Abstract:
The invention relates to a swallowable medication capsule capable  200  of dispensing fluid medicine stored in a medication compartment  211  through a valveless exit hole  207 . A vent hole  206  enables ventilation of an actuator cavity  212  which houses an actuator used for displacing a surface  205  which separates the medication cavity  211  and the actuator cavity  212 . By locating the vent and exit holes close to each other so that contact with contracting parts of the gastrointestinal tract and the exterior surface  221  is not able to prohibit a pressure passageway between the vent and exit holes, creation of a pressure difference of pressures in the medication and actuator cavity is prohibited.

Description:
PRIORITY APPLICATION 
     This Application is a 35 U.S.C. 371 National Stage Entry of and claims priority to PCT Application Serial No. PCT/US12/30332, entitled “Swallowable Medication Capsule,” filed on Mar. 23, 2012, which claims priority to U.S. Provisional Application Ser. No. 61/467,057, entitled “Swallowable Medication Capsule”, filed on Mar. 24, 2011, both of which are hereby incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a swallowable medication capsule, and in particular to avoiding unintended dispense of fluid medication. 
     BACKGROUND OF THE INVENTION 
     Swallowable electronic medication capsules are used for dispensing fluid medication to a patient. Preferably, the medication should be dispensed when the swallowable capsule is at a particular location in the gastrointestinal tract, e.g. in the small intestine. However, the medication may be dispensed inadvertently due to local pressure differences that are generated by peristaltic movements. This incidence arises particularly for medicine containers comprising a flexible closure member and without valves. 
     Accordingly, it is problem that electronic medication capsules may dispense fluid medication inadvertently due to actions on the capsule caused by peristaltic movements of the gastrointestinal tract. 
     US 2008269664 discloses a treatment system provided for traversing the alimentary tract. The system includes an ingestible capsule, which includes a gas pressurizing module providing a gas and at least one balloon in fluid communication with the gas pressurization module. The capsule further includes an exhaust channel in fluid communication with a respective balloon of the at least one balloon, and a depressurizing closure member for selectively controlling flow of gas between the balloon and the ambient surroundings of the capsule. The system further includes control circuitry for controlling the depressurizing closure member. 
     The inventor of the present invention has appreciated that an improved medication capsule is of benefit, and has in consequence devised the present invention. 
     SUMMARY OF THE INVENTION 
     It would be advantageous to achieve improvements of medication capsules, in particular, improvements which alleviates the above mentioned problem or, or other problems, of the prior art. 
     The better address one or more of these concerns, in a first aspect of the invention a swallowable medication capsule having an elongate shape is presented, where the capsule comprises:
         a wall forming an exterior surface of the capsule,   a medication compartment for containing a displacement actuator,   a displaceable surface arranged to be driven by the displacement actuator, where the medication compartment is partly defined by the displaceable surface,   a dispense channel providing a passageway between the medication compartment and an exit hole formed at the exterior surface for dispensing the fluid medication to the surroundings.   a vent channel providing a passageway between the actuator compartment and a vent hole formed at the exterior surface,       

     where a separation between the exit hole and the vent hole along an elongate axial direction of the elongate shape is less than the length of the medication compartment along the elongate axial direction. 
     Since the exit and vent holes are located relatively close, and at least closer than the length of the medication compartment, the holes will most likely experience the same environment pressure even if they are both blocked by the gastrointestinal wall at the same time. Therefore, the risk that different pressures are generated in the actuator and medication compartments is minimized. 
     The medication compartment may be defined at least partly by a part a first interior surface of the capsule, possibly an interior surface of the wall of the capsule. Also the actuator compartment may be partly defined by a part of a second interior surface of the capsule. Thus, the first and second interior surfaces may be different interior surfaces of the capsule or the same interior surface of the capsule. 
     The medication may be in the form of a fluid, a liquid, a gas, a gel or solid particles such as a powder. 
     In an embodiment the surface normal to the exterior surface at the location of the exit hole is substantially parallel with the surface normal to the exterior surface at the location of the vent hole. This means that if the vent and exit holes are located on a curved surface such as an ellipsoidal surface, then the holes may be located so close that the surface normal of exterior capsule surface at the location of the holes may be substantially parallel. 
     In an embodiment the surface normal to the exterior surface at the location of the exit hole and the surface normal to the exterior surface at the location of the vent hole are substantially perpendicular to the elongate axial direction. This means that if the vent and exit holes are located on a curved surface such as an ellipsoidal surface, then the holes may be located so close that the surface normal of exterior capsule surface at the location of the holes may be substantially perpendicular to the axial direction of the elongate capsule. If the capsule is cylindrical in shape, then the surface normal of the vent and exit holes are perpendicular to the axial direction of the cylindrical shape. 
     In an embodiment, the exterior surface of the capsule is formed by a cylindrical shell part having an exterior cylindrical surface, where the displaceable surface is arranged in the interior of the cylindrical part so that the displaceable surface divides the interior into adjacent sections forming the medication compartment and the actuator compartment, and where the exit hole and the vent hole are located on the same exterior cylindrical surface. 
     In an embodiment a part of the dispense channel and/or the vent channel extends within the wall of the capsule between two different locations on the exterior wall surface. Advantageously, the inlet to the dispense channel or the vent channel may be located at a different point of the elongate shape than the associated exit hole or vent hole to facilitate unconstrained location of the inlet holes and the vent and exit holes, e.g. for improved expelling of the medication. 
     In an embodiment the dispense channel which extends within the wall of the capsule has different channel directions so that at least one part of the channel provides a fluid passageway in a direction against the gravity, irrespective of the orientation of the swallowable medication capsule. 
     In an embodiment the dispense channel and/or the vent channel is formed as a groove in an outer shell of the capsule in combination with an inner shall providing a closure of the groove and where the inner shall has a hole providing a fluid passageway between the medication compartment and the groove. 
     In an embodiment the displaceable surface forms a fluid tight separation between the medication compartment and the actuator compartment. Thus, the displaceable surface may be membrane which forms a wall of the medication compartment which separates the medication compartment from the actuator compartment. 
     In an embodiment the capsule is constituted by a first part and a second part which are connectable, where the medication compartment is a self-confined entity comprised by the second part, and the actuator compartment is a self-confined entity comprised by the first part. 
     A second aspect of the invention relates to a method for providing a swallowable medication capsule having an elongate shape, where the capsule has a wall forming an exterior surface of the capsule, the method comprises
         providing a first part of the capsule where the first part comprises,
           an actuator compartment for containing a displacement actuator,   a vent channel providing a passageway between the actuator compartment and a vent hole formed at the exterior surface, and   
           providing a second part of the capsule where the second part comprises,
           a medication compartment for containing a medication.   a displaceable surface arranged to be driven by the displacement actuator, where the medication compartment is partly defined by the displaceable surface,   a dispense channel providing a passageway between the medication compartment and an exit hole formed at the exterior surface for dispensing the fluid medication to the surroundings,   
               

     where the first and second parts are connectable to form the elongate shaped capsule, and where the separation between the exit hole and the vent hole along an elongate direction of the elongate shape, when the first and second parts are connected, is less than the length of the medication compartment along the elongate direction. 
     Advantageously, the medication compartment may be comprised by a separate part which is connectable another part which comprises the actuator compartment. Thus, the part comprising the actuator compartment may be reused, whereas the part comprising the medication compartment may be disposable. 
     In general the various aspects of the invention may be combined and coupled in any way possible within the scope of the invention. These and other aspects, features and/or advantages of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. 
     In summary the invention relates to a swallowable medication capsule capable  200  of dispensing fluid medicine stored in a medication compartment  211  through a valveless exit hole  207 . A vent hole  206  enables ventilation of an actuator cavity  212  which houses an actuator used for displacing a surface  205  which separates the medication cavity  211  and the actuator cavity  212 . By locating the vent and exit holes close to each other so that contact with contracting parts of the gastrointestinal tract and the exterior surface  221  is not able to prohibit a pressure passageway between the vent and exit holes, creation of a pressure difference of pressures in the medication and actuator compartment is prohibited. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will be described, by way of example only, with reference to the drawings, in which 
         FIG. 1  shows a medication capsule  100  for illustration of a contraction of the gastrointestinal tract  150  which prohibits free fluid communication between the vent hole  102  and the dispensing exit hole  101 . 
         FIG. 2  shows a medication capsule  200  according to an embodiment of the invention where the vent hole  202  and the dispensing exit hole  201  are arranged close to each other, 
         FIGS. 3A and 3B  illustrate that the inlet to the vent or dispensing channel may be located remote from the respective vent or exit holes. 
         FIG. 4  shows a dispense channel formed as a serpentine to avoid dispense due to influence by the gravity force, and 
         FIG. 5  shows a detailed example of a medication capsule. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG. 1  shows a cross sectional view of swallowable medication capsule  100  designed to be swallowed by a patient and to dispense fluid medicine at a target location, e.g. when the capsule passes the small intestine. The capsule  100  includes an outer wall  120 , a medication compartment  111 , an actuator compartment  112  containing an actuator  130 , and a displaceable element  103  connected to the inner surface of the wall  120  by a flexible member  104 . The actuator  130  is capable of displacing the displaceable element  103  so as to reduce the volume of the medication compartment. The surface of the displaceable element  103  and the flexible member  104  together with the interior surface of the wall  120  defines the cavity of the medication compartment  111 . Accordingly, the displaceable member  103  is in fluid communication with the medication compartment  111  as well as the actuator compartment  112 . Fluid medication contained in the medication compartment  111  can be expelled to the surrounding environment of the capsule via a dispense channel  101  formed in the wall  120  by action of the displacement actuator  130 . 
     When the displaceable element  103  is pushed toward the medication compartment  111 , there will be a void space left behind in the actuator compartment. Therefore a vent channel  102  in the wall  120  is provided to equalize pressure differences between the environment and the actuator compartment. Thus, the displaceable element  103  can displace without need to overcome additional resistance due to under pressure from its previous advancement. 
     Since part of the medication compartment is made of the flexible member  104  and the displaceable element  103 , medication could be partially expelled if there is unbalanced pressure applied to the flexible member  104  and the displaceable element  103 . This may happen when the capsule experiences contractions of the gastrointestinal walls. If pressure communication through the vent channel  102  between the actuator compartment and medication compartment is not blocked, the flexible member  104  and element  103  will not experience unbalanced pressure. 
     However, when the capsule  100  passes through the gastrointestinal tract  150 , peistaltic movements of the wall  151  of the gastrointestinal tract causes contractions of the wall which may block pressure communication between the vent channel  102  and the dispense channel  101 . Thereby, a higher pressure in the actuator compartment may arise which presses against the flexible member  104 , thereby causing an undesired expelling of medication via the dispense channel  101 . 
       FIG. 2  shows a cross sectional view of a medication capsule according to an embodiment of the invention to avoid blockage of pressure communication between the actuator compartment and the medication compartment. The capsule  200  comprises an outer wall  220  having an exterior surface  221  and an interior surface  222 , where the interior surface defines a hollow interior of the capsule. 
     the capsule may have an ellipsoidal shape as shown in  FIG. 1 , a spherical shape, cylindrical shape or other shapes being suitable for a swallowable capsule. 
     The capsule  200  further comprises a medication compartment  211  which is bounded partly by the interior surface  222 , and an actuator compartment  212  which is also bounded partly by another part of the interior surface  222 . The actuator compartment  212  is intended to house a displacement actuator  130 . The displacement actuator  130  may be a linear motor driven piston. 
     The capsule  200  further comprises a displaceable surface  205  arranged to be driven by the displacement actuator  130 . The displaceable surface may be made up by surfaces of a displaceable element  203  which makes a fluid tight fit to the interior surface  222  of the wall  220 . As an example, the fluid tight fit may be embodied by a flexible member  204 , such as a bellows, connected to displaceable element  203  and the surface  222  of the wall  220 . In this example, the displaceable element  203  is displaceably connected to the displacement actuator  130  so that the displaceable element  203  can be pushed into the medication compartment  211 . The displaceable element  203 , possibly in combination with the flexible member  204 , forms a fluid tight displaceable surface  205  between the medication compartment and the actuator compartment. Accordingly, the displaceable surface  205  forms a wall of the medication compartment  222 . 
     Thus, the displaceable surface  205  may be embodied in different ways. Additional examples comprise an elastic foil and a flexible wall with a rolling-sock seal connected to the interior surface  221  of the wall  220 . It is understood that the displaceable surface  205  may be constituted by a physical entity such as a flexible wall or membrane, or the displaceable surface may merely be the surface of several components such as the surface  205  of the displaceable element  203  in combination with the flexible member  204 . Thus the displaceable surface  205  forms a fluid tight wall of the medication compartment  211 . 
     The actuator  130  is capable of displacing the displaceable surface  205 , e.g. by displacing the displacing element  203  which may be stiff or elastic, so as to reduce the volume of the medication compartment. The displaceable surface  205  together with the interior surface of the wall  120  defines the cavity of the medication compartment  111 . Accordingly, the medication compartment  211  is defined at least in part by the facing side of the displaceable surface  205  facing the medication compartment and the interior surface  222 . 
     Fluid medication contained in the medication compartment  211  can be expelled, by action of the displacement actuator  130 , to the surrounding environment through via a dispense channel  201  providing a passageway between the medication compartment  211  and an exit hole  207  formed at the exterior surface  221  of the wall  220 . 
     A vent channel  202  is provided to enable equalization of pressures in the medication compartment and the actuator compartment. The vent channel  202  provides a passageway between the actuator compartment  212  and a vent hole  206  formed in the exterior surface  221  of the wall  220  for enabling an air flow between the actuator compartment and the surroundings. 
     The vent channel  202 , the dispense channel  201 , the displaceable element  203  and the flexible member  204  have the same function as already described in connection with  FIG. 1 . 
     In the embodiment shown in  FIG. 2 , the distance  291  between the vent hole  206  and the exit hole  207  has been reduced so that when the wall  151  of gastrointestinal tract  150  contacts the exterior surface  221 , then it is more likely that both holes are experience the same environmental pressure or are in fluid communication. Thereby, the risk that peristaltic movements of the of the gastrointestinal tract causes different pressures in the actuator and medication compartments it minimized. 
     The swallowable medication capsule has an elongate shape such as an ellipsoid shape. The elongate shape of the capsule defines an elongate direction defined by a line connecting the extremities, i.e. points on the exterior surface  221  located farthest from each other. The length  292  is defined by the distance between the mentioned extremities. Accordingly, the medication capsule may have any enlongately shaped exterior shape; that is, a shape that generally has a length which is larger that the width of the shape. The elongate direction may further define a rotation symmetric axis of the elongate body. An axis may be defined being perpendicular to the elongate direction, which perpendicular axis has a length between intersection points with the exterior shape which is smaller than the length  292  between the mentioned extremities. The perpendicular axis may further define a second rotation symmetric axis of the elongate body. Examples of the elongately shaped body comprises an ellipsoid, a cylinder having rounded ends such as ellipsoid or spherically shaped ends, egg-shaped bodies which are only rotation symmetric about the elongate direction, and other arbitrarily shaped bodies. 
     The length  292  of the capsule may be in the range from 5 to 35 mm. Generally, the advantage of locating the vent and exit holes close for prohibiting different pressures in the actuator and medication compartment may be obtained when the axial distance (distance along the elongated direction of the capsule body)  291  between the vent hole  206  and the exit hole  207  are in the range is minimized, e.g. from 0.1 to 10 mm, preferably in the range between 0.1 to 3 mm measured as the shortest axial distance between edges of the holes. Since capsules  200  may vary in length depending on types of capsules, the effect of avoiding pressure differences may be obtained when the separation  291  between the exit hole and the vent hole along the elongate direction of the elongate capsule is less than one quarter of the length  292  along the elongate direction of the capsule. Alternatively, the effect of avoiding pressure differences may be obtained when the separation  291  between the exit hole and the vent hole along an elongate direction of the elongate shape of the capsule is less than the axial length  293  of the medication compartment measured from the axial point on the displaceable surface along the elongate axial direction to the distal axial point on the exterior surface. 
     As shown in  FIG. 2 , when the vent hole  206  and the exit hole  207  are located close to prohibit pressure differences, the surface normals  280  of the vent and exit holes are substantially parallel, i.e. the angle between the surface normals is less than 10 degrees. The surface normal  280  of the holes is defined as the surface normal to the exterior  221  of the capsule at the location (e.g. center location) of the exit hole  206  or at the location of the vent hole  207 . 
     Equivalently, the location of the vent hole  206  and the exit hole  207  may be defined by the criteria that the surface normal  280  to the exterior of the capsule at the location of the exit hole and the surface normal  280  to the exterior of the capsule at the location of the vent hole are substantially perpendicular to the elongate direction, since the vent and exit holes may be located on a surface of the capsule which is substantially parallel with the elongate direction. For example, the exterior of an elongate capsule may be cylindrical in shape and the vent and exit holes may be located on the same cylindrical surface, i.e. locations characterized in that the surface normal  180  at the location of the holes are normal to the elongate direction or the symmetry axis of the cylinder shaped exterior surface. 
     The dispense channel  201  and/or the vent channel  202  may be formed as a through hole in the wall  220  perpendicular to the exterior surface  221 . However, the dispense or vent channels need not be straight channels where the entrance hole to the channel and the exit hole or the vent hole are placed adjacent to each other. 
       FIG. 3A  shows an embodiment of the capsule  200  where a part of the dispense channel  201  extends within the wall  220  of the capsule parallel with the exterior surface  221  of the wall between two different locations at the exterior wall surface, e.g. first  391  and second  392  locations.  FIG. 3B  shows an embodiment of the capsule  200  where a part of the vent channel  202  extends within the wall  220  of the capsule between two different locations at the exterior wall surface, i.e. first  391  and second  392  locations. Accordingly, either one or both of the dispense channel  201  or the vent channel  202  may extend for some distance within the wall  220 . 
     Channels  201 ,  202  which extends along the wall  220  enables the entrance hole of the channels to be located at the interior surface  222  at a location different from the location of the vent hole  206  or the exit hole  207 . Thereby, the vent and exit holes may placed at arbitrary locations on the exterior surface  221 , e.g. at the apex of the capsule, or the entrance hole of the dispense channel may be placed at the apex of the interior surface  222  to facilitate the best expulsion of the fluid medicine whereas the exit hole is located close to the vent hole at a different exterior surface part. 
       FIG. 4  sows a cross sectional view of the capsule where the dispense channel extends along a spiral or serpentine path within the wall from the apex  491  to the exit hole  207  located approximately halfway between apexes of the elongate shell. The spiral shape is visible as the cross sectional view  493  of the channel. Thus, in an embodiment according to the invention, the dispense channel extends within the wall in a way so that the channel has different directions so that at least one part of the channel provides a fluid passageway in a direction against the gravity (e.g. pointing into the paper in  FIG. 4 ), irrespective of the orientation of the swallowable medication capsule. By shaping the channel so that one part of the passageway always points against the direction of gravity then the fluid medication, at least in a part of the dispense channel, will be affected by gravity in a direction that will force the fluid medication back towards the medication compartment so that unintended dispense is achieved. 
       FIG. 5  shows an example of a medication capsule  500  in detail. The elongate exterior surface  221  of the wall  220  of the medication capsule  500  is cylindrical in shape. The wall  220  is made up of different shell portions, such as shell portions  501  and  502 . The displaceable surface  205  is embodied by an elastic membrane which divides the interior volume of the cylindrical surface  221  of the capsule  500  to form the medication compartment  211  and the actuator compartment  212 . The elastic membrane is arranged to be deformed and pushed into the medication compartment by a displaceable element  203  which is displaceably contacted by a piston actuator  130 . 
     In general the capsule  200 ,  500  may comprise one or more vent holes  206  as well as exit holes  207  and associated vent and dispense channels, for example first and second vent holes  206   a ,  206   b  and first and second exit holes  207   a ,  207   b  as shown in  FIG. 5 . 
     In  FIG. 5  the exit hole  207   a  and the vent hole  206   a  are located on the same cylindrical surface  221  implying that the vent and exit holes can be located sufficiently close to minimize the risk of different pressures in the medication and actuator compartments. 
     In  FIG. 5  the dispense channel  201  propagates within the wall  200  to form a serpentine channel so that a part of the passageway of the channel always points against the direction of gravity so as to minimize the risk of unintended leakages of medication due to gravity influences. 
     The dispense channel  201  is formed as a groove  511  in the outer shell  501  of the capsule in combination with an inner shell  512  which closes the groove  511  to form the channel. The inner shell  512  is provided with a through hole  513  to provide a passageway from the medication compartment  211  to the dispense channel  201 . Thus, vent channels  202  and dispense channels  201  may be formed by a grove in an outer or inner shell part in combination with a matching inner or outer shall part. 
     The capsule may be assembled from first and second parts  581 ,  582  which are connectable to form the elongate shaped capsule. 
     The first part  581  comprises the actuator compartment  212 , the displacement actuator  130 , the vent channel  202  and the associated vent hole  206 . 
     The second part  582  comprises the medication compartment  211 , the dispense channel  201  and the associated exit hole  207 , and the displaceable surface  205  when the displaceable surface is in the form of a foil or membrane which forms a fluid tight circumferential connection with the interior surface  222  of the wall  220  of the second part. Accordingly, the membrane is capable of being displaced by the displacement actuator  530  when the first and second parts are assembled. 
     Accordingly, the medication compartment comprised by the second part  582  may be a self-confined entity connectable with the first part  581  comprising the actuator compartment. In this way the medication compartment and actuator compartment may be comprised by separate first and second parts  581 ,  582  which are attached together before use. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.