Opioid analgesics are further classified by their mechanism of action as __________, which bind to opioid pain receptors in the CNS to __________ the sensation of pain.

Opioid analgesics classified as agonists bind to opioid pain receptors in the central nervous system (CNS) and are designed to alter and reduce the sensation of pain. This is the primary mechanism through which opioids provide relief; they interact directly with the receptors that modulate pain perception, effectively diminishing the pain experience.

In this context, the term "alter" signifies that the experience of pain is modified, and "reduce" indicates a decrease in the overall sensation of pain. This dual action is essential for pain management strategies, particularly in acute and chronic pain conditions.

Other classifications like antagonists and partial agonists do not fulfill this mechanism in the same way, as they either block the receptors or activate them partially, which may not effectively reduce pain as needed. Understanding these mechanisms is critical for effective pain management in clinical practice.