Delivering therapeutic compounds into people or animals can be quite challenging. Digestive fluids destroy many compounds, including the biologics many pharmaceutical companies have been investigating lately. Taking drugs by injection doesn't appeal to most people, and increases the risk of infection from needles.
Transdermal drug delivery
One of the major functions of the skin is to keep out foreign agents. The skin does this with great efficiency, including keeping out pharmaceuticals. There are many advantages then, if the skin barrier can be overcome by transdermal delivery of pharmaceuticals. The drug can be released slowly and continuously into the system. Since the drug doesn't enter the body via the digestive tract it doesn't go through the liver's detoxification systems before reaching the parts of the body that need it. The only problem is getting the drug through the skin barrier.
What is a microemulsion?
Microemulsions have been under extensive study recently, as possible transdermal drug delivery systems. A microemulsion is a clear or transparent system with stable particles smaller than 150 nm. The emulsions which most of us are familiar with are cloudy or milky with large particles, and are not stable, eventually separating into its various phases.
Microemulsions are ideal for transdermal drug delivery. Once created, they are stable. They can carry both hydrophilic and lipophilic drugs. Due to their structure, microemulsions can carry very high concentrations of drugs, and have an enhanced ability to pass through the skin. The small size of the particles, action of the surfactants on the skin, and the continuously fluctuating interphases can breach the skin's barrier.
Studies of the ideal microemulsion to carry specific drugs into the body through the skin are ongoing. Reducing the particle size may improve the penetration of most emulsions. Varying the oils, surfactants, and viscosity of the microemulsion can all affect the ability of the microemulsion to deliver drugs through the skin. Microemulsions can even be created that only deliver drugs into the skin rather than through it. The cosmetic industry uses microemulsions to deliver anti-wrinkle products into the skin's layers.
Skin irritation?
One concern with the use of microemulsions to deliver drugs is their ability to irritate skin. In tests conducted to date, microemulsions, in general, seem to be far less irritating than solutions of sodium lauryl sulfate, a moderate to severe skin irritant. Most microemulsions have been about as irritating to the skin as saline. Test subjects exposed to microemulsions for up to four days exhibited no skin redness or apparent irritation.
Microemulsions show great promise as drug delivery systems. If your research lab needs particle size-reduction equipment to expedite research into the ideal microemulsion to carry a particular pharmaceutical across or into the skin, don't hesitate to contact us.
