Opioids are classified under which category related to their mechanism of action?

Opioids are classified as agonists because they bind to specific receptors in the brain and nervous system, primarily the mu, kappa, and delta opioid receptors. By activating these receptors, opioids can effectively reduce the perception of pain and produce feelings of euphoria and relaxation. The term "agonist" refers to substances that activate receptors to elicit a biological response, which is precisely what opioids do in the context of pain relief.

In contrast, analgesics is a broader category that includes various types of pain relief medications, not just opioids, while antagonists are substances that block or dampen the biological response by binding to receptors without activating them. Neuroleptics are primarily used to treat psychiatric conditions and do not relate to the pain management mechanisms of opioids. Thus, the classification of opioids as agonists is a precise reflection of their pharmacological action in pain relief.