Osmotic delivery system with membrane plug retention mechanism

Abstract

An osmotic delivery system has a membrane plug retention mechanism which can also be used to control the delivery rate of a beneficial agent from the osmotic delivery system. The osmotic delivery device includes an implant capsule containing a beneficial agent and an osmotic agent. Holes are formed along a side wall of the implant capsule at an open end of the capsule. When the membrane plug is inserted into the open end of the capsule, the membrane material swells into the holes in the capsule side wall creating a large frictional force which prevents expulsion of the membrane plug. A beneficial agent delivery rate of the osmotic delivery system is controllable by varying the size and number of the holes to change the amount of exposed surface area of the membrane plug. An increase in the surface area of the membrane plug exposed to the exterior environment causes a corresponding increase in the liquid permeation rate of the membrane and thus, increases the beneficial agent delivery rate.

1 . A method of making an osmotic delivery device comprising: 
 providing a delivery device body containing a beneficial agent to be delivered through a delivery orifice at a closed end of the delivery device body and an osmotic agent for drawing external liquids into the delivery device body to cause the beneficial agent to be delivered;    forming a plurality of holes in the delivery device body around the open end of the delivery device body;    securing an expandable, semipermeable membrane plug in the open end of the delivery device body by the plurality of holes formed in the delivery device body, the membrane plug expandable to extend into the plurality of holes to prevent expulsion of the membrane plug from the delivery device body.    
     
     
         2 . The method of making an osmotic delivery device according to  claim 1 , wherein the delivery device body further comprises a movable piston separating a first reservoir containing the beneficial agent from a second reservoir containing the osmotic agent and causing the beneficial agent to be delivered through the delivery orifice when the osmotic agent draws the external liquids through the membrane.  
     
     
         3 . The method of making an osmotic delivery device according to  claim 1 , further comprising causing external liquid to be drawn into the delivery device body through the membrane by way of the open end of the delivery device body and the plurality of holes.  
     
     
         4 . The method of making an osmotic delivery device according to  claim 1 , wherein forming a plurality of holes comprises forming cylindrical bores spaced in an annular configuration around a side wall of the delivery device body adjacent the open end of the delivery device body.  
     
     
         5 . The method of making an osmotic delivery device according to  claim 1 , wherein the delivery device body has a substantially cylindrical side wall and the plurality of holes are formed in the substantially cylindrical side wall.  
     
     
         6 . The method of making an osmotic delivery device according to  claim 1 , wherein the substantially cylindrical side wall includes an inwardly directed annular lip at the open end of the delivery device body which provides additional retention of the membrane in the delivery device body.  
     
     
         7 . The method of making an osmotic delivery device according to  claim 1 , wherein the membrane plug provides a semipermeable closure at the open end of the delivery device, the membrane plug allowing fluid to pass into the osmotic engine and preventing the osmotic engine from passing out of the capsule.  
     
     
         8 . A method of making an osmotic beneficial agent delivery device with a controllable beneficial agent delivery rate comprising: 
 providing a substantially cylindrical body having an open end and a beneficial agent delivery port at a closed end;    forming a plurality of openings in a side wall of the substantially cylindrical body at the open end, the plurality of openings formed of a size and number determined to achieve a predetermined beneficial agent delivery rate; and    inserting an expandable, semipermeable membrane plug in the open end of the body and covering the plurality of openings.    
     
     
         9 . The method of making an osmotic beneficial agent delivery device according to  claim 8 , wherein the plurality of openings are formed to allow fluid to pass through the side wall and through the membrane plug into an interior of the body.  
     
     
         10 . The method of making an osmotic beneficial agent delivery device according to  claim 8 , further comprising providing a separating member positioned within the substantially cylindrical body and movable in a longitudinal direction within the substantially cylindrical body to dispense a beneficial agent.  
     
     
         11 . The method of making an osmotic beneficial agent delivery device according to  claim 10 , further comprising positioning an osmotic engine adjacent one side of the separating member.  
     
     
         12 . The method of making an osmotic beneficial agent delivery device according to  claim 8 , wherein the plurality of openings in the side wall are through holes allowing fluid to pass through the plurality of openings into the membrane plug and into the osmotic engine within the substantially cylindrical body.  
     
     
         13 . The method of making an osmotic beneficial agent delivery device according to  claim 8 , wherein the plurality of openings are formed as cylindrical bores spaced in an annular manner around the side wall.  
     
     
         14 . The method of making an osmotic beneficial agent delivery device according to  claim 8 , wherein the substantially cylindrical body includes an inwardly directed annular lip at the open end of the substantially cylindrical body which provides additional retention of the membrane plug in the open end of the substantially cylindrical body.  
     
     
         15 . The method of making an osmotic beneficial agent delivery device according to  claim 8 , wherein the substantially cylindrical body further comprises a beneficial agent to be delivered through the delivery port of the substantially cylindrical body and an osmotic agent for drawing external liquids into the substantially cylindrical body to cause the beneficial agent to be delivered.  
     
     
         16 . The method of making an osmotic beneficial agent delivery device according to  claim 8 , wherein the substantially cylindrical body further comprises a movable piston separating a first chamber containing a beneficial agent from a second chamber containing an osmotic agent and causing the beneficial agent to be delivered through the delivery port when the osmotic agent draws external liquids through the membrane plug.  
     
     
         17 . A method of retaining a membrane plug in an implantable osmotic device comprising: 
 forming a substantially cylindrical membrane plug;    forming holes in a side wall of a capsule adjacent an open end of the capsule;    inserting the substantially cylindrical membrane plug into the open end of the capsule such that the membrane plug covers the holes formed in the side wall; and    causing the membrane plug to swell into the holes in the side wall to retain the membrane plug in the capsule.    
     
     
         18 . The method of retaining a membrane plug in an implantable osmotic device according to  claim 17 , wherein water passes into the capsule though the cylindrical membrane plug, through the open end of the capsule, and through the holes.  
     
     
         19 . The method of retaining a membrane plug in an implantable osmotic device according to  claim 17 , wherein the side wall of the capsule is formed to include an inwardly directed annular lip at the open end of the capsule which provides additional retention of the membrane in the delivery device body.  
     
     
         20 . The method of retaining a membrane plug in an implantable osmotic device according to  claim 17 , wherein the holes are formed to allow fluid to pass through the side wall and through the membrane plug into an interior of the capsule.  
     
     
         21 . The method of retaining a membrane plug in an implantable osmotic device according to  claim 17 , further comprising providing a beneficial agent within the capsule and a separating member positioned within the capsule, the separating member being movable in a longitudinal direction within the capsule to dispense the beneficial agent.  
     
     
         22 . A method of making an osmotic beneficial agent delivery device comprising: 
 providing a substantially cylindrical body having an open end and a plurality of openings in a side wall at the open end of the substantially cylindrical body; and    securing an expandable, semipermeable membrane plug into the plurality of holes formed in the open end of a delivery device body.    
     
     
         23 . The method of making an osmotic beneficial agent delivery device according to  claim 22 , wherein the side wall of the substantially cylindrical body is formed to include an inwardly directed annular lip at the open end of the substantially cylindrical body which provides additional retention of the expandable, semipermeable membrane plug in the substantially cylindrical body.  
     
     
         24 . The method of making an osmotic beneficial agent delivery device according to  claim 22 , wherein the plurality of openings are formed to allow fluid to pass through the side wall and through the expandable, semipermeable membrane plug into an interior of the substantially cylindrical body.  
     
     
         25 . The method of making an osmotic beneficial agent delivery device according to  claim 22 , further comprising providing a beneficial agent within the substantially cylindrical body and a separating member positioned within the substantially cylindrical body, the separating member being movable in a longitudinal direction within the substantially cylindrical body to dispense the beneficial agent.  
     
     
         26 . The method of making an osmotic beneficial agent delivery device according to  claim 25 , further comprising positioning an osmotic engine adjacent one side of the separating member.  
     
     
         27 . The method of making an osmotic beneficial agent delivery device according to  claim 22 , wherein the plurality of openings are formed as cylindrical bores spaced in an annular manner around the side wall.