Penetration Enhancer Excipients
About Penetration Enhancer Excipients
Permeation enhancer excipients help to absorb the active pharmaceutical ingredient (API) through the skin into the body. The ability of excipients to help absorb or dissolve depends largely on the chemical nature of the API.
Advantages of Penetration Enhancer Excipients
The ideal penetration enhancer should have no skin damage or irritation, no pharmacological activity, no allergies, stable physical and chemical properties, good compatibility with drugs and excipients, fast onset, long acting time, etc.
Classification of Penetration Enhancer Excipients
In fact, there is almost no penetration enhancer that fully meets the above requirements. Therefore, choosing a suitable penetration enhancer has become an important link in the development of transdermal absorption preparations (TTS). Commonly used penetration enhancers are:
Surfactant
Surfactant refers to a substance which can significantly reduce the surface tension of the target solution. It has a fixed hydrophilic oil-philic group that can be oriented on the surface of the solution. The molecular structure of surfactants is amphoteric: one end is hydrophilic group, the other end is hydrophobic group; Hydrophilic groups are often polar groups, such as carboxylic acid, sulfonic acid, sulfuric acid, amino or amine groups and their salts, hydroxyl, amide group, ether bond, etc., can also be used as polar hydrophilic groups; Hydrophobic groups are usually non-polar hydrocarbon chains, such as hydrocarbon chains with more than 8 carbon atoms.
Surfactants are divided into ionic surfactants (including cationic surfactants and anionic surfactants), non-ionic surfactants, amphoteric surfactants, complex surfactants, other surfactants and so on.
Dimethyl Sulfoxide and Its Analogues
Dimethyl sulfoxide (DMSO) is a chemical substance with the molecular formula (CH3)2SO. It is a colorless liquid and an important polar aprotic solvent. It is miscible with many organic solvents and water. Dimethyl sulfoxide has the special property of easily penetrating into the skin.
Organic Alcohol, Ethyl Acetate
Low alcohol as the solvent in the external preparation, can increase the
solubility of a drug, and often can promote the drug percutaneous absorption Commonly used ethanol, propylene glycol, etc., and its effect on promoting penetration increases with the carbon chain growth Ethyl acetate more effects of certain drugs to promote through ethanol, ethyl acetate and ethanol mixed use, also can achieve better promoting effect.
Terpene Class
Such as menthol, eucalyptus oil, limonene, as a component of aromatic oil, a lot of terpenes have certain pharmacological activity. Terpenes can promote the transdermal absorption of some drugs. For example, 1% menthol can increase the permeability of cortisone through the skin of hairless mice by 10 times and indomethacin by 140 times. Cineole can promote the percutaneous penetration of benzocaine.
Source: https://www.formulationbio.com/products/penetration-enhancer- excipients.html
