Abstract:
A device for the metered administration of a fluid drug. The device has a container having a piston for administering the fluid drug through an outlet of the container, a catheter connected to the outlet of the container, the catheter having a front end facing away from the outlet and being connected to an injection needle, and a valve positioned between the outlet and the injection needle in a flow cross section of the fluid drug, the valve having an inlet end adjacent the outlet and an outlet end adjacent the injection needle, wherein the valve permits flow of the fluid drug through the valve from the outlet to the injection needle when a fluid pressure exerted on the inlet end of the valve exceeds a pressure on the inlet end caused by the dead weight of the fluid drug.

Description:
This application claims the priority of German Patent Application No. 197 23 648.0, filed Jun. 5, 1997, which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention refers to a device for the metered administration and in particular the infusion of a fluid drug, comprising a container from which upon advancing a piston for administering said fluid drug the fluid drug is displaced in dosed manner through an outlet and a catheter connected to an outlet of said container, whose front end facing away from the outlet is connected to an injection needle, wherein a valve is positioned between the outlet and the injection needle in a flow cross section of the fluid drug and the valve, in order to prevent a self-discharge, only permits the flow to the front end of the catheter if the fluid pressure exerted in this direction exceeds a pressure on the valve caused by the dead weight of a fluid column in the device. 
   2. Description of the Related Art 
   In known infusion systems, the drug to be administered is stored in a container, normally an ampule, containing a carrier fluid in which the drug is dissolved—hereinafter referred to as fluid drug—between a movable piston and a container outlet. The rear end of a catheter is connected to the container outlet. The front catheter end contains an injection needle for administering the fluid drug into a human or animal body, which in most cases often remains there for the administration over several days. Where the fluid drug container is located at a greater height than the front end of the catheter or the needle, there is the danger that with sufficient height difference between the container and the front end of the catheter, the container could discharge itself as a result of the force of the fluid column. 
   In case of insulinisation, where portable infusion devices are used, i.e. pump devices, used catheters can exceed a length of 1 m. The longest catheter currently used with an infusion device has a length of some 1.1 m. Where the device with the container is vertically arranged above the user, i.e. during night time, this creates a hydrostatic base pressure of approx. 0.1 bar, if apart from the purely statistical pressure due to the dead weight of the fluid drug, no further effects such as frictional losses, discharge or capillary effects are considered and a density equal to that of water is assumed for the fluid drug. 
   In order to prevent the undesired discharge as a result of the fluid column pressure, the side friction between the piston displaceably arranged in the container and the container wall could be increased, which, however, would lead to other disadvantages. As a further solution the piston could be attached to the driven member, thus preventing a lowering of the fluid surface in the container and consequently a self-discharge. In known systems, the piston is screw-fitted to the driven member. This, however, adversely affects the cost of the device. This solution can also not be used for ready-to-use ampules as the piston is not prepared for a screw connection. 
   SUMMARY OF THE INVENTION 
   The invention has the task to provide a device for the metered administration of a fluid drug from a fluid container in which an uncontrolled discharge under conditions experienced in the daily operation is prevented. 
   This task is solved by a valve which is positioned between the outlet and the injection needle in a flow cross section of the fluid drug and which valve, in order to prevent a self-discharge, only permits the flow to the front end of the catheter if the fluid pressure exerted in this direction exceeds a pressure on the valve caused by the dead weight of a fluid column in the device. 
   The invention is based on a device for the dosed administration of a fluid drug, in which the drug is held in a container from which it is displaced in a dosed manner for administration by the advancing of a piston, movably held in the container, towards a container outlet. The rear end of such a catheter is directly connected to the outlet of the container via an outlet section or piece provided for the connection of a catheter. Usually, hose-shaped catheters are used. Rigid catheters could, however, also be used. The free front end of the catheter is connected to an injection needle for the administration of the drug or can be connected to said needle. The term administering refers in this instance to infusions and injections, as well as a combination of both types of administration. The invention is particularly relevant for the use with infusion elements or devices. These preferably consist of portable devices for insulin treatment. 
   According to the invention a valve for administering a drug is positioned in a flow cross-section of the fluid drug between the container outlet and the injection needle. In order to prevent a self-discharge, the valve is dimensioned in such a way that a flow to the front end of the catheter is only possible if the fluid pressure in this direction exceeds a pressure on the valve caused by the dead weight of a fluid column in the device. In case of a mass produced device for a whole range of catheters of different lengths, the valve is dimensioned for the use with the longest catheter, i.e. for the maximum possible fluid column. 
   The valve is advantageously designed as a one-way valve, ideally preventing a reflow into the container. Preferably, the valve is a return valve. 
   In order to impede the metered administration of the drug as little as possible whilst at the same time safely preventing a self-discharge, the valve is preferably designed in such a way that it only permits the flow to the front end of the catheter if the fluid pressure in this direction exceeds the maximum possible pressure of the fluid column, preferably multiplied with a safety factor. As in this case the valve is used in medical applications, the safety factor should preferably have a value of 3. With a maximum catheter length of approx. 1 m and a negligible fluid column in the container, the maximum fluid pressure at the free end of the catheter is approx. 0.1 bar, so that the valve in this case is designed to open only if a fluid pressure of 0.3 bar is exceeded. This is also the dimension for the preferred application in a portable infusion pump. 
   Although the valve could, in principle, be arranged at any point between the container outlet and an injection needle, it is preferably arranged as close as possible to the outlet of the container. In this arrangement the valve will, in case of a return valve, also effectively prevent the reflow into the container. 
   To accommodate the valve an outlet piece could, for instance, be arranged in the area of the container outlet. 
   According to a particularly preferred embodiment, the valve is arranged in a housing serving as a connection section for the catheter. The valve can consequently be easily replaced together with the catheter. 
   The valve contains a valve body as a sealing element, preferably made from elastic material, sealing in its assembled condition a feed line, i.e. sealing its at least one opening. The feed line directly in front of the valve body can be a connecting needle, piercing a membrane during the connection of the catheter to the container outlet and thus providing a fluid connection. The last section of the feed pipe with the aperture sealed by the valve body, can also be formed by the said housing in which, for instance, such a connection needle is accommodated. 
   The sealing of the flow cross section can be achieved by the effect of a sealing lip on a narrower, exactly defined contact surface formed at the valve body or at the feed line. Achieving the sealing with at least one sealing lip surrounding the at least one aperture of the feed line, has the advantage that the pressure at which the valve opens and closes, can be defined. The feed pipe arrangement has the advantage of a simple valve housing production. 
   In a further embodiment, the elastic valve body is a hollow cylinder and is attached to the feed line like a hose. The at least one sealable aperture of the feed line is arranged in a surface area of the feed pipe. The feed pipe and the valve body arranged over the feed pipe, co-operate in the manner of a bicycle tube valve. 
   A particular simple design of a valve body is a sealing stopper made from elastic material, closing the flow cross-section of a fluid drug in a stopper-like fashion. The sealing stopper can contain a pre-manufactured aperture, which during its application remains, however, closed until the said, sufficiently high fluid pressure is exerted on the sealing stopper. In order to simplify the production of the valve, the aperture is only created after the installation of the sealing stopper in the housing, by a connecting needle which when inserted into the housing initially completely pierces the sealing stopper and is then retracted to some extent so that the created aperture is sealed again by the elastic mass of the sealing stopper. 
   Further valves according to the invention contain an elastic valve body operating in the manner of a heart valve. 
   Furthermore, also a spring-loaded valve body, containing a pressure spring, could be used. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred embodiments of the invention are explained below with reference to the figures in which: 
       FIG. 1  represents a device according to the invention, including a valve, preventing an uncontrolled discharge of a drug and 
       FIGS. 2–21  represent alternative embodiments of the valve and its arrangement according to  FIG. 1 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  represents a device for the metered administration of a fluid drug. The shown embodiment can be used as a device for an infusion or an injection system. For the purpose of a preferred application only infusion and in particular the infusion of insulin will be referred to below. 
   The insulin dissolved in a carrier fluid is contained in a container or an ampule I, secured  21  on a rack or in a housing G. The ampule  1  accommodates a freely displaceable piston  2 . By advancing the piston  2  in a direction of an outlet  4  of the container  1 , insulin fluid is displaced from the ampule  1 . A driven member  3  of a preferably motorized drive element for the piston  2  affects the advancement of the piston by exerting pressure on the rear side of said piston. There is no interlocking or material connection between the driven member  3  and the piston  2 . Piston  2  is only held in the ampule  1  by the frictional forces of the side wall required to achieve imperviousness. The advancing movement of the driven member  3  and thus of the piston  2  is exactly controlled to discharge the insulin in a finely dosed manner through the outlet  4 . 
   The outlet  4  is sealed by a fluid-proof membrane  6  before the first use of the ampule  1 . Upon connection of an infusion catheter  8 , the membrane  6  is pierced by a connecting needle  7  that is arranged in the housing  20 . The housing  20  serves as a connecting section for the catheter  8 . The rear end of the catheter is attached to the conically shaped front end of the housing or of the connecting section  20 . The rear end of the connecting section  20  is screwed on or screwed in or fixed with a snap-in lock to the outlet section  5 , extending the outlet  4 . An infusion needle  9  is connected to the front, free end of the catheter  8 . 
   In this arrangement in which the infusion needle  9  is inserted by the patient into the skin and in which his pump unit including the ampule  1  has been fixed or stored with a height differential H above the injection area, for instance during night time, the pressure of the fluid column between the front end and the infusion needle  9  and the fluid surface in ampule  1  created by the height differential H is constantly exerted on the front end of the injection needle  9 . As a result of this pressure, insulin would continuously be released at the front end of the infusion needle  9 . 
   In order to prevent this, a passive one- or two-way valve  30 , and in particular a return valve is arranged in the flow cross-section of the insulin fluid within the connecting section  20 . The valve  30  only permits a flow from the outlet  4  into the catheter  8  if the fluid pressure in the direction of the infusion needle exceeds the pressure of the fluid column with a maximum height differential H by a stipulated safety factor. In cases where the valve  30  is designed as a passive one-way valve, i.e. a simple return valve, it also prevents the reflow of the fluid drug into the ampule  1  and further increases the functional safety of the pump. 
     FIG. 2  shows a first embodiment of a connecting section including a valve. The connecting section of this embodiment is made up of two parts, a first upstream housing section  10  and a second downstream housing section  20 . The complete housing  10 ,  20  is rotation symmetrical to its straight longitudinal center line, arranged in flow direction. A separating surface between the two housing sections  10  and  20  is positioned vertically to the flow direction. The separating surface accommodates a valve body  31  made of elastic material that is pressed by connecting the two housing sections  10  and  20  circumferentially along its outer peripheral edge between the two housing sections  10  and  20 . The separating surfaces are thus sealed by the valve body  31 . Furthermore, the circumference of the housing sections  10  and  20  is annually welded in position S. Subject to the material the valve body  31  is preferably incorporated in this welded connection. 
   The valve body  31  is formed by a circular membrane disc, possibly containing an axially protruding ring web. In its installed condition its central section serves as a valve disc. The circular valve disc is surrounded by one or several apertures  32 . The outer annular section provides the said fixing between the two housing sections  10  and  20 . 
   The two housing sections  10  and  20  both contain a central bore  13  and  21 . The bores  13  and  21  are flush. In the bore of the first housing section  10  the connecting needle  7  is inserted and attached in an upstream housing cone  11 . In order to achieve a swirl-free flow, the bore in the first housing section  10  is of a diameter corresponding to the external diameter in its upstream section and to the internal diameter of the needle  7  in its connected downstream section. This not only creates a feed line  13  with a continuous smooth wall, but also a shoulder  12  against which the downstream end of the needle  7  abuts. At the downstream end of the feed line  13  the first housing section  10  forms a web surrounding the line aperture  13   a  in form of a sealing lip  15 , whose face is preferably rounded. 
   The valve body  31  is pretensioned over the circular sealing lid  15 . For this purpose, the inside of the first housing section  10  tapers off against the direction of the flow from the sealing lip  15  protruding into the flow direction. The sealing lip  15  is thus surrounded by a tapered ring surface  14 . Like the sealing lip  15 , the circular area  14  is surrounded by a protruding annular ring  16  raised in the direction of flow from the annular surface  14  which is opposed by a respective recess on the side of the second housing section  20 . Before assembling the two housing sections  10  and  20 , the valve body  31  lies slightly distanced by the sealing lip  15  in its external circumference on the first housing section  10  and is therefore also slightly distanced from the circular surface  14 . By pressing both the housing sections  10  and  20  together, the valve body disc  31  is bent over the sealing lip  15  towards the external circumference of the circular surface  14  and is thus simultaneously pretensioned on the sealing lip  15 . The annular ring  16  pushes the valve body disc  31  into the recess of the second housing section  20 , achieving an annular clamping of the valve body disc and simultaneously a good seal. The sealing lip  15  and the valve body  31  seal a flow cross section along the circumferential narrow contact area  33  which the sealing lip  15  presses against the valve body  31 . 
   The design of the valve body  31  as a simple membrane disc and the arrangement of the sealing lip  15  on a comparatively rigid housing achieve particularly good reproducible valve characteristics as well as an easily produced elastic valve body  31 . The downstream face of the first housing section  10  over which the valve body  31  is tensioned and said valve body  31  itself are dimensioned in such a way that the valve body  31  in the position shown in assembled condition in  FIG. 2  is pressed with such a pre-tensioning force against the contact surface  33  by the sealing lip  15  that the application force in the contact surface  33  exceeds the pressure created in the device according to  FIG. 1  by the fluid column at the maximum height differential H on the flow cross-section of the sealing lip. 
   When this maximum pressure of the fluid column is exceeded by a stipulated safety factor, the valve body  31  is lifted from its seat at the sealing lip  15 . The insulin fluid can now flow through the feed line  13 , around the sealing lip  15  and through one or several apertures  32  concentrically arranged around the sealing lip  15  within the valve body  31  and can flow downstream of the valve body  31  via the bore serving as outlet line  21  into the hose catheter. In the other direction, the valve represents a secure return-flow barrier. 
   Directly behind the valve body  31  a cavity is formed in the second housing section  20  into which the housing body  31  can expand. To avoid the rear downstream side of body  31  coming into contact with the internal wall of the second housing section  20  and possibly blocking the flow apertures  32 , radially extending spacer fins  22  protrude from the internal wall of the second housing section  20  in the direction of the valve body  31 . 
     FIG. 3  shows an embodiment derived from the valve of  FIG. 2 . The function of the valve is the same as for the previous valve. The elastic valve body  31  is in this embodiment formed by a membrane with a double-T-shaped circular cross-section. The ring web  31  protruding from the outer circumference of the membrane disk on both sides, serves to secure the joints of both housing sections  10  and  20 . At the same time, it represents a comparatively large forming mass for sealing the housing. In this embodiment both housing sections  10  and  20  are connected by a snap connection. For the snap connection, the second housing section  20  is inserted into the hollow cylindrical first housing section  10 , opening on the downstream side and then locked. For this purpose, the second housing section  20  contains a groove  28  in its external circumference and the first housing section  10  contains a radial circumferential locking fin  18 , radially protruding towards the inside, which engages into the groove  28 . 
   A third embodiment, in which the sealing lip is formed on the housing, is shown on  FIG. 4 . In this embodiment, the valve body  31 , according to  FIG. 2  is shown together with the snap connection shown, in principle, in  FIG. 3 . In the embodiment of  FIG. 4 , a simpler construction of the first housing section  10  is shown, in which the accommodation for the connecting needle  7  is formed by a simple bore into which, after the valve body  31  has been inserted in the first housing section  10  and both housing sections  10  and  20  have been snapped  16  together, the connecting needle  7  is inserted or pushed through up to a position relative to the surface  14  in which it tensions the subsequently inserted valve body  31  with the required tension force. For this purpose, the downstream end of the connecting needle  7  forms the sealing lip  15 . It is therefore rounded so that the valve body  31  cannot be damaged. The retrospective insertion of the needle  7  can compensate for manufacturing tolerances of the valve body  31  as the needle  7  is inserted to precisely the point at which the desired application force of the valve body  31  to the sealing lip on the needle side is achieved. With regards to the further details we refer to the description relating to  FIGS. 2 and 3 . 
     FIG. 5  also shows an embodiment in which the sealing lip  15  is provided on the housing side. As in the embodiment according to  FIG. 4 , said sealing lip is formed by the rear end of the connecting needle  7 . In contrast to the aforementioned valve constructions, the valve body  31  consisting of a circular membrane disc punched out of elastic material, does not contain any apertures. The valve body  31  is no longer tensioned on a circular ring between the housing sections  10  and  20  but instead only on some circular segments  50  and  51 , thus causing the fluid drug to be passed through the aperture channels  53  outside of the circular disc diameter of the valve body  31  and to the outlet bore  21 . 
   The pre-tensioning of the valve body  31  is in this case also carried out after the valve body  31  is inserted into a housing part and both housing parts have been assembled, by inserting the connecting needle  7  into the upstream section of the housing  10  until the valve body  31  is pretensioned to such an extent that the desired piercing pressure for the valve is achieved. 
   If the fluid pressure in the feed line  13  exceeds the application force of the valve body  31  on the sealing lip  15 , an annular flow gap is opened at the contact surface  33 . The insulin fluid can flow through this annular gap and then through the aperture channels  53  of the valve body  31  and is discharged via the aperture line  21 . 
     FIGS. 6 to 9  show further valve embodiments, in which the desired sealing or piercing characteristics are achieved with the aid of a sealing lip. In these embodiments the sealing lip is, however, provided on the elastic valve body  31 . For these examples, we also refer to the above description. Only the different characteristics are explained. 
   In the valve according to  FIG. 6 , the connecting needle  7  protrudes once again into the first housing section  10 . On the second housing section  20  opposing the downstream aperture  13   a  of the connecting needle  7 , the elastic valve body  31  is fixed with a downstream valve body extension  36  having a dove-tailed longitudinal section. The extension  36 , which widens downstream, is seated in a flange-like holding section  23  protruding from the second housing section  20  towards the connecting needle  7 . The valve body  31  is shaped like a pot opening towards the direction of flow. At the upstream edge of the pot a circumferential sealing lip  35  radially protrudes towards the inside. When installed, this sealing lip  35  seals around the external surface of the connecting needle  7 . Only when the fluid pressure on the inside of the pot exceeds the pressure exerted on the contact surface  33  formed by the pretension force on the external surface of the connecting needle  7 , a gap is released along this contact surface through which the fluid from the feed line  13  can flow into the recess in the housing  10 ,  20  around the pot-like valve body  31 . The housing cavity is connected to the outlet line  21  in the second housing section  20  via one or several and in the embodiment two apertures  21   a , which are not covered on the base of the valve body support  23 . 
   The embodiment according to  FIG. 7  shows a particularly simple housing design. The second housing section  20  consists of a hollow cylinder with a large upstream aperture and a discharge bore  21  centrally connected to it. The valve body  31  is accommodated in the aperture. The first housing section  10  is a circular cylindrical assembly insert, holding the connecting needle  7  and which is screwed in or fixed in other ways in the aperture of the second housing section  20 . 
   The valve body  31  is attached to the holding section  23  in a similar way as shown in  FIG. 6 . The valve body has a mushroom shape. The curved mushroom surface faces against the direction of flow. At its downstream circumference, the curved mushroom surface is pretensioned as a sealing lip  35  against the internal wall  24  of the aperture bore in housing  20 . 
     FIG. 8  shows an embodiment with an approximate hollow semi-spherical valve body  31 . The valve body  31  is attached to the housing in the same way as the valve bodies of  FIGS. 6 and 7 . The housing corresponds to the housing of  FIG. 7 . The valve body  31  is pressed with its upstream, circumferential face, forming the contact surface  33  against a simple planar counter surface of the assembly insertion section  10  surrounding the downstream aperture  13   a  of the feed line  13 . The valve body  31  provides a bell-shaped seal for feed line  13 . 
   The valve body  31  used for the embodiment according to  FIG. 9  differs from the previously described embodiment mainly by the fluid pressure being generated not within the sealing lip  35  but in a circular area around this sealing lip  35 , 
   In the valve body  31  according to  FIG. 9  the central aperture  32 —preferably a simple bore—is enclosed by a sealing lip  35 . The sealing lip  35  is surrounded by a tapered circular area which in turn is surrounded by ring web  34  protruding from the tapered ring surface in the same direction as the sealing lip  35 . Preferably the sealing lip  35  has been tapered itself in relation to the ring web  34 . In order to be able to pretension the valve body  31 , an annular groove in the downstream face of the first housing section  10  is formed deeper than the distance between the faces of the external ring web  34  and the sealing lips  35  in the initial condition of the valve body  31 . Upon positioning the external ring web  34  into the receiving groove of the first housing section and pressing the ring web fully into this groove, the sealing lip  35  is pressed against the planar surface of the first housing section  10  surrounded by the ring groove. The feed line  13  in the first housing section  10  is not centered in this embodiment. It ends at the downstream face within the tapered ring web at a point between the sealing lip  35  and the ring web  34  of the valve body  31 . In this way, an annular pressure area is formed. If the application pressure of the sealing lip  35 , created by the elastic pretensioning of the valve body  31 , is exceeded in this annular area, the sealing lip  35  is lifted off its counter face. A flow is then facilitated from the feed line  13  to the outlet line  21  via the circular area and the bore  32 . 
     FIGS. 10 and 11  show valves similar to bicycle tube valves. The valve bodies  37  are formed by hose sections. Both embodiments have a single-section housing  20 . The respective valve body  37  can be retained on the needle  7  or in the housing  20  or between both of these elements due to its functional design. 
   In  FIG. 10  a simple hose section  37  is placed on the downstream end of the feed line  13 . In this embodiment said end is formed by the connecting needle  7 . On its face, the feed line  13  is closed at its downstream end. The feed line  13  contains one or several radial apertures  13   a  in its end section protruding into the housing  20 , which are surrounded and consequently sealed by the hose-like valve body  37 . The face seal of the feed line  13  could also be formed by the sack-like valve body  37 , to produce the feed line  13  by cutting it from an endless hollow needle. 
   In the embodiment according to  FIG. 10  the cavity in housing  20  is lined with an elastic sealing material  37 . After the lining, the feed line  13  is pushed through the sealing material. If necessary, the sealing material can also be pre-pierced to facilitate the introduction of the feed line  13 . 
   In  FIG. 12  a two-section housing  10 ,  20  is shown in connection with the hose-like valve body  37 . The fluid from the ampule passes via a feed line  13  and via at least one connection  13   a —preferably a connection bore—to the external surface of the first housing section. Downstream of the connection  13   a , at least one further connecting channel  13   c  is arranged at the external surface of the first housing section  10 , ending in groove  13   b . At least one further connecting channel  13   c  leads to the outlet line  21  in the catheter. The connection bore  13   a  and the groove  13   b  are separated by an intermediate web formed by the outer surface of the first housing section. The valve body  37  is tightly tensioned around the outer surface of the first housing section  10  and forms a seal between the connecting bore  13   a  and the groove  13   b . The groove  13   b  is preferably a circumferential groove. 
   The embodiment of  FIG. 12  shows a particularly good external seal at the sealing surfaces  14   a ,  24   a  and  14   b ,  24   b . In these sealing areas, the first and second housing sections  10 ,  20  are provided with matching conical surfaces  14   a ,  24   a  and  14   b ,  24   b  in between which the upstream and the downstream end of the valve body  37  are clamped when joining the housing sections. The connecting bore  13   a , the interim web and the groove  13   b  leave sufficient room in the second housing section  20  for the valve body  37  to expand in order to create the flow connection between the connection bore  13   a  and the groove  13   b  once the pretension pressure has been exceeded. The dotted lines show the expanded condition of the valve body  37 . The second housing body  20  contains the pressure compensation aperture  29 , so that ambient pressure always exists around the outside of the valve body  37 . 
     FIG. 13  shows a single-section housing  20  comparable to  FIGS. 10 and 11 , containing a narrow first bore in its upstream section and, in comparison, a wider second bore in its downstream section. The first bore ends in the second and serves as a narrow guide and seat for the connecting needle  7 . A valve body in form of a simple sealing stopper  38  has been pressed or cast into the wider downstream bore. The valve is created during the insertion of the connecting needle  7 , during which the connecting needle  7  fully pierces the sealing stopper  38  and is then pulled out a little after the piercing operation. In this way an aperture  32   a  is created in the sealing stopper  38 . The valve of  FIG. 13  has the advantage that the connecting needle  7  or the feed line  13  can be created by simply cutting them from a continuous hollow needle. 
   The embodiments according to  FIGS. 14 to 16  show valves operating in a manner of a heart valve. The valve bodies  39  of  FIGS. 14 and 15  are formed by simple circular discs, incorporating slits  32   a . The housings contain an assembly insertion section  10  for insertion into the second housing section  20  with a simple inlet bore, which optionally ends in the outlet bore in the second housing section  20  via an interim stage. The downstream face of the assembly insertion section  10  presses the valve bodies  39  against the shoulder in the housing section  20  surrounding the transition between the inlet and outlet bore. 
   Whilst the valve body  39  of  FIG. 14  only contains a slit with sealing lips  32   a  formed in the direction of flow, the valve seat  39  of  FIG. 15  contains two cross slits  32   a.    
   In the arrangement according to  FIG. 16 , a cavity is arranged in the housing  20  directly downstream of the valve body  39 , into which the valve body  39  can expand. This valve body  39  also contains slits. As a result of the fluid pressure, the valve body fills like a bubble until it finally opens. It is less rigid than the valve body  39  described in  FIGS. 14 and 15 . 
     FIGS. 17 to 21  show valves whose elastic valve body  41  is tensioned by pressure springs to achieve the desired valve effect. 
   The valve body  41  of the valve according to  FIG. 17  is spherical and is pressed by a pressure spring  42  against the direction of flow into the downstream aperture  13   a  of the feed line  13  serving as valve seat. The pressure spring  42  is passed through a central cylinder  23  of housing  20  pointing to the downstream aperture of the feed line  13 . At its downstream end the cylinder  23  contains a flange with an aperture  21   a  through which the fluid flows into the outlet line  21  after opening the valve. 
     FIG. 18  shows an arrangement similar to that of  FIG. 17 . The valve body  41  of  FIG. 19  has a conical shape at its upstream end. The downstream aperture of the feed line  13 , forming the valve seat, also expands in the same conical manner. Furthermore the downstream end of the valve body  41  contains a cylindrical extension  46 , guiding the pressure spring  42  at the valve body  41 . 
   The valve body  41  of  FIG. 19  once again presses its conical surface into the valve seat formed by the aperture in the feed line  13 . The application pressure is generated by the plastic spring  42 . 
   In  FIG. 20  the valve body  41  is preferably a simple disc, secured at the upstream face of a cylindrical guide body  43 . The guide body  43  contains longitudinal grooves  44  in its external surface. The guide body  43  is a hollow cylinder with a cylinder base at the upstream end on which the valve body  41  is positioned and to which it is fixed and from which an internal guide extension  46  protrudes into the direction of the flow. Via this guide extension  46  the pressure spring  42  is tensioned. The guide body  43  contains radial apertures  45  in its longitudinal grooves  44  through which the fluid drug can flow into the inside of the hollow cylindrical guide body  43  and from there through the outlet line  41  into the catheter. 
   In the valve of  FIG. 21  the valve body  41  is arranged as a flat valve around a rotary axis  47 , laterally to the flow direction and directly at the downstream aperture of the feed line  13 . At its rear downstream side, this return flap  41  is tensioned by a leg spring  42  for the closing of the feed line aperture. The leg spring  42  is inserted into the housing section  20  in such a way that its spring axis  48  is parallel to the return flap rotary axis  47 , with the first leg of the L-shaped spring  42  pressing against the rear side of the return flap  41  and the second leg pressing against the internal wall of the housing  20  serving as counter-section. The spreading force of the angled leg spring  42  securely presses the return flap  41  against the downstream aperture of the feed line  13 . The second spring leg protrudes into an axial bore in the second housing section  20  and the first leg is inserted into a groove at the rear of the valve body  41 ; it may also be rigidly attached to the valve body  41 . The spring axis  48  is formed only by the leg spring  42  which requires no further counter-section at  48 . 
   The described combinations of valve bodies and housings can also be used with other combinations of the described housings and valve bodies.