When humans began to use natural addictive substances, there was no universal control. In the Greco-Roman era, opium was even considered a panacea. It was not until the Sino-British opium trade dispute in the 19th century that led to the two opium wars that an international consensus was gradually reached, starting with opium for control, and then expanding to marijuana and coca as well as their related products, collectively known as narcotic drugs. Three international drug control conventions were thus enacted to restrict these narcotics and psychoactive agents only for medical and scientific purposes.

In the 1990s, due to the spread of infectious diseases such as HIV/AIDS caused by the sharing of needles by heroin users, the "Harm Reduction Strategy," mainly including "methadone maintenance therapy" and "needle exchange program," was implemented. In history, therefore, human experience in managing addictive substances is mostly inferred from the use of opioids. However, from the historical experience, even if severe punishments are conducted, the effect of control is still limited. And to this day, humans still face the harm of such substances, so the harm reduction strategy has to be compromised as an alternative. In the United States, the opioid pandemic occurred since the past decade has not been resolved so far. Obviously, in addition to strict control on the supply side and harm reduction strategies, scholars and experts need to continue to work hard to find more effective ways to treat and rehabilitate drug users with substance use disorders. After 2000, ketamine was abused and became one of the categories of new psychoactive substances (NPS) defined by the United Nations Office on Drugs and Crime (UNODC). Due to its wide-spread abuse, ketamine is currently scheduled as Class III controlled drug for medical/scientific purposes and Class III illegal drug (毒品) if diverted or abused. In the past two years, the anesthetic etomidate has become a new substance of abuse, but because it has not yet been defined by the UNODC, it can be regarded as an alternative NPS. At present, etomidate is listed as a Class IV controlled drug and Class II illegal drug, indicating its use and management must be handled carefully.

This study will focus on opioids, along with addictive anesthetics, to decipher the dividing line between the legitimate medical use and illegal abuse of addictive drugs.