Prepared by: Hiren Patel (M.Pharm sem III )

APMCCPER,Himatnagar

Content Introduction Pharmacokinetics of Ion Transfer Basic Circuit of Iontophoresis Movement of Ions In Solution Movement of Ions In Tissue Iontophoresis Techniques Selection of the Appropriate Ion Chemical Treatment Burns

Iontophoresis

The transfer of ions across the skin (transdermal)by use of continuous direct current

It is a Painless, Sterile, Noninvasive Technique

Demonstrated To Have A Positive Effect On The Healing Process

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. 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

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

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

Basic Circuit of Iontophoresis

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.

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

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

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

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

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.

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.

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

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

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

¨ 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

¨ Adjustable Timer¨ Up to 25

min

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

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

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 be shaved 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

1. Attach self-adhering active electrode to skin

1. Attach self-adhering active electrode to skin

2. Inject ionized solution into the chamber

1. Attach self-adhering active electrode to skin

2. Inject ionized solution into the chamber

3. 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)

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 IonInflammation¨ Dexamethasone (-)¨ Hydrocortisone (-)¨ Salicylate (-)

Spasm¨ Calcium (+)¨ Magnesium(+)

Analgesia¨ Lidocaine (+)¨ Magnesium (+)

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

Open Skin Lesions¨ Zinc(+)

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

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