Iontophoretic treatment device

Details Iontophoretic treatment device Iontophoretic treatment device

2002-04-18

2004-08-10

Casler, Brian L. (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Infrared, visible light, ultraviolet, x-ray or electrical...

C607S120000, C607S039000

Reexamination Certificate

active

06775570

ABSTRACT:

TECHNICAL FIELD
The present invention relates to apparatus and methods for delivering drugs or other beneficial agents. More specifically, the present invention relates to iontophoretic electrotransport devices and methods of their use in delivering treatment to a body.
BACKGROUND
Iontophoretic transport of drug or biological treatments is well known, and is commonly used as one way to transport such treatments across a surface and into a body. Many iontophoretic devices have been developed, as witnessed by the quantity of issued patents and pending applications mentioning such phenomena. A representative such application, titled “Rate adjustable drug delivery system” filed by Birch Point Medical, Inc., was published Jul. 12, 2001 as international publication No. WO 01/49365 A1. The '49365 application is hereby incorporated by this reference as though set forth in full herein.
Existing iontophoretic devices may generally be classified into two groups based upon their electromotive source. The first such group may be characterized as disposable, and are driven by a galvanic or electrochemical reaction encompassing electrodes bathed in an electrolyte carrying the treatment ions and offering a relatively low voltage. Such devices inherently require long treatment time intervals. Such devices are also generally constructed to be inexpensive, used once, and then thrown away. The second type of iontophoretic device typically is driven by an auxiliary power module. While treatment time requirements for devices having auxiliary power modules are generally reduced, the power modules are expensive, and so typically must be reused.
A representative disposable device, generally indicated at
30
in
FIG. 1
, can be constructed on an adhesive strip
33
. Cationic chamber
35
and anionic chamber
37
are formed in the adhesive strip
33
to create separated volumes in which to house cationic and anionic treatment materials, respectively. An electrolytic cell created by a chemical reaction between the cationic and anionic electrodes in an electrolyte provides the electromotive force to operate the device for ion transfer to a patient. A first electrode
39
installed in the cationic chamber and a second electrode
41
installed in the anionic chamber are connected by a conductor
43
to form an electron transporting leg of an electric circuit. Application of the adhesive strip to a human body completes the circuit, and initiates a flow of treatment ions through the patient's skin.
An electrode
39
maybe formed from zinc, with an electrode
41
being made from silver chloride. The electrolyte contained in the cationic chamber
35
and anionic chamber
37
directly contacts the skin to be treated, and necessarily is limited in reactivity to avoid skin irritation. Conductive salt solutions (such as 1% NaCl) commonly are employed as electrolytes due to their compatibility with a patient's skin. A device
30
, as described, will generate an electromotive force for ion transfer totalling about 1 Volt. In use of a device
30
, there is some possibility that a desired treatment chemical may undesirably interact with the electrolyte, electrode, or a product of the galvanic reaction, thereby compromising a treatment.
An alternative construction of a disposable type device is generally indicated at
50
in FIG.
2
. As a way to increase the voltage between the cationic chamber
35
and anionic chamber
37
, a plurality of galvanic cells may be arranged in electrical series on an adhesive strip
33
. Two such cells are illustrated in the embodiment
50
. A first electrode
39
in the cationic chamber
35
is connected in series to electrode
53
in cell
55
. Electrode
57
, also housed in cell
55
, is then connected in series to electrode
59
in cationic chamber
37
. Such a two cell arrangement can effectively double the voltage generated by the device, and can therefore reduce a length of treatment time required. Additional cells may be added in series, however, the adhesive strip
33
rapidly becomes crowded, thereby limiting the practical range in electromotive force for a device
30
.
FIG. 3
illustrates an exploded cross-section view through a device
30
. As illustrated, the cationic chamber
35
and anionic chamber
37
typically are open toward the patient. Some sort of substrate
59
typically is provided as a receptor to hold the treatment chemicals (beneficial agent) or electrolyte in a chamber prior to installation of adhesive strip
33
onto a patient. Substrates
59
typically are made from gauze, cellulose, cotton, or other hydrophilic material. It is common practice to saturate the substrates
59
just prior to attaching an adhesive strip
33
to a patient for a treatment session. Substrates
59
may be loaded with treatment substances using a syringe or any other convenient transfer implement.
A representative device driven by a reusable auxiliary power module is illustrated generally at
60
in
FIG. 4. A
power module
63
typically houses sophisticated electronics, and is relatively expensive (power modules are generally not regarded as single use, disposable items). Power module
63
may provide a substantial voltage to cause ion migration through a body. Applied voltages may reach perhaps 90 Volts, although perhaps for only a very short period of time to initiate ion transfer. Depending upon the skin contact area for ion transfer from a treatment chamber and the composition of the beneficial agent, a patient may perceive a burning sensation under an applied voltage of only 30 volts. Power modules maybe attached directly to an adhesive strip
33
, as illustrated, but are more commonly connected in-circuit between the cationic chamber
35
and anionic chamber
37
using wires, or extension leads
65
, to permit some degree of motion for a patient undergoing a treatment.
The electronics portion of a power module
63
may be constructed to generate a range of voltages, hold a voltage substantially constant for a period of time, or cause a programmable range in voltage over a period of time. Similar modulation may be made by a power module
63
to a current flowing in the circuit. However, power modules
63
represent an expense and may cause inconvenience in that operators may require special expertise to properly configure the module for a particular treatment.
A patient would benefit from a simple, disposable, iontophoretic device capable of higher voltage and more sustained current transmission than commercially available disposable devices, but being less costly than devices requiring an electronic module. An improvement in current transmission to minimize a polarization effect in commercially available disposable devices would also be an advance. A disposable iontophoretic device having a treatment time operably controlled by the working life of a disposable power source having a square-wave current flow would be an additional advance.
SUMMARY OF THE INVENTION
The invention provides an apparatus and method for delivering a treatment to a body by way of an iontophoretic transport procedure. A device constructed according to principles of the instant invention provides a low cost, disposable, single use, fast and accurate, iontophoretic fluid delivery device for external or implantable use. A body may be construed specifically as a mammalian (e.g. human or animal) body, or alternatively and generally, as a container of an electrolyte. A treatment to be applied to a body by the instant device and method may be either cationic-based, or anionic-based.
An iontophoretic fluid delivery device within contemplation typically includes a cationic chamber, an anionic chamber, and an electromotive force to promote ion exchange between a body and one or both of the chambers. The cationic and anionic chambers define separate volumes in which are held cationic and anionic substances, respectively. A wall of each chamber provides a passageway, or opening, through which ions may migrate. The passageways are generally oriented and arranged on a surface of a container to enable

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