iontophoresis n.
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  1. Iontophoresis Chapter 6

  2. IONTOPHORESIS • Use of Direct Current to facilitate delivery of ions into the skin for therapeutic purposes. • Mechanism of delivery: “LIKE CHARGES REPEL”

  3. Positive Electrode (anode) delivers + ions Negative Electrode (cathode) delivers - ions

  4. 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

  5. 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

  6. Iontophoresis vs Phonophoresis • Both Techniques Deliver Chemicals To Biologic Tissues • Phonophoresis Uses Acoustic Energy (Ultrasound) To Drive MoleculesInto Tissues • Iontophoresis Uses Electrical Current To Transport IonsInto Tissues

  7. 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.

  8. 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

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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

  21. 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

  22. Iontophoresis Techniques

  23. Iontophoresis Generators • Produce continuous direct current * • Assures unidirectional flow of ions • *One study has shown that drugs can be delivered using AC current

  24. 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

  25. Iontophoresis Generator • Adjustable Timer • Up to 25 min

  26. Iontophoresis Generator • Lead wires • Active electrode • Inactive electrode

  27. 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

  28. 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

  29. 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

  30. 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

  31. 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.

  32. 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

  33. 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

  34. Electrode Preparation • Attach self-adhering active electrode to skin

  35. Electrode Preparation • Attach self-adhering active electrode to skin • Inject ionized solution into the chamber

  36. 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

  37. 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

  38. 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)

  39. 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

  40. Indications – evidence based

  41. Iontophoresis: Evidence Based

  42. Biophysical Effects • Dependant on Medication • See following chart

  43. Sample Medications

  44. Inflammation Dexamethasone (-) Hydrocortisone (-) Salicylate (-) Spasm Calcium (+) Magnesium(+) Analgesia Lidocaine (+) Magnesium (+) Edema Hyaluronidase(+) Salicylate (-) Mecholyl(+) Open Skin Lesions Zinc(+) Scar Tissue Chlorine(-) Iodine(-) Salicylate(-) Selecting the Appropriate Ion

  45. 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

  46. 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

  47. 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