Surgery – Means for introducing or removing material from body for... – Infrared – visible light – ultraviolet – x-ray or electrical...
Reexamination Certificate
1998-06-10
2001-09-11
Seidel, Richard K. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Infrared, visible light, ultraviolet, x-ray or electrical...
C600S372000
Reexamination Certificate
active
06289241
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally concerns methods and apparatus for electrotransport. More specifically, methods of the present invention concern conduction of electrotransport with selected control of active electrode reservoir environment, to advantage. The present invention also specifically concerns apparatus for providing controlled active electrode environment electrotransport.
Two methods of electrotransport to which the invention has particular preferred application are iontophoresis and electro-osmosis. Some of the principles described herein may be applied to passive delivery processes (not involving electrotransport) to advantage.
BACKGROUND OF THE INVENTION
The present invention concerns preferred methods and apparatus for transdermal delivery or transport of therapeutic agents, typically through electrotransport.
Herein the term “electrotransport” is used to refer to methods and apparatus for transdermal delivery of therapeutic agents, whether charged or uncharged, by means of an applied electromotive force to electrolyte-containing reservoir. The particular therapeutic agent being delivered may be charged or uncharged, depending upon the particular method chosen. When the therapeutic species being delivered is charged, the process is referred to as iontophoresis. When the therapeutic species delivered is uncharged, it may be considered delivered by means of electro-osmosis techniques or other electrokinetic phenomenon such as electrohydrokinesis, electro-convection or electrically-induced osmosis. In general, these latter electrokinetic delivery processes of uncharged species into a tissue result from the migration of solvent, in which the uncharged species is dissolved, as a result of the application of electromotive force to the electrolyte reservoir. Of course during the process, some transport of charged species will take place as well.
In general, iontophoresis is an introduction, by means of electric current, of ions of soluble salts into the tissues of the body. More specifically, iontophoresis is a process and technique which involves the transfer of ionic (charged) species into a tissue (for example through the skin of a patient) by the passage of a electric current through an electrolyte solution containing ionic molecules to be delivered (or precursors for those ions), upon application of an appropriate electrode polarity. That is, ions are transferred into the tissue, from an electrolyte reservoir, by application of electromotive force to the electrolyte reservoir.
Much of the discussion herein will focus on techniques for iontophoresis, and apparatus therefor.
However, the methods and apparatus will be understood'to be applicable to electrotransport generally, including electrokinetic phenomena involving transport of an uncharged therapeutic species. A reason for this, is that such phenomena generally involve the transport of some charged species, which is accompanied by the desired movement of an uncharged therapeutic species.
Assume, for example, that the patient to receive the therapeutic ion treatment is a human and the medication is to be transferred through the skin. Through iontophoresis, either positively charged drugs (medication) or negatively charged drugs (medication) can be readily transported through the skin and into the patient. This is done by setting up an appropriate potential between two electrode systems (anode and cathode) in electrical contact with the skin. If a positively charged drug is to be delivered through the skin, an appropriate electromotive force can be generated by orienting the positively charged drug species at a reservoir associated with the anode. Similarly, if the ion to be transferred across the skin is negatively charged, appropriate electromotive force can be generated by positioning the drug in a reservoir at the cathode. Of course, a single system can be utilized to transfer both positively charged and negatively charged drugs into a patient at a given time; and, more than one cathodic drug and/or more than one anodic drug may be delivered from a single system during a selected operation.
For general discussions of iontophoresis see: Phipps, J. B. et al; “Transport of Ionic Species Through Skin”;
Solid State Ionics;
Vol. 28-30, p. 1778-1783 (1988); Phipps, J. B., et al; “Iontophoretic Delivery of Model Inorganic and Drug Ions”;
J. Pharm. Sciences;
Vol. 78, No. 5, p. 365-369 (May 1989); and, Chien, Y. W. et al; “Iontophoretic Delivery of Drugs: Fundamentals, Developments and Biomedical Applications”;
J. Controlled Release,
Vol. 7, p. 1-24 (1988). The disclosures of these three references are incorporated herein by reference.
Electrotransport processes, including iontophoresis, have found a wide variety of therapeutic applications. Such applications have sometimes involved the delivery of ionic drugs, i.e., charged organic medications or therapeutic metal ions. Applications have involved both treatments of conditions and also diagnostics. For example, iontophoresis techniques have been utilized to deliver pilocarpine, a substance utilized in the diagnosis of cystic fibrosis. It has also been utilized to deliver hyaluronidase, for treatment of scleroderma and lymphedema. It has further been utilized for allergy testing, delivery of metallic ions for treatment of fungal infections, venereal diseases, ulcers, bursitis, and myopathies; delivery of vasodilators; and, for delivery of anesthetics and steroids. See for example Chien, Y. W., et al., supra.
A wide variety of iontophoresis devices are resently known. See for example: Phipps et al., U.S. Pat. No. 4,744,788; Phipps et al., U.S. Pat. No. 4,747,819; Tapper et al., European Patent Application Publication No. 0318776; Jacobsen et al., European Patent Application Publication No. 0299631; Petelenz et al., U.S. Pat. No. 4,752,285; Sanderson et al., U.S. Pat. No. 4,722,726; and Parsi, E. J., U.S. Pat. No. 4,731,049. The disclosures of these seven references are incorporated herein by references.
In typical, conventional, electrotransport devices, for example iontophoresis devices, two electrodes are generally used. Both electrodes are disposed so as to be an intimate electrical contact with some portion (typically skin) of the subject (human or animal) typically by means of two remote electrolyte-containing reservoirs, between which current passes as it moves between the skin and the electrodes. One electrode, generally referred to herein as the “active” electrode, is the electrode from which the substance (medicament, drug precursor or drug) is delivered or driven into the body by application of the electromotive force. The other electrode, typically referred to as an “indifferent” or “ground” electrode, serves to close the electrical circuit through the body. In some instances both electrodes may be “active”, i.e. drugs may be delivered from both. In such cases each electrode will serve as the “companion”, “indifferent”, “remote” or “ground” electrode, to the other. That is, classification of an electrode as “active” or “indifferent” is done by reference to a particular material being delivered. Herein the term electrode, or variants thereof, when used in this context refers to an electrically conductive member, through which a current passes during operation.
If the electrotransport method is iontophoresis, generally the active electrode includes the therapeutic species as a charged ion, or a precursor for the charged ion, and the transport occurs through application of the electromotive force to the charged therapeutic species. If other electrotransport phenomenon are involved, the therapeutic species will be delivered in an uncharged form, transfer being motivated, however, by electromotive force.
For example, the applied current may induce movement of a non-therapeutic species, which carries with it water into the subject. The water may have dissolved therein the therapeutic species. Thus, electrotransport of the non-therapeutic charged species induces movement of the therapeutic but non-charged species.
In conjunction wit
ALZA Corporation
Merchant & Gould P.C.
Seidel Richard K.
Thompson Michael M.
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