8.4.1 A brief introduction of the history of TDD technology
TDD technology has a long history.As early as the Spring and Autumn Period and Warring States Period，more than 30 kinds of prescriptions of plasters were recorded in the Preions for Fifty-Two Diseases.In contrast，the development history of TDD technology in modern medicine is not long.It was not until the 1870s that the anisodamine patch was approved by the US FDA for motion sickness as the first transdermal patch.So far，TDD technology has undergone four generations.(https://www.daowen.com)
