Electrochemically driven drug dispenser

• US 4,886,514 A
• Filed: 03/02/1989
• Issued: 12/12/1989
• Est. Priority Date: 05/02/1985
• Status: Expired due to Term

• Current Assignee: Cardinal Health 303 Incorporated (Cardinal Health, Inc.)
• Original Assignee: Ivax Corporation (Teva Pharmaceutical Industries, Ltd.)
• Inventors: Maget, Henri J. R.
• Primary Examiner(s): Rosenbaum, C. Fred
• Assistant Examiner(s): Rose, Sharon
• Application Number:
  US07/318,488
• Time in Patent Office: 285 Days
• Field of Search: 604/890.1, 604/891.1, 604/892.2, 604/19, 604/20, 604/31, 604/67, 604/93, 604/95, 604/96-100, 604/131
• US Class Current: 604/891.1
• CPC Class Codes: A61M 2005/14204 with gas-producing electrochemical cell
• CPC Class Codes: A61M 5/14276 specially adapted for implantation

Abstract

An electrochemically driven drug dispenser for dispensing a drug at a controlled rate. The drug dispenser includes an electrochemical pump which pumps an electrochemically active fluid from a first compartment through a membrane into a scond compartment. As the fluid enters the second compartment it exerts pressure on a diaphragm separating the second compartment from a chamber containing a drug to be administered. As the pressure increases, the drug is expelled. In the absence of any pumping action, the fluid moves between the two compartments by diffusion through the membrane at a rate which is characteristic of the membrane and determined by any pressure difference between the two compartments. The pumping rate is determined by the magnitude of an electric current applied to the pump, and by varying the pumping rate with reference to the diffusion rate any of a variety drug administration rates can be implemented. A pressure sensor may be included in the pump for more precise control of the pumping rate. The membrane may be fabricated of electrolytic and non-electrolytic portions so that a desired diffusion rate can be achieved.

Claims

1. An electronchemically driven drug dispenser comprising:

a container;

separating means disposed in the container and defining therein a drug chamber for receiving a drug and a gas pressure pump chamber separated from the drug chamber by the separating means;

an electrochemically active gas disposed in the pump chamber;

a membrane disposed in the pump chamber and defining therein a first pressure containment compartment and a second compartment, the separating means comprised in a side of the second compartment, the membrane comprising a non-electrolytic portion and an electrolytic portion, the non-electrolytic portion characterized by a first rate of diffusion of the gas therethrough from one of the components to the other, the diffusion rate being proportional to any difference between the pressure of the gas in one compartment and the pressure of the gas in the other compartment;

first and second electrodes disposed in the first and second compartments, respectively, on opposing sides of the electrolytic portion of the member, the gas being electrochemically reversibly active so as to enter into an anodic reaction at one electrode in which anodic reaction molecules of the gas are converted into ions that are transportable through the membrane and a cathodic reaction at the other electrode in which cathodic reaction ions are reconverted back into molecules of the gas;

means to provide an electric current to the electrodes, the current being operative to transport the ions through the electrolytic portion of the membrane whereby the gas is effectively pumped from one compartment to the other at a pumping rate determined by the polarity and magnitude of the current, the net rate of flow of the gas from one compartment to the other being equal to an algebraic sum of the pumping rate and the diffusion rate; and

first control means to vary the magnitude and direction of the current with reference to the first diffusion rate to cause the gas to flow from the first compartment to the second sufficient to exert pressure on the separting means to discharge a drug from the chamber at a predetermined rate.

2. A drug dispenser according to claim 1 and further comprising a drug disposed in the drug chamber.

3. A drug dispenser according to claim 1 and further comprising a delivery port and a check valve through which a drug can be discharged from the drug chamber.

4. A drug dispenser according to claim 1 and further comprising a permeable membrane through which a drug can be discharged from the drug chamber.

5. A drug dispenser according to claim 1 wherein the gas comprises hydrogen.

6. A drug dispenser according to claim 1 wherein the gas comprises oxygen.

7. A drug dispenser according to claim 1 wherein the separating means comprises a flexible diaphragm.

8. A drug dispenser according to claim 1 wherein the separating means comprises a sliding wall.

9. A drug dispenser according to claim 1 wherein the control means linearly varies the magnitude to the current at a rate proportional to the diffusion rate, causing the gas to flow from the first compartment to the second at a constant net rate and thereby discharging the drug at a constant rate.

10. A drug dispenser according to claim 1 wherein the control means intermittently varies the magnitude of the current according to the diffusion rate, causing the gas to flow intermittently from the first compartment to the second and thereby discharging the drug at a pulsating rate.

11. A drug dispenser according to claim 1 wherein the electrolytic portion of the membrane is characterized by a second rate of diffusion of the gas therethrough from one of the compartments to the other and wherein the control means varies the magnitude of the current with reference to both diffusion rates.

12. A drug dispenser according to claim 11 wherein the control means linearly varies the magnitude of the current at a rate proportional to both diffusion rates, causing the gas to flow from the first compartment to the second at a constant net rate and thereby discharging the drug at a constant rate.

13. A drug dispenser according to claim 11 wherein the control means intermittently varies the magnitude of the current according to both diffusion rates, causing the gas to flow intermittently from the first compartment to the second and thereby discharging the drug at a pulsating rate.

14. An electrochemically driven drug dispenser comprising:

a container;

separating means disposed in the container and defining therein a drug chamber for receiving a drug and a gas pressure pump chamber separated from the drug chamber by the separating means;

an electrochemically active gas disposed in the pump chamber;

a membrane disposed in the pump chamber and defining therein a first pressure containment compartment and a second compartment, the separating means comprised in a side of the second compartment, the membrane comprising a non-electrolytic portion and an electorlytic portion, the non-electrolytic portion characterized by a first rate of diffusion of the gas therethrough from one of the compartments to the other, the diffusion rate being proportional to any difference between the pressure of the gas in one compartment and the pressure of the gas in the other compartment, and the electrolytic portion characterized by a second rate of diffusion of the gas therethrough from one of the compartments to the other;

first and second electrodes disposed in the first and second compartments, respectively, on opposing sides of the electrolytic portion of the membrane, the gas being electrochemically reversibly active so as to enter into an anodic reaction at one electrode in which anodic reaction molecules of the gas are converted into ions that are transportable through the membrane and a cathodic reaction at the other electrode in which cathodic reaction ions are reconverted back into molecules of the gas;

pressure sensing means to sense the pressure of the gas in one of the compartments;

means to provide an electric current to the electrodes, the current being operative to transport the ions through the electrolytic portion of the membrane whereby the gas is effectively pumped from one compartment to the other at a pumping rate determined by the polarity and magnitude of the current, the net rate of flow of the gas from one compartment to the other being equal to an algebraic sum of the pumping rate and the diffusion rate; and

control means, responsive to the pressure sensing means to vary the magnitude and direction of the current with reference to the pressure of the gas to cause the gas to flow from the first compartment to the second and sufficient to exert pressure on the separating means to discharge a drug from the drug chamber at a predetermined rate.

15. A drug dispenser according to claim 14 wherein the control means linearly varies the magnitude of the current at a rate proportional to the sensed pressure, causing the gas to flow from the first compartment to the second at a constant net rate and thereby discharging the drug at a constant rate.

16. A drug dispenser according to claim 14 wherein the control means intermittently varies the magnitude of the current according to the sensed pressure, causing the gas to flow intermittently from the first compartment to the second and thereby discharging the drug at pulsating rate.