Patent Publication Number: US-8986250-B2

Title: Drug delivery platform utilizing hydrogel pumping mechanism

Description:
FIELD OF THE INVENTION 
     This invention relates generally to microfluidic devices, and in particular, to a drug delivery platform utilizing a hydrogel pumping mechanism to provide controlled infusion of a drug to an individual. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     As is known, the pharmaceutical industry has had limited success overcoming the challenges of delivering pharmaceuticals to patients. The oral ingestion of pharmaceuticals is considered the safest, most convenient and most economical method of drug administration. As compared to present alternatives, patient acceptance and adherence to a dosing regimen is typically higher among orally delivered pharmaceuticals. However, the oral delivery of many pharmaceuticals is not possible because the pharmaceuticals are either too large or too electrically charged to pass through the small intestine to reach the bloodstream. In addition, many pharmaceuticals which are unable to withstand the environment of the digestive tract or to penetrate the dermis need to be injected into the patient (e.g. insulin, proteins). 
     In order to overcome the problems associated with orally delivered pharmaceuticals, transdermal drug delivery patches have been developed. Transdermal drug delivery patches incorporate a medication and are intended to adhere to the skin of an individual. Molecules of the medication pass through the skin and into the bloodstream of the individual thereby delivering a specific dose of medication. While functional for their intended purposes, these patches have certain inherent limitations. By way of example, since the skin is a very effect barrier, existing transdermal drug delivery patches can only be used to deliver small molecule drugs such as nicotine and birth control. Alternatively, other transdermal technologies have been developed that utilize pressurized gas or voltage to move larger drug molecules across the skin barrier into the bloodstream. Again, while functional for their intended purposes, use of these technologies are limited to smaller volume injections and may have the undesired effect of altering the medications supplied to individuals. Therefore, a transdermal drug delivery device that provides controlled infusion of a drug to an individual without the use of pressurized gas or voltage would constitute a significant advancement in the art. 
     Therefore, it is a primary object and feature of the present invention to provide a drug delivery device that provides controlled infusion of a drug to an individual without the use of pressurized gas or voltage. 
     It is a further object and feature of the present invention to provide a drug delivery device that provides controlled infusion of a drug to an individual while maximizing the volume of drug delivered. 
     It is a still further object and feature of the present invention to provide a drug delivery device that provides controlled infusion of a drug to an individual that is simple to utilize and inexpensive to manufacture. 
     In accordance with the present invention, a drug delivery platform is provided for delivering a controlled infusion of a drug to an individual. The drug delivery platform includes a reservoir for receiving the drug therein and a pressure source engageable with the reservoir. The pressure source is movable between a first configuration and a second configuration wherein the pressure source exerts a pressure on the reservoir to urge the drug therefrom. An output conduit is provided for transmitting the drug into the individual. An actuation mechanism is operatively connected to the pressure source and the output conduit. The actuation mechanism is movable between a non-actuated position and an actuated position wherein pressure source moves from the first configuration to the second configuration and wherein the input of the output conduit communicates with the drug and the output end of the output conduit is receivable in the individual. 
     The pressure source includes a hydrogel that expands in response to a predetermined stimulus, such as a fluid. The drug delivery platform further includes an initiation fluid wherein the actuation mechanism includes an initiation conduit having an input and output. The input of the initiation conduit communicates with the initiation fluid and the output of the initiation conduit communicates with the pressure source in response to the actuation mechanism in the actuated position. A barrier is positioned between the initiation fluid and the pressure source. The barrier defines a channel network communicating with the pressure source and having an input that communicates with the output of the initiation conduit in response to the actuation mechanism in the actuated position. A fluid diverter may be provided to direct fluid from the output of the initiation conduit to the channel network. The channel network includes a plurality of circular, concentric channels. 
     The actuation mechanism includes a biasing structure for urging the actuation mechanism towards the non-actuated position. The reservoir has first and second ends and includes an output adjacent the first end. The pressure source is positioned adjacent to the second end of the reservoir. 
     In accordance with a further aspect of the present invention, a drug delivery platform is provided for delivering a controlled infusion of a drug to an individual. The drug delivery platform includes an initiation fluid and a reservoir for receiving the drug therein. A pressure source is engageable with the reservoir. The pressure source is movable between a first configuration and a second configuration wherein the pressure source exerts a pressure on the reservoir to urge the drug therefrom. An output conduit has an input and output, and an initiation conduit has an input and output. An initiation button is operatively connected to the output and initiation conduits. The initiation button is movable between a non-actuated position and an actuated position. With initiation button in the non-actuated position, the input of the initiation conduit is isolated from the initiation fluid and the output of the initiation conduit is isolated from the pressure source. In addition, the input of the output conduit is isolated from the drug and the output of the conduit is isolated from the individual. With the initiation button in the actuated position, the input of the initiation conduit communicates with the initiation fluid and the output of the initiation conduit communicates with the pressure source, and the input of the output conduit communicates with the drug and the output of the output conduit is receivable in the individual. 
     A barrier may be positioned between the initiation fluid and the pressure source. The barrier defines a channel network communicating with the pressure source and has an input that communicates with the output of the initiation conduit in response to the initiation button in the actuated position. A fluid diverter directs fluid from the output of the initiation conduit to the channel network. The channel network may include a plurality of circular, concentric channels. 
     The drug delivery platform includes a biasing structure for urging the initiation button towards the non-actuated position. The reservoir has first and second ends and includes an output adjacent the first end. The pressure source is positioned adjacent the second end of the reservoir. 
     In accordance with a still further aspect of the present invention, a drug delivery platform is provided for delivering a controlled infusion of a drug to an individual. The drug delivery platform includes a reservoir for receiving the drug therein. The reservoir has a first end and a second end. An expansion structure is positioned over the first end of the reservoir. The expansion structure has a first configuration and an expanded second configuration wherein the expansion structure exerts a pressure on the reservoir to urge the drug therefrom. An output conduit is movable between a retracted position and an extended position. An actuation mechanism is operatively connected to the expansion structure and the output conduit and is movable between a non-actuated position and an actuated position. The expansion structure moves from the first configuration to the second configuration in response to the actuation mechanism moving to the actuated position. The output conduit moves from the retracted position to the extended position to deliver the drug to the individual therethrough in response to actuation mechanism moving to the actuated position. 
     The expansion structure includes a hydrogel that expands in response to a predetermined stimulus, such as an initiation fluid. The actuation mechanism includes an initiation conduit having an input and output. The input of the initiation conduit communicates with the initiation fluid and the output of the initiation conduit communicates with the hydrogel in response to the actuation mechanism in the actuated position. 
     A barrier is positioned between the initiation fluid and the expansion structure. The barrier defines a channel network communicating with the expansion structure and having an input that communicates with the output of the initiation conduit in response to the actuation mechanism in the actuated position. A fluid diverter directs fluid from the output of the initiation conduit to the channel network. The channel network includes a plurality of circular, concentric channels and the actuation mechanism includes a biasing structure for urging the actuation mechanism towards the non-actuated position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings furnished herewith illustrate a preferred construction of the present invention in which the above advantages and features are clearly disclosed as well as others which will be readily understood from the following description of the illustrated embodiments. 
       In the drawings: 
         FIG. 1  is an isometric view of a drug delivery platform in accordance with the present invention; 
         FIG. 2  is an exploded view of the drug delivery platform of the present invention; 
         FIG. 3  is an isometric view, sectioned in two different planes, showing the drug delivery platform of the present invention in a non-actuated position; 
         FIG. 4  is an isometric view, sectioned in two different planes, showing the drug delivery platform of the present invention in an actuated position; 
         FIG. 5  is a cross sectional view of the drug delivery platform of the present invention taken along line  5 - 5  of  FIG. 3 ; 
         FIG. 6  is a cross sectional view of the drug delivery platform of the present invention taken along line  6 - 6  of  FIG. 4 ; 
         FIG. 7  is a cross sectional view of the drug delivery platform of the present invention, similar to  FIG. 5 , with the pressure source in an expanded configuration; 
         FIG. 8  is a cross sectional view of a middle insert for the drug delivery platform of the present invention taken along line  8 - 8  of  FIG. 2 ; 
         FIG. 9  is a bottom, isometric view of the middle insert of the drug delivery platform of the present invention taken from a first side of the middle insert; and 
         FIG. 10  is a bottom, isometric view of the middle insert of the drug delivery platform of the present invention taken from a second side of the middle insert. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Referring to  FIG. 1 , a drug delivery platform in accordance with the present invention is generally designated by the reference numeral  10 . It is intended for drug delivery platform  10  to be affixed to an individual, as hereinafter described, to provide a controlled infusion of a drug to the individual. As best seen in FIGS.  2  and  5 - 7 , drug delivery platform  10  includes base  12  having a generally circular body portion  13  and an ear portion  15  projecting radially from the outer periphery of body portion  13 . Guide passageways  17  and  19  extend through ear portion  15  of base  12  to accommodate corresponding guide pins  21  and  23 , respectively, for reasons hereinafter described. Base  12  further includes a generally flat lower surface  14  and an upper surface  16 . Adhesive pad  18  includes an upper surface  20  affixed to lower surface  14  of base  12  in any conventional manner and a lower surface  22  having an adhesive thereon for interconnecting drug delivery platform  10  to an individual at a user desired location. 
     Upper surface  16  of body portion  13  of base  12  includes a generally circular recess  24  adapted for receiving bladder  26  therein. Generally circular groove  27  extends about the outer periphery of recess  24  and is adapted for receiving enlarged outer end  30   a  of lip  30  of bladder  26 . Shoulder  28  extends radially inward from inner edge  27   a  of groove  27  for supporting lip  30  of bladder  26 . Upper surface  16  of ear portion of base includes concave-shaped recess  34  adapted for receiving output end  36  of bladder  26 . Needle passageway  25 ,  FIGS. 3-4 , interconnects concave-shaped recess  34  and lower surface  14  of base  12 . In addition, circular recess  38  extends into upper surface  16  of ear portion  15  of base  12  and defines generally cylindrical support post  39 . Support post  39  in recess  38  is adapted for receiving lower end  40  of spring  42  thereon, for reasons hereinafter described. Support post  39  may extend beyond upper  16  of ear portion  15  of base  12  to align the various components of drug delivery platform  10  of the present invention. 
     Drug delivery platform  10  further includes a pressure source such as hydrogel disc  44 . Hydrogel disc  44  includes an upper surface  46  and a lower surface  48  interconnected by outer periphery  47 . Hydrogel disc  44  is positionable on upper surface  50  of bladder  26  at a location adjacent end  52  opposite output end  36  of bladder  26 , for reasons hereinafter described. It is contemplated for hydrogel disc  44  to expand in response to a predetermined stimulus such as exposure to a fluid or the like. 
     Drug delivery platform  10  further includes a middle insert  56  having a lower surface  60  receivable on upper surface  16  of base  12  so as to capture bladder  26  and hydrogel disc  44  therebetween and an upper surface  60 . Middle insert  56  is further defined by a generally circular body portion  62  having an ear portion  64  projecting radially from the outer periphery thereof. Guide passageways  63  and  65  extend through ear portion  64  of middle insert  56  to accommodate corresponding guide pins  21  and  23 , respectively, for reasons hereinafter described. Needle passageway  67  and spring passageway  66  also extend through ear portion  64  of middle insert  56  between upper and lower surfaces  58  and  60 , respectively. Needle passageway  67  is axially aligned with concave-shaped recess  34  in upper surface  16  of base  12 , while spring passageway  66  is axially aligned with circular recess  38  extending into upper surface  16  of ear portion  15  of base  12 . Spring passageway  66  has a diameter sufficient to accommodate spring  42 , for reasons hereinafter described. 
     As best seen in FIGS.  2  and  8 - 10 , lower surface  60  of body portion  62  of middle insert  56  includes a generally circular recess  68  terminating at inner terminal surface  80 . Generally circular groove  70  extends about the outer periphery of recess  68  and is adapted for receiving enlarged edge  30   a  of lip  30  of bladder  26 ,  FIGS. 5-7 . Shoulder  72  extends radially inward from inner edge  70   a  of groove  70 . Lower surface  60  of ear portion  64  of middle insert  56  further includes concave-shaped recess  74  extending radially outwardly from inner edge  72   a  of shoulder  72 . Concave-shaped recess  74  is adapted for receiving output end  36  of bladder  26 . Needle passageway  76  extends between upper surface  58  of middle insert  56  and concave-shaped output recess  74 , for reasons hereinafter described. 
     Terminal surface  80  of recess  68  in body portion  62  of middle insert  56  includes defined by concentric inner and outer, generally circular, flow channels  82   a  and  82   b , respectively. Recessed portion  84  of terminal surface  80  extends about and is radially spaced from outer flow channel  82   b . A plurality of spokes  86   a - 86   e  extend from a common point  88  located at the center of inner flow channel  82   a  so as to interconnect recessed portion  84  of terminal surface  80  with inner and outer flow channels  82   a  and  82   b , respectively. Recessed portion  84  of terminal surface  80  communicates with a needle passageway  90  through input channel  92 . Needle passageway  90 , in turn, communicates with concave-shaped recess  94  in upper surface  58  of ear portion  64  of middle insert  56 . Flow diverter  96  projects from recessed portion  84  of terminal surface  80  at a location between input  92  and outer flow channel  82   b . In the depicted embodiment, flow diverter  96  is generally crescent-shaped. However, other shapes are possible without deviating from the scope of the present invention. 
     Referring specifically to  FIGS. 9-10 , a plurality of circumferentially spaced ledges  100   a - 100   e  project from terminal surface  80  of middle insert  56 . Inner edges  102   a - 102   b  of ledges  100   a - 100   e , respectively, are intended to align hydrogel disc  44  captured between bladder  26  and middle insert  56  of drug delivery platform  10 , as hereinafter described. 
     Referring back to FIGS.  2  and  5 - 7 , upper surface  58  of body portion  62  of middle insert  56  includes a generally circular recess  106  adapted for receiving bladder  108  therein. Shoulder  110  extends about the outer periphery of recess  106  and is adapted for receiving peripheral edge  112  of bladder  108  thereon. Recess  106  communicates with concave-shaped recess  94 , which in turn, is adapted for receiving output end  114  of bladder  108 . 
     Cover  116  is receiveable on upper surface  58  of middle insert  56 . Cover  116  includes an upper surface  132  and a lower surface  120 . Cover  116  is further defined by a generally circular body portion  121  and an ear portion  123  projecting radially from the outer periphery of body portion  121 . Lower surface  120  of body portion  121  has a recess  122  therein adapted for receiving bladder  108 . Shoulder  124  extends about the outer periphery of recess  122  and is adapted for engaging peripheral edge  112  of bladder  108 . In addition, lower surface  120  of ear portion  123  of cover  116  includes a concave-shaped recess  128  for accommodating output end  114  of bladder  108 . Needle passageway  130  extends between concave-shaped recess  128  in lower surface  120  of cover  116  and upper surface  132  of cover  116 , for reasons hereinafter described. 
     Ear portion  123  of cover  116  further includes guide passageways  133  and  135  extending therethrough for accommodating corresponding guide pins  21  and  23 , respectively, for reasons hereinafter described. Needle passageway  138  and spring passageway  140  also extend through ear portion  123  of cover  116  between upper and lower surfaces  132  and  120 , respectively. Needle passageway  138  is axially aligned with concave-shaped recess  94  in upper surface  58  of middle insert  56 , while spring passageway  140  is axially aligned with spring passageway  66  through ear portion  64  of middle insert  56  and with circular recess  38  extending into upper surface  16  of ear portion  15  of base  12 . Spring passageway  140  has a diameter sufficient to accommodate spring  42 , for reasons hereinafter described. 
     In order to actuate drug delivery platform  10 , initiation button  142  is provided. Initiation button  142  includes a generally flat base  144  having an upper surface  146  and a lower surface  148 . Guide wall  150  depends from the outer periphery of base  142  and extends about the outer periphery of ear portion  123  of cover  116 . Guide wall  150  includes recess  152  therein so as to allow base portion  144  of initiation button  142  to partially overlap upper surface  132  of cover  116 . Guide pins  21  and  23  depend from lower surface  148  and are slidably received in corresponding guide passageways  133  and  135 , respectively, to guide movement of initiation button  142  between a non-actuated position,  FIGS. 3 and 5 , and an actuated position, FIGS.  4  and  6 - 7 . It is noted that initiation button  142  may include third guide pin  137 ,  FIGS. 3-4 , for further guiding movement of initiation button  142  between the non-actuated and actuated positions. Cover  116  further includes first and second, generally tubular, needle supports  156  and  158 , respectively, depending from lower surface  148  of base  144 . First needle support  156  is adapted for receiving upper end  160  of initiation needle  162 . First needle support  156  is axially aligned with and has a diameter less than needle passageway  130  through cover  116 . As best seen in  FIGS. 5-7 , initiation needle  162  includes an output  163  at lower end  166  thereof and an input  164  centrally located between upper end  160  and lower end  166  thereof. 
     Second needle support  158  is adapted for receiving upper end  168  of output needle  170 . Referring to  FIGS. 3-4 , output needle  170  includes an output  172  at lower end  174  thereof and an input  176  at a location between upper end  168  and lower end  174  thereof. Output needle  170  extends through needle passageway  138  in cover  116 ; needle passageway  67  through middle insert  56 ; output end  36  of bladder  26 ; and needle passageway  25  through base  12 . It can be appreciated that the outer surface of output needle  170  and output end  36  of bladder  26  form a fluid-tight relationship for maintaining a drug in bladder  26  when drug delivery device is not actuated, as hereinafter described. 
     Initiation button  142  further includes a generally tubular spring retainer  178  depending from lower surface  148  of base  144  and adapted for receiving upper end  180  of spring  42  therein. Spring  42  passes through spring passageway  140  in cover  116 ; spring passageway  66  in middle insert  56 ; and into recess  38  in base  12  about support post  39 . As described, it can appreciated that initiation button  142  is movable between the first non-actuated position,  FIGS. 3 and 5 , and the second actuated position, FIGS.  4  and  6 - 7 , against the bias of spring  42 . 
     In operation, the drug delivery platform  10  is assembled as heretofore described wherein bladder  108  is filled with a fluid to which hydrogel disc  44  is responsive and bladder  26  is filled with a predetermined drug. Lower surface  22  of adhesive pad  18  is affixed to an individual at a desired location so as to interconnect drug delivery platform  10  to the individual. Referring to  FIGS. 3 and 5 , with initiation button  142  in its non-actuated state, input  164  of initiation needle  162  is isolated from output end  114  of bladder  108  and such that output  163  of initiation needle  162  is isolated from input  192  to recess surface  84  of terminal surface  80  of middle insert  56 . In addition, with initiation button  142  in the non-actuated position, input  176  of output needle  170  is isolated from output end  36  of bladder  26  and output  172  of output needle  170  is isolated from the individual to which the drug in bladder  26  is to be administered. 
     Referring back to  FIGS. 4 and 6 , in order to actuate a drug delivery platform  10 , initiation button  142  is pressed against the bias of spring  42  such that initiation needle  162  pierces output end  114  of bladder  108 . As a result, input  164  of initiation needle  162  communicates with the interior of bladder  108  via output end  114  and output  163  of initiation needle  162  communicates with input channel  92  of recessed portion  84  of terminal surface  80  in middle insert  56 . In addition, with initiation button  142  in the actuated position, input  176  of output needle  170  communicates with the interior of bladder  26  through output end  36  and output  172  of output needle  170  is received within the individual to which the drug is to be administered. 
     Referring to  FIG. 7 , with initiation button  142  in the actuated position, fluid flows from the interior of bladder  108  into initiation needle  162  through input  164  thereof. The fluid exits initiation needle  162  through output  163  and flows onto recessed portion  84  of terminal surface  80  through input channel  92 . Flow diverter  96  causes the fluid to flow about the entirety of recessed portion  84  of terminal surface  80  into spokes  86   a - 86   b , thereby directing the fluid into flow channels  82   a  and  82   b . Thereafter, the fluid is distributed onto a substantial portion of upper surface  46  of hydrogel disc  44  and about the outer periphery thereof. In response, hydrogel disc  44  expands thereby providing pressure onto bladder  26 . Flow diverter  96  acts to prevent hydrogel disc  44  from expanding in such a manner as to block input channel  92  and prevent additional fluid from flowing onto recessed portion  84  of terminal surface  80  therethrough. As heretofore described, hydrogel disc  44  is positioned adjacent end  52  of bladder  26  such that expansion of hydrogel disc  44  urges the drug within bladder  56  toward output end  36  thereof. Under pressure, the drug flows from the output end  36  of bladder  26  into output needle  70  through input  176  thereof. Thereafter, the drug exits output needle  170  through output  172  and is dispensed into the individual. 
     It can be appreciated that since the rate of expansion of hydrogel disc  44  controls the flow rate of the drug from bladder  26  into the individual, the desired delivery profiles such as bolus injections, constant infusion, delayed onset or the like are possible simply by altering the chemistry of hydrogel disc  44 . It can also be appreciated the output  172  of output needle  170  can be replaced with a microneedle array or like without deviating from the scope of the present invention. 
     Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing and distinctly claiming the subject matter that is regarded as the invention.