Sacrificial electrode design and delivery species suitable for prolonged iontophoresis application periods

1. A wearable iontophoresis device for the prolonged delivery of a positively charged pharmaceutical species from a salt formulation comprising:

(a) a readily oxidizable metal-based sacrificial anode in the form of a generally planar layer having a connecting neck area that has a width that is generally 5% or more of the maximum electrode width dimension such that said sacrificial anode will remain connected for the desired operating life of the sacrificial anode;

wherein the sacrificial anode is configured to have a minimum operating life of at least 6 hours under skin-safe conditions and is entirely consumed during the prolonged operation of the sacrificial anode; and

(b) a drug delivery gel pad in electrical contact with said anode for accommodating a gel containing a positively charged pharmaceutical species in salt form formulated for transdermal delivery.

2. A device as in claim 1 wherein said width of said neck area is ≧10% of said maximum anode width.

3. A device as in claim 1 wherein said salt is a hydrochloride.

4. A device as in claim 3 wherein said hydrochloride is donepezil HCl.

5. A device as in claim 1 wherein said readily oxidizable metal is silver.

6. A device as in claim 3 wherein said readily oxidizable metal is silver.

7. A device as in claim 4 wherein said readily oxidizable metal is silver.

8. A device as in claim 1 wherein said anode has a surface having a rough texture in contact with said drug delivery pad thereby increasing the contact area therebetween.

9. A device as in claim 5 wherein said anode has a surface having a rough texture in contact with said drug delivery pad thereby increasing the contact area therebetween.

10. A device as in claim 1 wherein said anode includes a plurality of neck connecting segments.

11. A device as in claim 7 wherein said anode includes a plurality of neck connecting segments.

12. A device as in claim 1 comprising circuit components to control output current such that said drug delivery is made using a current density ≦100 μA lcm 2 .

13. A device as in claim 1 wherein said anode has a maximum life of 7 days or more.

14. A device as in claim 12 wherein said anode has a maximum life of 7 days or more.

15. A device as in claim 1 wherein said anode is formed as a layer on said drug delivery pad.

16. A device as in claim 1 wherein said positively charged species is donepezil.

17. A device as in claim 1 including a readily reducible cathode in series with said anode.

18. A device as in claim 17 that operates at a stable pH at both electrodes.

19. A device as in claim 4 wherein the concentration of said donepezil HCl is generally 10% or less and is contained in an aqueous hydrogel.

20. A sacrificial anode for an iontophoresis device for long term operation comprising:

(a) an amount of readily oxidizable metal forming a continuous layer on a drug delivery gel pad substrate, wherein the amount is entirely consumed during the prolonged operation of the sacrificial anode;

(b) a conductive connecting segment connecting said continuous layer in an iontophoresis circuit, said connecting segment having a width generally 5% or more of the maximum width of said sacrificial anode such that said anode will remain connected for the designed operating life of the anode; and

(c) wherein said drug delivery gel pad has a rough surface.

21. A sacrificial anode as in claim 20 wherein the thickness of said silver is from about 5 microns to about 50 microns.

22. A sacrificial anode as in claim 20 wherein said width of said connecting segment is ≧10% of said maximum anode width.

23. A sacrificial anode as in claim 21 wherein said width of said connecting segment is ≧10% of said maximum anode width.

24. An iontophoresis device for the prolonged delivery of a positively charged species from an HCl salt formulation comprising:

(a) a silver-based sacrificial anode in the form of a generally planar layer having a neck area of a width that is generally 5% or more of the maximum electrode width dimension such that said sacrificial anode will remain connected for the designed operating life of the sacrificial anode and a compatible readily reduced cathode,

wherein the silver-based sacrificial anode is configured to have a minimum operating life of at least 6 hours and is entirely consumed during the prolonged operation of the sacrificial anode;

(b) an absorbent drug delivery pad in electrical contact with said anode for receiving and absorbing a gel containing a positively charged species in hydrochloride salt form for delivery; and

(c) circuit components to control output current such that drug delivery is made using a current generally ≦100 μA/cm 2 .

25. A device as in claim 24 wherein said width of said neck area is 10% of said maximum anode width.

26. A device as in claim 24 wherein said hydrochloride is donepezil HCl.

27. A device as in claim 24 wherein said silver-based anode has a rough surface texture and forms a layer on said drug pad.

28. A method of fabricating a sacrificial anode for use in drug delivery, the method comprising:

silk screening an amount of readily oxidized metal in a manner sufficient to form a layer on an absorbent drug delivery gel pad for containing an amount of a conductive hydrogel including a pharmaceutical species, wherein said sacrificial anode is provided with a connecting neck area such that it will remain connected in a corresponding circuit for the designed operating life of the anode.

29. A method as in claim 28 wherein the sacrificial anode is fabricated with a neck area generally ≧5% of the greatest width of the anode.

30. A method as in claim 28 wherein the readily oxidized metal is silver.

31. A method as in claim 29 wherein the readily oxidized metal is silver.

32. A method as in claim 28 wherein the surface of the gel pad is rough.

33. A method as in claim 28 including formulating an amount of a salt of said pharmaceutical species in said hydrogel and causing said hydrogel to be absorbed into said gel pad.

34. A method as in claim 33 wherein said salt is a hydrochloride.

35. A method as in claim 33 wherein said salt is donepezil HCl.

36. A method of transdermally administering a positively charged pharmaceutical substance to a subject for a prolonged period in a skin-safe manner comprising:

(a) providing a wearable iontophoresis device as in claim 1 in which the positively charged species is added in gel form; and

(b) applying said iontophoresis device to the skin of a subject for a period of from 6 hours to 7 days.

37. A method as in claim 36 wherein said pharmaceutical species is selected from the group consisting of analgesics, anti-emetics, agents useful in treating Alzheimer's disease and substances that are normally skin irritants.

38. A method as in claim 37 wherein said species is donepezil.

39. A device as in claim 1 wherein said pharmaceutical species is selected from the group consisting of analgesics, anti-emetics, agents useful in treating Alzheimer's disease and substances that are normally skin irritants.

40. A device as in claim 24 wherein said pharmaceutical species is selected from the group consisting of analgesics, anti-emetics and substances that are normally skin irritants.

41. A device as in claim 28 wherein said pharmaceutical species is selected from the group consisting of analgesics, anti-emetics and substances that are normally-skin irritants.

42. A device as in claim 24 wherein said circuit components comprise a silver chloride cathode.

43. A device as in claim 1 , wherein said device further includes an integrated source of electric power.

44. A device as in claim 20 , wherein said device further includes an integrated source of electric power.

45. A device as in claim 24 , wherein said device further includes an integrated source of electric power.

46. A device as in claim 28 , wherein said device further includes an integrated source of electric power.

47. A wearable iontophoresis device for the prolonged delivery of a positively charged pharmaceutical species from a salt formulation comprising:

(a) a readily oxidizable metal-based sacrificial anode in the form of a generally planar layer having a connecting neck area that has a width that is generally 5% or more of the maximum electrode width dimension such that the sacrificial anode will remain connected for the desired operating life of the anode;

(b) wherein the sacrificial anode is configured to have a minimum operating life of at least 6 hours under skin-safe conditions;

(c) a drug delivery gel pad in electrical contact with said anode for accommodating a gel containing a positively charged pharmaceutical species in salt form formulated for transdermal delivery; and

(d) an integrated source of electric power.