Iontophoretic drug delivery system

The iontophoretic drug delivery system includes electrodes controlled by a microprocessor controller to drive charged molecules contained in a drug reservoir through the skin into the issues of a patient. The iontophoretic drug delivery system further includes an antenna connected to the programmable microprocessor. The antenna allows for the programming of the microprocessor and for the exchange of patient, drug, and treatment related information between the microprocessor and an external device. The iontophoretic drug delivery system is also provided with buttons to allow a patient to manually activate the drug delivery system. The iontophoretic drug delivery system is housed within a thin polyester film membrane.

FIELD OF THE INVENTION

The present invention relates to the field of devices and systems for delivering drugs to medicate a patient, and more particularly to an iontophoretic drug delivery system.

BACKGROUND OF TEE INVENTION

Iontophoresis is a drug delivery system. Iontophoresis is a non-invasive method of propelling charged molecules, normally medication or bioactive-agents, transdermally by repulsive electromotive force. By applying a low-level electrical current to a similarly charged drug solution, iontophoresis repels the drug ions through the skin to the underlying tissue. In contrast to passive transdermal patch drug delivery, iontophoresis is an active (electrically driven) method that allows the delivery of soluble ionic drugs that are not effectively absorbed through the skin.

An electrode drives charged molecules into the skin. Drug molecules with a positive charge are driven into the skin by an anode and those molecules with a negative charge are driven into the skin by a cathode.

There are a number of factors that influence iontophoretic transport including skin pH, drug concentration and characteristics, ionic competition, molecular size, current, voltage, time applied and skin resistance. Drugs typically permeate the skin via appendageal pores, including hair follicles and sweat glands.

Iontophoresis has numerous advantages over other drug delivery methods. The risk of infection is reduced because iontophoresis is non-invasive. Also, iontophoresis provides a relatively pain-free option for patients who are reluctant or unable to receive injections. For skin tissues, drug solutions may be delivered directly to the treatment site without the disadvantages of injections or orally administered drugs. Further, iontophoresis minimizes the potential for further tissue trauma that can occur with increased pressure from an injection.

SUMMARY OF THE INVENTION

An iontophoretic drug delivery system is disclosed. The iontophoretic drug delivery system includes electrodes controlled by a microprocessor controller to drive charged molecules through the skin into the tissues of a patient The iontophoretic drug delivery system further includes a wireless signal receiver connected to the microprocessor controller. The wireless signal receiver allows for the programming of the microprocessor and for the exchange of patient, drug, and treatment related information between the microprocessor and an external device. The microprocessor may be programmed through the wireless signal receiver with drug delivery schedule information, including frequency and dosage, for a particular patient and medication. A drug reservoir contains charged drug molecules that are driven into the skin by the electrodes. The operation of the electrodes, frequency, duration, and level of voltage applied, is controlled by the microprocessor. A battery provides power to the iontophoretic device.

The iontophoretic drug delivery system may be optionally housed within a thin polyester film membrane. The iontophoretic drug delivery system is configured in the shape of a generally flexible patch that adheres to the skin of a patient with an adhesive. In one embodiment, the edges of the flexible patch may be provided with a high tack adhesive to maintain the integrity of the skin-patch boundary. A lower tack adhesive is provided within the internal area of the flexible patch to make the purposeful removal of the patch from the use less painful. The drug reservoirs can be formed of a membrane or a gel pad in which charged drug particles are injected.

The iontophoretic drug delivery system may contain different various numbers of drug reservoirs depending upon the particular treatment. Where a single drug is being delivered, the system may contain a single drug reservoir adjacent one electrode. Where a treatment requires two drugs that have oppositely charged solutions, the system may include a reservoir adjacent each of the oppositely charged electrodes. Where multiple drugs having the same charge are used, they may be either mixed into a single drug reservoir or placed in multiple drug reservoirs each adjacent a respective electrode having the same electric charge.

The size of the electrodes may vary in different embodiments depending upon the strength of the electrical current needed to be produced in order to drive drug molecules of various sizes into a patient's skin.

In one exemplary embodiment, the electrodes and the microprocessor, battery and antenna are attached on opposite sides of a flexible sheet. The electrodes, microprocessor, battery and antenna are electrically connected utilizing conductive silver ink. Through holes formed in the flexible sheet electrically connect the electrodes to the microprocessor, battery and antenna. The microprocessor and battery are attached to the system using conductive cement.

In another embodiment, the system main contain various sensors to measure parameters such as patient skin temperature, moisture at the system/patient skin interface, or other patient or drug delivery related parameters.

Other objects, features and aspects of the invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

While the invention has been shown and described with reference to a particular embodiment thereof, it will be understood to those skilled in the art, that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

FIG. 1discloses an exploded isometric view of an iontophoretic drug delivery system10. System10provides a non-invasive method of propelling high concentrations of a charged substance, normally medication or bioactive-agents, transdermally by repulsive electromotive force. Iontophoretic drug delivery system10includes a microprocessor controller12, a battery14, an antenna16, printed flexible wiring18, an electrode20, and an electrode22. Drug reservoirs24are coupled to electrodes20and22. Electrodes20and22and drug reservoirs24are contained in flexible layer26that conforms to the patient's body in the area of application. Layer26and layer28are bonded together to seal and protect microprocessor controller12, battery14, antenna16, and printed flexible wiring18. The construction and configuration shown is an example and not intended to be limiting.

Antenna16provides a wireless capability for system10to communicate with other external devices. In an exemplary embodiment, antenna16may be an RFID antenna, a blue-tooth enabled device, an infra-red wireless device, or another wireless signal receiver. Antenna16may function as an RFID antenna or can receive signals from an outside device through capacitive coupling. Antenna16can also be configured in the shape of inductive coils in order to receive signals from an outside device through inductive coupling.

A high-tack adhesive30is placed on an outer edge of layer26and a low-tack adhesive32is placed within the internal area of the skin contacting surface of layer26. High-tack adhesive30extends around the periphery of layer26and secures the outer edge of system10to the skin of a patient. High-tack adhesive30is used to prevent moisture or physical force from peeling system10off of the skin of a patient. Low-tack adhesive32is placed in the internal area of layer26(i.e. inward with respect to the high tack adhesive30) to maintain contact between system10and the skin of the patient. The use of low-tack adhesive32makes removal of system10from the skin of a patient less painful, while the high tack adhesive30provides stronger bonding at the periphery where it is needed most to prevent lifting of the edge of system10or exposing system10to moisture. A preferred type of adhesive for high-tack adhesive30is a silicone based adhesive that is rapidly cured with an electron beam or UV radiation. Preferably, the adhesive is not present between the drug reservoir24and the skin, as this contact could alter the properties of adhesive30and/or influence the release of the drug. System10eliminates any interaction between the drug and adhesive matrix. In an exemplary embodiment, these adhesives may have peel strengths of 8.5 or 9.3 lbs/in. Adhesives with stronger or weaker peel strengths may be used with system10.

A release layer34is placed over adhesive30and32to protect adhesive30and32. Layer34is removed from system10just prior to bonding system10to the skin of a patient. Layer34makes sufficient contact with adhesive30and32to hold layer34to system10while allowing a user to easily peel layer34off of system10. Typically, layer34is coated with a silicone based release coating to ensure that it can be peeled off without degrading adhesives30and32.

Charged drug molecules are contained within drug reservoirs24, which faces the patient's skin through an opening in layer26. Drug reservoirs24may be a gel pad or membrane to which the charged drug molecules contained in a solution are applied or injected. By impregnating a gel pad or membrane with charged drug molecules, the charged drug molecules are not able to readily be absorbed into a patient's body without the operation of electrodes20and22. In one embodiment, drug reservoirs24are a conductive medium to support the function of electrodes20and22. By making drug reservoirs24also a conductive medium, system10can function with a lower amount of current, thereby extending battery14life and reducing the amount of current put into a patient's skin, of which a high amount of current can cause irritation. Typically, the solution is injected through a port into drug reservoirs24. Electrodes20and22drive the charged drug molecules out of drug reservoirs24into the skin of a patient. Where the reservoir24includes a gel, the drug in ionic form may be mixed with the gel matrix cured together and assembled into the system10.

The basis of ion transfer lies in the principle that like poles repels and unlike poles attract. Ions, being particles with a positive or a negative charge are repelled into the skin by an identical charge the electrode places over it. When a direct electric current activates electrodes20and22, anions in the solution, ions with a negative charge, are repelled from the negatively charged electrode. Positively charged ions (cations) are likewise repelled from the positive electrode. The electrical current drives ions through the skin that would not be absorbed passively. The quantity of ions that are made to cross the skin barrier is proportional to the current density and to the amount of time the current flows through the solution. Current density is determined by the strength of electric field and the electrode size. A desired current strength is in the range of 0.4 mA or 2.0 mA per square inch of electrode20and22surface. This current strength is below sensory perception of a typical human patient. If electrodes20and22are too small, thereby concentrating the current (or if the current is too high), it may be more uncomfortable for the patient, as the current density may be sensed as an irritant.

Electrodes20and22and flexible printed wiring18are preferably made from a flexible material that can bend with layer26in conformity to the application area of the patient's body. One exemplary flexible material is silver conductive ink with resistivity of 8 to 10 milliohms per square. The resistivity of silver conductive irk within the range of 8 to 10 milliohms per square is desirable in order to have sufficient current to drive drugs into the stratum corneum. The ink may be silver (Ag), for example, and may be printed (e.g. by screen printing or gravure rolling) onto layer26. Most commercially available silver conductive inks have a resistivity in the range of 14 to 18 milliohms per square, which limits the current available to drive the drugs through the stratum corneum. Electrodes20and22may be formed of silver chloride (AgCl).

System10includes two electrodes20and22. In a particular drug treatment, the charged drug molecules will typically have one charge. Thus, only one of electrodes20or22can drive the charged drug molecules into the skin of the patient. The electrode that drives the charged drug molecules into the patient's skin is sometimes referred to as an active electrode, which is coupled with drug reservoir24. A passive electrode that is not coupled to a drug reservoir24completes the circuit with the active electrode for creating a current for driving charged drug molecules into the patient's skin. In other drug treatments, the solutions containing charged drug molecules may have both positive and negative charges. In that example, both electrodes are active electrodes and both are coupled to a drug reservoir24.

In many drug treatments, a single drug is used. However, it is common for the efficacy of many drugs to be increased by combining their delivery with other drugs. Thus, system10may be configured to deliver multiple types of charged drug molecules. In the case where the multiple drug molecules have the same charge, those drugs may be combined into a single solution and delivered from a single drug reservoir24. In other embodiments where the multiple drugs have the same charge, but need to be delivered to the patient at different times or in different quantities, multiple electrodes22with multiple drug reservoirs24may be used. In a case where there are two drugs having molecules of opposite polarity, both electrodes20and22are provided with drug reservoirs24for delivering their respective drugs to the patient. In one embodiment, drug reservoirs24are formed of hydro-gel (i.e., a water-based gel). In another embodiment, drug reservoirs24are formed on a membrane. The size electrodes20and22will vary depending upon the size of the charged drug molecule that they are trying to repel into the patient's skin. Thus, in embodiments where multiple electrodes with multiple drug chambers24are used, the sizes of the electrodes and drug chambers may vary,

One or both electrodes20and22are made of Ag/AgCl printable conductive ink coating. Electrodes20and22are covered by drug reservoirs24, which may be formed from hydrogel that contains the charged drug molecules. Electrodes20and22are printed to the flexible printed wiring18with a highly conductive Polymer Thick Film (PTF) ink. In a preferred embodiment, a lead-free, silver loaded isotropic conductive cement is used that provides an electrical and mechanical connection having resistance to moisture and thermal shock.

Battery14powers system10. It is desirable to make battery14as thin as possible, along with the rest of system10, in order to enhance the ability of system10to adhere to a patient's skin with minimal disruption to the patient. Battery cells on the order of 0.7 mm thickness can generate up to 3.0 volts of electricity and multiple arrays can generate and control up to 9.0 volts of electricity. This amount of power allows for wireless programming and data acquisition with microprocessor controller12through antenna16. The type and construction of the battery is not intended to be limiting.

Iontophoretic drug delivery system10may be used, in one exemplary embodiment, as a method of local drug delivery in a variety of clinical settings. System10can administer a local anesthetic to prevent painful sensations during skin puncture procedures, such as gaining venous access or injecting a drug intradernally or subcutaneously. System10can also deliver nonsteroidal anti-inflammatory drugs and corticosteroids inpatients with musculoskeletal inflammatory conditions.

The rate, timing and pattern of drug delivery using iontophoretic drug delivery system10is controlled with microprocessor controller12by varying the electrical current applied to electrodes20and22. Microprocessor controller12can be programmed to provide a variety of drug delivery profiles where the duration and frequency of drug delivery is varied based upon the treatment parameters. The speed with which a drug delivery system can provide efficacious blood levels of the target drug determines the onset of therapeutic action. Iontophoretic drug delivery system10allows many drugs to pass directly through the skin into underlying issue and the bloodstream at a rate that is significantly more rapid than oral or passive transdermal drug delivery methods. Microprocessor controller12is programmed wirelessly through antenna16. In one exemplary embodiment, microprocessor controller12to configured accept programming once and only once, thereby ensuring that system10could not be erroneously reprogrammed or purposefully misprogrammed by various electronic devices.

As an option, microprocessor controller12may also perform the function of data acquisition of drug delivery information on the actual drug delivery performed by system10. Drug delivery information, for example, can include an electronic record of the date, time and quantity of each dose delivered; providing information for determining patient compliance. Electrodes20and22can be used to determine whether system10is in contact with the patient's skin by the operation of electrodes20and22and the resistivity of the patient's skin in the electrode-skin-electrode circuit formed when system10is in contact with the patient's skin.

As an option, system10also may include a manual button array36(shown inFIG. 20). Manual button array36is coupled to microprocessor controller12. Manual button array36allows a patient to manually operate system10. System10is preferably programmed with drug delivery information to automatically deliver drugs to the patient. A patient can deviate from or override this program and manually operate system10to deliver drugs with manual button array36. Manual button array36can allow a patient to deviate from the drug delivery information and provide either longer or shorter drug dosages more or less often than instructed in the drug delivery information. A patient can also turn off system10with manual button array36, for example when they are feeling negative side affects from the drug delivery.

Electrodes20and22, flexible printed wiring18, antenna16and other circuitry components in system10, in a preferred embodiment, are made from Polymer Thick Film (PTF) flexible circuits that are manufactured using a technology that consists of a low-cost polyester dielectric substrate and screen-printed thick film conductive inks. These circuits are made with an additive process involving the high-speed screen printing of conductive ink. Multi-layer circuits are manufactured using dielectric materials as an insulating layer, and double-sided circuits using printed through-hole technologies.FIGS. 4-15show an exemplary method of fabricating system10. Both active and passive surface mount components can be adhered to PTF flexible circuit assemblies with Conductive Adhesives (CA's) or with Anisotropic Conductive Adhesives (ACA's). In a preferred embodiment, to ensure optimal performance when system10is flexed, all components are encapsulated between layers26and28, which are bonded together using a hydrophobic UV-cured material developed specifically for medical applications.

It is advantageous to utilize PTF flexible circuits because they are inherently less costly than for example copper based circuits. PTF are formed on a dielectric substrate that circuit traces are printed directly upon. In addition, PTF typically uses a PET substrate which is significantly less expensive than the polyimide substrate which is commonly used in copper circuitry. In addition, as PTF circuits are more environmentally friendly as they are printed directly and do not require the removal of materials where chemicals are used to selectively etch away the copper foil to leave behind a conductive pattern.

The charged drug molecules vary in size for different drug compounds. Larger drug molecules require stronger electromagnetic forces to drive them into the skin of a patient. Smaller drug molecules require lesser electromagnetic forces to drive them into the skin of a patient. Thus, it is desirable to vary the size of electrodes20and22based upon the size of the drug compounds in order to deliver an optimal amount of electromagnetic force to drive the drug molecules into the patient's skin. System10is therefore preferably manufactured for a specific drug molecule size by having a tailored size for each electrode20and22.

The table shown below provides an exemplary list of drugs, the charge of the drug molecules and solution, and the purpose/condition for which the drugs are used.

In various embodiments, the flux of charged drug molecules from drug reservoirs24into the patient's skin can be increased through the use of a skin permeation enhancer. A permeation enhancer is any chemical or compound that, when used in conjunction with the charged drug molecule, increases the flux of charged drug molecules from drug reservoir24into the skin of the patient. That is, skin permeation enhancers is a substance that enhances the ability of the charged drug molecule transfer from the drug reservoir and permeate into the patient's skin.

Such use of a permeation enhancers is advantageous because it reduces the amount of electrical power required to transfer the drug from a reservoir24and into the patient's skin. This means that less current can be used, which in turn reduces the potential for skin irritation. And it also means less power is drawn, meaning the battery can be made smaller and/or last longer.

The enhancer may be an excipient, i.e., a medicinally inactive agent, included in the reservoir24with the charged drug molecule. Preferably, where a gel is used in the reservoir to carry the drug, the permeation enhancer and the drug are soluble in the gel but not chemically bonded to the gel network, thus enabling them to more easily transfer from the gel to the skin. In some embodiments, the enhancer may be a molecule with a charge similar to the associated drug molecule.

For example, oleic acid has an synergistic effect on the ability of iontophoresis to promote skin permeation of insulin. The use of propylene glycol further increased this effect. One exemplary incipient that can enhance the flux of charged drug molecules from system10into a patient by means of iontophoresis is a fatty acid having from 1-9 carbon atoms. Preferably, the incipient contains at least one C2-C6fatty acid. By means of an example, the fatty acid may be selected from the group of propionic acid, valeric acid, 2-methylbutanoic acid, 3-methylbutanoic acid, and combinations thereof. In one example, the fatty acid is a mixture of propionic acid and valeric acid.

The permeation enhancer need not be in the reservoir24with the drug, and could be applied to the skin contacting surface of the reservoir24. This could help create an interface between the reservoir24and the skin for enhancing permeation of the drug.

FIG. 2discloses an isometric view of an iontophoretic drug delivery system10. Battery14, antenna16, and flexible printed wiring18are shown adhered to layer26with layer28partially pealed away.FIG. 2demonstrates the flexibility of system10that enables system10to conform to the contours of a patient's body and be able to deform during normal activity and movement of the patient's body. In addition, this figure shows how system10, when assembled, is a thin patch that intrudes minimally upon the patient's daily functions.

FIG. 3discloses an isometric see-through view of an iontophoretic drug delivery system10. Microprocessor controller12, battery14, antenna16, printed flexible wiring18, electrodes20and22, and drug reservoirs24are shown sandwiched between layers26and28. Manual button array36allows a patient to manually operate system10. An indicator light84provides a visual indication of the status of system10. Indicator light84is preferably a multi-colored LED, which may for example show green when operating normally, flash orange in a low power state, or flash red when a system failure occurs, as a non-limiting example. System10can include a variety of sensors37to monitor various parameters in the patient/system10environment. These parameters can include, by means of a non-limiting example, moisture, temperature, system10/patient physical contact, and various patient parameters such as skin temperature, heart rate, etc. Information from sensors37can be used to provide positive feedback to system10. For instance, if sensors37detect moisture at the system10/patient skin interface, that may indicate that the patient is sweating. With this information, system10may be programmed to either increase the voltage delivered to electrodes20and22to drive the charged drug molecules through the added layer of sweat. Alternatively, system10may be programmed to stop delivery of the charged drug molecules until after the patient stops sweating and the sweat has evaporated.

FIGS. 4-14disclose a process of forming circuitry for an iontophoretic drug delivery system10.FIG. 4depicts a printing of circuitry38on a primary component side40of layer26. Layer26is preferably made of a thin flexible film, such as polyethylene terephthalate (PET). Circuitry38is made of conductive silver ink that is printed onto layer26. InFIG. 4A, antenna16is printed along with wirings18that interconnect antenna16, battery14, and microprocessor controller12.

FIG. 5depicts a deposition of dielectric material42on primary component side40of layer26. Dielectric material42covers wirings18that interconnect antenna16, battery14, and microprocessor controller12. Dielectric material42does not cover antenna16. At this step, through holes54are formed by laser cutting layer26. The dielectric material is printed on to layer26. The dielectric is printed using a magnesium silicate pigment that is bound with urethane acrylate.

FIG. 6depicts a printing of circuitry44on a secondary component side46of layer26. Circuit44includes wirings48for electrodes20and22and wirings50for connecting electrodes20and22to battery14and microprocessor controller12. Circuitry44is made of conductive silver ink that is printed onto layer26. Secondary component side46makes contact with a patient's skin.

FIG. 7depicts a formation of electrodes20and22on secondary component side46of layer26. Electrodes20and22are formed on top of wirings48. Electrodes20and22are formed of silver or silver chloride. In a preferred embodiment, wirings48have a higher resistivity than electrodes20and22. Electrodes20and22may be made from a material having a resistivity lower than wirings48in order to deliver a desirable amount of electricity to a patient's skin that is just below a patient's sensory perception. Thus, in addition to varying electrode size to alter the amount of electricity delivered by electrodes20and22to accommodate drug molecules of varying sizes, the materials used to form electrodes20and22may also be varied to affect these parameters as well.

The larger of the two electrodes22would contain the positivity or negatively charged drug molecule. The smaller of the two electrodes20would be the return and would contain only the hydrogel material. For positively charged drug molecules, the larger electrode22is constructed of silver ink with one or multiple print passes as well as varied silver loading. The return electrode20is constructed of silver/silver chloride ink with one or multiple print passes as well as varied silver chloride loading. For a negatively charged drug molecules, the larger electrode22is constructed of silver/silver chloride ink with one or multiple print passes as well as varied silver chloride loading. The return electrode20is constructed of silver ink with one or multiple print passes as well as varied silver loading.

This combination of material and material sets enhances the drug delivery performance, stabilizes the pH and increases the delivery time of the patch system.

FIG. 8depicts a deposition of dielectric material52on secondary component side46of layer26. Dielectric material52is deposited to cover wirings50. The dielectric material is not deposited on electrodes20or22.

FIG. 9depicts a filing of through holes54in layer26. Through holes54are filled with a conductive material in order to electrically couple wirings50to circuitry38. This conductive material is preferably printed silver ink.

FIG. 10depicts the attachment of laser or die cut foam56to secondary component side46of layer26. Foam56is cut to have openings58. Openings58are provided for the formation of drug reservoirs24. Openings58coincide with the position of electrodes20and22on top of which drug reservoirs24are formed. Foam56is attached to secondary component side46of layer26. In another embodiment, printed silicone adhesive is used in place of foam56.

FIG. 11depicts a formation of drug reservoirs24on secondary component side46of layer26. In this exemplary embodiment, drug reservoirs24are formed from hydro-gel that is deposited within openings58of foam56over electrodes20and22.

FIG. 12depicts a deposition of conductive epoxy60on primary component side40of layer26. Conductive epoxy60is deposited in the pattern shown inFIG. 12to secure microprocessor controller12and battery14onto layer26and place those components into electrical connection with circuitry38.

FIG. 13depicts a placement of components12and14on primary component side40of layer26. Microprocessor12and battery14are attached to layer26over the positions where conductive epoxy60(shown inFIG. 12) was deposited. The components labeled with the label “D” are diodes, the components labeled with “C” are capacitors, and the components labeled with “R” are resistors.

FIG. 15illustrates a completed primary component side40of layer26. Microprocessor controller12and battery are mounted to layer26. Antenna16is formed and connected to microprocessor controller12with wirings18. Through holes54interconnect microcontroller12and battery14to electrodes20and22on the secondary component side46of layer26. Circuitry38includes a switching regulator and associated components as well as a charge pump for increased electrical output.

FIG. 16illustrates a completed secondary component side46of layer26. Drug reservoirs24are formed over electrodes20and22and are surrounded by foam tape56. The outer edges of secondary component side46are covered with high-tack adhesive30. The central portion of secondary component side46is covered with low-tack adhesive. Wirings50connect electrodes20and22to battery14and microprocessor controller12by through holes54.

FIG. 17illustrates a side view of iontophoretic drug delivery system10. Layer28is shown covering microprocessor controller12, battery14, and antenna16. Microprocessor controller12, battery14and antenna16are attached to primary component side40of layer26. On the secondary component side46of layer26, electrodes20and22are printed on layer26. Layer26is attached to foam layer56, in which drug chambers24are formed. Adhesives30and32are placed on the bottom surface of layer56(as shown inFIG. 18).

FIG. 18illustrates an adhesive pattern on secondary component side46of layer26. The peripheral portion of secondary component side46is covered with high tack adhesive30. The dashed inner portion of secondary component side46is covered with low tack adhesive32. Electrodes20and22and drug chambers24are not covered with any adhesive so that the adhesive does not interfere with the transference of charged drug molecules from drug chambers24into the patient's skin.

FIG. 19illustrates an alternative embodiment for iontophoretic drug delivery system10. System10includes a first drug reservoir58formed on an electrode60, which is formed on printed circuit62. System10includes a second drug reservoir64formed on an electrode66, which is formed on printed circuit68. System10also includes a third drug reservoir70formed on electrode72, which is formed on printed circuit74. Printed circuits62,68and74are connected with printed wirings50that lead to through holes54. Electrodes60,66, and70are coupled to separate terminals of microprocessor controller12and are operated independently of each other by microprocessor controller12. Electrodes60,66and70are varied in size according to the variance in size of the charged drug molecules that electrodes60,66and70drive into a patient's skin.

FIG. 20illustrates a side view of a manual button array36for manually operating an iontophoretic drug delivery system10. Manual button array, in this exemplary non-limiting embodiment, is formed of one or more poly-dome switch assemblies36. Poly-dome switch assemblies36.

While the invention has been shown and described with reference to a particular embodiment thereof, it will be understood to those skilled in the art, that various changes in form and details may be made therein without departing from the spirit and scope of the invention.