Transdermal administration for drug absorption

Transdermal administration (TDA) is a method of drug delivery in which a drug is rubbed on the skin surface and absorbed through the intact skin. It is traditionally believed that intact skin is generally poorly able to absorb drugs, and that only a few organic solvents or organophosphate esters with strong lipid solubility can be absorbed through the intact skin, and toxic reactions can occur.

However, in recent years, it has been found that some drugs can still be absorbed percutaneously, especially in the thinner parts of the skin (such as behind the ear, inner arm, chest area, scrotal skin, etc.) or the skin with inflammation and other pathological changes. Children's skin also has a faster rate of transdermal absorption than adults because of its higher water content. Especially when the drug is then added to promote dermal absorption agents, such as azone (azone), dimethyl sulfoxide, lauric acid, etc. made of patch or ointment, transdermal administration of the drug can be local or systemic efficacy, such as nifedipine, estradiol, fentanyl, etc. made of patch can be absorbed by the skin, resulting in systemic efficacy. Patch can also be made into extended-release dosage form to maintain a lasting effect, such as nitroglycerin extended-release patch, only once a day, can be used for the whole day to prevent angina attacks. In addition, the plasters of ancestral medicine are also administered transdermally to produce local therapeutic effects. Therefore, transdermal drug delivery is also an effective route of drug delivery.