Abstract:
A device for placement in an environment, particularly a humid environment, for delivery of medication to said environment. The device comprises a reservoir ( 103 ) having an orifice ( 104 ), a conveying unit for conveying a reservoir&#39;s content ( 106 ) through the orifice ( 104 ) and an actuator arrangement for driving the conveying unit. In order to provide a reliable delivery of medication in a humid environment, the conveying unit comprises an auger ( 110 ) extending in the reservoir ( 103 ).

Description:
CROSS REFERENCE TO RELATED CASES 
     Applicants claim the benefit of International Application Number PCT/IB2009/052575, filed Jun. 17, 2009, and Provisional Application Ser. No. 61/073,778, filed Jun. 19, 2008. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a device for placement in an environment for delivery of medication to said environment, comprising a reservoir having an orifice, a conveying unit for conveying a reservoir&#39;s content through the orifice and an actuator arrangement for driving the conveying unit. The invention further relates to a capsule provided with the device for placement in an environment to deliver medication to said environment. 
     BACKGROUND OF THE INVENTION 
     In WO 94/07562 delivery capsules are disclosed which include a beneficial agent and an activating mechanism, which delivery capsules are designed to deliver the beneficial agent in a pulsatile manner through the orifice. The pulsatile delivery is achieved by a pair of guide members inside the capsule, one secured to the capsule itself and the other to a movable partition. 
     Techniques disclosed in WO 94/07562 have limited ability to deliver a powder like medication in a humid environment to said environment since the techniques have no facility to annul a solidification of the powder like medication induced by humidification. 
     OBJECT OF THE INVENTION 
     It is an object of the invention to provide a device for a more reliable delivery of a medication in a humid environment. 
     SUMMARY OF THE INVENTION 
     The object of the invention is achieved by the device according to the invention which is characterized in that the conveying unit comprises an auger extending in the reservoir. By extending the auger in the reservoir, mechanical interaction with the reservoir&#39;s content is arrived at. As a result of the presence of at least a portion of the auger in the reservoir, in addition to conveying the powder like medication to the orifice of the reservoir, a solidification of a powder like medication contained in the reservoir through humidification in a moist environment or by way of a humidity already contained in the powder, is annulled through pulverization. Here, solidification of the powder like medication ranges from a wet paste to a solid. It is noted that the actuator arrangement can include one or more actuators known per se, such as a spring actuator, an electromagnetic actuator, a hydraulic actuator or a piezoelectric actuator. The auger can be made from a biocompatible plastic or a stainless steel. 
     In a preferred embodiment according to the invention, the conveying unit comprises a piston for pressurizing the reservoir&#39;s content. With that, under the pressure provided by the piston, the reservoir&#39;s content is continuously fed into an auger&#39;s helical flighting. As a result, a revolution of the auger eventuates at a well defined amount of powder like medication conveyed through the orifice. 
     In a further embodiment according to the invention, the conveying unit is provided with a facility for pretensioning the piston to the reservoir&#39;s content. As a result, a continuous energizing of the actuator arrangement for pressurizing the reservoir&#39;s content is not needed. 
     In a further embodiment according to the invention, the piston is driveable by the auger. As a result, the prerequisite for a further actuator to drive the piston is circumvented. 
     In an embodiment according to the invention a surface profile of the piston matches a profile of a reservoir&#39;s surface adjacent to or surrounding the orifice. As a result the residual reservoir&#39;s content is minimized. With that the yield of a capsule provided with this embodiment according to the invention is maximized. 
     In a further embodiment according to the invention, the conveying unit comprises a collapsible barrier for pressurizing the reservoir&#39;s content. The collapsible barrier is conformable to a curved surface of revolution enveloping the auger. By selecting the dimensions of the curved surface of revolution enveloping the auger to be sufficiently small, a residual reservoir&#39;s content is minimized. With that a yield of a capsule provided with this embodiment according to the invention is maximized. 
     In a further embodiment according to the invention, the auger has an axially varying helical flighting height. Herein the helical flighting height is defined as a radius measured from an auger&#39;s axis of revolution to a curved surface of revolution enveloping the auger. 
     In an embodiment according to the invention, the axially varying helical flighting height increases with an axial distance measured from the orifice. As a result, an axially oriented pressure gradient can be exerted by the auger on the reservoir&#39;s content contained within a volume established by a revolution of the auger. The helical flighting height preferably monotonically increases with the distance from the orifice. Proximal to the orifice, the helical flighting height matches a size of the orifice with the purpose of continuation of the auger up to and including the reservoir&#39;s orifice. 
     In an embodiment according to the invention the auger has an axially varying helical flighting pitch. In this text, the helical flighting pitch is defined as an axial distance covered by a complete turn of the helical flighting. 
     In a further embodiment according to the invention the helical flighting pitch increases with the axial distance measured from the orifice. As a result, an axially oriented pressure gradient can be exerted by the auger on the reservoir&#39;s content contained within the volume established by a revolution of the auger. Preferably, the helical flighting pitch monotonically increases with the distance from the orifice. 
     In a further embodiment according to the invention the device comprises a measuring apparatus for measuring a quantity of the reservoir&#39;s content conveyed through the orifice. Based on a measurement acquired by way of the measuring apparatus, the actuator arrangement can be controlled. As a result, a more accurate dosing of powder like medication to an environment is obtained. 
     In an embodiment according to the invention the measuring apparatus comprises a revolution counter for counting a number of revolutions made by the auger. Assuming that the helical flighting height and the helical flighting pitch are both known, the number of revolutions made by the auger provides an accurate measurement for the amount of the reservoir&#39;s content conveyed through the orifice. 
     The capsule according to the invention is defined in claim  13 . The capsule can be made of any suitable material, such as a biocompatible plastic. Apart from being non-reactive to a medication or an acid, a biocompatible plastic material has a density which is larger than water which will ensure the capsule neither to float above water nor to be detained inside a gastrointestinal tract. 
     The invention is highly suitable for application in the field of targeted and precisely controlled delivery of a medication, especially a powder like medication, to an environment, particularly a humid environment, which environment may be inside a human or an animal body. A likely environment is a gastrointestinal tract. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention and its advantages are further elucidated by way of example with reference to the drawings in which: 
         FIG. 1  schematically displays an embodiment of the device according to the invention, wherein a piston is driveable by an actuator arrangement. 
         FIG. 2  schematically shows an embodiment of the device according to the invention, wherein a collapsible barrier is arranged for pressurizing a reservoir&#39;s content. 
         FIG. 3  schematically depicts an embodiment of the device according to the invention, in which a piston is arranged for pressurizing a reservoir&#39;s content, wherein a spring facility serves for pretensioning the piston. 
         FIG. 4  schematically shows an embodiment of the device according to the invention, wherein a piston is driveable by an auger. 
         FIG. 5  schematically displays an embodiment of the device according to the invention, wherein a piston&#39;s surface profile matches a reservoir&#39;s surface profile surrounding an orifice. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  displays a preferred embodiment according to the invention in the form of a capsule  102  comprising a reservoir  103 . The capsule  102  is at made of a biocompatible plastic, such as a medical grade polyethylene. The reservoir  103  is provided with an orifice  104 . The orifice  104  can be provided with a hydrophobic coating as to minimize a diffusion into the reservoir  103  of a humidity present in a moist environment surrounding the capsule  102 . The reservoir  103  contains a reservoir&#39;s content  106  which is a powder like medication. An actuator arrangement comprises an actuator  107  and a further actuator  108 . The actuator  107 , which is a spring actuator, an electromagnetic actuator, a hydraulic actuator or a piezoelectric actuator, causes an auger  110  to rotate around an axis of revolution  112  during use. The auger  110  is made of a biocompatible plastic or a stainless steel and extends into the reservoir  103  in order to provide a mechanical interaction with the reservoir&#39;s content  106  with the purpose of both conveying the reservoir&#39;s content  106  to the orifice  104  and annulling a solidification of the reservoir&#39;s content  106 . The solidification of the reservoir&#39;s content  106  is caused by way of a humidification in the moist environment surrounding the capsule  102  or by way of a humidity already contained in the reservoir&#39;s content  106 . The solidification of the reservoir&#39;s content  106  is annulled by way of pulverization through a revolution of the auger  110  during use. The auger  110  is provided with a helical flighting  114 . The helical flighting has a helical flighting height h which monotonically increases with an axial distance from the orifice  104 . Proximal to the orifice  104 , the helical flighting height h matches a size s of the orifice with the purpose of continuation of the auger  110  up to and including the orifice  104 . In addition to that, the helical flighting  114  has a helical flighting pitch p which monotonically increases with an axial distance measured from the orifice  104 . As a result an axially oriented pressure gradient can be exerted on the reservoir&#39;s content  106  contained within a volume, which volume is established by a revolution of the auger  110 . A piston  116  serves for pressurizing the reservoir&#39;s content  106 . With that, under a pressure provided by the piston  116  during use, the reservoir&#39;s content  106  is continuously fed into the helical flighting  114  of the auger  110 . The piston  116 , which is made of a biocompatible plastic or a stainless steel and is optionally provided with a non-sticky coating, is driveable by the further actuator  108 . The further actuator  108  is an electromagnetic actuator or a hydraulic actuator. A measurement apparatus  120 , comprising a revolution counter, serves for measuring a number of revolutions made by the auger  110 . A measurement signal generated by the measurement apparatus  120  serves for controlling the actuator  107  and the further actuator  108 . Since the helical flighting height h and the helical flighting pitch p are both known, the number of revolutions made by the auger  110  provides a measurement for the amount of the reservoir&#39;s content  106  conveyed through the orifice  104 . For the purpose of a high auger transportation efficiency, an inside surface of the reservoir  103  can be provided with a non-sticky coating whereas the helical flighting  114  of the auger  110  can be provided with certain roughness features. 
       FIG. 2  displays an embodiment according to the invention in the form of a capsule  202  comprising a reservoir  203 . The capsule  202  is made of a biocompatible plastic. The reservoir  203  is provided with an orifice  204 . The reservoir  203  contains a reservoir&#39;s content  206  which is a powder like medication. An actuator arrangement  207  comprises an actuator  207  and a further actuator  208 . The actuator  207 , which is a spring actuator, an electromagnetic actuator, a hydraulic actuator or a piezoelectric actuator, causes an auger  210  to revolute during use around an axis of revolution  212 . The auger  210  is provided in the reservoir  203  in order to provide mechanical interaction with the reservoir&#39;s content  206  with the purpose of both conveying the reservoir&#39;s content  206  to the orifice  204  and annulling a solidification of the reservoir&#39;s content  206 . The auger  210  is provided with a helical flighting  214 . The helical flighting has a helical flighting height h which monotonically increases with an axial distance from the orifice  204 . Proximal to the orifice  204 , the helical flighting height h matches a size s of the orifice with the purpose of continuation of the auger  210  up to and including the orifice  204 . In addition to that, the helical flighting  214  has a helical flighting pitch p which monotonically increases with an axial distance from the orifice  204 . A collapsible barrier  216  for pressurizing the reservoir&#39;s content  206  is contained in the reservoir  203 . With that, under the pressure provided by the collapsible barrier  216 , the reservoir&#39;s content  206  is continuously fed into the helical flighting  214  of the auger  210 . The collapsible barrier  216  is conformable to a tube like grid  218  installed around the auger  210  which tube like grid  218  is to prevent the collapsible barrier  216  from contacting the auger  210 . By choosing a radius r of the grid  218  minimally, i.e. by choosing it only slightly larger than the maximum level of the helical flighting height h, a residue of the reservoir&#39;s content  206  is minimized. The collapsible barrier  216  is compressible by the further actuator  208 . The further actuator  208  comprises a cartridge  220  that releases an inert gas upon actuation in the volume established by the reservoir  203 , the collapsible barrier  216  and a seal  222  as to provide a pressure to the collapsible barrier  216 . A measurement apparatus  224  comprising a revolution counter, serves for measuring a number of revolutions made by the auger  210 . A measurement signal generated by the measurement apparatus  224  serves for controlling the actuator  207  and the further actuator  208 . 
       FIG. 3  displays an embodiment according to the invention in the form of a capsule  302  comprising a reservoir  303 . The reservoir is provided with an orifice  304 . The reservoir  303  contains a reservoir&#39;s content  306  which is a powder like medication. An actuator arrangement comprises an actuator  308 . The actuator  308  causes an auger  310  to revolute around an axis of revolution  312  during use. The auger  310  is present in the reservoir  303  in order to provide a mechanical interaction with the reservoir&#39;s content  306  with the purpose of both conveying the reservoir&#39;s content  306  to the orifice  304  and annulling a solidification of the reservoir&#39;s content  306 . The auger  310  is provided with a helical flighting  314 . The helical flighting has a helical flighting height h which increases with an axial distance from the orifice  304 . Proximal to the orifice  304 , the helical flighting height h matches a size s of the orifice with the purpose of continuation of the auger  310  up to and including the orifice  304 . In addition to that, the helical flighting  314  has a helical flighting pitch p which increases with an axial distance from the orifice  304 . As a result an axially oriented pressure gradient can be exerted on the reservoir&#39;s content  306  contained within a volume which volume is established by a revolution of the auger  310 . A piston  316  serves for pressurizing the reservoir&#39;s content  306 . With that, under a pressure provided by the piston  316  during use, the reservoir&#39;s content  306  is continuously fed into the helical flighting  314  of the auger  310 . The piston  316  is pretensioned to the reservoir&#39;s content  306  by way a facility for pretensioning. The facility for pretensioning comprises an elastic mechanical spring  318 . The facility for pretensioning the piston  316  to the reservoir&#39;s content  306  may alternatively comprise an air spring, a repulsive magnetic element or a combination thereof. Trough this, a continuous energizing of an actuator to provide a pressure to the reservoir&#39;s content  304  is prevented from. A measurement apparatus  320  comprising a revolution counter, serves for measuring a number of revolutions made by the auger  310 . A measurement signal generated by the measurement apparatus  320  serves for controlling the actuator  308 . 
       FIG. 4  displays an embodiment according to the invention in the form of a capsule  402  comprising a reservoir  403 . The reservoir is provided with an orifice  404 . The orifice  404  can be provided with a hydrophobic coating as to minimize a diffusion into the reservoir  403  of a humidity present in a moist environment surrounding the capsule  402 . The reservoir  403  contains a reservoir&#39;s content  406  which is a powder like medication. An actuator arrangement comprises an actuator  408 . The actuator  408 , which is a spring actuator, an electromagnetic actuator, a hydraulic actuator or a piezoelectric actuator, causes an auger  410  to rotate around an axis of revolution  412  during use. The auger  410  extends into the reservoir  403  with the purpose of providing a mechanical interaction with the reservoir&#39;s content  406 . The auger  410  is provided with a helical flighting  414 . The helical flighting has a helical flighting height h which increases with an axial distance from the orifice  404 . Proximal to the orifice  404 , the helical flighting height h matches a size s of the orifice with the purpose of continuation of the auger  110  up to and including the orifice  404 . In addition to that, the helical flighting  414  has a helical flighting pitch p which increases with an axial distance from the orifice  404 . A piston  416  serves for pressurizing the reservoir&#39;s content  406 . The piston  416  for pressurizing the reservoir&#39;s content  406  is driveable by the auger  410 . For driving the piston  416 , the auger  410  is supplied with an auger screw thread  418  for cooperation with a piston screw thread  420 . A rail  422  is supplied to the reservoir  402  to accurately guide a displacement of the piston  416  and to prevent the piston  416  from rotating with the auger  410 . A measurement apparatus  424  comprising a revolution counter is arranged for measuring a number of revolutions made by the auger  410 . A measurement signal generated by the measurement apparatus  424  serves for controlling the actuator  408 . 
       FIG. 5  displays an embodiment according to the invention in the form of a capsule  502  comprising a reservoir  503 . The reservoir  503  is provided with an orifice  504 . The reservoir  503  contains a reservoir&#39;s content  506  which is a powder like medication. An actuator arrangement comprises an actuator  508 . The actuator  508  causes an auger  510  to revolute around an axis of revolution  512  during use. The auger  510  extends in the reservoir  503  in order to provide a mechanical interaction with the reservoir&#39;s content  506  with the purpose of both conveying the reservoir&#39;s content  506  to the orifice  504  and annulling a solidification of the reservoir&#39;s content  506 . The auger  510  is provided with a helical flighting  514 . A piston  516  for pressurizing the reservoir&#39;s content  506  is driveable by the auger  510 . With that, under a pressure provided by the piston  516  during use, the reservoir&#39;s content  506  are continuously fed into the helical flighting  514  of the auger  510 . For driving the piston  516 , the auger  510  is supplied with a constant helical flighting height h and a constant helical flighting pitch p. The helical flighting  514  is in cooperation with a piston screw thread  518 . A rail  520  is supplied to the reservoir  502  to accurately guide a displacement of the piston  516  and to prevent the piston  516  from rotating with the auger  510 . By driving the piston  516  through the auger  510 , the prerequisite for a further actuator to drive the piston  516  is circumvented. The piston  516  has a surface profile  522  that corresponds to a reservoir&#39;s surface profile  524  adjacent to the orifice  504 . Consequently, the piston  516  is transportable as far as the reservoir&#39;s orifice  504 . As a result, a residue of the reservoir&#39;s content  506  is minimized. A measurement apparatus  526  comprising a revolution counter is arranged counting a number of revolutions made by the auger  510 . A measurement signal generated by the measurement apparatus  526  is serving for controlling the actuator  508 . 
     While the invention has been illustrated and described in detail in the drawings and in the foregoing description, the illustrations and the description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. It is noted that the apparatus according to the invention and all its components can be made by applying processes and materials known per se. In the set of claims and the description the word “comprising” does not exclude other elements and the indefinite article “a” or “an” does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope. It is further noted that all possible combinations of features as defined in the set of claims are part of the invention.