Transcript Iontophoresis

Iontophoresis
Chapter 6
IONTOPHORESIS
• Use of Direct Current to facilitate
delivery of ions into the skin for
therapeutic purposes.
• Mechanism of delivery:
“LIKE CHARGES REPEL”
Positive Electrode
(anode) delivers + ions
Negative Electrode
(cathode) delivers - ions
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
 Duration of Tx:
 Based on intensity
desired usually every
other day for 3 weeks
 Indications
 Acute or Chronic Inflam
 Arthritis
 Myositis
 Myofacial Pain
Syndromes
 Invasive method for
delivering drugs
 Contraindications
 Hypersensitivity to
electrical currents
 Contraindications to
meds.
 Pain of unknown origin
 Precautions
 Prescription
 Dosage
 Do not reuse electrode
 Burns if intensity to
great
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 1020 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
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
Indications – evidence based
Condition
Ions
Benefit Reference
Yes
Kahn, 1982, Reidle et
all 2000, Montorsi et all
2000, Rothfield et al
1967
Inflamm. Disorders Dex
Musc.
Yes
Bertolucci, 1982,
Delacerda, 1982Harris,
1982, Pellecchia et al
1994,
TMJ
Dex & dex/lido
Yes
Braun 1987; Reid et al
1994;Schiffman et al
1996
TMJ
Epicondylitis
Epicondylitis
Carpal tunnel
Edema
Hydrocort/US
Dex
Na+ Salcycil.
Dex
Hualuronidase
No
No
Yes
Yes
Yes
Kahn, 1980
Plantar Faciitis
Dex/lido.
Panus et al 1996
Demiratas et al 1998
Banta, 1994
Magistro 1964, Boone
1969
Iontophoresis: Evidence Based
Condition
Ions
Benefit Reference
Scar Tissue
Iodine
Yes
Tennenbaum, 1980
Tendon Adhesion
Iodine
Yes
Langley 1984
Subdeltoid Bursa
Magnesium
Yes
Weinstein et al 1958
Plantar warts
Salicylate
Yes
Gordon et al 1969
Heel Pain
Myositis Oss.
Myopathy
Postsurgical hip
pain
Acetate
Acetate
Calcium
Salicylate
Yes
Yes
?
Yes
Japour et al, 1999
Weider, 1992
Kahn, 1975
Garzione, 1978
Biophysical Effects
Dependant on Medication
See following chart
Sample Medications
Meds
Pathology
Dose
Polarity
Acetic Acid
Myositis
80mA/min
+
Dexamethasone Inflammation 41mA/min
& Lidocain & Pain control & 40 mA
-
Lidocain &
Epinphrine
Pain Control
30mA/min
+
Lidocain &
Epinphrine
Pain Control 20 mA/min
+
Dexamethasone Inflammation 41mA/min
-
Selecting the Appropriate Ion

Inflammation






Calcium (+)
Magnesium(+)
Analgesia


Lidocaine (+)
Magnesium (+)
Edema

Dexamethasone (-)
Hydrocortisone (-)
Salicylate (-)
Spasm





Open Skin Lesions


Hyaluronidase(+)
Salicylate (-)
Mecholyl(+)
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
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