Following completion of this chapter, the student will be able to:
Differentiate between iontophoresis and phonophoresis.
Explain the basic mechanisms of ion transfer.
Establish specific iontophoresis application procedures and techniques.
Identify the different ions most commonly used in iontophoresis.
Choose the appropriate clinical applications for using an iontophoresis technique.
Establish precautions and concerns for using iontophoresis treatment.
Iontophoresis is a therapeutic technique that involves the introduction of ions into the body tissues by means of a direct electrical current.1 Originally referred to as ion transfer, it was first described by LeDuc in 1903 as a technique of transporting chemicals across a membrane using an electrical current as a driving force.2 Since that time, the use and popularity of iontophoresis has varied. The expansion of available medications for delivery via iontophoresis has drawn new attention to this therapeutic modality. Iontophoresis has several advantages as a treatment technique that involves little to no patient discomfort, is a sterile, noninvasive technique for introducing specific ions into tissue at a greater rate than conventional forms of delivery that has been demonstrated to have a positive effect on the healing process.3,123
Although specific statutes relative to the use of iontophoresis vary from state to state, the clinician must be aware that the majority of medications used in iontophoresis require a physician’s prescription for use. Typically, the patient is responsible for filling the prescription and bringing the medication to the treatment session. Clinicians must be aware of state law that may regulate the ability of a clinical setting to store medication for individual patients. Medications prescribed for one patient cannot be used for other patients, so the traditional practice of clinics having a single prescription of medication shared among all patients should be avoided.
IONTOPHORESIS VERSUS PHONOPHORESIS
It is critical to point out the difference between iontophoresis and phonophoresis since the two techniques are often confused and occasionally the two terms are erroneously interchanged. It is true that both techniques are used to deliver chemicals to various biologic tissues. Phonophoresis, which is discussed in detail in Chapter 10, involves the use of acoustic energy in the form of ultrasound to drive whole molecules across the skin into the tissues, whereas iontophoresis uses an electrical current to transport ions into the tissues.97 While both treatment techniques have been found to be effective at increasing skin permeability to allow for transfer of ions into target tissue, one recent study comparing the procedures found phonophoresis to be superior to iontophoresis in the delivery of methotrexate.127
Exercise 6–1 Clinical Decision-Making
A physician sends the clinician a prescription for using topical hydrocortisone to treat plantar fasciitis but does not specify whether phonophoresis or iontophoresis should be used. What should determine the clinician’s decision to use one or the other?
BASIC MECHANISMS OF ION ...