controlled substance [Fr, controle, to register; L, substantia, essence] , any drug defined in the five categories of the federal Controlled Substances Act of 1970. The categories, or schedules, cover opium and its derivatives, hallucinogens, depressants, and stimulants. Schedule I drugs have a high abuse potential and no approved medical uses. Drugs in Schedules II to V all have approved medical indications, with decreasing abuse and dependence liabilities as the schedule number increases. In Canada, categories are identified by Health Canada’s Office of Controlled Substances (OCS).
