What Factors Impact the Iontophoresis-Based Treatment?
Iontophoresis is becoming a revolutionary way to treat hyperhidrosis. This condition consists of sweating heavily, and it is a bothering symptom in various parts of the body, including hands and feet. Iontophoresis is a technique designed to create ions out of water molecules and other soluble substances. After the target substance is converted into polarized particles with an electrical charge, a mild electrical current creates an electromagnetic gradient in the skin that allows molecules to migrate to deeper layers. This is a non-invasive method to deliver certain substances to deep tissues or the bloodstream.
However, the success of an iontophoresis-based therapy for hyperhidrosis depends on various factors, including skin-related factors and others that would depend on the procedure and the adjustments of the device.
What factors influence iontophoresis as a treatment?
We can name at least 7 different factors that influence the results of iontophoresis. They are as follows:
- The skin barrier: The skin barrier is the highway where ions will travel to reach deeper layers. It is the outer surface, always in contact with the microcirculation of the skin. According to studies, the segment of the skin where the majority of ionized substances will reach is the basal membrane of the epithelial tissue and the subcutaneous tissue. Different types of epithelium in the body may have a different configuration of the skin barrier, and applying iontophoresis in a relatively thin layer of skin as in the hands will not be the same as doing so in areas of the skin with hyperkeratosis. Thus, the thickness and configuration of the skin play a significant role in the outcome of iontophoresis.
- The effects of skin pH: When we talk about pH, it is a measure of how many free hydrogen atoms there are in a substance or the skin. As it is, the pH of a substance has a significant role in how this substance is transported. Similarly, the pH of the transporter element or tissue (the skin in iontophoresis) modulates whether or not specific molecules will be transported successfully. The difference between skin pH and the pH of the solution that is used during the procedure is a fundamental factor that will ultimately modulate whether or not the treatment will be successful. For instance, an acidic pH in the skin against an alkaline pH in the target substance will favor the absorption of substances or drug. However, extreme pH differences may also be responsible for side effects such as skin burns and irritation.
- The molecular weight of the target substance: It is imperative to consider the molecular weight of the substance that is meant to travel through the skin. A higher molecular weight may lead to a higher ionization of the solution, and it will favor absorption through an alternating current.
- Electroosmosis: Osmosis is a natural process through which a substance in a higher concentration travels to an area of lower concentration. Electroosmosis is almost the same thing, but taking into consideration electrical charges instead of substance concentration. The skin has both positive and negative charges when it has an acidic pH, which is why it is called an isoelectric barrier. Depending on the electrical charges achieved in the solution, electroosmosis may drag water and the target substance through the skin into the basal membrane or lead to skin secretion instead of absorption. Thus, it is essential to adjust the electrical gradient very carefully to achieve the best results.
- Ionic transport: The skin is also resistant to osmotic movement of substances through the outer layers, especially one of them called stratum corneum. However, during iontophoresis, the sweat glands and the hair follicles react to the passage of electrical current and turn into a highway of electrically charged ions. This passage is regulated by the principles of electroosmosis, which means that depending on the electric potential in the stratum corneum and the solution used during the procedure, you will get a varying rate of skin absorption.
- Ionic concentration and conductivity: The conductivity of a substance is the potential it has to transport ions through a membrane, namely the skin. It depends on various things, and one of them is the concentration of ions and the electrical charge. That is why drugs in iontophoresis need to be partially diluted in water, because a higher concentration of ions in a solution would result in a higher competition of ions to travel through the skin, and may lead to dramatic changes in the skin pH and skin burns. Thus, achieving a target ionic concentration of substances is essential to avoid side effects.
- Time and intensity of treatment: Time of exposure and intensity of the electrical current are both critical factors in the absorption of drugs and to treat hyperhidrosis. The type of electrical current that is used is also a fundamental factor, and certain studies have found good results with pulsed electrical current or alternating current, depending on the type of molecule that is meant to travel through the skin. The intensity of the electrical current should be able to maintain high conductivity, stabilizing the pH of the skin, and favoring electroosmosis without becoming a source of undesired side effects.
Is it going to cure hyperhidrosis?
The principles of iontophoresis are not new, but its application in the medical field is starting to develop. Thus, there is not a fixed concentration of the solution or dose of the electrical current recommended for each condition and to favor the absorption of each drug. Still, it is an effective treatment for hyperhidrosis, and even though it takes time and requires treatment sessions, the majority of patients with this condition report a significant improvement of their symptoms and feel satisfied with their results.
We still do not fully understand the full extent and application of iontophoresis, but so far, it’s turning into a promising way to deliver drugs without invasive procedures or side effects. It is an effective way to control hyperhidrosis and an exciting field of ongoing clinical research.