Opioids are a class of drugs that derive from, or mimic, natural substances found in the opium poppy plant. Opioids work in the brain to produce a variety...

The opioid epidemic, also referred to as the opioid crisis, is the rapid increase in the overuse, misuse/abuse, and overdose deaths attributed either...

Opioid receptors are a group of inhibitory G protein-coupled receptors with opioids as ligands. The endogenous opioids are dynorphins, enkephalins, endorphins...

An opioid antagonist, or opioid receptor antagonist, is a receptor antagonist that acts on one or more of the opioid receptors. Naloxone and naltrexone...

The μ-opioid receptors (MOR) are a class of opioid receptors with a high affinity for enkephalins and beta-endorphin, but a low affinity for dynorphins...

There is an ongoing opioid epidemic (also known as the opioid crisis) in the United States, originating out of both medical prescriptions and illegal...

Opioid use disorder (OUD) is a substance use disorder characterized by cravings for opioids, continued use despite physical and/or psychological deterioration...

An opioid overdose is toxicity due to excessive consumption of opioids, such as morphine, codeine, heroin, fentanyl, tramadol, and methadone. This preventable...

Opioid withdrawal is a set of symptoms (a syndrome) arising from the sudden cessation or reduction of opioids where previous usage has been heavy and...

The κ-opioid receptor or kappa opioid receptor, abbreviated KOR or KOP for its ligand ketazocine, is a G protein-coupled receptor that in humans is encoded...