Indicator for iontophoresis system

• US 5,246,417 A
• Filed: 12/11/1991
• Issued: 09/21/1993
• Est. Priority Date: 12/11/1991
• Status: Expired due to Term

• Current Assignee: ALZA Corporation (Johnson & Johnson)
• Original Assignee: ALZA Corporation (Johnson & Johnson)
• Inventors: Theeuwes, Felix, Haak, Ronald P., Roe, David K.
• Primary Examiner(s): Rosenbaum, C. Fred
• Assistant Examiner(s): Rafa, Michael
• Application Number:
  US07/806,055
• Time in Patent Office: 650 Days
• Field of Search: 128/798, 128/802, 128/803, 604/20
• US Class Current: 604/20
• CPC Class Codes: A61N 1/0436 Material of the electrode
• CPC Class Codes: A61N 1/044 Shape of the electrode
• CPC Class Codes: A61N 1/0448 Drug reservoir
• CPC Class Codes: A61N 1/325 for iontophoresis, i.e. transfer of media in ionic state by an electromotoric force into the body electrodes for external use A61N1/0428

Abstract

Apparatus (11) for delivery of a medicament, drug or other therapeutic agent transdermally to a body by iontophoresis is provided. The apparatus (11) provides a means (13) for measuring and displaying the cumulative amount of the medicament delivered to the body by monitoring the amount of a metal, initially present at the anode (45), that is transferred to the cathode (41) in a subsidiary electrolyte cell (47) through which the drive current for the apparatus (11) passes. Optionally, the apparatus also provides a plurality of light emitting devices (63-1) that display a measure of the cumulative amount of medicament delivered, by use of visually distinguishable light colors or by use of binary encoding in the light display.

Claims

1. Iontophoresis apparatus that provides an indication of the cumulative amount of a therapeutic agent delivered through a body surface of a patient, the apparatus comprising:

a first electrode assembly containing a therapeutic agent to be delivered and adapted to be placed in agent transmitting relation with a body surface of a patient;

a second electrode assembly, adapted to be placed in ion transmitting relation with the body surface at a location spaced apart from the first electrode assembly;

an electrical current source, electrically connected to one of the first and second, electrode assemblies;

a means for measuring the cumulative amount of electrical charge transferred in a given time period as a function of the product of current and time, which cumulative charge transferred is a relative measurement of cumulative amount of agent delivered; and

a display means for displaying a visually perceptible output of the cumulative amount of agent delivered relative to a total potential dosage, said display means being electrically connected in series with the first and second electrode assemblies and with the current source.

2. The apparatus of claim 1, wherein said display means has a first terminal and a second terminal and displays the cumulative amount of electrical charge transferred between the first and second terminals.

3. The apparatus of claim 2, wherein said measuring means and display means comprise an anode having a selected metal coating on its surface and electrically connected to one of said first terminal and said second terminal, a cathode electrically connected to the other of said first terminal and said second terminal, and an electrolyte solution that surrounds at least a portion of the anode and the cathode and provides an electrically conducting path between the anode and the cathode and provides a path for transport to the cathode of ions of the selected metal of the anode coating, wherein visually perceptible amounts of metal are deposited at the cathode, which deposition occurs upon reduction of metal cations at the cathode during agent delivery.

4. The apparatus of claim 3, wherein said selected metal for said anode coating is selected from the group consisting of copper, silver, nickel, mercury, chromium, iron, lead and tin.

5. The apparatus of claim 3, wherein said electrolyte solution comprises an aqueous solution of a water-soluble salt.

6. The apparatus of claim 3, wherein said electrolyte solution is selected from the group consisting of sulfuric acid, citric acid, phosphoric acid, pyrophosphoric acid, fluobric acid, oxalic acid cyanide and ammonium hydride.

7. The apparatus of claim 3, wherein said electrolyte solution includes dissolved metal ions of a predetermined concentration, the metal ions being selected from the group consisting of copper, silver, nickel, mercury, iron, lead and tin.

8. The apparatus of claim 1, wherein said current source comprises a battery.

9. The apparatus of claim 8, wherein said current source further comprises current control means for limiting said current so that said current lies between predetermined lower and upper limits.

10. The apparatus of claim 8, wherein said current source includes current control means for controlling said current in a determinable, time-varying manner.

11. The apparatus of claim 10, wherein said current control means comprises:

a resistor, having a first terminal and a second terminal, with its first terminal connected to said current source;

a junction field effect transistor, having a source, a gate and a drain, having its source electrically connected to the second terminal of the resistor, having its gate electrically connected to the first terminal of the resistor, and having its drain electrically connected to said first electrode assembly.

12. The apparatus of claim 11, wherein said resistor is a variable resistor having a predetermined range of resistance values.

13. The apparatus of claim 11, wherein said current control means further comprises a second resistor of predetermined resistance value that is connected between said drain of said field effect transistor and one of said first and second electrode assemblies.

14. The apparatus of claim 10, wherein said current control means comprises:

a resistor, having a first terminal and a second terminal, with its first terminal connected to said current source;

a junction field effect transistor, having a source, a gate and a drain, having its source electrically connected to the second terminal of the resistor, having its gate electrically connected to the first terminal of the resistor, and having its drain electrically connected to one of said first and second electrode assemblies.

15. The apparatus of claim 14, wherein said resistor is a variable resistor having a predetermined range of resistance values.

16. The apparatus of claim 14, wherein said current control means further comprises a second resistor of predetermined resistance value that is connected between said drain of said field effect transistor and one of said first and second electrode assemblies.

17. The apparatus of claim 10, wherein said current control means includes patient-activated signal means, connected to said current source, for delivering increased current of a predetermined magnitude for a time interval of predetermined delivery length when the patient-activated signal means is activated by the patient.

18. The apparatus of claim 17, wherein said current control means delivers increased current of approximately constant magnitude during at least a portion of said time interval.

19. The apparatus of claim 17, wherein said patient-activated signal means includes lock-out means for precluding delivery of said current of increased magnitude for a time interval of a predetermined lock-out length after said patient-activated signal means has been activated and has delivered said current of increased magnitude.

20. The apparatus of claim 1, wherein said cumulative amount of electrical charge delivered by the apparatus is divided into a plurality of N non-overlapping ranges, the apparatus further comprising a plurality of N activatable visible light devices, numbered 1, 2, . . . , N, with each of said visible light devices corresponding to a different one of the non-overlapping ranges of said cumulative amount of electrical charge delivered and being controlled and activated by said display means, whereby if said cumulative amount of electrical charge delivered lies in one of the non-overlapping ranges, one visible light device is activated and displays light.

21. The apparatus of claim 1, wherein said cumulative amount of electrical charge, denoted Δ

μ

, delivered by the apparatus is divided into a plurality of approximately 2^N non-overlapping ranges with a maximum value of μ

₀, where N is a predetermined positive integer, the apparatus further comprising a plurality of at least N activatable visible light devices, numbered k=1,2, . . . , N, that are controlled by said display means so that if Δ

μ

satisfies the inequalities ##EQU2## with each coefficient n_k =0 or 1, visible light device number k is activated if n_k =1 and is inactivated if n_k =0.

22. The apparatus of claim 1, wherein said cumulative amount of electrical charge, denoted Δ

μ

, delivered by the apparatus is divided into a plurality of approximately 2^N non-overlapping ranges with a maximum value of μ

₀, where N is a predetermined positive integer, the apparatus further comprising a plurality of at least N activatable visible light devices, numbered k=1, 2, . . . , N, that are controlled by said display means so that if Δ

μ

satisfies the inequalities ##EQU3## with each coefficient n_k =0 or 1, visible light device number k is activated if n_k =0 and is inactivated if n_k =1.

23. The apparatus of claim 1, wherein the apparatus has a plurality of L operating conditions associated therewith and numbered j=1, 2, . . . , L, where L is a positive integer satisfying the inequalities 2^M-1 <

L≦

2^M for a predetermined positive integer M, the apparatus further comprising a plurality of M activatable visible light devices, numbered m=1,2, . . . , M and controlled by said display means, so that, if operating condition number j is present and the number j is expressible as ##EQU4## where n_m =0 or n_m =1, visible light device number m is activated if n_m =1 and is not activated if n_m =0.

24. The apparatus of claim 1, wherein the apparatus has a plurality of L operating conditions associated therewith and numbered j=1,2, . . . , L, where L is a positive integer satisfying the inequalities 2^M-1 <

L≦

2^M for a predetermined positive integer M, the apparatus further comprising a plurality of M activatable visible light devices, numbered m=1,2, . . . , M and controlled by said display means, so that, if operating condition number j is present and the number j is expressible as ##EQU5## where n_m =0 or n_m =1, visible light device number m is activated if n_m =0 and is not activated if n_m =1.

25. The apparatus of claim 1, wherein said first electrode assembly comprises an electrically conducting layer and an ionically conducting layer that contains said therapeutic agent in an ionized or ionizable form.

26. The apparatus of claim 1, wherein said first electrode assembly further comprises an ionically conducting adhesive layer, positioned between and electrically connected to said first electrode assembly and said body surface of said patient.

27. The apparatus of claim 1, wherein said second electrode assembly comprises an electrically conducting layer and an ionically conducting layer that contains an electrolyte in ionized or ionizable form.

28. The apparatus of claim 1, wherein said first electrode assembly further comprises an ionically conducting adhesive layer, positioned between and electrically connected to said second electrode assembly and said body surface of said patient.

29. The apparatus of claim 1, wherein the cumulative amount of therapeutic agent delivered through the body surface is substantially directly proportional to the cumulative amount of charge transferred through the apparatus.

30. The apparatus of claim 1, wherein said display means comprises a plurality of visible light emitting devices and means for activating each of the devices at different non-overlapping ranges of cumulative electrical charge passed through the apparatus.

31. The apparatus of claim 30, wherein each of said plurality of visible light emitting devices displays a light having a color visually distinguishable from the other visible light emitting devices.