Claims for Patent: 6,195,582

Summary for Patent: 6,195,582

Title:	Electrotransport device electrode assembly having lower initial resistance
Abstract:	The present invention relates generally to an electrotransport device for transdermally or transmucosally delivering a beneficial agent (e.g., a drug) to the body surface of a patient or for transdermally or transmucosally sampling a body analyte. Most particularly, the present invention relates to a configured and electrochemically reactive electrode assembly having improved start-up electrical performance and improved lag time to compliant agent delivery.
Inventor(s):	Scott; Erik R. (Golden Valley, MN)
Assignee:	ALZA Corporation (Mountain View, CA)
Application Number:	09/239,708
Patent Claims:	1. An electrotransport device for delivering or sampling an agent through a body surface, the device including an anodic electrode assembly, a cathodic electrode assembly and a source of electrical power electrically connected to the anodic and cathodic electrode assemblies, at least one of the anodic and cathodic electrode assemblies comprising: an electrode composed at least in part of a solid phase electrochemically reactive material, the electrode having an initial electrical resistance, the electrode becoming less resistant upon exposure to electric current; an electrolyte reservoir containing therein the agent to be delivered or capable of receiving the agent to be sampled, said reservoir when in use positioned in ion-transmitting relation with the body surface; an electric current collector, discrete from the electrode, having an electrical resistance less than the electrical resistance of the electrode, the current collector conducting electric current between the power source and the electrode; wherein at a time when the device begins applying electrotransport current, the electrode, the current collector and the electrolyte reservoir form a common boundary. 2. The device of claim 1, wherein the electrode assembly having the common boundary condition is the cathodic electrode assembly and the electrochemically reactive material is reducible. 3. The device of claim 2, wherein the reducible material is selected from the group consisting of metal compounds, metal complexes, intercalation compounds, carbon intercalation hosts hosting an alkali metal, and electrochemically reducible polymers. 4. The device of claim 3, wherein the reducible material is a compound or a complex having a formula MX, wherein M is an electrochemically reducible metal and X is selected from the group consisting of halides, polymeric anions, and low molecular weight anions. 5. The device of claim 4, wherein M is selected from the group consisting of silver, copper and zinc. 6. The device of claim 4, wherein MX comprises a silver halide. 7. The device of claim 3, wherein the intercalation compound has a formula M.sub.x (WO.sub.3).sub.y, wherein M is a metal, x is a number greater than or equal to zero, and y is a number greater than zero. 8. The device of claim 3, wherein the metal compound has a formula M.sub.x [Fe(CN).sub.6 ].sub.y, wherein x and y are numbers greater than zero. 9. The device of claim 2, wherein the electrode comprises a silver chloride foil. 10. The device of claim 1, wherein the agent is a body analyte to be transdermally sampled by the device, the device having a body analyte-receiving reservoir in at least one of the anodic and cathodic electrode assemblies. 11. The device of claim 10, wherein the body analyte is non-ionic and is received in at least one of (i) a cathodic reservoir in the cathodic electrode assembly and (ii) an anodic reservoir in the anodic electrode assembly. 12. The device of claim 11, wherein the non-ionic body analyte is glucose. 13. The device of claim 10, wherein the body analyte is cationic and is received in a cathodic reservoir in the cathodic electrode assembly. 14. The device of claim 10, wherein the body analyte is anionic and is received in an anodic reservoir in the anodic electrode assembly. 15. The device of claim 1, wherein the electrode has an initial electrical sheet resistance of greater than 100 ohms/square. 16. The device of claim 15, wherein the current collector has an electrical sheet resistance that is less than one-half the sheet resistance of the electrode. 17. The device of claim 1, wherein the electrode comprises a polymer matrix and the electrochemically reactive material is contained in said matrix. 18. The device of claim 17, wherein the polymer matrix, at the time when the device begins applying electrotransport current, is substantially free of any electrically conductive material. 19. The device of claim 1, wherein the electrode assembly having the common boundary condition is the anodic electrode assembly and the electrochemically reactive material is oxidizable. 20. The device of claim 19, wherein the oxidizable material is selected from the group consisting of a leuco form of polyaniline and transition metal halide-intercalated carbon or graphite. 21. The device of claim 19, wherein the anodic electrode comprises a polyaniline sheet. 22. The device of claim 1, wherein the agent is a therapeutic agent to be delivered by the device through skin, at least one of the anodic and cathodic electrode assemblies having a reservoir containing the therapeutic agent. 23. The device of claim 22, wherein the agent is cationic and is contained in an anodic reservoir within the anodic electrode assembly, the anodic electrode assembly being a donor electrode assembly. 24. The device of claim 22, wherein the agent is anionic and is contained in a cathodic reservoir within the cathodic electrode assembly, the cathodic electrode being a donor electrode. 25. The device of claim 1, wherein the electrode is oxidized or reduced upon exposure to electric current to a form having a lower electrical sheet resistance than said initial electrical sheet resistance. 26. The device of claim 1, wherein the power source applies an electric current i through the current collector to the electrode, the common boundary having a length I, the ratio of l:i being at least 0.1 cm/mA. 27. The device of claim 1, wherein the common boundary has a length of at least 0.1 cm. 28. The device of claim 1, wherein the solid electrochemically reactive material has a solubility in the electrolyte of less than about 1 mg/ml. 29. The device of claim 1, wherein the common boundary has a shape selected from the group consisting of linear, rectangular, circular, and elliptical. 30. The device of claim 1, wherein the electrode assembly with the common boundary has a plurality of said common boundaries. 31. The device of claim 1, wherein the electrode consists essentially of the electrochemically reactive material. 32. The device of claim 1, wherein the current collector is comprised of a material selected from the group consisting of metals and carbon. 33. The device of claim 1, wherein the current collector is selected from the group consisting of an electrically conductive adhesive and an electrically conductive trace. 34. The device of claim 1, wherein the electrolyte reservoir comprises an aqueous solution. 35. The device of claim 1, wherein the electrolyte reservoir comprises a gel. 36. The device of claim 1 wherein the electrode has an initial electrical sheet resistance of greater than about 10,000 ohms/square. 37. The device of claim 1 wherein the electric current collector has an initial electrical sheet resistance of less than about 50,000 ohms/square. 38. The device of claim 1 wherein the electric current collector has an initial electrical sheet resistance of less than about 1,000 ohms/square. 39. The device of claim 1 wherein the electric current collector has an initial electrical sheet resistance of less than about 10 ohms/square.