Iontophoresis

Iontophoreis

Introduction of Ions Into The Body Using Direct Electrical Current

Transports Ions Across A Membrane Or Into a Tissue

It is a Painless, Sterile, Noninvasive Technique

Demonstrated To Have A Positive Effect On The Healing Process

Iontophoresis vs Phonophoresis

Both Techniques Deliver Chemicals To Biologic Tissues

Phonophoresis Uses Acoustic Energy (Ultrasound) To Drive Molecules Into Tissues

Iontophoresis Uses Electrical Current To Transport Ions Into Tissues

Pharmacokinetics of Ion Transfer

Transdermal iontophoresis delivers medication at a constant rate so that the effective plasma concentration remains within a therapeutic window for an extended period of time. Therapeutic window - the plasma concentrations

of a drug which should fall between a minimum concentration necessary for a therapeutic effect and the maximum effective concentration above which adverse effects may possibly occur.

Pharmacokinetics of Ion Transfer

Iontophoresis appears to overcome the resistive properties of the skin to charged ions

Iontophoresis decreases absorption lag time while increasing delivery rate when compared with passive skin application

Iontophoresis provides both a spiked and sustained release of a drug reducing the possibility of developing a tolerance to drug

Pharmacokinetics of Ion Transfer

Rate at which an ion may be delivered is determined by a number of factors The concentration of the ion The pH of the solution Molecular size of the solute Current density Duration of the treatment

Pharmacokinetics of Ion Transfer Mechanisms of absorption of drugs administered

by iontophoresis similar to administration of drugs via other methods

Advantages of taking medication via transdermal iontophoresis relative to oral medications Concentrated in a specific area Does not have to be absorbed within the GI tract Safer than administering a drug through injection

Movement of Ions In Solution

Ionization- Soluable compounds dissolve into ions suspended in solutions that are called electrolytes

Electrophoresis- Movement of ions in solution according to the electrically charged currents acting on them.

Movement of Ions In Solution

Cathode = Negatively charged electrode Highest concentration of electrons Repels negatively charged ions Attracts positively charged ions Accumulation of negatively charged ions in a

small area creates an acidic reaction

Movement of Ions In Solution

Anode = Positively charged electrode Lower concentration of electrons Repels positively charged ions Attracts negatively charged ions Accumulation of positively charged ions in a

small area creates an alkaline reaction

Movement of Ions In Solution

Positively charged ions are driven into tissues from positive pole

Negatively charged ions are driven into tissues from negative pole

Knowing correct ion polarity is essential

Movement of Ions In Tissue

Force which acts to move ions through the tissues is determined by Strength of the electrical field Electrical impedance of tissues to

current flow

Movement of Ions In Tissue Strength of the electrical field is

determined by the current density Difference in current density between

the active and inactive electrodes establishes a gradient of potential difference which produces ion migration within the electrical field

Active electrode- the one being used to drive the ion into the tissue

Movement of Ions In Tissue

Current density may be altered by Increasing or decreasing current

intensity Changing the size of the electrode

Increasing the size of the electrode will decrease current density under that electrode.

Movement of Ions In Tissue

Current density should be reduced at the cathode (negative electrode)

Alkaline reaction (+ions) is more likely to produce tissue damage than acidic reaction(- ions)

Thus negative electrode should be larger (2x) to reduce current density.

Movement of Ions In Tissue

Higher current intensities necessary to create ion movement in areas where skin and fat layers are thick further increasing chance of burns around negative electrode

Sweat ducts are primary paths by which ions move through the skin and act to decrease impedance facilitating the flow of direct current as well as ions

Movement of Ions In Tissue

The quantity of ions transferred into the tissues through iontophoresis is directly proportional to Current density at the active

electrode Duration of the current flow Concentration of ions in solution

Movement of Ions In Tissue

Once the ions pass through skin they recombine with existing ions and free radicals in the blood thus forming the necessary new compounds for favorable therapeutic interactions

Iontophoresis Techniques

Iontophoresis Generators

Produce continuous direct current *

Assures unidirectional flow of ions

– *One study has shown that drugs can be delivered using AC

current

Iontophoresis Generator

Intensity control 1 to 5 mA Constant voltage

output that adjusts to normal variations in tissue impedance thus reducing the likelihood of burns

Automatic shutdown if skin impedance reduces to preset limit

Iontophoresis Generator Adjustable Timer

Up to 25 min

Iontophoresis Generator Lead wires

Active electrode Inactive electrode

Current Intensity

Low amperage currents appear to be more effective as a driving force than currents with higher intensities

Higher intensity currents tend to reduce effective penetration into the tissues

Recommended current amplitudes used for iontophoresis range between 3-5 mA

Current Intensity

Increase intensity slowly until patient reports tingling or prickly sensation

If pain or a burning sensation occur intensity is too great and should be decreased

When terminating treatment intensity should be slowly decreased to zero before electrodes are disconnected

Current Intensity

Maximum current intensity should be determined by size of the active electrode

Current amplitude usually set so that current density falls between 0.1-0.5 mA/cm2 of the active electrode surface

Treatment Duration Treatment duration ranges between 10-20

minutes with 15 minutes being an average

Patient should be comfortable with no reported or visible signs of pain or burning

Check skin every 3-5 minutes looking for signs of skin irritation

Decrease intensity during treatment to accommodate decrease in skin impedance to avoid pain or burning

Traditional Electrodes

Older electrodes made of tin, copper, lead, aluminum, or platinum backed by rubber

Completely covered by a sponge, towel, or gauze which contacts skin

Absorbent material is soaked with ionized solution

Ion ointment should be rubbed into the skin and covered by some absorbent material.

Commercial Electrodes

Sold with most iontophoresis systems Electrodes have a small chamber covered by a

semipermiable membrane into which ionized solution may be injected

The electrode self adheres to the skin

Electrode Preparation To ensure maximum contact

of electrodes skin should beshaved and cleaned

prior to attachment of the electrodes

Do not excessively abrade skin during cleaning since damaged skin has lowered resistance to current and a burn might occur more easily

Electrode Preparation

Attach self-adhering active electrode to skin

Electrode Preparation

Attach self-adhering active electrode to skin

Inject ionized solution into the chamber

Electrode Preparation

Attach self-adhering active electrode to skin

Inject ionized solution into the chamber

Attach self-adhering inactive electrode to the skin and attach lead wires from generator to each

Electrode Placement

Size and shape of electrodes can cause variation in current density (smaller = higher density)

Electrodes should be separated by at least the diameter of active electrode Wider separation minimizes

superficial current density decreasing chance for burns

Selecting the Appropriate Ion

Negative ions accumulating at the positive pole or anode Produce an acidic reaction through the

formation of hydrochloric acid Produce softening of the tissues by

decreasing protein density-useful in treating scars or adhesions

Some negative ions can also produce an analgesic effect (salicylates)

Selecting the Appropriate Ion

Positive ions that accumulate at the negative pole Produce an alkaline reaction with the

formation of sodium hydroxide Produce hardening of the tissues by

increasing protein density

Selecting the Appropriate Ion Inflammation

Dexamethasone (-) Hydrocortisone (-) Salicylate (-)

Spasm Calcium (+) Magnesium(+)

Analgesia Lidocaine (+) Magnesium (+)

Edema Hyaluronidase(+) Salicylate (-) Mecholyl(+)

Open Skin Lesions Zinc(+)

Scar Tissue Chlorine(-) Iodine(-) Salicylate(-)

Treatment Precautions Problems which might potentially arise

from treating a patient using iontophoresis may for the most part be avoided if the athletic trainer Has a good understanding of the existing

condition which is to be treated Uses the most appropriate ions to accomplish

the treatment goal Uses appropriate treatment parameters and

equipment set-up

Chemical Treatment Burns

Most common problem is a chemical burn which occurs as a result of direct current itself and not because of the ion being used Continuous direct current creates migration of

ions which alters the normal pH of the skin Chemical burns typically result from accumulation

of sodium hydroxide at cathode Alkaline reaction causes sclerolysis of local tissues Decreasing current density by increasing size of

cathode can minimize potential for chemical burn

Thermal Treatment Burns

Thermal burns may occur due to high resistance to current flow created by poor contact of the electrodes with the skin Electrodes are not moist enough Wrinkles in the gauze or paper towels

impregnated with the ionic solution Space between the skin and electrode

around the perimeter of the electrode Body weight resting on top of electrode