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Pain Management 2026 | Practice
Questions & Verified Answers | Advanced
Pharmacology Review
1. Which opioid receptor is primarily responsible for supraspinal
analgesia, respiratory depression, and euphoria?
a. Kappa (κ)
b. Delta (δ)
c. Mu (μ)
d. Nociceptin (NOP)
Answer: c. Mu (μ)
Rationale: Mu-opioid receptors (MOR) are the primary targets
for most clinically used opioids. Activation produces analgesia,
but also respiratory depression, sedation, euphoria, and physical
dependence. Kappa receptors mediate spinal analgesia and
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dysphoria; delta receptors have a role in mood and analgesia;
NOP is involved in pain modulation but not typical opioid effects.
2. Which of the following opioid agonists has the highest intrinsic
activity at the mu receptor?
a. Morphine
b. Fentanyl
c. Buprenorphine
d. Naloxone
Answer: b. Fentanyl
Rationale: Fentanyl is a high-efficacy full agonist with very high
intrinsic activity. Buprenorphine is a partial agonist (lower intrinsic
activity). Naloxone is an antagonist (zero intrinsic activity).
Morphine is a full agonist but less potent than fentanyl.
3. A partial mu-opioid agonist would be expected to:
a. Produce maximal analgesia equal to morphine at high doses
b. Have a ceiling effect for both analgesia and respiratory
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depression
c. Have no risk of withdrawal in opioid-dependent patients
d. Be completely devoid of adverse effects
Answer: b. Have a ceiling effect for both analgesia and
respiratory depression
Rationale: Partial agonists have a lower maximal effect. At high
doses, further increases produce little additional effect. This
provides a ceiling for respiratory depression, which is a safety
advantage. However, they can precipitate withdrawal in
patients dependent on full agonists.
4. Which of the following is a pure opioid antagonist?
a. Naltrexone
b. Pentazocine
c. Nalbuphine
d. Butorphanol
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Answer: a. Naltrexone
Rationale: Naltrexone, naloxone, and nalmefene are pure
antagonists with no agonist activity. Pentazocine, nalbuphine, and
butorphanol are agonist-antagonists (partial
agonists/antagonists).
5. A patient chronically taking morphine develops tolerance.
Which statement correctly describes opioid tolerance?
a. Tolerance develops equally to all opioid effects
b. Tolerance to respiratory depression is minimal and protective
c. Tolerance to constipation develops rapidly
d. Cross-tolerance between different opioid classes is complete
Answer: b. Tolerance to respiratory depression is minimal and
protective
Rationale: Tolerance to analgesia and euphoria develops, but
tolerance to respiratory depression is limited. This is why
escalating doses can still cause respiratory arrest. Constipation
Pain Management 2026 | Practice
Questions & Verified Answers | Advanced
Pharmacology Review
1. Which opioid receptor is primarily responsible for supraspinal
analgesia, respiratory depression, and euphoria?
a. Kappa (κ)
b. Delta (δ)
c. Mu (μ)
d. Nociceptin (NOP)
Answer: c. Mu (μ)
Rationale: Mu-opioid receptors (MOR) are the primary targets
for most clinically used opioids. Activation produces analgesia,
but also respiratory depression, sedation, euphoria, and physical
dependence. Kappa receptors mediate spinal analgesia and
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dysphoria; delta receptors have a role in mood and analgesia;
NOP is involved in pain modulation but not typical opioid effects.
2. Which of the following opioid agonists has the highest intrinsic
activity at the mu receptor?
a. Morphine
b. Fentanyl
c. Buprenorphine
d. Naloxone
Answer: b. Fentanyl
Rationale: Fentanyl is a high-efficacy full agonist with very high
intrinsic activity. Buprenorphine is a partial agonist (lower intrinsic
activity). Naloxone is an antagonist (zero intrinsic activity).
Morphine is a full agonist but less potent than fentanyl.
3. A partial mu-opioid agonist would be expected to:
a. Produce maximal analgesia equal to morphine at high doses
b. Have a ceiling effect for both analgesia and respiratory
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depression
c. Have no risk of withdrawal in opioid-dependent patients
d. Be completely devoid of adverse effects
Answer: b. Have a ceiling effect for both analgesia and
respiratory depression
Rationale: Partial agonists have a lower maximal effect. At high
doses, further increases produce little additional effect. This
provides a ceiling for respiratory depression, which is a safety
advantage. However, they can precipitate withdrawal in
patients dependent on full agonists.
4. Which of the following is a pure opioid antagonist?
a. Naltrexone
b. Pentazocine
c. Nalbuphine
d. Butorphanol
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Answer: a. Naltrexone
Rationale: Naltrexone, naloxone, and nalmefene are pure
antagonists with no agonist activity. Pentazocine, nalbuphine, and
butorphanol are agonist-antagonists (partial
agonists/antagonists).
5. A patient chronically taking morphine develops tolerance.
Which statement correctly describes opioid tolerance?
a. Tolerance develops equally to all opioid effects
b. Tolerance to respiratory depression is minimal and protective
c. Tolerance to constipation develops rapidly
d. Cross-tolerance between different opioid classes is complete
Answer: b. Tolerance to respiratory depression is minimal and
protective
Rationale: Tolerance to analgesia and euphoria develops, but
tolerance to respiratory depression is limited. This is why
escalating doses can still cause respiratory arrest. Constipation
