Which statement defines opioid mixed agonist-antagonists?

Which statement defines opioid mixed agonist-antagonists?

• A. Stimulate some opioid receptors while blocking others at the same time
• B. Fully activate all receptors
• C. Block all receptors
• D. Have no analgesic effect

Answer: (A)

Mixed agonist-antagonists act by engaging some opioid receptor types while blocking others. In practice, these drugs typically act as agonists at one receptor (usually kappa) and antagonists at another (mu). This dual action provides analgesia mainly through the receptor they activate, while dampening mu-mediated effects such as euphoria and respiratory depression. However, because they block mu receptors, they can precipitate withdrawal in people who are dependent on mu agonists. They also tend to have a ceiling on respiratory depression, which can make them safer in some settings, though their analgesic effect may be less robust for severe pain and they can cause dysphoria or psychotomimetic effects due to kappa activation. This combination of stimulating some receptors while blocking others is what defines opioid mixed agonist-antagonists.

Mixed agonist-antagonists act by engaging some opioid receptor types while blocking others. In practice, these drugs typically act as agonists at one receptor (usually kappa) and antagonists at another (mu). This dual action provides analgesia mainly through the receptor they activate, while dampening mu-mediated effects such as euphoria and respiratory depression. However, because they block mu receptors, they can precipitate withdrawal in people who are dependent on mu agonists. They also tend to have a ceiling on respiratory depression, which can make them safer in some settings, though their analgesic effect may be less robust for severe pain and they can cause dysphoria or psychotomimetic effects due to kappa activation. This combination of stimulating some receptors while blocking others is what defines opioid mixed agonist-antagonists.