Definition: Seminaphthalidine is a type of pain reliever medication. It acts as an opioid agonist, meaning it binds to and activates receptors on cells in the central nervous system that are involved in pain perception, release, and transmission. Seminaphthalidine works by blocking certain types of pain signals, which can help reduce pain intensity and duration. It is commonly used for a variety of conditions including chronic pain, neuropathic pain, and inflammatory pain.