Expert consensus of the Chinese Association for the Study of Pain on pain treatment with the transdermal patch

Table 3 Development of transdermal patch[14]

Classification	Characteristic
First-generation transdermal patch	The drug should have suitable properties (highly potency, low molecular weight and lipophilic) to solve the problem of low oral bioavailability, to reduce the frequency of drug administration or to achieve stable drug administration
Second-generation transdermal patch	This generation of patch can promote and improve the percutaneous absorption of small molecule drugs by means of a chemical penetration enhancer, ion introduction or ultrasound
Third-generation transdermal patch	These patches help to promote percutaneous absorption of macromolecules, including therapeutic proteins and vaccines