Iontophoresis is a technique that uses a low-level electrical current to transfer ions through the skin for therapeutic purposes. It works by using the electrical polarity of ions - ions with the same polarity as the electrode they are placed under will be repelled into the skin, while ions with opposite polarity will be attracted. The current must be direct current applied at low intensity for short durations. Proper electrode size and ionic solution are required to avoid burns or irritation. Iontophoresis can be used to deliver medications for conditions like inflammation, pain, and skin problems.

1. Iontophoresis
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2. Iontophoresis
• The term iontophoresis is simply defined
as ion transfer (ionto = ion; phoresis =
transfer).
• Introduction of ions into the body using
direct electrical current
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3. Iontophoresis
• It is a specialized technique of electrical
stimulation that uses electrical polarity of
continuous direct current to ionize
medicines placed beneath surface
electrodes and transfers them into the
body through the skin
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4. Iontophoresis vs Phonophoresis
• Iontophoresis uses electrical current to
transport ions into tissues
• Phonophoresis uses acoustic energy
(ultrasound) to drive molecules into
tissues
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5. How does it work?
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6. Basic Principles
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Current Required
Ionic Polarity
Low-level Amplitude
Electrode Size
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7. Current Required
• In order to 'drive' the ions into the tissues, a DIRECT
(Galvanic) CURRENT needs to be employed
• A monophasic pulsed application can also be used
• Constant current is preferable to constant voltage thus, the magnitude of the applied current will not
exceed the preset level in terms of skin resistance.
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8. Ionic polarity
• The basis of successful ion transfer lies in physics principle
“like poles repel and unlike poles attract’
• Ions with a polarity which is the same as that of the
stimulating electrode are repelled into the skin
• the electrode under which the ionic solution is placed is called
the ACTIVE electrode
• The other electrode, which is used to complete the circuit is
most commonly called the DISPERSIVE, INDIFFERENT,
INACTIVE or RETURN electrode.
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9. Low-level Amplitude
• low-level amplitude is more effective
• The treatment is usually applied with currents
up to 5mA
• with low ionic concentrations – up to 5%,
• Treatment times are typically in the 10 - 30
minute range
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10. Electrode Size
• the negative electrode should be made
larger than the positive electrode (usually
twice)
• enlarging the negative electrode size
lowers the current density on the negative
pad, leading to reduction of irritation.
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11. Physiological changes
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Ion penetration
Acid / alkaline reactions
Hyperemia
Dissociation
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12. Ionic Penetration
• penetration does not exceed 1 mm,
• subsequent deeper absorption through the
capillary circulation.
• The bulk of deposited ions at the active
electrode are stored, to be depleted by the
sweep of circulating blood.
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13. Acid / alkaline reactions
• Will get ACID accumulation under the POSITIVE
(anode) electrode (weak HCl)
• This is because the negatively charged chloride ions
(Cl- from NaCl) is attracted towards the anode.
• This is considered sclerotic, which tends to harden
tissues, serving as an analgesic agent due to local
release of oxygen.
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14. Acid / alkaline reactions
• Will get ALKALINE accumulation under the NEGATIVE
(cathode) electrode
• because the positively charged sodium ions (Na+ from NaCl)
will move towards the cathode.
• The Na+ ions react with water to form sodium hydroxide
(NaOH).
• considered sclerolytic, which is a softening agent due to the
hydrogen release, serving in the management of scars and
burns.
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15. Hyperemia
• Both the positive and negative electrodes produce
hyperemia and heat due to the resulting vasodilatation.
• The cathodal hyperemia is generally more pronounced
and takes more time to disappear than that of the anode.
• Generally, hyperemia under both electrodes does not
lasts more than one hour.
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16. Dissociation
• ionizable substances dissociate in solution
releasing ions,
• with the passage of direct current into the
solution migrate toward the other pole.
• Gets absorbed through the capillary circulation.
• This is the concept of ion transfer.
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17. Complications
• Chemical burns
• Heat burns
• Sensitivities and allergic reactions to ions
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18. Chemical burns
• This is due to excessive formation of the strong sodium
hydroxide at the cathode.
• The skin becomes pinkish initially, to be grayish and oozing
wound few hours later.
• These burns take a long time to heel
• Should be treated with antibiotics and sterile dressings.
• Burns under the anode are rare,
• Appears as a hardened red area similar to a scab.
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19. Heat burns
– occurs due to excessive heat buildup in areas
with high resistance
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Most of these burns occurs when
the electrodes are not moist enough,
they are not fitting well or
not in good contact with the skin.
– Should be treated with antibiotics and sterile
dressings.
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20. Allergic reactions to ions
• If the patient is allergic to seafood, “iodine” should not
be used.
• Patients with an active peptic ulcer or gastritis, react
poorly to “hydrocortisone”.
• Patients, who have problems with aspirin, react poorly
to “salicylates”.
• Patients sensitive to metals may react to “copper, zinc
or magnesium”.
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21. Indications
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Local anesthesia.
Inflammatory conditions.
Relief of pain.
Skin conditions.
Tension headache.
Inhibition of spasticity.
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22. Selecting the Appropriate Ion
• Inflammation
Dexamethasone (-)
Hydrocortisone (-)
Salicylate (-)
• Spasm
Calcium (+)
Magnesium (+)
• Analgesia
Lidocaine (+)
Magnesium (+)
• Open Skin Lesions
Zinc (+)
Prescription required
• Edema
• Hyaluronidase(+)
• Salicylate (-)
• Mecholyl (+)
• Scar Tissue
• Chlorine (-)
• Iodine (-)
• Salicylate (-)
• Hyperhydrosis
• Tap Water
• Glycopyrronium
Bromide (+)
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23. Contraindications
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Open wounds or burns.
Patients with cardiac pacemakers.
Allergy to medication.
Loss of sensation.
Greasy or dirty skin.
Sole of foot (hard for the ions to pass
inside).
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24. Precautions
• Don’t use two chemicals under the same
electrode, even if they are of the same
polarity.
• Don’t administer ions with opposite
polarities during the same treatment
session.
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25. Current Density
the current density is measured in mA/cm2
If the current density reaches too high a level, tissue
damage, especially skin burn, may ensue.
It is suggested that a Maximum Safe Current Density
of;
0.5mA/cm2 is applicable at the negative(cathode) and
1.0mA/cm2 at the positive(anodal) electrode.
(Belanger, 2010)
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26. Current Intensity
Calculated as
• Maximum Current (mA) =
Maximum Safe Current Density (mA/cm2)
X Electrode area (cm2)
• Recommended current intensity is 3 to
5 mA
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27. Treatment Time
Treatment Time: ranges between 10 - 20 min.
Patient should be comfortable with no
reported or visible signs of pain or burning
Check skin every 3-5 minutes for signs of
skin irritation
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28. Formula for iontophoresis
I x T x ECE = grams of substance introduced,
Where:
I: (Intensity) measured in amperes.
T: (Time) measured in hours.
ECE: (Electro-Chemical Equivalent) represents standardized
figures for ionic transfer with known currents and time factors.
As the determination of the ECE for many complex
substances is very difficult, fewer milligrams of these complex
substances will penetrate the skin.
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29. Electrodes
• Traditional Electrodes
• Commercial Electrodes
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30. Traditional Electrodes
• Older electrodes made of tin, copper, lead, aluminum,
or platinum backed by rubber
• Completely covered by sponge, towel, or gauze which
contacts skin
• Absorbent material is soaked with ionized solution
(medication)
• If medicated ointment is used, it should be rubbed into
the skin and covered by some absorbent material
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31. Commercial Electrodes
Sold with most
iontophoresis systems
Electrodes have a
small chamber covered
by a semipermeable
membrane into which
ionized solution may be
injected
The electrode self
adheres to the skin
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32. 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 the
generator
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33. Application
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The skin should be abrasion / cut free and
the area carefully washed (soap & water is fine).
Dry electrodes are inappropriate and should not be used.
If pregelled electrodes are being used, ensure that a good even contact is
achieved.
Adequate fixation of the electrode and pad to the skin needs to be carefully
maintained.
Uneven current distribution can easily lead to skin burns and/or irritation
Explain to the patient what is expected and ensure that they know to report
immediately if any untoward or painful sensations are felt.
Turn the current up slowly to the required amount
At the end of the treatment time, ensure that the current is turned down
slowly.
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34. References
1.
2.
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5.
6.
7.
http://www.electrotherapy.org/modality/iontophoresis?highlight=iontophore
sis , Tim Watson (2012)
Iontophoresis from internet, n.p.
Jennifer Doherty-Restrepo, Iontophoresis. PET 4995: Therapeutic
Modalities. Ppt presentation
Low J, Reed A. Electrotherapy explained, 4th edition, Elsevier, 2006; pp
193 – 195
Foster A, Palastanga N. Clayton’s electrotherapy,9th edition, AITBS
Publishers, pp 85 – 86
Mitra PK. Handbook of practical electrotherapy,1 edition, Jaypee
publications. 2006; pp 61 – 64
Singh Jagmohan. Textbook of Electrotherapy, 2 edition, 2012;pp 128 –
129
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