Which of the following is commonly used mu-opioid receptor agonist for cancer or postsurgical pain?

• A. Morphine
• B. Fentanyl
• C. Hydromorphone
• D. All of the above

Answer: (D)

Strong mu-opioid receptor agonists are the mainstay for treating moderate to severe pain from cancer or after surgery. Morphine is the classic opioid used in this setting, versatile across routes of administration, and effective for cancer-related and postoperative pain. Fentanyl is a highly potent, rapid-onset opioid, excellent for intraoperative analgesia and for managing acute postoperative pain; its transdermal form is also used for chronic cancer pain. Hydromorphone is another potent mu agonist, often chosen when morphine is not well tolerated or when there are renal impairment considerations, and it is commonly used for both postoperative and cancer pain.

Because each of these agents is a commonly used mu-opioid receptor agonist in the cancer or postsurgical context, the correct choice is all of the above.