Iontophoresis
Encyclopedia
Iontophoresis is a technique using a small electric charge to deliver a medicine or other chemical through the skin. It is basically an injection without the needle. The technical description of this process is a non-invasive method of propelling high concentrations of a charged substance, normally a medication or bioactive agent, transdermally by repulsive electromotive force using a small electrical charge applied to an iontophoretic chamber containing a similarly charged active agent and its vehicle. One or two chambers are filled with a solution containing an active ingredient and its solvent, also called the vehicle. The positively charged chamber, called the anode
, will repel a positively charged chemical, whereas the negatively charged chamber, called the cathode
, will repel a negatively charged chemical into the skin.
Iontophoresis is well classified for use in transdermal drug delivery. Unlike transdermal patches, this method relies on active transportation within an electric field. In the presence of an electric field electromigration
and electroosmosis are the dominant forces in mass transport. These movements are measured in units of chemical flux
, commonly µmol/cm2h. For more information see Fick's Law of Diffusion
.
Iontophoresis is commonly used by physical therapists for the application of anti-inflammatory
medications. Common diagnoses treated with Iontophoresis include plantar fasciitis
, bursitis
, and some types of hyperhidrosis
. In this specific application, the solution chosen is usually tap water
, but better results can be obtained using glycopyrronium bromide, a cholinergic
inhibitor. Iontophoresis of acetylcholine
is used in research as a way to test the health of the endothelium
by stimulating endothelium-dependent generation of nitric oxide
and subsequent microvascular vasodilation. Acetylcholine is positively charged and, therefore, placed in the anode.
Anode
An anode is an electrode through which electric current flows into a polarized electrical device. Mnemonic: ACID ....
, will repel a positively charged chemical, whereas the negatively charged chamber, called the cathode
Cathode
A cathode is an electrode through which electric current flows out of a polarized electrical device. Mnemonic: CCD .Cathode polarity is not always negative...
, will repel a negatively charged chemical into the skin.
Iontophoresis is well classified for use in transdermal drug delivery. Unlike transdermal patches, this method relies on active transportation within an electric field. In the presence of an electric field electromigration
Electromigration
Electromigration is the transport of material caused by the gradual movement of the ions in a conductor due to the momentum transfer between conducting electrons and diffusing metal atoms. The effect is important in applications where high direct current densities are used, such as in...
and electroosmosis are the dominant forces in mass transport. These movements are measured in units of chemical flux
Flux
In the various subfields of physics, there exist two common usages of the term flux, both with rigorous mathematical frameworks.* In the study of transport phenomena , flux is defined as flow per unit area, where flow is the movement of some quantity per time...
, commonly µmol/cm2h. For more information see Fick's Law of Diffusion
Fick's law of diffusion
Fick's laws of diffusion describe diffusion and can be used to solve for the diffusion coefficient, D. They were derived by Adolf Fick in the year 1855.- Fick's first law :...
.
Uses
Reverse iontophoresis is the term used to describe the process by which molecules are removed from within the body for detection. In reverse iontophoresis, the negative charge of the skin at buffered pH causes it to be permselective to cations, causing solvent flow towards the anode. This flow is the dominant force, allowing movement of neutral molecules, including glucose, across the skin. This technology is currently being used in such devices as the GlucoWatch, which allows for blood glucose detection across skin layers using reverse iontophoresis.Iontophoresis is commonly used by physical therapists for the application of anti-inflammatory
Anti-inflammatory
Anti-inflammatory refers to the property of a substance or treatment that reduces inflammation. Anti-inflammatory drugs make up about half of analgesics, remedying pain by reducing inflammation as opposed to opioids, which affect the central nervous system....
medications. Common diagnoses treated with Iontophoresis include plantar fasciitis
Plantar fasciitis
Plantar fasciitis is a painful inflammatory process of the plantar fascia, the connective tissue on the sole of the foot.Longstanding cases of plantar fasciitis often demonstrate more degenerative changes than inflammatory changes, in which case they are termed plantar fasciosis. The suffix...
, bursitis
Bursitis
Bursitis is the inflammation of one or more bursae of synovial fluid in the body. The bursae rest at the points where internal functionaries, such as muscles and tendons, slide across bone. Healthy bursae create a smooth, almost frictionless functional gliding surface making normal movement painless...
, and some types of hyperhidrosis
Hyperhidrosis
Hyperhidrosis is the condition characterized by abnormally increased perspiration, in excess of that required for regulation of body temperature.-Classification:Hyperhidrosis can either be generalized or localized to specific parts of the body...
. In this specific application, the solution chosen is usually tap water
Tap water
Tap water is a principal component of "indoor plumbing", which became available in urban areas of the developed world during the last quarter of the 19th century, and common during the mid-20th century...
, but better results can be obtained using glycopyrronium bromide, a cholinergic
Cholinergic
The word choline generally refers to the various quaternary ammonium salts containing the N,N,N-trimethylethanolammonium cation. Found in most animal tissues, choline is a primary component of the neurotransmitter acetylcholine and functions with inositol as a basic constituent of lecithin...
inhibitor. Iontophoresis of acetylcholine
Acetylcholine
The chemical compound acetylcholine is a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans...
is used in research as a way to test the health of the endothelium
Endothelium
The endothelium is the thin layer of cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. These cells are called endothelial cells. Endothelial cells line the entire circulatory system, from the heart...
by stimulating endothelium-dependent generation of nitric oxide
Nitric oxide
Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...
and subsequent microvascular vasodilation. Acetylcholine is positively charged and, therefore, placed in the anode.