Which of the following is NOT a primary function of opioid analgesics?

Opioid analgesics primarily serve to alleviate pain by interacting with opioid receptors in the central nervous system. One of their essential functions includes reducing pain sensation, which is a direct consequence of their action on these receptors.

Another important function of opioids is their ability to suppress the cough center in the brain. This is beneficial in clinical scenarios where cough suppression is necessary, such as in certain pulmonary conditions.

However, the function of reducing airway inflammation is not associated with the mechanism of action of opioid analgesics. Instead, medications such as corticosteroids or other anti-inflammatory agents are typically employed to address inflammation in the airways. Opioids do not contribute to this function, thus making it the correct choice in identifying what is not a primary action of these drugs.

Finally, blocking CNS receptors from opioids does not accurately describe a primary function of opioid analgesics. Instead, these medications work by activating, not blocking, opioid receptors to achieve pain relief and other actions.