Naloxone blocking fentanyl from mu-opioid receptor, illustration - Stockillustratie

Illustration of naloxone (orange), an opioid antagonist, blocking the opioid fentanyl (red) from the mu-opioid receptor (blue). Opioid receptors are found on nerve cells. Binding by opioid drugs such as fentanyl depresses the nervous and respiratory systems, which in cases of overdose can be lethal. Naloxone competes with and replaces the opioid drug, reducing the harmful effects of the opioid