The term opioids refers to any drug that produces a similar effect to an opiate. These drugs are often synthetic or partially synthetic. Sometimes, addiction treatment centers use synthetic opioids to treat opiate addiction. Much like opiates, opioid use runs the gamut from medically acceptable to illicit. Opioid drugs include: Methadone, Percocet, Vicodin, Demerol, and Oxycodone.