The Use of Penetration Enhancers to Increase Diffusion in Transdermal Applications

In the field of pharmacology, studies are being conducted to enable drugs in transdermal and percutaneous applications to penetrate human skin more quickly.

One of the main reasons for the need for rapid diffusion in such applications is the presence of a superficial barrier layer on the skin. The structure of keratinized cells, separated by thin lipid layers within this barrier, has an effect that hinders diffusion through the skin. This barrier system is called the stratum corneum. It is crucial for the diffusion process to occur as quickly as possible by bypassing the stratum corneum.

Therefore, penetration enhancing agents are used in transdermal applications to increase diffusion through the skin. The most commonly used penetration enhancer in pharmacology is Benzyl Alcohol.

The penetration enhancing agents used in such applications should not irritate the skin, be non-toxic, and their standard usage rates must not be exceeded.

What are the Usage Concentrations and Effects in Production?

Benzyl Alcohol is non-irritating to the skin and non-toxic for use in such applications. It is also free from physical therapeutic effects that could occur in the human body during use.

Benzyl alcohol taken into the body is cleanly metabolized to benzoic acid and subsequently excreted from the body as hippuric acid.

It is used as a main component in drugs applied percutaneously to some young infants.

The usage ratio can be at least 1% benzyl alcohol dissolved in at least 50% alcohol. The primary alcohol with which benzyl alcohol is mixed is ethyl alcohol.

What Can Be Done to Increase the Diffusion Rate?

There are several methods for the effective systemic application of drugs. These include practices such as dilution in Benzyl alcohol or increasing the drug's contact time with the skin.

In transdermal applications, increasing the drug's contact with the skin is achieved by thickening the solution (giving it consistency) to prevent it from flowing easily and to ensure it remains on the application area. By creating a non-flowing solution, it can be easily applied to the skin and form a coating.

The gelling and thickening agents used here are Carbomer types.

How is Carbomer Used in Transdermal Applications?

Carbomer is a polymer commonly used in transdermal applications. It is a polymer that gellifies upon contact with water. This gel helps the drug adhere to the skin and ensures its controlled release. It also increases the viscosity of the transdermal gel. This facilitates easy application to the skin and prevents the gel from running.