Final answer:
Controlled substances are drugs regulated by prescription requirements due to their potential for abuse and addiction, which includes a range of opioid medications.
Step-by-step explanation:
Drugs that are controlled by prescription requirements due to the risk of addiction or abuse are classified as controlled substances. These include a range of opioid medications such as Opium, Heroin, Fentanyl, Morphine, Oxycodone, Vicodin, and methadone, which are prescription pain relievers known for their potential for abuse and dependency. This differs from over-the-counter (OTC) drugs, like aspirin or ibuprofen, which do not require a doctor's prescription and are considered safe for use without a medical practitioner's direct supervision. The Food and Drug Administration (FDA) maintains strict regulations to ensure the safety and efficacy of these controlled substances.