Chap 6- Iontophoresis

8/7/2019 Chap 6- Iontophoresis

http://slidepdf.com/reader/full/chap-6-iontophoresis 1/42



Iontophoresis



Iontophoreis

Introduction of Ions Into The Body UsingDirect Electrical Current

Transports Ions Across A Membrane Or Into a TissueIt is a Painless, Sterile, Noninvasive

TechniqueDemonstrated To Have A Positive EffectOn The Healing Process



Iontophoresis vs Phonophoresis

Both Techniques Deliver Chemicals ToBiologic Tissues

Phonophoresis Uses Acoustic Energy(Ultrasound) To Drive Molecules IntoTissues

Iontophoresis Uses Electrical Current ToTransport I ons Into Tissues



Pharmacokinetics of Ion Transfer

Transdermal iontophoresis deliversmedication at a constant rate so that the

effective plasma concentration remainswithin a therapeutic window for an extendedperiod of time.

j Therapeutic window - the plasmaconcentrations of a drug which should fallbetween a minimum concentration necessaryfor a therapeutic effect and the maximumeffective concentration above which adverseeffects ma ossibl occur.




Iontophoresis appears to overcome theresistive properties of the skin to charged io

Iontophoresis decreases absorption lag timwhile increasing delivery rate when compar with passive skin application

Iontophoresis provides both a spiked andsustained release of a drug reducing thepossibility of developing a tolerance to drug




R ate at which an ion may be deliveredis determined by a number of factors

j The concentration of the ionj The pH of the solutionj Molecular size of the solutej

Current densityj Duration of the treatment



Pharmacokinetics of Ion Transfer Mechanisms of absorption of drugsadministered by iontophoresis similar to administration of drugs via other methods

Advantages of taking medication viatransdermal iontophoresis relative to oral

medicationsj Concentrated in a specific areaj Does not have to be absorbed within the G I tractj

Safer than administering a drug through injection





Movement of Ions In Solution

Cathode = Negatively charged electrodej Highest concentration of electronsj Repels negatively charged ionsj Attracts positively charged ionsj Accumulation of negatively charged ions in a

small area creates an a cidic reaction




Anode = Positively charged electrodej L ower concentration of electronsj Repels positively charged ionsj Attracts negatively charged ionsj Accumulation of positively charged ions in a

small area creates an alkaline reaction




Positively charged ions are driven intotissues from positive pole

Negatively charged ions are driven intotissues from negative poleKnowing correct ion polarity is essential



Movement of Ions In Tissue

F orce which acts to move ions throughthe tissues is determined by

j Strength of the electrical fieldj Electrical impedance of tissues to current

flow




Strength of the electrical field isdetermined by the current density

j Difference in current density between theactive and inactive electrodes establishesa gradient of potential difference whichproduces ion migration within the electricalfield

j Active electrode- the one being used to drivethe ion into the tissue




Current density may be altered byj Increasing or decreasing current intensityj Changing the size of the electrode

Increasing the size of the electrode willdecrease current density under that electrode.




Current density should be reduced atthe cathode (negative electrode)

Alkaline reaction (+ions) is more likely toproduce tissue damage than acidic reaction(-ions)Thus negative electrode should be larger (2x)

to reduce current density.




Higher current intensities necessary tocreate ion movement in areas whereskin and fat layers are thick further increasing chance of burns aroundnegative electrode

Sweat ducts are primary paths by whichions move through the skin and act todecrease impedance facilitatingthe flow of direct current as well asions




The quantity of ions transferred into thetissues through iontophoresis is directlyproportional to

j Current density at the active electrodej Duration of the current flow

j Concentration of ions in solution




O nce the ions pass through skin theyrecombine with existing ions and freeradicals in the blood thus forming thenecessary new compounds for favorable therapeutic interactions



Iontophoresis Techniques



Iontophoresis Generators

j Produce continuousdirect current *

j Assures unidirectionalflow of ions

± *One study has shownthat drugs can bedelivered using AC

current



Iontophoresis

Generator j Intensity control

j 1 to 5 mAj

Constant voltageoutput that adjusts tonormal variations intissue impedancethus reducing the

likelihood of burnsj Automatic shutdown

if skin impedancereduces to preset

limit



Iontophoresis

Generator j Adjustable Timer

j Up to 25 min



Iontophoresis

Generator j L ead wires

j Active electrodej Inactive electrode



Current Intensity

Low amperage currents appear to bemore effective as a driving force than

currents with higher intensitiesHigher intensity currents tend to reduceeffective penetration into the tissues

R ecommended current amplitudes usedfor iontophoresis range between 3-5 mA



Current Intensity

Increase intensity slowly until patientreports tingling or prickly sensation

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

When terminating treatment intensityshould be slowly decreased to zerobefore electrodes are disconnected



Current Intensity

Maximum current intensity should bedetermined by size of the active

electrodeCurrent amplitude usually set so thatcurrent density falls between 0.1-0.5mA/cm 2 of the active electrodesurface



Treatment Duration

Treatment duration ranges between 10-20 minutes with 15minutes being an averagePatient should be comfortable with noreported or visible signs of pain or burning

Check skin every 3-5 minutes lookingfor signs of skin irritationDecrease intensity during treatment to

accommodate decrease in skin



Traditional Electrodes

O lder 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 withionized solutionIon ointment should be rubbed into theskin and covered by some absorbent



Commercial Electrodes

Sold with most iontophoresis systemsElectrodes have a small chamber covered by

a semipermiable membrane into whichionized solution may be injectedThe electrode self adheres to the skin





Electrode Preparation

Attach self-adhering activeelectrode to skin




Attach self-adhering activeelectrode to skinInject ionized solution intothe chamber




Attach self-adhering activeelectrode to skinInject ionized solution intothe chamber Attach self-adheringinactive electrode to the

skin and attach lead wiresfrom generator to each





Selecting the Appropriate Ion

N egative ions accumulating at the positivepole or anode

j Produce an acidic reaction through theformation of hydrochloric acidj Produce softening of the tissues by decreasing

protein density-useful in treating scars or adhesions

j Some negative ions can also produce ananalgesic effect (salicylates)



Selecting the Appropriate Ion

Positive ions that accumulate at thenegative pole

j Produce an alkaline reaction with theformation of sodium hydroxidej Produce hardening of the tissues by

increasing protein density



Selecting the Appropriate IonInflammation

j Dexamethasone (-)j Hydrocortisone (-)

j Salicylate (-)Spasm

j Calcium (+)j Magnesium(+)

Analgesiaj L idocaine (+)j Magnesium (+)

Edemaj Hyaluronidase(+)j Salicylate (-)

j Mecholyl(+)Open Skin L esions

j Z inc(+)

Scar Tissuej Chlorine(-)j Iodine(-)j Salicylate(-)



Treatment Precautions

Problems which might potentially arisefrom treating a patient usingiontophoresis may for the most part beavoided if the athletic trainer

j Has a good understanding of the existingcondition which is to be treated

j Uses the most appropriate ions toaccomplish the treatment goalj Uses appropriate treatment parameters

and equipment set-up



Chemical Treatment Burns

Most common problem is a chemical burnwhich occurs as a result of direct currentitself and not because of the ion beingused

j Continuous direct current creates migration of ions which alters the normal pH of the skin

j Chemical burns typically result fromaccumulation of sodium hydroxide at cathode

j Alkaline reaction causes sclerolysis of localtissues

j Decreasin current densit b increasin size



Thermal Treatment Burns

Thermal burns may occur due to highresistance to current flow created by

poor contact of the electrodes with theskinj Electrodes are not moist enoughj Wrinkles in the gauze or paper towels

impregnated with the ionic solutionj Space between the skin and electrode

around the perimeter of the electrode

j Body weight resting on top of electrode



Documents

Chap 6- Iontophoresis