Commonly used opioids include oxycodone (OxyContin), propoxyphene (Darvon), hydrocodone (Vicodin), hydromorphone (Dilaudid), morphine(MS Contin), meperidine (Demerol), and diphenoxylate (Lomotil). Common central nervous system depressants include barbiturates such as pentobarbital sodium (Nembutal), and benzodiazepines such as diazepam (Valium) and alprazolam (Xanax). Stimulants include multiple formulations of amphetamine-based drugs with brand names of Adderall, Ritalin, Concerta, Dexedrine, etc. Prescription drugs that are abused or used for non-medical reasons can alter brain activity and lead to dependence. Commonly abused classes of prescription drugs include opioids (often prescribed to treat pain), central nervous system depressants (often prescribed to treat anxiety and sleep disorders) and stimulants (prescribed to treat narcolepsy, ADHD, and obesity). Long-term use of opioids or central nervous system depressants can lead to physical dependence and addiction. Taken in high doses, stimulants can lead to compulsive use, paranoia, dangerously high body temperatures, irregular heartbeat, and psychosis.