New Uses for Iontophoresis

Iontophoresis is an effective way to resolve nagging inflammatory musculoskeletal conditions.

The pounding athletes give their bodies day after day often leaves them with chronic, persistent pain. When traditional treatment offers no relief, athletic trainers and therapists can turn to iontophoresis, a noninvasive technique first introduced in the mid-1700s.

Today, it’s gaining popularity as an effective way to resolve nagging inflammatory musculoskeletal conditions.

Iontophoresis offers many advantages. It’s nontraumatic, painless, cost-efficient and portable. It also gives you the ability to deliver a larger quantity of medicine into a more localized treatment area without the risk, inconvenience and discomfort of an injection.

Concentrating treatment to a specific area also prevents the absorption and subsequent loss of medication into the gastrointestinal tract. By this same principle, less of the drug enters the systemic circulation to be metabolized by the liver. The chances of overdose or insufficient dosage are reduced. And drugs with a short half-life may be used more effectively.

Applications and Indications

Iontophoresis has successfully treated conditions such as tendinitis, bursitis, tenosynovitis and arthritis. It’s now being used for treating plantar fasciitis, patellar tendinitis and Achilles tendinitis; conditions that often don’t respond well to the traditional regime of ice, stretching, ultrasound and nonsteroidal anti-inflammatory medications.

The common feature in these conditions is localized inflammation, whether acute or subacute. Iontophoresis allows a drug to be sent directly to the inflamed area. The target should be near the skin’s surface, since most anti-inflammatories can penetrate only up to 1.5 cm. For this reason, consider the amount of subcutaneous fat in patients when determining whether they’re candidates for this treatment.

Recognized as a negative ion with the ability to absorb calcium, iontophoresis of acetic acid has helped resolve myositis ossificans.¹ This condition is a reactive lesion occurring in soft tissues, and at times close to the bone and periosteum, resulting from direct trauma to a muscle. If not treated properly, calcification can occur within two to three weeks, and surgical intervention is sometimes required.

Contraindications and Concerns

Although iontophoresis offers many advantages, you must take certain precautions. Do not use it if patients have skin reaction sensitivity or if they’re sensitive to aspirin, metals or seafood. It’s also contraindicated if patients have stomach ulcers or asthma.³ Other considerations include broken or abraded skin, drug allergies and skin with decreased sensation, because patients must be able to provide feedback. Iontophoresis never should be done in the cranial or orbital regions or in those patients who require a pacemaker. In addition, take special care with patients who have diabetes or are pregnant.

The biggest problem resulting from iontophoresis is chemical burns to the skin at the treatment spot. The direct current being passed through the tissues causes the ions to migrate and alter the normal pH of the skin. Chemical burns usually occur from sodium hydroxide that accumulates at the cathode, producing an alkaline reaction. You can avoid this problem by increasing the size of the cathode in relation to the anode, or by simply turning down the intensity of the device.

Treatment Protocol

Although all therapists have their own methods, we outline the following as general guidelines for using iontophoresis:

• Prepare the skin: Swab areas of electrode placement with alcohol. Clip excessive hair in the area as needed, but do not shave the skin because this may abrade or irritate it. Avoid existing skin lesions or abrasions. In addition, avoid scar tissue–unless you’re specifically treating it–and scaly skin.
• Educate patients: Inform them that they may feel a slight buzzing or tingling sensation under one or both electrodes. Emphasize that the treatment should not be uncomfortable and to notify you immediately if it becomes so.
• Set up parameters: The polarity of the active electrode should be the same as the polarity of the medication. Slowly increase the intensity to the desired current density. Set the treatment time. For a typical treatment of 40mA, you might set up treatment for 10 minutes of 4.0 mA/min or 20 minutes of 2.0 mA/min.
• Following treatment: Remove electrode pads. Inspect the skin for burns or reactions. You may apply aloe or cream to the skin.
• Typical treatment regimen: Depending on the patient, treatment may take place daily or every other day. Some patients will respond after only one or two treatments. Most will respond within three to six treatments.

Iontophoresis is not for everyone. If the patient is still not responding after six treatments, stop and consider alternative methods.

Of course, iontophoresis alone is only one component of relief from sports injury. It’s suitable to use with other modalities, such as ice, heat, ultrasound and electrical stimulation. Stretching and massage are also pieces in this puzzle of healing. With any treatment modality or drug therapy, therapeutic exercise must be performed concurrently under the supervision of a physician and therapist. Modalities and iontophoretic drug therapy exist primarily to reduce pain and inflammation so we can properly rehabilitate the joint or structure.

The field of sports medicine is continuing to advance, and the quality of care is constantly improving. Iontophoresis is an effective, comfortable and timely treatment for pain, which is exciting and encouraging for athletes and their therapists.

References

1. Psaki, C.G., & Carroll, J. (1955). Acetic acid ionization: A study to determine the absorptive effects upon calcified tendonitis of the shoulder. Physical Therapy Review, 35, 84-87.
2. Tyler, J.L., Derbekyan, V., & Lisbona, R. (1984). Early diagnosing of myositis ossificans with To99m diphosphonate imaging. Clinical Nuclear Medicine, 9, 460-462.
3. Prentice, W.E. (1999). Therapeutic modalities in sports medicine (4th ed.). Chapter 6. Boston: McGraw-Hill.

Resources

Chen, U.W., & Banga, A.K. (1989). Iontophorestic (transdermal) delivery of drugs: Overview of historical development. Journal of Pharmaceutical Sciences, 78, 353-354.

Mandeleco, C.F. (1978). Application of iontophoresis for noninvasive administration of lidocaine hydrochloride in the ionized form (Dissertation, University of Utah, Salt Lake City).

Into the Skin

Iontophoresis is defined as the introduction of various ions into the skin by means of electricity.¹ It generally involves the migration of ions in solution into the body through a direct electrical current. In therapeutic medicine, these ions may be any of several pain-relieving or anti-inflammatory medications.

Put into solution, inorganic compounds dissociate into positively and negatively charged cations and anions. As current flow is passed through the solution, positively charged cations move toward the cathode, or negatively charged electron, and negatively charged anions move toward the positive electrode, referred to as the anode.

Ions Used in Iontophoresis

When administering iontophoresis, make sure the electrode with the same polarity as the medication is attached to the drug-containing pad. The current repels the like charges, and the ions are driven across the skin membrane, usually via hair follicles and sweat ducts.^2-4 The active pad is placed directly over the treatment area, and a dispersive grounding pad is attached away from the active pad over a healthy muscle belly to complete the circuit. Pads may be placed anywhere from 4 to 18 inches apart, depending on the area of the body.

Although paper towels or gauze soaked with the medicine may be used, commercially manufactured pads or electrodes disperse the ions most effectively for drug delivery. Because only ions of the same polarity as the active electrode will be transferred into the body, you must know the polarity of the chosen drug before treatment.

Regulating the amount of current flow (in mA) and the duration of current flow (min) controls drug delivery into the body. Commercial iontophoresis machines allow you to control these factors. The molecular weight of the drug and its degree of ionization also affect the rate of drug delivery. Larger drugs are delivered at a slower rate, and highly ionized drugs are more strongly driven.^2-4

References

1. Thomas, C.L., ed. (1977). Taber’s Cyclopedic Medical Dictionary (13th ed.). Philadelphia: F.A. Davis.
2. Sloan, J., & Soltani, K. (1986). Iontophoresis in dermatology. Journal of the American Academy of Dermatology, 15, 671-84.
3. Abramson, H. & Gorin, M. (1940). Skin permeability. Cold Spring Harbor Symposia on quantitative biology, 8, 272.
4. Rosendal, T. (1942). Studies on the conducting properties of the human skin to direct current. Acta Physiologica Scandinavica, 5, 130.

Resource

Stralka, S.W., Head, P.L., & Mohr, K. (1996). The clinical use of iontophoresis. Physical Therapy Products, 3, 48-51.

— Stephanie L. Stradley, ATC, and Thomas W. Kaminski, PhD, ATC/L