Iontophoresis is used most often in physical therapy to assuage pain and inflammation, but is not exclusive to this arena, as there are applications in dentistry, lab technology, and other fields of medicine. So, exactly how does iontophoresis work?
Many PT patients who are receiving this novel treatment ask, “How does iontophoresis work on alleviating muscle and joint pain?” The answer is quite simple: Iontophoresis is a technique that delivers medication for pain or inflammation directly into the skin with use of an electric current. The term “iontophoresis” literally means transferring of ions (ionto = ion; phoresis = transfer). By using this technique, one can provide medicine directly into the affected area at the muscular or tendon level. The first proposals for the use of an electric current in drug delivery dates as far back as the mid 18th century. But, it wasn’t until the early 1900’s when the treatment really gained momentum. At that time, administration of metal ions as well as alkaloids was tried. Until the early 20th century, current mediated drug delivery was known as "cataphoresis". Fritz Frankenhäuser is said to have introduced the term "iontophoresis" before 1908. Recently, researchers talk about "electrically-assisted transdermal drug delivery". The technique was never widely adopted but always proved useful to some extent in solving particular drug delivery problems. Now, at the dawn of the 21st century, attempts are being made to achieve iontophoretic delivery of peptides and proteins. [1]
Benefits of Using Iontophoresis
The iontophoresis benefits include:
- Delivers the medication right into the affected area
- Painless delivery
- Easy application
- Relatively low chances of infection or trauma as it is a non-invasive treatment method
Because of these benefits, medical professionals use this method as an alternative to injections for the treatment of:
- Pain
- Swelling
- Muscle Contusion or Sprain/Strain
- Tendon or bursa inflammation
- Tendon impingement
Application: How Does Iontophoresis Work?
The main principle of iontophoresis is “like charges repel each other and opposite charges attract each other.” Water-soluble medication must be used for iontophoresis. The positively charged medication is applied on a positively charged electrode and the negatively charged medication is applied on the negatively charged electrode on the skin. For an example, a positive ions medication is applied on a positively charged electrode. This electrode is applied over the tissue into which the medication ions are to be delivered. So, the positive ions will be repelled from a positively charged electrode and will enter into the patient’s skin. The direct current moves the ions through the patient's skin. An external energy source is applied in the form of a direct electrical current. This assists the movement of ions, drives the medications across the skin, and thus, increases the rate of delivery.
Commonly Used Medications
The most common medications applied with iontophoresis are:
- Corticosteroids
- Prednisone
- Dexamethasone
- Anti-inflammatory drugs
If you are a rehab professional not in a direct practice state, you will need a doctor’s prescription to use a medication. So, please make sure you check the regulation for your state prior to considering this treatment.
How to Use Iontophoresis
There are many specific machines that can be utilized for iontophoresis, including machines that a patient can use at home. These devices are solely designed to deliver this type of treatment. Some modern multifunction devices will include iontophoresis-type currents as menu options as well. In addition, there are wireless application devices. With this kind of machine, an electrode patch is applied for 12 - 24 hours (depending on the dose). It is removed and discarded after this time period. A patient will need to have intact cognition for this kind of treatment.
Optimal Protocol
The optimal protocol for iontophoresis is: Direct current 1.0 - 4.0 mA - amplitude 20 - 40 minutes or treatment time 40 - 80 mA/ min for current delivery method The examples of medication and their permeability on electrodes include:
- Dexamethasone: negative pole
- Hydrocortisone: positive pole
- Lidocaine : positive pole
- Prednisone: negative pole
- Calcium Chloride: negative pole
How much medication should be used?
Research suggests applying the medication of 4 to 5 mg/mL of water or 2% of concentrated medication onto the electrode. Again, you need to have an appropriate script from a physician to use this medication.
When to Avoid Iontophoresis
Iontophoresis is contraindicated in the following conditions:
- Impaired sensation
- Allergy to the medication in use
- High anxiety level with electric current
- Impaired cognition (this applies mainly for the patient who desires to use a portable wireless machine)
- Open wound
- Metal implant to the area
- Bleeding disorders
- Circulatory disorders
References: [1] Pharmazie. 2001 Jul;56(7):583-7.