Drugs acting on the brain, spinal cord, or peripheral nerves, following ATC Group N (Nervous System). Belongs here: an analgesic, an anesthetic, an anticonvulsant, an antipsychotic, an antidepressant, a mood stabilizer, a sedative, a stimulant used for a nervous system indication, and an opioid or an agent that blocks opioid receptors. Does not belong here: an anti-inflammatory drug classified primarily by its action on the musculoskeletal system rather than as a nervous system analgesic, grouped under musculoskeletal system agents.