The Controlled Substances Act (CSA) was passed in 1970 by the Congress of Richard Nixon and soon after signed into law. Under the terms of the CSA, the Food and Drug Administration (FDA) and the Drug Enforcement Agency (DEA) would be responsible for classifying drugs into one of five categories called “schedules” based on their supposed abuse potential or known medical applications. In theory, Schedule I drugs have the highest abuse potential with no medical purpose. They also carry the heaviest penalties associated with their use or possession. Schedule V drugs, on the other end of the spectrum, have medical applications but also have a low abuse potential.
The CSA has been amended several times. One major amendment was introduced in 2000, the Hillory J. Farias and Samantha Reid Date-Rape Drug Prohibition Act. Under this amendment, gamma-hydroxybutyric acid (GHB) was placed into Schedule I, and sodium oxybate was placed into Schedule III.
Schedule I drugs
Drugs with high abuse potential that have no known medical use. Currently, the drugs listed under Schedule I include:
Historically, the scheduling of many of these controlled substances is subject more to political whims rather than to scientific principles. Several studies have been published demonstrating a significant clinical benefit of many Schedule I drugs.
Schedule II drugs
These drugs have a high potential for abuse, but also have a documented medical application. These drugs may only be distributed under prescription or in case of an emergency. These drugs include:
Schedule III drugs
Drugs classified under Schedule III have a lower abuse potential than Schedule I or Schedule II drugs. They have a medically identified purpose, but may still produce a form of dependence if used improperly. They currently include:
Barbiturates with an intermediate time course of action (talbutal or butalbital)
Dihydrocodeine when compounded with other substances, to a certain dosage and concentration.
Schedule IV drugs
Schedule IV drugs generally have low abuse potential, and have a use in the clinical setting. There is a risk of dependence, but this may depend on use of drugs that are schedule III or up. Some schedule IV drugs include:
Benzodiazepines (Xanax, valium)
Schedule V drugs
As with above, schedule V drugs are those with low abuse potential and a clinical use. These drugs may lead to dependence if abused. Some schedule V drugs are listed below:
Anticonvulsants such as pregabalin
Antidiarrheal drugs (some are psychoactive)
Promethazine + codeine as a cough suppressant