the cover from the cover receiving portion. 
         [0023]    The relative motion between the first container or the second container and the fluid connection means may be caused by a dismounting of the whole cover or of only a portion of the cover from the cover receiving portion. 
         [0024]    The cover receiving portion may be arranged to at least partially encircle at least a portion of at least one of the first container, the second container, and the fluid connection means. 
         [0025]    An arrangement or device as defined by any of the above aspects of the invention makes it possible to ensure both safety and a high level of purity throughout the mixing procedure because the user is not in risk of accidental needle sticks, as any sharp objects may be arranged unexposed, and because selected parts of the arrangement may be sterilised before assembly and made inaccessible to the user during use. Furthermore, since the cover shields at least an operable portion of the first container, e.g. the entire first container, the arrangement enables a construction by which the user cannot accidentally activate this container prematurely to thereby lose some of its contents to the surroundings. 
         [0026]    In particular embodiments the fluid connection means establishes fluid communication between the interior of the first container and the interior of the second container in response to the dismounting of the cover from the cover receiving portion. Thereby, it is ensured that fluid communication between the two containers is properly established before the user gains access to operate any volume altering means of the arrangement, excluding any potential erroneous operation of the device in relation thereto. Since the cover must be removed from the cover receiving portion anyway to enable operation of the device, it is both convenient and time saving to provide for a simultaneous automatic execution of another mandatory action. 
         [0027]    In the present context “a dismounting of the cover from the cover receiving portion” means a relative motion between the cover and the cover receiving portion eventually leading to a disengagement of or a termination of interaction between the two. It is noted that the actual disengagement or termination of interaction may occur simultaneously with or subsequent to the particular effect which the relative motion between the cover and the cover receiving portion induces. 
         [0028]    Further, in the present context “an operable portion of the first container” should be understood as a portion of the first container which can be operated by the user to perform an action which has an effect on the contents thereof, e.g. a portion of an actuator for a displaceable wall which can be moved relative to the remaining portion of the first container to selectively decrease and increase its internal volume. A specific example hereof is a piston rod adapted to move a piston in a syringe barrel. 
         [0029]    The second container may be co-axially aligned with the first container and the fluid connection means, whereby a slender configuration of the device is enabled. This is preferred by some users, as a slender device may more easily fit into e.g. a pocket or a small handbag. A longitudinal axis of the first container may define the axis of alignment. In particular, the fluid connection means may be arranged axially between the first container and the second container. In such an arrangement a relative converging motion between at least one of the first container and the fluid connection means and the second container and the fluid connection means necessarily entails a relative converging motion between the first container and the second container. 
         [0030]    Following establishment of fluid communication between the first container and the second container, the first medium may be transferred to the second container via the fluid connection means to mix with the second medium to produce a resulting drug product, and the drug product may subsequently be transferred the opposite way to the first container via the fluid connection means. 
         [0031]    The cover may form part of an enclosure for the first container, the second container, and the fluid connection means. Thereby, a controlled environment for these components may be established to reduce or eliminate the risk of impurities being introduced into the resulting drug product. 
         [0032]    In particular embodiments the cover is a rigid cap adapted to form part of an at least partly rigid enclosure for the first container, the second container, and the fluid connection means. Such an enclosure further allows a user to bring the device about in e.g. a pocket or a handbag without having to fear that an interaction with other contents thereof might cause an unintended activation of the first container. 
         [0033]    The volume of the variable volume chamber may be varied by operation of an actuator, and the cover may be adapted to shield at least an operable portion of the actuator when mounted on the cover receiving portion. 
         [0034]    The fluid connection means may comprise a base section arranged, e.g. extending transversally, between the first container and the second container, a first hollow penetration member protruding axially from a first face of the base section in the direction of the first container, and a second hollow penetration member protruding axially from a second face of the base section in the direction of the second container. The first penetration member may comprise first piercing means, such as a pointed end, adapted to penetrate a closure of the first container. Similarly, the second penetration member may comprise second piercing means adapted to penetrate a closure of the second container. The interiors of the respective first and second hollow penetration members may be fluidly connected at the base section. In some embodiments, the respective first and second hollow penetration members are co-axially aligned at each side of the base section. Such a configuration may be especially suitable for use in a device where the two containers are also co-axially aligned. 
         [0035]    The first penetration member may initially be encapsulated by a first penetrable sheath element, and the second penetration member may initially be encapsulated by a second penetrable sheath element, each sheath element being capable of maintaining an internal environment for the respective penetration member, which is characterised by a specific airborne particulate cleanliness. Thereby, the fluid connection means may e.g. be sterilised and the penetration members may be covered by the respective sheath elements in an aseptic cleanroom area before assembly of the medical device, securing a high level of cleanliness for the flow route. During use of the medical device, in connection with the establishment of fluid communication between the first container and the second container, the first sheath element is then penetrated by the first penetration member prior to the first container closure, and, likewise, the second sheath element is then penetrated by the second penetration member prior to the second container closure. 
         [0036]    The cover and the cover receiving portion may be adapted for threaded engagement via a first track section having a first pitch, and the dismounting of the cover from the cover receiving portion may cause a relative helical motion between the first container and the cover or the cover receiving portion, which is defined by a second track section having a second pitch. 
         [0037]    The second pitch may be greater than the first pitch to reduce the relative angular displacement between the cover and the cover receiving portion required to cause fluid connection to be established between the first container and the second container, thereby increasing the user convenience of the device. 
         [0038]    In particular embodiments the pitch difference is adapted to cause an establishment of fluid communication between the first container and the second container upon less than one full revolution of the cover relative to the cover receiving member. 
         [0039]    The cover receiving portion may be arranged on a coupling element, and the second container may be locked against at least distal motion relative to the coupling element. For example, the coupling element may comprise reception means, such as e.g. a clamp structure, for receiving and retaining the second container. Thereby, a converging relative motion between the first container and the second container is easily controllable, as it involves only a unidirectional motion of the first container towards a stationary second container. 
         [0040]    As used herein in relation to the above aspects of the invention, the term “distal” refers to a portion, position or direction opposite or away from the operable portion of the first container, whereas “proximal”, conversely, refers to a portion, position or direction close to or towards the operable portion of the first container. 
         [0041]    The medical device may further comprise a first container support element adapted to, e.g. releasably, hold and/or support the first container, and a guide interface structured to provide for a guided relative motion between the first container support element and the second container during the dismounting of the cover ( 4 ) from the cover receiving portion ( 40 ). The cover may be structured to interact with the first container support element to activate the first container support element in response to a dismounting motion of the cover relative to the cover receiving portion, and the guide interface may be structured to displace an activated first container support element towards the second container. 
         [0042]    The guide means, or the guide interface, guiding the relative motion between the first container and the second container may comprise cooperating threaded sections providing for a helical motion of the first container relative to the coupling element. Alternatively, the guide means, or the guide interface, may be structured to provide for a translational relative motion between the first container and the coupling element. Further, alternatively or additionally, the guide means may comprise cooperating threaded sections providing for guided motion of the second container relative to the coupling element. 
         [0043]    The cooperating threaded sections may be provided as a first thread on the coupling element and a mating first container support thread on the first container support element. The coupling element may further comprise a second thread adapted for engagement with a cover thread on the cover for mounting, respectively dismounting, of the cover on/from the coupling element. The first thread and the second thread may be opposite in the sense that the first thread may be a left-hand thread and the second thread a right-hand thread, or vice versa. Further, the first thread may be an internal thread in the coupling element, while the second thread may be an external thread on the coupling element. The first thread thereby cooperates with an external thread on the first container support element and the second thread cooperates with an internal thread in the cover. 
         [0044]    The cover may be operatively coupled with the first container via cover engagement means on or in the cover interacting with container engagement means associated with the first container. In the present context, the term “associated with the first container” should be understood as either “arranged on the first container” or “arranged on a separate element connected to the first container”. 
         [0045]    For example, the cover may be operatively coupled with the first container via the first container support element. The cover engagement means may be structured for engagement with container engagement means on the first container support element to ensure joint rotational motion of the cover and the first container support element when the cover performs a rotational motion in a dismounting direction relative to the cover receiving portion. In that case, a unidirectional rotational lock between the first container and the first container support element may be incorporated to ensure joint rotational motion of the first container and the first container support element when the first container support element and the cover rotate jointly. 
         [0046]    Alternatively, the cover may be coupled directly to the first container through interacting cover engagement means and container engagement means provided on the first container. 
         [0047]    The cover engagement means may comprise longitudinally extending ribs on interior surface portions of the cover, and the container engagement means may comprise pawls configured for engagement with the respective ribs, each pawl being capable of sliding axially along a rib. In particular, the operative coupling between the cover and the first container may comprise a ratchet adapted to allow rotation of the cover in one direction relative to the first container and to prevent rotation of the cover in the opposite direction relative to the first container. Alternatively, the cover engagement means may comprise a curved, e.g. helical, groove and the container engagement means may comprise a cam adapted to slide in the groove in response to a relative axial motion between the cover and the cover receiving portion. 
         [0048]    The combination of the rotational coupling between the cover and the first container and the opposite first and second threads provide for an arrangement wherein a rotation of the cover relative to the cover receiving portion results in an axial opposite displacement of the cover and the first container relative to the coupling element. Thereby, while the cover is gradually unscrewed from the second thread the first container is lead towards the second container, e.g. carried by the first container support element, along the first thread. 
         [0049]    The pitch of the first thread may be greater than the pitch of the second thread, whereby the axial movement of the first container relative to the coupling element is longer than the axial movement of the cover relative to the coupling element upon a given angular displacement of the cover along the second thread, giving a result corresponding to what is described in the above in connection with the first and second track sections 
         [0050]    The guide means may be configured to lead the first container support thread to the end of the first thread during establishment of fluid communication between the first container and the second container. The fluid connection means may be mounted in a hollow portion of the first container support element by e.g. a friction fit, in which case when the first container support thread travels the first thread the first container is moved towards the fluid connection means which is again moved towards the second container. In case the operative coupling between the cover and the first container prevents relative rotational motion between the two during dismounting of the cover from the cover receiving portion but allows relative rotational motion between them during mounting of the cover onto the cover receiving portion, an arrangement is provided in which the cover is irremovably re-mountable on the cover receiving portion. This is due to the fact that when the first container support thread is at the end of the first thread, the first container support element is not capable of rotating any further with respect to the coupling element. Hence, once the cover is re-mounted on the second thread it cannot be released from it because the cover is locked against rotation relative to the first container support element. 
         [0051]    Alternatively, the cover engagement means may comprise a helical track on or in an interior surface portion of the cover, the container engagement means may comprise a track follower on the first container support element, and the first container support element may be rotationally locked with respect to the coupling element, e.g. splined thereto, such that a relative rotational motion between the cover and the cover receiving portion along the first track section causes a non-rotational relative motion between the first container support element and the coupling element, leading the first container non-rotationally towards the second container. 
         [0052]    The fluid connection means may be carried by the first container support element before and during the relative motion between the first container and the second container. In particular, the first container support element may comprise first positioning means interacting with the first face of the base section and second positioning means interacting with the second face of the base section to translationally fix the fluid connection means relative to the first container at a position in which the first penetration member is spaced apart from the first container closure, and the first positioning means may be configured to automatically abort the interaction with the first face upon penetration of the second container closure by the second penetration member, thereby enabling relative translational motion between the fluid connection means and the first container. 
         [0053]    Such a construction will provide for a complete control of the position of the fluid connection means before and during establishment of fluid communication between the first container and the second container. Not only is the fluid connection means stably arranged relative to the two containers, the order of penetration of the respective container closures is predetermined. During the first part of the operation the fluid connection means moves translationally towards the second container along with the first container support element, due to the interaction between the first positioning means and the first face, until the second container closure is penetrated by the second penetration member. Thereafter, due to the first positioning means ceasing to interact with the first face, the further translational movement of the first container support element towards the second container causes a relative translational motion between the first container and the fluid connection means until the first container closure is penetrated by the first penetration member. 
         [0054]    A penetration sequence control of this type may be incorporated to ensure that fluid access to the second container is obtained before the first container closure is penetrated. In some cases, a reverse penetration sequence could cause an undesired application of a portion of the first medium to the exterior of the second container, giving rise to uncertainty as regards to the actual volumetric ratio of the media being mixed, and thereby to the potency of the final drug product. 
         [0055]    In particular embodiments the first positioning means comprises a plurality of radially deflectable legs extending axially from a circumferential base of the first container support element, each leg comprising an inwardly extending abutment surface for abutment with a portion of the first face, and the coupling element comprises a plurality of sloping guide surfaces configured to guide the plurality of radially deflectable legs radially outwards upon penetration of the second container closure by the second penetration member during the relative motion between the first container support element and the second container, whereby the abutment surfaces are brought out of contact with the first face. 
         [0056]    The coupling element may further comprise locking means for interacting with the first container support element to translationally fix the first container support element with respect to the second container upon the subsequent penetration of the first container closure by the first penetration member. Thereby, it is ensured that the first container and the second container remain fluidly connected during the entire process of transferring the first medium to the second container and the mixture from the second container to the first container. 
         [0057]    In some embodiments, each of the plurality of radially deflectable legs further comprises a catch portion, and the coupling element further comprises a plurality of ramp portions, each ramp portion being structured to deflect one of the radially deflectable legs radially outwards during the relative motion between the first container support element and the second container and to allow the radially deflectable leg to elastically recover beyond a ramp edge such that the catch portion snap fits to a distal side of the ramp portion. 
         [0058]    In particular embodiments, the first container is a syringe type applicator comprising a cylindrical barrel and a piston defining a syringe compartment for holding the first medium. The piston is capable of sliding motion with respect to the barrel by operation of a piston rod to selectively decrease and increase the volume of the syringe compartment. Thereby, the first medium can be easily transferred from the first container to the second container through the fluid connection means and easily transferred back to the first container, e.g. as a component of a mixture in case the second container initially contains a miscible medium. 
         [0059]    The syringe type applicator may be removably mounted in the first container support element, whereby after effectuating the above described fluid transfer, the syringe type applicator may be removed from the first container support element and used as an administration device. 
         [0060]    In particular embodiments, the syringe type applicator comprises a Luer outlet and a penetrable syringe stopper adapted to seal the outlet before use of the medical device. The Luer outlet then enables attachment of selective suitable delivery means, such as e.g. an infusion set, for percutaneous access to a subject user. 
         [0061]    The medical device may be structured to retain the syringe stopper during removal of the syringe type applicator from the first container support element. The unidirectional rotational lock between the first container and the first container support element may thus comprise a threaded Luer collar on the syringe type applicator and a mating thread on a syringe stopper retaining member which is translationally locked to the syringe stopper and rotationally as well as unidirectionally translationally locked with respect to the first container support element. Thereby, when the syringe type applicator is released from the first container support element by unscrewing of the Luer collar from the thread on the syringe stopper retaining member, the syringe stopper is prevented from moving relative to the first container support element, and the Luer outlet is automatically exposed to the surroundings, eliminating an additional manual syringe stopper removal step. 
         [0062]    The syringe type applicator may further be adapted for re-mounting in the first container support element. Thereby, the user will not have to worry about where to place the administration device after use. In case the cover is irremovably re-mountable on the cover receiving portion, as described in the above, the cover may even be used to collect the disposables, such as e.g. the infusion set, after administration and to provide for a closed storage space for the used syringe type applicator and the disposables through re-mounting on the cover receiving portion. Since the piston rod has advanced the piston to the distal most position in the barrel during emptying of the syringe type applicator the axial dimension of the syringe type applicator is significantly reduced compared to its initial axial dimension. This leaves sufficient room for the disposables in the established storage space between the end portion of the piston rod and the cover. Hence, the medical device can e.g. be used as a safe and inaccessible sharps container after transfer and delivery of the contents of the two containers. 
         [0063]    The medical device may further comprise a base element surrounding at least a portion of the coupling element. The base element and the coupling element may be structured to enable a limited relative rotation of the two, e.g. guided by a bayonet groove in the coupling element adapted for slidable reception of a cam on the base element. The second container may be supported by a second container support element arranged non-rotatably relative to the base element, e.g. via an axial groove on one entity and a mating axial track on the other, or via other suitable mechanical engagement structures. The second container support element may comprise a second container support thread adapted for mating engagement with a third thread on the coupling element. 
         [0064]    The third thread may be arranged distally of the first and second threads and may be structured to cause the second container support element to perform an axial displacement towards the fluid connection means in response to a rotation of the coupling element relative to the base element. Thereby, by causing a relative rotational motion between the base element and the coupling element the second container can be forced against the fluid connection means to provide a firmer mechanical attachment thereto, increasing the robustness of the arrangement. 
         [0065]    A relative rotational motion between the base element and the coupling element may be performed automatically during the unscrewing of the cover from the second thread on the coupling element when the first container support thread travels the first thread, depending on the present frictional relationships between the individual materials and structures. 
         [0066]    Alternatively, or additionally, a relative rotational motion between the base element and the coupling element may be performed automatically during the unscrewing of the cover from the second thread on the coupling element subsequent to the first container support thread having travelled to the end of the first thread. This may be obtained by ensuring that the distance the cover thread has to travel along the second thread to release the cover from the coupling element is longer than the distance the first container support thread has to travel along the first thread to reach the end of the first thread. Hence, if the second thread is longer than the first thread, the first container support thread reaches the end of the first thread, and fluid connection is established between the first container and the second container, during dismounting of the cover from the cover receiving portion, while the cover thread is at an intermediate position relative to the second thread in which the cover is still not released from the coupling element. Whether or not the coupling element and the base element have undergone a relative rotation during the travel of the cover thread to the intermediate position, once the first container support thread is at the end of the first thread a further application of a torque to the first container support element, e.g. from the further rotation of the cover, may cause a joint rotation of the first container support element and the coupling element relative to the base element. Thereby, an arrangement is provided wherein the tightening of the second container to the fluid connection means is automatically executed during a final dismounting rotation of the cover. 
         [0067]    Alternatively, a relative rotational motion between the base element and the coupling element may be performed manually, e.g. by turning an exposed portion of the coupling element about the general axis while clutching the base element. 
         [0068]    The second container support element may comprise an at least partly enclosing frame adapted to accommodate the second container. In some embodiments, the second container support element comprises a cylindrical case which together with the base element encapsulates the second container to render the second container inaccessible to subject users. The cylindrical case is provided with an internal thread which mates with the third thread on the coupling element. 
         [0069]    It is noted that whereas the third thread has been described in the foregoing as forming part of the coupling element, the third thread may alternatively be provided on a separate element which is rotatably locked with respect to the coupling element. 
         [0070]    The second container support element may further comprise bias means structured to exert a biasing force on the second container for biasing the second container towards the first container. In particular embodiments, the bias means comprises one of more spring members arranged in a bottom portion of the second container support element. 
         [0071]    During assembly of the medical device it may be important to secure a specific position of the first container support element relative to the coupling element, e.g. to ensure a correct placement of the fluid connection means to avoid premature penetration of the container closures. This may be accomplished through a marker that defines a particular relative position of the first container support thread and the first thread on the coupling element. Such a marker may comprise a first catch geometry associated with the first container support thread and a mating second catch geometry associated with the first thread. 
         [0072]    In some embodiments, the first catch geometry comprises a notch structure in the first container support thread and the second catch geometry comprises a deflectable finger structure at the start of the first thread which is adapted to ride along the first container support thread in a deflected state, during an initial joining of first container support element and the coupling element, until it reaches the notch structure. At this point, the deflectable finger structure becomes unloaded and enters into a mating engagement with the notch structure to prevent the first container support thread from being moved reversely along the first thread beyond the notch structure. However, importantly, the engagement is of the type which allows further joining of the first container support element and the coupling element. 
         [0073]    When the deflectable finger structure enters into the notch structure it emits a click sound to provide an audible alert that the desired relative position of the first container support element and the coupling element has been reached. 
         [0074]    In a particular embodiment of the invention a medical device is provided comprising a syringe holding a first medium, the syringe having a tip portion defining a syringe outlet, and a Luer connector arranged at the tip portion, a syringe tip cap for sealing the syringe outlet, a tip cap retainer structured to non-releasably hold the syringe tip cap, the tip cap retainer comprising a coupling portion adapted for releasable connection with the Luer connector, a vial holding a second medium, the vial being axially aligned with the syringe and having a neck portion defining a vial outlet, and a vial stopper for sealing the vial outlet, a cylindrical coupling element comprising a vial retaining portion adapted to receive and hold the vial, and a cap receiving portion comprising a first helical track, a cap releasably mounted on the cap receiving portion to cover at least a portion of the syringe, the cap comprising a second helical track, and a first track follower adapted for mating engagement with the first helical track, a fluid connection unit arranged axially between the syringe and the vial and comprising a transversal base, a first pointed structure extending in a first direction from the transversal base for penetrating the syringe tip cap, and a second pointed structure extending in a second direction from the transversal base for penetrating the vial stopper, and a syringe holder rotationally locked with respect to the coupling element and structured to rotationally and translationally retain the tip cap retainer, the syringe holder comprising a second track follower adapted for mating engagement with second helical track such that a rotation of the cap relative to the cap receiving portion causes a translational movement of the syringe holder towards the vial, the syringe holder further comprising support means for stable positioning of the fluid connection unit in a position in which the first pointed structure is spaced apart from the syringe tip cap, the support means comprising a proximally oriented support surface adapted to abut a distally oriented surface of the transversal base, and a distally oriented support surface adapted to abut a proximally oriented surface of the transversal base, wherein the distally oriented support surface is adapted to be moved out of abutment with the transversal base in response to the syringe holder reaching a position relative to the vial in which the second pointed structure has penetrated the vial stopper. A vial casing adapted to cover at least a portion of the vial is optionally included. If so, the vial casing is rotationally and translationally fixed with respect to the coupling element. 
         [0075]    An important factor for the outcome of certain disease related events, such as e.g. spontaneous bleeding episodes for a person with haemophilia, is the so-called time-to-treatment. In order to reduce the time-to-treatment, e.g. for people with bleeding disorders, devices offering a high degree of portability are desirable, because such devices are more likely to be carried about during the day, thereby generally increasing availability at a sudden onset of bleeding. One aspect of portability is the physical size of the device. For a syringe type device which includes an elongated drug reservoir and a piston rod for activation of a piston, a telescopic piston rod system may be employed to reduce the axial dimension of the device. However, a telescopic piston rod mechanism can be fiddly to handle for a person in a stressful situation, and this may lead to a less than optimal treatment. 
         [0076]    In a further aspect of the invention a medical device is provided comprising: a container defining a variable volume chamber adapted to hold a fluid medium, an actuation element for varying the volume of the chamber, a cover receiving portion, and a cover removably mounted on the cover receiving portion to shield at least an operable portion of the actuation element, wherein the actuation element is extendable from a first axial dimension to a second axial dimension, and wherein the cover is coupled with the actuation element and configured to extend the actuation element from the first axial dimension to the second axial dimension in response to the cover undergoing relative motion with respect to the cover receiving portion. 
         [0077]    In particular, the actuation element may be extended from the first axial dimension to the second axial dimension in response to the cover being dismounted from the cover receiving portion. 
         [0078]    The above solution enables an automatic actuator extension e.g. by removal of a cover, such as a packaging or a portion of a packaging. Specifically, the medical device may comprise a syringe comprising a syringe barrel holding a volume of a substance, which syringe barrel is closed at one end by a movable piston, and a piston rod operatively coupled with the piston and adapted to move the piston in the syringe barrel to expel at least a portion of the substance therefrom through a syringe outlet, and the removable cover may be adapted to cover a user operable portion of the piston rod in a pre-use state of the device. 
         [0079]    In terms of the syringe the present solution enables an automatic extension of the piston rod from an initial storage state to an extended state in response to a relative motion between the syringe and the syringe cover, e.g. during removal of the syringe cover from the syringe. 
         [0080]    In case the syringe cover is adapted to cover an operable portion of the piston rod to thereby prevent the piston rod from premature operation a removal of the syringe cover is necessary before the substance can be administered. In other words, the present solution utilises an already included step to execute an additional step automatically, thereby avoiding further user operation and, additionally, ensuring correct extension of the piston rod. 
         [0081]    Notably, the actuation element may be extendable from the first axial dimension to the second axial dimension while the volume of the variable volume chamber is maintained constant, thereby preventing a premature pressure variation in the variable volume chamber. 
         [0082]    The volume of the variable volume chamber may be varied by actuation of a movable wall, and the actuation element may comprise a first actuation element portion and a second actuation element portion capable of undergoing relative axial displacement from a first relative axial position defining the first axial dimension of the actuation element to a second relative axial position defining the second axial dimension of the actuation element. The first actuation element portion may be coupled with the movable wall, and the second actuation element portion may be coupled with the cover so that an axial displacement of the cover in a proximal direction relative to the cover receiving portion causes a displacement of the second actuation element portion in the proximal direction relative to the first actuation element portion. 
         [0083]    In case of the syringe the piston rod may comprise a hollow cylindrical first piston rod portion and a hollow cylindrical second piston rod portion arranged concentrically with the first piston rod portion to provide a telescopic construction by which the second piston rod portion is slidable relative to the first piston rod portion to increase the overall length of the piston rod. 
         [0084]    The second piston rod portion may be arranged at least partially within the first piston rod portion. Alternatively, the first piston rod portion may be arranged at least partially within the second piston rod portion. 
         [0085]    The static friction between the first piston rod portion and the second piston rod portion may be lower than the static friction between the piston and the syringe barrel. This will ensure that the piston remains stationary in the syringe barrel while the second piston rod portion is slid along the first piston rod portion during the relative motion between the cover and the cover receiving portion. 
         [0086]    In particular embodiments the first actuation element portion and the second actuation element portion are adapted to interlock in response to the actuation element being extended to the second axial dimension to thereby provide a rigid construction which may be manipulated by the user to advance the movable wall in a controlled manner. For example, one of the first piston rod portion and the second piston rod portion may comprise a reception geometry, and the other of the first piston rod portion and the second piston rod portion may comprise a flexible catch geometry adapted to engage with the reception geometry when the actuation element is extended to the second axial dimension, where the flexible catch geometry is biased towards the one of the first piston rod portion and the second piston rod portion during extension of the actuation element from the first axial dimension to the second axial dimension. 
         [0087]    The cover may comprise first engagement means and the second actuation element portion may comprise second engagement means releasably engaged with the first engagement means. Further, the first engagement means and the second engagement means may be configured to automatically disengage upon extension of the actuation element from the first axial dimension to the second axial dimension. In that connection, it is noted that the actual disconnection of the cover from the second actuation element portion may require an axial movement of the cover relative to the second actuation element portion subsequent to the interlocking of the first actuation element portion and the second actuation element portion. 
         [0088]    An automatic disengagement of the first engagement means and the second engagement means will allow the cover to be completely removed from the rest of the medical device without the user having to engage in an additional handling step. For people with impeded dexterity this may reduce the time required to prepare the device for drug administration significantly. 
         [0089]    Specifically, one of the first engagement means and the second engagement means may comprise a protrusion and the other of the first engagement means and the second engagement means may comprise a flexible catch structure adapted to receive and hold the protrusion. 
         [0090]    In some embodiments the protrusion comprises a radially enlarged section, and the flexible catch structure comprises a plurality of radially deflectable arms which are adapted to engage with the radially enlarged section to initially limit or prevent motion of the cover relative to the second actuation element portion in at least the proximal direction and further to deflect radially to thereby disengage from the radially enlarged section upon extension of the actuation element to the second axial dimension and in response to further proximal force application by the protrusion. 
         [0091]    The medical device may further comprise a container support element, with respect to which the container is translationally fixed, and guide means. The cover may be operatively coupled with the container support element and configured to activate the container support element in response to a dismounting motion of the cover relative to the cover receiving portion, and the guide means may be structured to displace an activated container support element in a distal direction relative to the cover receiving portion. 
         [0092]    Such a construction will e.g. lead the container (and the first actuation element portion being coupled with the movable wall) axially in the opposite direction of the cover (and the second actuation element portion being coupled with the cover) during dismounting of the cover from the cover receiving portion, whereby a smaller axial movement of the cover relative to the cover receiving portion is needed to extend the actuation element to the second axial dimension. If the relative motion between the cover and the cover receiving portion is defined by a threaded interface, this means that the threaded interface may be designed such that the relative angular displacement between the cover and the cover receiving portion required to dismount the cover from the cover receiving portion is reduced, thereby increasing the user convenience of the device, as a user may only have to turn the cover e.g. one full revolution instead of e.g. two full revolutions to expose the container for operation. 
         [0093]    The relative motion between the cover and the cover receiving portion may be defined by a first threaded section having a first pitch, and an activated container support element may undergo a relative helical motion with respect to the cover or the cover receiving portion which is defined by a second threaded section having a second pitch, said second pitch being greater than the first pitch. 
         [0094]    Compared to a construction having first and second threaded sections of the same pitch this will provide an augmentation of the axial displacement of the container relative to the cover receiving portion and will thereby allow for an even further reduction of the relative angular displacement between the cover and the cover receiving portion required to extend the actuation element to the second axial dimension and to dismount the cover from the cover receiving portion. In other words, the user convenience of the device may be increased even more, as in this case a user may only have to turn the cover e.g. half a revolution instead of e.g. two full revolutions to expose the container for operation. 
         [0095]    The cover may be a protective cap forming part of an enclosure for the container. Thereby, a controlled internal environment may be established to reduce or eliminate the risk of the fluid medium being exposed to impurities. In particular embodiments the cover is a rigid cap adapted to form part of an at least partly rigid enclosure for the container. Such an enclosure further allows a user to bring the device about in e.g. a pocket or a handbag without having to fear that an interaction with other contents thereof might cause an unintended activation of the container. 
         [0096]    The extendable actuation element solution is particularly applicable in a medical device of the fluid transfer device type disclosed in connection with any of the other aspects of the invention, i.e. in a device which further comprises a reservoir adapted to hold a substance to be mixed with the fluid medium, and a fluid connection unit adapted to establish a fluid communication between the container and the reservoir. Particularly, the reservoir may be arranged distally of the container, and the fluid connection unit may be arranged at least partially between the container and the reservoir. 
         [0097]    Thus, in a further aspect of the invention a medical device is provided comprising a syringe holding a first medium, the syringe comprising a syringe barrel having a tip portion defining a syringe outlet, a slidable piston arranged in the syringe barrel, and a piston rod adapted to displace the piston in the syringe barrel, a penetrable syringe tip cap for sealing the syringe outlet, a vial holding a second medium, the vial being axially aligned with the syringe and having a neck portion defining a vial outlet, and a penetrable vial stopper for sealing the vial outlet, a coupling element comprising a vial holding portion adapted to receive and hold the vial, and a cover receiving portion, a cover releasably mounted on the cover receiving portion to shield at least a portion of the piston rod, the cover and the cover receiving portion being configured for relative motion along a first helical path, a fluid connection unit arranged axially between the syringe and the vial and comprising a transversal base, a first pointed structure extending in a first direction from the transversal base for penetrating the syringe tip cap, and a second pointed structure extending in a second direction from the transversal base for penetrating the vial stopper, a syringe holder for retaining the syringe, the syringe holder being rotationally locked with respect to the coupling element and configured for relative motion with respect to the cover along a second helical path such that a rotation of the cover relative to the cover receiving portion causes a translational movement of the syringe holder towards the vial, wherein the piston rod comprises a first piston rod portion and a second piston rod portion axially displaceable with respect to the first piston rod portion from a first relative position, defining an initial state of the piston rod, to a second relative position, defining an extended state of the piston rod, and wherein the first piston rod portion is coupled with the piston and the second piston rod portion is coupled with the cover such that the first piston rod portion and the second piston rod portion undergo relative motion from the first relative position to the second relative position in response to a dismounting of the cover from the cover receiving portion. 
         [0098]    U.S. Pat. No. 5,466,220 also discloses a drug vial mixing and transfer device comprising a vial and a syringe arranged head-to-head. The syringe holds a cannula for piercing the vial and thereby establishing fluid communication between the vial interior and the syringe interior. A plunger within the syringe is operable to transfer fluid between the syringe and the vial. Following a reconstitution procedure the syringe is removed from the vial and used to administer the drug. While this device overcomes some of the drawbacks of the traditional way of mixing substances it offers no flexibility with respect to the type of delivery means to be employed, as the cannula is fixed to the syringe. The user can therefore not use e.g. an infusion set for IV administration should she/he so desire. Furthermore, the cannula may become blunted by the piercing of the vial during the establishment of the fluid communication between the syringe and the vial. This may cause discomfort to the user during the subsequent skin penetration. 
         [0099]    WO 97/46203 also discloses a needle assembly for use with a prefilled syringe. The needle assembly is fitted over a vial and includes a Luer fitting for reception of the syringe. The Luer fitting is initially kept sterile with a film seal which is adapted to be peeled off or pierced by the syringe nozzle before attachment of the syringe to the Luer fitting. Following attachment of the syringe and transfer of fluid between the syringe and the vial, the syringe is removed from the needle assembly and a separate injection needle is fastened to the syringe for administration of the drug. While this arrangement may offer greater flexibility with respect to the use of delivery means for providing access and delivery to the body, it includes at least one additional step of attaching a syringe to the assembly before reconstitution can be performed. Each added step in the mixing procedure may cause a loss of valuable time for the person in need of a fast administration. 
         [0100]    In view thereof, it is a further object of the invention to provide an arrangement for fast and easy readying of a medical applicator, such as e.g. a syringe. In particular, it is an object to provide an arrangement by which a medical applicator is automatically readied for attachment of suitable delivery means upon removal from a dedicated holder and, further, to provide a fluid transfer device, such as e.g. a mixing device, incorporating such an arrangement. 
         [0101]    Thus, in a further aspect of the invention a medical arrangement is provided comprising a medical applicator defining a general axis and having an outlet through which a volume of a substance is transferable, a support member for holding the medical applicator, and a closure member for sealing the outlet. The closure member is removably attached to the medical applicator and the medical applicator is arranged removably in the support member. Furthermore, the closure member is arranged irremovably with respect to the support member. 
         [0102]    Such an arrangement enables a fast readying of the medical applicator for drug delivery because when the medical applicator is removed from the support member the closure member remains with the closure member. An infusion set or a cannula, or other suitable delivery means selected by the user according e.g. to the specific recommended compartment of administration, may then be connected to the exposed outlet for ready access to the body. 
         [0103]    The closure member may be locked to the support member via a bi-directional translational coupling with a closure retaining element which is itself rotationally and translationally locked to the support member. The closure member may further be rotationally locked to the support member. Alternatively, the closure member may be locked directly to the support member. 
         [0104]    The closure member may comprise an elastic material with a high sealing capacity, such as e.g. rubber, whereas the closure retaining element may comprise a more rigid material for ensuring a sufficient engagement between the two. 
         [0105]    The closure retaining element may comprise reception means for receiving the outlet of the medical applicator. In some embodiments, the reception means comprises a threaded section structured for mating engagement with a threaded Luer connector surrounding the outlet. In other embodiments, the reception means comprises a collar adapted for engagement with a Luer taper in a Luer-Slip type fitting. 
         [0106]    In a further aspect of the invention a fluid transfer device incorporating the medical arrangement according to the previous aspect of the invention is provided. The fluid transfer device may further comprise a container co-axially aligned with the medical applicator, the container comprising an opening and a container closure for the opening. Fluid connection means may be arranged at least partially between the medical applicator and the container and may comprise a first penetration member for penetrating the closure member, a second penetration member for penetrating the container closure, and a lumen extending through the first penetration member and the second penetration member. Furthermore, spacer means may be provided structured to enable a relative axial motion between the medical applicator and the container from a first position in which the medical applicator and the container are fluidly unconnected to a second position in which the first penetration member has penetrated the closure member and the second penetration member has penetrated the container closure to thereby establish fluid communication between the medical applicator and the container. 
         [0107]    Such a fluid transfer device may be used for mixing substances, e.g. for mixing liquids or for reconstitution of a powder using a solvent, to obtain an administrable drug. The medical applicator may be a prefilled syringe and the fluid transfer device including the medical arrangement may be pre-assembled by the manufacturer. In that case an easy to use device with few manual operating steps may be provided. 
         [0108]    The spacer means may comprise a spacer means thread adapted for mating engagement with a support member thread on the support member, providing for a helical advancement of the support member, and thereby the medical applicator, relative to the spacer means. 
         [0109]    The fluid transfer device may further comprise drive means for causing the relative axial motion between the medical applicator and the container from the first position to the second position. Such drive means may comprise a drive element adapted to engage with the medical applicator or the support member and rotate the medical applicator or the support member relative to the spacer means. In particular embodiments, the drive element comprises a cover member adapted to cover at least an operable portion of the medical applicator before use thereof. The cover is then rotationally coupled with the medical applicator, e.g. via the support member. 
         [0110]    In case the medical applicator is releasably locked to the reception means via a Luer lock type fitting the cover may be structured to rotate the support member in a direction which fastens the Luer lock connection. Thereby, it is ensured that the medical applicator rotates with the support member during the activation thereof by the cover. 
         [0111]    After establishment of fluid communication between the medical applicator and the container, transfer of liquid from the medical applicator to the container, mixing of substances in the container, and transfer of an administrable drug from the container to the medical applicator, the medical applicator may simply be unscrewed from the reception means, whereby the closure member will automatically be retained in the device due to its fixation to the support member. The closure member is therefore automatically removed from the outlet when the medical applicator is released from the support member to allow the user to quickly attach a desired delivery means. 
         [0112]    In a further aspect of the invention an assembly is provided comprising a first container comprising a variable volume chamber holding a first medium, reception means adapted to receive and retain a second container holding a second medium, and fluid connection means for establishing fluid connection between the first container and the second container, when the second container is retained by the reception means. The assembly further comprises a cover receiving portion and a cover removably mounted thereon to shield at least a portion of the first container. The cover is operatively coupled with the fluid connection means and configured to cause a relative converging motion between at least one of a) the first container and the fluid connection means and b) the reception means and the fluid connection means in response to a dismounting of the cover from the cover receiving portion. 
         [0113]    In a further aspect of the invention an assembly is provided comprising a first container holding a first medium and defining a general axis, reception means for mechanical coupling with a second container holding a second medium, and fluid connection means for establishing fluid connection between the first container and the second container, when the second container is coupled with the reception means, the fluid connection means being arranged at least partially between the first container and the reception means. The assembly further comprises a cover receiving portion and a cover removably mounted thereon to shield at least an operable portion of the first container. Guide means are also provided, the guide means being structured to guide a relative motion between the first container and the reception means from a first relative position in which the first container and the reception means are spaced apart a first axial distance to a second relative position in which the first container and the reception means are spaced apart a second axial distance, the second axial distance being smaller than the first axial distance. The cover is operatively coupled with the first container so as to cause a relative motion between the first container and the reception means from the first relative position to the second relative position in response to a relative motion between at least a portion of the cover and the cover receiving portion. 
         [0114]    The assembly is suitable for use in combination with a second container in a medium transfer arrangement as described in the above. 
         [0115]    In particular embodiments, the reception means is structured to co-axially align the second container with the first container to thereby provide a slender configuration of the assembly. 
         [0116]    The reception means may comprise a snap structure, or other suitable engagement structures, adapted to receive and retain a dedicated portion of the second container. Such a snap structure may comprise a number of deflectable elastic arms, each arm being supported at one end by e.g. the coupling element, on which the cover receiving portion is arranged, and having a hook member at the opposite end for engaging the second container. Such a design would allow the user to e.g. place the second container on a flat surface and snap the assembly over it, to thereby provide a medical device as described in connection with the previous aspects of the invention, before commencing a removal of the cover from the cover receiving portion. 
         [0117]    The device and the assembly according to the invention are particularly applicable for mixing liquids as well as for reconstituting a powder using a solvent. Non-exhaustive examples of suitable drugs which may be provided in a powdered form include various factor products for use in the treatment of haemophilia, growth hormone, antibiotics and fertility drugs. 
         [0118]    In the present specification, reference to a certain aspect or a certain embodiment (e.g. “an aspect”, “a first aspect”, “one embodiment”, “an exemplary embodiment”, or the like) signifies that a particular feature, structure, or characteristic described in connection with the respective aspect or embodiment is included in, or inherent of, at least that one aspect or embodiment of the invention, but not necessarily in/of all aspects or embodiments of the invention. It is emphasized, however, that any combination of features, structures and/or characteristics described in relation to the invention is encompassed by the invention unless expressly stated herein or clearly contradicted by context. 
         [0119]    The use of any and all examples, or exemplary language (e.g., such as, etc.), in the text is intended to merely illuminate the invention and does not pose a limitation on the scope of the same, unless otherwise claimed. Further, no language or wording in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0120]    In the following the invention will be further described with references to the drawings, wherein 
           [0121]      FIG. 1  is an exploded view of a drug mixing arrangement according to an embodiment of the invention, 
           [0122]      FIG. 2  is a longitudinal section view of the arrangement of  FIG. 1 , in a pre-use state, 
           [0123]      FIG. 3  is a longitudinal section view of the arrangement after fluid connection is established between the included reservoirs, 
           [0124]      FIG. 4  is a longitudinal section view of the arrangement after complete removal of the cover, 
           [0125]      FIG. 5  is a close-up perspective view of a mechanical connection between the cover and the syringe holder, 
           [0126]      FIG. 6  is a transverse section view along line A-A of  FIG. 3 , 
           [0127]      FIGS. 7   a  and  7   b  are longitudinal section views illustrating an operative connection between a cover and a syringe holder in a drug mixing arrangement according to another embodiment of the invention, 
           [0128]      FIG. 8  is a perspective view of a syringe holder for use in the arrangement of  FIG. 1 , and 
           [0129]      FIG. 9  is a longitudinal section view of the arrangement of  FIG. 1  after re-mounting of the emptied syringe and the cover. 
           [0130]      FIG. 10  is an exploded view of a drug mixing arrangement according to another embodiment of the invention, 
           [0131]      FIG. 11  is a longitudinal section view of the arrangement of  FIG. 10 , in a pre-use state, 
           [0132]      FIG. 12  is a longitudinal section view of the arrangement during establishment of fluid connection between the included reservoirs, 
           [0133]      FIG. 13  is a longitudinal section view of the arrangement after establishment of fluid connection and subsequent complete removal of the cover, 
           [0134]      FIG. 14  is a perspective view of the extendable piston rod used in the arrangement, 
           [0135]      FIGS. 15   a  and  15   b  are perspective proximal, respectively distal views of the distal portion of the cover, 
           [0136]      FIGS. 16   a  and  16   b  are different perspective views of the syringe support element, 
           [0137]      FIG. 17   a  is a top view of the syringe support element, 
           [0138]      FIG. 17   b  is a bottom view of the syringe support element, 
           [0139]      FIG. 18  is a perspective view of the syringe closure retaining element, 
           [0140]      FIG. 19  is a perspective view of the penetrable syringe closure, 
           [0141]      FIGS. 20   a  and  20   b  are, respectively, a side view and a perspective view of the coupling element, and 
           [0142]      FIG. 21  is a perspective sectional view of a portion of the coupling element detailing the various guide surfaces used in the interaction with the syringe support element. 
       
    
    
       [0143]    In the figures like structures are mainly identified by like reference numerals. 
       DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0144]    When in the following relative expressions, such as “upwards” and “downwards”, are used, these refer to the appended figures and not necessarily to an actual situation of use. The shown figures are schematic representations for which reason the configuration of the different structures as well as their relative dimensions are intended to serve illustrative purposes only. 
         [0145]      FIG. 1  is an exploded perspective view of a mixing device  1  for reconstitution of a powdered drug in a vial  20  using a solvent from a syringe  10 . The vial  20  comprises a wall  21  having an opening which is sealed by a vial stopper  23  (not visible in this view) and a seal cap  22 . The vial  20  is arranged in a vial holder  2  which serves to position and protect the vial  20 . A lock ring  3  is fitted over a portion of the vial holder  2  and locked against rotation relative to the vial holder  2  via a longitudinal internal rib (not visible) engaging a longitudinal groove  9  in the outer surface of the vial holder  2 . A tower  25  protrudes axially from the seal cap  22  in the direction away from the vial  20 . The tower  25  has an inner circumferential sealing rim  26  at its end portion, the purpose of which is explained below. 
         [0146]    In the disclosed embodiment the wall  21  is made of glass and the vial holder  2  is made of a transparent plastic. Other suitable materials may, however, be chosen depending on the specific application of the mixing arrangement  1 . 
         [0147]    The lock ring  3  is connected to a coupling element  40  via a cam  91  on the interior surface of the lock ring  3  and a cam receiving bayonet groove (not visible) in an exterior surface of the coupling element  40 . In the pre-assembled state of the mixing device  1  the cam  91  is positioned at the end of the bayonet groove, whereby the lock ring  3  and the coupling element  40  are prevented from relative translational motion but allowed to undergo a limited relative rotation. 
         [0148]    The coupling element  40  is a tubular sleeve which further comprises an exterior thread  43  at its distal end portion for engagement with an interior thread  7  (not visible in this view) in the vial holder  2 , and an interior thread  41  at its proximal end portion for engagement with an exterior thread  31  of a syringe holder  30 . The interior thread  41  ends at a flexible lock arm  44 , the purpose of which is described in detail below. The coupling element  40  also has an exterior thread  42  arranged proximally of the exterior thread  43 . The pitch of the interior thread  41  is greater than the pitch of the exterior thread  42 . 
         [0149]    The syringe holder  30  has a proximal portion adapted to receive and hold a portion of the syringe  10 , and a distal portion which carries the exterior thread  31  and which is designed to accommodate a connector piece  50  comprising a sleeve body  51  and a distally pointing hollow spike member  52 . A number of ratchet arms  32  are arranged equidistantly along the circumference of a central portion of the syringe holder  30 . The purpose of these ratchet arms  32  will be clear from the below. 
         [0150]    The syringe  10  comprises a barrel  11 , the outlet of which is surrounded by a threaded Luer collar  13  and sealed by a syringe stopper  60 . A user manipulable piston rod  14  having a push face  15  for easy operation is adapted to drive a piston  19  (not visible in this view) inside the barrel  11 . At its proximal end portion the barrel  11  holds a flange carrier  80  provided with opposite spreadable wings  81  for offering a more ergonomic grip of the syringe  10 . 
         [0151]    A cap  4  is adapted to cover the syringe  10  during storage and transportation of the mixing device  1  to prevent operation of the piston rod  14  and thereby to ensure that pressure is not prematurely applied to the contents of the syringe  10 . The cap  4  has an interior thread  5  (not visible in this view) adapted to engage with the exterior thread  42  for positioning of the cap  4  relative to the coupling member  40 . 
         [0152]      FIG. 2  is a longitudinal section view of the mixing device  1  in the assembled state, prior to a first use thereof, showing further details of the arrangement. This state corresponds to the one in which the mixing device  1  is intended to be delivered by the manufacturer. The piston rod  14  is in a retracted position in the barrel  11 , thereby defining a syringe interior  18  capable of holding a certain volume of a solvent (not shown). The piston rod  14  is coupled firmly to the piston  19  via a jagged coupling head  16 . The cap  4  is fitted snugly around a collar  17  at the proximal end of the syringe  10  and the wings  81  are folded down along the barrel  11 . This provides a user friendly slender configuration of the mixing device  1 . 
         [0153]    A Luer  12 , defining an outlet of the syringe  10 , protrudes into the distal portion of the syringe holder  30  and is retained therein via a screw thread connection between the Luer collar  13  and a threaded inner portion  71  of a stopper retainer  70 . A couple of protrusions  72  are provided on the stopper retainer  70  to rotationally lock the stopper retainer  70  with respect to the syringe holder  30 . This is described in more detail in connection with  FIG. 6 . A lock snap  74  on the syringe holder  30  is engagement with the protrusions  72  to provide a bi-directional translational coupling between the stopper retainer  70  and the syringe holder  30 . A portion of the syringe stopper  60  is wedged between the Luer  12  and the threaded inner portion  71  and thereby provides a fluid tight engagement with the exterior surface of the Luer  12 . The syringe stopper  60  carries a filter  69  for filtering out any impurities of a passing liquid and has a penetrable section  61  allowing for easy rupturing of the syringe sealing by a suitable tool. 
         [0154]    The connector piece  50  is slidably received in the hollow interior of the distal portion of the syringe holder  30 . The sleeve body  51  supports a transverse spike base  54  which carries the distally pointing hollow spike member  52  as well as a proximally pointing hollow spike member  53 . In the depicted state of the mixing device  1  the hollow spike member  53  is arranged just distally of the penetrable section  61  and the hollow spike member  52  is arranged just proximally of a penetrable section  24  of the vial stopper  23 . The syringe  10  and the vial  20  are therefore fluidly unconnected at this point. The syringe stopper  60  has at its distal end a circumferential sealing lip  62  which is adapted to sealingly engage with an interior portion of the sleeve body  51  to provide a fluid tight compartment  56  for the hollow spike member  53 . Similarly, the tower  25  with the sealing rim  26  provides a fluid tight compartment  57  for the hollow spike member  52 . This particular construction thus enables the incorporation of a sterilised sub-assembly comprising the syringe stopper  60 , the connector piece  50  and the vial stopper  23  during assembly of the mixing device  1 , and further ensures that sterility of the respective hollow spike members  52 ,  53  is maintained throughout storage, transportation and use of the mixing device  1  with no need for additional sterile barriers. 
         [0155]    One or more vents  59  are provided in the sleeve body  51  to allow gas, e.g. air, entrapped within the sterile compartment  56  to escape during establishment of fluid connection between the syringe  10  and the vial  20 , as will be explained in more detail below. 
         [0156]    The coupling element  40  has a number of circumferentially spaced apart catch arms  45  extending downwards from a transversal portion at the end of the interior thread  41  for securing firm attachment of the vial  20 . The wall  21  defines a vial interior  28  capable of holding an amount of powdered drug (not shown) to be reconstituted by the solvent from the syringe  10 . The wall  21  is flexibly supported by leaf springs  8  in the bottom of the vial holder  2  to account for manufacturing tolerances. 
         [0157]      FIG. 3  shows the mixing device  1  after unscrewing of the cap  4  from the exterior thread  42  and an automatically effected establishment of fluid connection between the syringe interior  18  and the vial interior  28 . The cap  4  still covers the syringe  10 , although now the cap  4  can be easily removed by simply pulling it away from the coupling element  40 . 
         [0158]    Axially extending ribs  6  are arranged on an interior surface of the cap  4  for engagement with the ratchet arms  32 , providing for a unidirectional rotational coupling between the cap  4  and the syringe holder  30 , ensuring that the cap  4  and the syringe holder  30  are locked against relative rotation during unscrewing of the cap  4  from the exterior thread  42 . The exterior thread  42  is a right-hand thread and the interior thread  41  is a left-hand thread, so when the cap  4  is unscrewed from the exterior thread  42 , and the cap  4  thereby is moved axially away from the coupling element  40 , the exterior thread  31  is screwed further into the interior thread  41 , whereby the syringe holder  30  is moved axially in the opposite direction towards the vial  20 , while the ratchet arms  32  slide along the ribs  6 . Because the pitch of the interior thread  41  is greater than the pitch of the exterior thread  42  the syringe holder  30 , and thereby the syringe  10 , moves axially a longer distance towards the vial  20  than the cap  4  moves away from the coupling element  40  during unscrewing of the cap  4  from the exterior thread  42 . The pitch difference in the present embodiment is designed to move the exterior thread  31  to the end of the interior thread  41 , and thereby to establish a fluid connection between the syringe  10  and the vial  20 , upon less than one full revolution of the cap  4  relative to the coupling element  40 . 
         [0159]    As can be seen from the figure, in this state of the mixing device  1  the hollow spike member  52  has penetrated the penetrable section  24  and entered partly into the vial interior  28  and the hollow spike member  53  has penetrated the penetrable section  61  and entered partly into a chamber provided in the syringe stopper  60  between the penetrable section  61  and the filter  69 . The syringe interior  18  and the vial interior  28  are thereby in fluid communication via a lumen  55  extending through the respective spike members  52 ,  53  and the spike base  54 . 
         [0160]    In  FIG. 4  the cap  4  has been removed from the coupling element  40  and the piston rod  14  is operable for firstly driving the solvent out of the syringe  10  and into the vial  20  and subsequently withdrawing the reconstituted product from the vial  20  back into the syringe  10 . 
         [0161]      FIG. 5  is a close-up perspective view of a portion of the mixing device  1  showing the operative coupling between the cap  4  and the syringe  10 . For the sake of clarity a portion of the cap  4  has been cut away to reveal the engagement of one of the ratchet arms  32  with one of the ribs  6 . This ratchet mechanism will cause the cap  4  to slave the syringe holder  30 , and thereby the syringe  10 , when turned in the counter-clockwise direction, whereas the ribs  6  will ride over the ratchet arms  32  when the cap  4  is turned in the clockwise direction, enabling relative rotational movement between the cap  4  and the syringe holder  30  when the cap  4  is screwed onto the exterior thread  42 . 
         [0162]      FIG. 6  is a transverse section view along line A-A of  FIG. 3 , showing more clearly the interaction between the ribs  6  and the ratchet arms  32 . It further shows the rotational lock between the syringe holder  30  and the stopper retainer  70 . As can be seen the protrusions  72  fit into respective indentations  33  in the central portion of the syringe holder  30 , whereby the stopper retainer  70  is forced to follow any rotational motion of the syringe holder  30 . 
         [0163]      FIGS. 7   a  and  7   b  sketch the operative coupling between a cap  4 ′ and a container holder  30 ′ via a coupling element  40 ′ in relation to a mixing device according to an alternative embodiment of the invention. For the sake of clarity both receptacles have been left out of these illustrations, but it is clear that during normal use the container holder  30 ′ carries a substance holding receptacle in line with what is described in connection with the previous embodiment. The principle of the operative coupling between the cap  4 ′ and the container holder  30 ′ is the same as between the cap  4  and the syringe holder  30 , except that in this embodiment there is a 1:1 relationship between axial movements of the cap  4 ′ and the container holder  30 ′ during unscrewing of the cap  4 ′ from the coupling element  40 ′. 
         [0164]    The cap  4 ′ has an internal thread  5 ′ structured for mating engagement with an external thread  42 ′ on the coupling element  40 ′, and the container holder  30 ′ has an external thread  31 ′, of the same pitch as that of the internal thread  5 ′, structured for mating engagement with an internal thread  41 ′ in the coupling element  40 ′. The container holder  30 ′ is further provided with a flange  32 ′ adapted for sliding abutment with a rib  6 ′ on the inner surface of the cap  4 ′. When the cap  4 ′ is caused to perform a counter-clockwise rotation in the direction T relative to the coupling element  40 ′ the rib  6 ′ abuts the flange  32 ′ and slaves the container holder  30 ′ in the same direction. The interior thread  41 ′ is a left-hand thread and the exterior thread  42 ′ is a right-hand thread, so when the cap  4 ′ is thus rotated counter-clockwise relative to the coupling element  40 ′ the cap  4 ′ moves axially upwards in the direction R, while the container holder  30 ′ moves axially downwards in the direction A. 
         [0165]      FIG. 8  is a perspective view of the syringe holder  30  showing a notch  34  approximately half-way down the thread  31 . The notch  34  is adapted for engagement with the flexible lock arm  44  during assembly of the mixing device  1  when the exterior thread  31  is screwed into the interior thread  41  and serves specifically to position the syringe holder  30  relative to the coupling element  40 . When the flexible lock arm  44  slides along the distal most portion of the exterior thread  31  during the initial engagement it is deflected out of its relaxed state, and when it reaches the notch  34  it abruptly returns to the relaxed state, preventing a reverse relative rotational motion between the syringe holder  30  and the coupling element  40  beyond that point. Thereby, the exact axial position of the syringe holder  30  relative to the coupling element  40  can be determined in the assembly process which again provides for a correct axial positioning of the ratchet arms  32  relative to the ribs  6 . 
         [0166]      FIG. 9  is a longitudinal section view of the mixing device  1  after use, i.e. after mixing of the solvent and the powdered drug and parenteral delivery of the final product from the syringe  10  via suitable delivery means such as an infusion set or a cannula. The syringe  10  has been re-inserted in the syringe holder  30  and the cap  4  has been re-mounted onto the coupling element  40 . Since the syringe  10  is now empty only a small portion of the piston rod  14  projects from the barrel  11  which leaves a free storage space  99  between the push face  15  and the proximal portion of the cap  4 . The storage space  99  is intended for reception of items used in connection with the administration of the drug, particularly of the used delivery means. The mixing device  1  is therefore applicable as a sharps container after use. 
       Operation of the Mixing Device Represented by FIGS. 1-9 
       [0167]    In the following a situation of use of the mixing device  1  will be described. In order to gain access to the piston rod  14  a subject user grips the lock ring  3  and holds it between two or more fingers of one hand. She or he then grips the cap  4  with the other hand and makes a turning motion to unscrew the interior thread  5  from the exterior thread  42 . The cap  4  will be released from the coupling element  40  upon less than one full relative revolution. During the relative rotation of the cap  4  and the coupling element  40  the ribs  6  engage the ratchet arms  32  to thereby slave the syringe holder  30 . Due to the interior thread  41  being a left-hand thread and the exterior thread  42  being a right-hand thread, the syringe holder  30  is forced downwards towards the vial  20  as the cap  4  moves upwards away from the lock ring  3 . The engagement between the lock snap  74  and the protrusions  72  will cause the stopper retainer  70  to move downwards with the syringe holder  30 , and since the syringe  10  is threadedly coupled with the stopper retainer  70  via the Luer collar  13  and the threaded inner portion  71  the syringe  10  will be forced to follow the downward movement of the syringe holder  30 . 
         [0168]    The connector piece  50  is held in the distal portion of the syringe holder  30  by a friction fit and as the exterior thread  31  travels along the interior thread  41  during the relative rotational motion between the cap  4  and the coupling element  40 , and the syringe  10  and the vial  20  are thereby gradually brought closer to one another, the connector piece  50  will move further into the distal portion of the syringe holder  30 . During the travel of the exterior thread  31  in the interior thread  41  the hollow spike member  52  will be pressed against the penetrable section  24  and the hollow spike member  53  will be pressed against the penetrable section  61 . Further converging motion of the syringe  10  and the vial  20  will eventually cause the hollow spike member  52  to penetrate the penetrable section  24  and the hollow spike member  53  to penetrate the penetrable section  61  to thereby establish fluid communication between the syringe interior  18  and the vial interior  28 . When the exterior thread  31  has travelled to the end of the interior thread  41  the hollow spike member  52  resides within a hollow of the vial stopper  23  distally of the penetrable section  24 , and the hollow spike member  53  resides within a space  68  in the syringe stopper  60  delimited by the penetrable section  61  and the filter  69 . In the course of entry of the hollow spike member  53  into the space  68  the circumferential sealing lip  62  slides along the interior wall of the sleeve body  51 . One or more vents  59  in the form of axially extending ribs on the interior wall of the sleeve body  51  allow the compressed air in the compartment  56  to escape as the syringe stopper  60  is moved into abutment with the spike base  54 . The vents  59  extend from the spike base  54  and end just distally of the initial, pre-use position of the syringe stopper  60 . Thereby, the compartment  56  can be maintained sterile until use of the mixing device  1 , while the syringe stopper  60  during use can be moved relative to the sleeve body  51  without resistance from entrapped air. 
         [0169]    The thread engagement between the exterior thread  42  and the interior thread  5  is longer than the thread engagement between the exterior thread  31  and the interior thread  41 , so when the exterior thread  31  has travelled to the end of the interior thread  41  and fluid communication has been established between the syringe interior  18  and the vial interior  28  via the lumen  55  the cap  4  is still not released from the coupling element  40 . Hence, it is guaranteed that the user cannot accidentally apply pressure to the syringe interior  18  through operation of the piston rod  14  until fluid communication is properly established between the syringe  10  and the vial  20 . 
         [0170]    During subsequent dismounting movement of the interior thread  5  along the exterior thread  42 , the engagement between the ribs  6  and the ratchet arms  32  will still transfer the rotation of the cap  4  to the syringe holder  30 . However, as the exterior thread  31  is no longer capable of relative motion with respect to the interior thread  41 , the syringe holder  30  and the coupling element  40  are forced to perform a joint rotational motion relative to the lock ring  3 . This is enabled by the cam  91  moving in the bayonet groove in the exterior surface of the coupling element  40 . The rotation of the coupling element  40  relative to the lock ring  3  causes a relative rotational motion between the coupling element  40  and the vial holder  2 . Because the coupling element  40  is prevented from translational motion relative to the lock ring  3  and because the vial holder  2  is prevented from rotating relative to the lock ring  3  this relative rotational motion between the coupling element  40  and the vial holder  2  causes the interior thread  7  to travel along the exterior thread  43 , whereby the vial holder  2  is forced upwards towards the syringe holder  30 . Thereby, the connection between the vial  20  and the coupling element  40  is tightened because the vial holder  2  presses the vial  20  against the transversal portion of the coupling element  40 . This eliminates the risk of production tolerances being the cause of a loose connection between the hollow spike member  52  and the vial  20 . 
         [0171]    The joint rotation of the syringe holder  30  and the coupling element  40  is relatively small as it corresponds to the last part of the rotation of the cap  4  that releases the interior thread  5  from the exterior thread  42 . When the cap  4  is released from the exterior thread  42  it can be removed to expose the syringe  10  for operation. At this point the user holds the mixing device  1  such that the syringe  10  faces upwards. By depression of the piston rod  14  the piston  19  is advanced in the barrel  11  to force the solvent out through the Luer  12 , further through the lumen  55  and into the vial  20 , where it mixes with the powdered drug. The mixing device  1  is then turned up-side down and the piston rod  14  is gradually released to allow the built up pressure in the vial  20  to cause or assist a transfer of the mixed product out of the vial  20 , through the lumen  55  and into the syringe  10 . Alternatively, or additionally, the piston rod  14  is pulled backwards in the barrel  11  to cause or assist the transfer of the mixed product from the vial  20 . 
         [0172]    Once the mixed product is fully contained within the syringe  10 , the syringe  10  is removed from the rest of the arrangement. This is done by gripping the syringe holder  30  with one hand and the collar  17  with the other hand and then rotating the syringe  10  relative to the syringe holder  30 . Because of the locking engagement between the protrusions  72  and the indentations  33  when the syringe  10  is rotated relative to the syringe holder  30  the Luer collar  13  is screwed out of engagement with the threaded inner portion  71 . A circumferential groove  63  in the syringe stopper  60  is engaged by a mating ridge  73  on the stopper retainer  70  to lock the syringe stopper  60  against axial movement relative to the stopper retainer  70 . Thereby, when the Luer collar  13  is released from the threaded inner portion  71  the syringe  10  can be easily removed from the stopper retainer  70 , leaving the syringe stopper  60  in the remaining part of the mixing device  1 . Thus, the syringe  10  is ready for connection with e.g. a cannula or a catheter immediately upon removal from the arrangement, without the user having to manually detach the syringe stopper  60  from the Luer  12  first. This reduces the number of manual steps to be performed even further. The wings  81  can be unfolded to provide for a better grip of the syringe  10  during the following administration. 
         [0173]    After completed administration the user may re-install the syringe  10  in the syringe holder  30  by attaching the Luer collar  13  to the threaded inner portion  71 . The used cannula and/or catheter may be placed in the cap  4 , whereafter the cap  4  may be re-mounted on the coupling element  40 . Since the piston rod  14  is now fully depressed in the barrel lithe storage space  99  is sufficiently large to accommodate such items. During the re-mounting of the cap  4  on the coupling element  40  the ribs  6  will ride over the ratchet arms  32  as the interior thread  5  is screwed onto the exterior thread  42 . Once the cap  4  is repositioned on the coupiing element  40  it cannot be removed again because a dismounting movement of the interior thread  5  relative to the exterior thread  42  would cause the ribs  6  to engage the ratchet arms  32  to slave the syringe holder  30  in the direction of rotation of the cap  4 . However, as the exterior thread  31  is at the end of the interior thread  41 , the syringe holder  30  is not capable of performing any further rotation in that direction, and the cap  4  is thereby locked on the coupling element  40 . The mixing device  1  is thus also applicable as a safe, disposable sharps container after completed administration of the mixed product. 
         [0174]      FIG. 10  is an exploded perspective view of a mixing device  100  for reconstitution of a powdered drug in a vial  120  using a solvent from a syringe  110 . The vial  120  comprises a wall  121  having an opening which is sealed by a vial stopper  123  (not visible in this view) and a seal cap  122  having a central opening which exposes a penetrable portion  124  of the vial stopper  123 . The vial  120  is arranged in a rigid vial holder  102  which serves to protect the vial  120  from mechanical impacts. A lock ring  103  is translationally and rotationally fixed to the vial holder  102  and is arranged to encircle a distal portion of a coupling element  140  which carries a proximal cap receiving portion in the form of an exterior thread  142 . 
         [0175]    In the disclosed embodiment the wall  121  is made of glass and the vial holder  102  is made of a transparent plastic. Other suitable materials may, however, be chosen depending on the specific application of the mixing arrangement  100 . 
         [0176]    The syringe  110  comprises a barrel  111 , the outlet of which is surrounded by a threaded Luer collar  113  and sealed by a syringe stopper  160  (not visible in this view). A user manipulable piston rod  114  having a push face  115  for easy operation is adapted to drive a piston  119  (not visible in this view) inside the barrel  111 . At its proximal end portion the barrel  111  carries a flange  80  which serves as an enlarged transversal section to offer a more ergonomic grip of the syringe  10  as well as a mechanical stop to prevent the piston rod  114  from being pulled completely out of the barrel  111 . 
         [0177]    The syringe  110  is supported by a syringe holder  130  to which it is translationally and rotationally releasably fixed via a stopper retainer  170 . The syringe holder  130  comprises a track follower  131 , designed to travel a suitable helical track, and is configured to accommodate a connector piece  150  comprising a spike base  154  from which a distally pointing hollow spike member  152  (not visible in this view) extends towards the vial  120  and a proximally pointing hollow spike member  153  (not visible in this view) extends towards the syringe  110 . The spike member  153  is covered by a penetrable sheath  186  which is sealingly connected to a proximal face of the spike base  154 . Likewise, the spike member  152  is covered by a penetrable sheath  187  which is sealingly connected to a distal face of the spike base  154 . The spike base  154  further carries a plurality of proximally pointing stabilising fingers  188 . 
         [0178]    A cap  104  is adapted to cover the syringe  110  during storage and transportation of the mixing device  100  to prevent unintended operation of the piston rod  114  and thereby to ensure that pressure is not prematurely applied to the contents of the syringe  110 . The cap  104  has a distal cap end portion  104   a  which holds a distal interior thread section  105  (not visible in this view) adapted for engagement with the exterior thread  142  and a proximal interior thread  141  (not visible in this view) for engagement with the track follower  131 . The cap further has a proximal cap end portion  104   b  which is coupled with the piston rod  114  in a manner that will be explained below. 
         [0179]      FIG. 11  is a longitudinal section view of the mixing device  100  in the assembled state, prior to a first use thereof, showing further details of the arrangement. This state corresponds to the one in which the mixing device  100  is intended to be delivered by the manufacturer. The piston rod  114  is in a retracted position in the barrel  111 , thereby defining a syringe interior  118  capable of holding a volume of a solvent (not shown). The piston rod  114  is coupled firmly to the piston  119  via a jagged coupling head  116 . 
         [0180]    The piston rod  114  comprises an outer tube  114   a , which is translationally locked with respect to the coupling head  116 , and an inner tube  114   b  which is axially slidable relative to the outer tube  114   a . The inner tube  114   b  has a couple of radially deflectable distal sections  114   c , each terminating in a radially outwardly protruding portion  114   d , forming a hook. In a non-loaded condition of the inner tube  114   b  the radial dimension across the outwardly protruding portions  114   d  is larger than the inner diameter of the outer tube  114   a . Hence, in the shown pre-use state of the mixing device  100  the outwardly protruding portions  114   d  are biased towards the inner wall of the outer tube  114   a  due to the distal sections  114   c  being elastically inwardly deflected by the contact between the outwardly protruding portions  114   d  and the inner wall of the outer tube  114   a . The outwardly protruding portions  114   d  are configured to slide along the inner wall of the outer tube  114   a  during extension of the piston rod  114  until they reach respective side apertures  114   k  in the outer tube  114   a . The side apertures  114   k  are adapted to receive the outwardly protruding portions  114   d  as they are forced thereinto when the distal sections  114   c  relax at the relative axial position of the outer tube  114   a  and the inner tube  114   b  that defines the extended state of the piston rod  114  (see  FIG. 12 ). 
         [0181]    A protrusion  104   c  extends distally from the proximal cap end portion  104   b  of the cap  104  and terminates in a radially enlarged knob  104   d  positioned just distally of a pair of radially inwardly protruding end portions  114   e  of the inner tube  114   b . The radially inwardly protruding end portions  114   e  are arranged on respective radially deflectable fingers  114   h  (see  FIG. 14 ) at the proximal end portion of the inner tube  114   b.    
         [0182]    A Luer  112 , defining an outlet of the syringe  110 , protrudes into the distal portion of the syringe holder  130  and is retained therein via a screw thread connection between the Luer collar  113  and a threaded portion  171  of a stopper retainer  170 . The stopper retainer  170  is translationally and rotationally locked with respect to the syringe holder  130 , i.a. via a plurality of circumferentially spaced apart pawls  138 , and the syringe stopper  160  is translationally locked with respect to the stopper retainer  170  by a wedge portion  173 . This is described in further detail below. A proximal portion of the syringe stopper  160  is sandwiched between the Luer  112  and the threaded portion  171  and thereby provides a fluid tight engagement with the exterior surface of the Luer  112 . A distal portion of the syringe stopper  160  has a penetrable section  161  allowing for easy rupturing of the syringe sealing by a suitable tool. 
         [0183]    The connector piece  150  is accommodated by the syringe holder  130 , as described further below, and is arranged axially between the syringe  110  and the vial  120  such that the spike member  152  is positioned just proximally of, but spaced apart from, the penetrable portion  124  of the vial stopper  123 , and the spike member  153  is positioned just distally of, but spaced apart from, the penetrable section  161  of the syringe stopper  160 . The syringe  110  and the vial  120  are therefore fluidly unconnected at this point. 
         [0184]    The connector piece  150  has been sterilised before assembly of the medical device  100 , such that the sheath  186 , formed from a material which is permeable to e.g. a sterilisation gas but impermeable to germs, provides a sealed space  156  for the spike member  153  having a high airborne particulate cleanliness, and such that the sheath  187 , formed from the same or a like material as the sheath  186 , provides a sealed space  157  for the spike member  152  having a similarly high airborne particulate cleanliness, thereby ensuring a sterile flow route through a lumen  155  (see  FIG. 12 ) defined by the two hollow spike members  152 ,  153  and the spike base  154 . 
         [0185]    The coupling element  140  has a number of circumferentially spaced apart catch arms  145  extending upwards from a circumferential interior portion and a number of circumferentially spaced apart abutment surfaces  144  (see  FIG. 12 ) for securing translational retainment of the vial  120 . The coupling element  140  is itself translationally fixed with respect to the lock ring  103  via a plurality of circumferentially distributed edges  191 . A sealing ring  199 , e.g. made from a suitable rubber, is arranged between the lock ring  103 , the coupling element  140 , and the distal cap end portion  104   a  to provide a fluidly sealed internal environment for the syringe  110 , the connector piece  150 , and the vial  120  in the pre-use state of the mixing device  100 . The wall  121  defines a vial interior  128  capable of holding an amount of powdered drug (not shown) to be reconstituted by the solvent from the syringe  110 . 
         [0186]      FIG. 12  shows the mixing device  100  during dismounting of the cap  104  from the cap receiving portion of the coupling element  140 . The interior thread section  105  is not yet completely disengaged from the exterior thread  142 , so the cap  104  is only loosened. During the travel of the interior thread section  105  along the exterior thread  142  the track follower  131  has travelled along the interior thread  141 , displacing the syringe holder  130 , and thereby the syringe  110 , distally towards the vial  120 . During the first part of the distal displacement of the syringe holder  130  the spike member  152  has penetrated the sheath  187  and the penetreble portion  124  of the vial stopper  123 . Subsequently, the spike member  153  has penetrated the sheath  186  and is, in the shown state of the mixing device  100 , transpiercing the penetrable section  161  of the syringe stopper  160 , i.e. a fluid connection between the syringe interior  118  and the vial interior  128  is yet only close to being properly established. Further, the distal displacement of the syringe  110  relative to the coupling element  140  and the proximal displacement of the cap  104  relative to the coupling element  140  have caused the knob  104   d  to interface with the inwardly protruding end portions  114   e  and pull the inner tube  114   b  proximally relative to the outer tube  114   a , whereby the outwardly protruding portions  114   d  has slid axially along the inner wall of the outer tube  114   a  until they have reached the side apertures  114   k . At this point the deflectable distal sections  114   c  have forced the outwardly protruding portions  114   d  into engagement with the side apertures  114   k  to thereby interlock the outer tube  114   a  and the inner tube  114   b , securing an extended state of the piston rod  114 . 
         [0187]    The piston rod  114  is designed such that the friction between the outer tube  114   a  and the inner tube  114   b  is significantly lower than the friction between the piston  119  and the barrel  111 , whereby it is ensured that the dismounting of the cap  104  from the cap receiving portion and the induced extension of the piston rod  114  does not affect the position of the piston  119  in the syringe  110 . 
         [0188]    Further unscrewing of the cap  104  will displace the syringe holder  130  a little further distally to allow the spike member  153  to completely penetrate the syringe stopper  160  and thereby ensure proper establishment of a fluid communication between the syringe interior  118  and the vial interior  128 . The last part of the relative axial motion between the syringe  110  and the cap  104  will also cause the knob  104   d  to elastically deflect the fingers  114   h  radially outwards to allow complete disengagement of the protrusion  104   c  from the inner tube  114   b  and thereby of the cap  104  from the syringe  110 . 
         [0189]      FIG. 13  shows the mixing device  100  after removal of the cap  104  and collapse of the syringe interior  118  by depression of the piston rod  114 . The solvent originally contained in the syringe  110  has now been transferred to the vial  120  for reconstitution of the powdered drug therein. 
         [0190]      FIG. 14  is a perspective view of the extendable piston rod  114  between its collapsed and extended states. It is i.a. seen that the deflectable fingers  114   h  are formed in the inner tube  114   b  by the provision of parallel longitudinal slits  114   g.    
         [0191]      FIG. 15   a  is a perspective proximal view of the distal cap end portion  104   a , showing the proximal interior thread  141 . An arrowhead  195  on the exterior surface informs the user of the dismounting direction of rotation of the cap  104  relative to the lock ring  103 . Further, to improve the user&#39;s grip on the cap  104  longitudinal grooves  196  are distributed about the circumference of the distal cap end portion  104   a . Corresponding grooves may be provided on the exterior surface of the lock ring  103 . 
         [0192]      FIG. 15   b  is a perspective distal view of the distal cap end portion  104   a , showing the distal interior thread section  105 . By comparison with  FIG. 15   a  it is clear that the pitch of the distal interior thread section  105  is significantly smaller than the pitch of the proximal interior thread  141 . 
         [0193]      FIG. 16   a  is a perspective proximal view of the syringe holder  130 , detailing its particular configuration. Three track followers  131  are distributed evenly about the circumference of a base ring  135 , each track follower  131  comprising an inclined leading face  131   a  and a similarly inclined trailing face  131   b  arranged to fit in the interior thread  141 . Six legs extend distally from the distal portion of the base ring  135  and together form a tubular skeletal structure. There are three supporting legs  137  and three guiding legs  136  distributed circumferentially in an alternating fashion. Each supporting leg  137  comprises a support surface  137   a  for interaction with the distal face of the spike base  154 , and each guiding leg  136  comprises an abutment surface  136   a  axially spaced apart from the support surfaces  137   a  for interaction with the proximal face of the spike base  154 . The axial distance between the support surfaces  137   a  and the abutment surfaces  136   a  correspond to the thickness of the spike base  154 , and the support surfaces  137   a  and the abutment surfaces  136   a  thus together function as axial retention means for the connector piece  150 . The distal end portion of each guiding leg  136  is provided with a transverse beam structure  136   b  of circumferentially larger dimension than the rest of the guiding leg  136 . 
         [0194]      FIG. 16   b  is a perspective distal view of the syringe holder  130 . From this figure it is seen that the transverse beam structures  136   b  are arranged to provide circumferential protrusions  136   c  from both sides of the guiding legs  136 . 
         [0195]      FIG. 17   a  is a top view of the syringe holder  130 , showing a pair of opposed circumferentially spaced apart vertical stop surfaces  133   a ,  133   b  that provide a recess  133  for rotational retention of the stopper retainer  170 , three circumferentially evenly distributed distally pointing ratchet arms  138  and three circumferentially evenly distributed proximally pointing ratchet arms  139 . 
         [0196]      FIG. 17   b  is a bottom view of the syringe holder  130 . It shows that the proximally pointing ratchet arms  139  are arranged on the supporting legs  137 . 
         [0197]      FIG. 18  is a perspective view of the stopper retainer  170 . It shows the threaded portion  171  arranged on a connecting pipe having a central opening  179  for reception of the syringe stopper  160  and the Luer  112 . The stopper retainer  170  further comprises a stepped cylindrical frame  175  carrying the wedge portion  173  and a pair of circumferentially spaced apart vertical walls  172   a ,  172   b  adapted for interaction with the stop surfaces  133   a ,  133   b.    
         [0198]      FIG. 19  is a perspective view of the syringe stopper  160  which has a proximal tubular section  169  for reception of the Luer  112 , a central collar  164  and a distal collar  165 . The wall portion connecting the central collar  164  and the distal collar  165  is conical and structured to receive the wedge portion  173  for translational retention of the syringe stopper  160  to the stopper retainer  170 . 
         [0199]      FIG. 20   a  is a side view of the coupling element  140 , showing a plurality of circumferentially distributed lugs  148  for engagement with the edges  191  for translational fixation of the lock ring  103  to the coupling element  140 . A circumferential narrowing  149  is provided for reception of the sealing ring  199 . A plurality of guide structures  146  are provided for interaction with the guiding legs  136  during a relative axial motion between the coupling element  140  and the syringe holder  130 , as will be explained in further detail below. 
         [0200]      FIG. 20   b  is a perspective distal view of the coupling element  140  and shows three circumferentially spaced apart longitudinal channels  143 , each channel  143  being adapted to allow passage of one of the guiding legs  136  during relative axial motion between the coupling element  140  and the syringe holder  130 , and three longitudinal passages  147 , each passage  147  being adapted to allow passage of one of the supporting legs  137  during relative axial motion between the coupling element  140  and the syringe holder  130 . During the passage of the guiding legs  136  through the longitudinal channels  143  each circumferential protrusion  136   c  slides along at least a portion of a guide structure  146 . The longitudinal channels  143  and the longitudinal passages  147  provide for a splined relationship between the coupling element  140  and the syringe holder  130 , i.e. allowing only non-rotational relative motion therebetween. 
         [0201]      FIG. 21  is a perspective cross-sectional view of the coupling element  140 , detailing the configuration of the guide structures  146 . Each guide structure  146  comprises a proximal straight, vertical (or substantially vertical) guide surface  146   a , and a distal straight, vertical (or substantially vertical) guide surface  146   c , that are bridged by an inclined guide surface  146   b . Further, at the distal end portion of the distal guide surface  146   c  a ramp  146   d  is provided which connects the distal guide surface  146   c  with a stop surface  146   e.    
         [0202]    Operation of the Mixing Device Represented by  FIGS. 10-21   
         [0203]    In the following a situation of use of the mixing device  100  will be described. The user actions required to fluidly connect the syringe  110  and the vial  120 , reconstitute the powdered drug, and remove the syringe  110  from the syringe holder  130  are identical to what is described above in connection with the mixing device  1 . However, the response of the mixing device  100  to at least some of the user actions is different from that of the mixing device  1 , as will be clear from the below. 
         [0204]    In order to gain access to the piston rod  114  and transfer the solvent from the syringe interior  118  to the vial interior  128  a subject user firstly grips the mixing device  100  by the lock ring  103  and holds the lock ring  103  between two or more fingers of one hand, preferably with the syringe  110  pointing upwards. She or he then grips the cap  104  with the other hand and makes a turning motion in the direction of the arrowhead  195  to unscrew the interior thread  105  from the exterior thread  142 . The cap  104  will be released from the coupling element  140  upon half a revolution. 
         [0205]    During the dismounting motion of the cap  104  relative to the cap receiving portion (constituted by the exterior thread  142 ) the track followers  131  travel along the interior thread  141 , and the syringe holder  130 , being splined to the coupling element  140  via the interaction between the guiding legs  136 , respectively the supporting legs  137 , and the channels  143 , respectively the passages  147 , is forced non-rotationally downwards towards the vial  120 . Because the syringe  110  is translationally locked with respect to the stopper retainer  170 , due to the connection between the Luer collar  113  and the threaded portion  171 , and the stopper retainer  170  is translationally locked with respect to the syringe holder  130 , due to the fixation of the distal end portion of the stepped cylindrical frame  175  between the ratchet arms  138 ,  139 , the syringe  110  is displaced downwards along with the syringe holder  130 . 
         [0206]    The downward movement of the syringe holder  130  causes a downward movement of the connector piece  150  due to the fixation of the spike base  154  between the abutment surfaces  136   a  and the support surfaces  137   a . The distally directed force on the proximal face of the spike base  154  applied by the abutment surfaces  136   a  will cause the spike member  152  to encounter the vial stopper  123 , penetrate the sheath  187  and the penetrable portion  124  and enter into the vial interior  128 . As this happens, the circumferential protrusions  136   c  travel along the vertical guide surfaces  146   a . Following complete penetration of the penetrable portion  124  the further downward movement of the syringe holder  130  causes the circumferential protrusions  136   c  to reach and travel the inclined guide surfaces  146   b , whereby the guiding legs  136  are forced to deflect radially outwards, freeing the proximal face of the spike base  154  from the abutment surfaces  136   a . During the subsequent downward movement of the syringe holder  130  the connector piece  150  therefore undergoes relative axial motion with respect to the guiding legs  136 , whereby the spike member  153  is eventually brought into contact with the syringe stopper  160  and caused to penetrate the sheath  186  and the penetrable section  161 . As this happens, the circumferential protrusions  136   c  travel along the vertical guide surfaces  146   c.    
         [0207]    Following complete penetration of the penetrable section  161  and thereby establishment of a fluid communication between the syringe interior  118  and the vial interior  128  a small final downward movement of the syringe holder  130  causes the circumferential protrusions  136   c  to pass over the ramps  146   d  and snap behind them, whereupon the stop surfaces  146   e  act to prevent any return movement of the guiding legs  136  in the channels  143 , effectively locking the syringe holder  130  axially to the coupling element  140 . 
         [0208]    Simultaneously with, or subsequent to, the locking of the syringe holder  130  to the coupling element  140  the interior thread  105  disengages from the exterior thread  142 , and the cap  104  is dismounted from the cap receiving portion. However, the downward displacement of the syringe holder  130  not only causes the syringe  110  and the vial  120  to fluidly connect, it also extends the piston rod  114  from the collapsed state shown in  FIG. 11  to the extended state shown in  FIG. 12 . As the stopper retainer  170  is forced downwards by the engagement with the syringe holder  130 , so is the syringe  110  containing the piston  119 . Because the outer tube  114   a  is translationally locked to the piston  119  via the coupling head  116  and the inner tube  114   b  is coupled with the cap  104  via the knob  104   d  the outer tube  114   a  is forced to move downwards a distance corresponding to the movement of the syringe holder  130 , while the inner tube  114   b  is forced to move upwards a distance corresponding to (or nearly corresponding to depending on whether an initial clearance is provided between the knob  104   d  and the end portions  114   e ) the axial movement of the cap  104  relative to the coupling element  140 . This relative axial motion between the outer tube  114   a  and the inner tube  114   b  causes the outwardly protruding portions  114   d  to slide along the inner wall of the outer tube  114   a  until they reach and snap into the side apertures  114   k . At this point the outer tube  114   a  and the inner tube  114   b  are translationally locked to one another, and the user will perceive the piston rod  114  as if it consisted of a single cylindrical piece. Further dismounting motion of the cap  104  relative to the cap receiving portion causes the knob  104   d  to deflect the fingers  114   h  radially outwards and pass the end portions  114   e , whereby the cap  104  disconnects from the piston rod  114 . 
         [0209]    The cap  104  is now both disengaged from the exterior thread  142  and the piston rod  114 , and it can thus be removed to expose the syringe  110  for operation. At this point the user holds the mixing device  100  such that the syringe  110  faces upwards. By depression of the piston rod  114  the piston  119  is advanced in the barrel  111  to force the solvent out through the Luer  112 , further through the lumen  155  and into the vial  120 , where it mixes with the powdered drug. The mixing device  100  is then turned up-side down and the piston rod  114  is gradually released to allow the built up pressure in the vial  120  to cause or assist a transfer of the mixed product out of the vial  120 , through the lumen  155  and into the syringe  110 . Alternatively, or additionally, the piston rod  114  is pulled backwards in the barrel  111  to cause or assist the transfer of the mixed product from the vial  120 . 
         [0210]    Once the mixed product is fully contained within the syringe  110 , the syringe  110  is removed from the rest of the arrangement. This may be done e.g. by gripping the lock ring  103  with one hand and the Luer collar  113  with a couple of fingers of the other hand and then rotating the Luer collar  113  relative to the syringe holder  130 . Because the stopper retainer  170  is rotationally locked with respect to the syringe holder  130 , due to the interaction between the respective vertical walls  172   a ,  172   b  and stop surfaces  133   a ,  133   b , the Luer collar  113  is easily unscrewed from the threaded portion  171 . Further, since the syringe stopper  160  is translationally fixed to the stopper retainer  170 , due to the interface of the wedge portion  173  with the central collar  164  and the distal collar  165 , when the Luer collar  113  disengages from the threaded portion  171  the syringe stopper  160  remains in the stopper retainer  170 , leaving the Luer  112  exposed. Thus, the syringe  110 , containing the administrable drug, is ready for connection with e.g. a cannula or a catheter immediately upon removal from the syringe holder  130 , without the user having to manually detach the syringe stopper  160  from the Luer  112  first, and the rest of the mixing device  100  can be discarded.