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9# Opioids
1. Pain is best defined as:
A purely sensory experience
A sensory and emotional experience associated with tissue damage
A reflex response to injury
Loss of sensation
Explanation:
Pain includes both sensory and emotional components related to actual or potential tissue damage.
2. Analgesia differs from anesthesia because analgesia:
Relieves pain without loss of consciousness
Eliminates all sensations
Always causes motor paralysis
Requires general anesthesia
Explanation:
Analgesia reduces pain while other sensations and consciousness remain intact.
3. Opioid receptors belong to which receptor family?
Ligand-gated ion channels
Receptor tyrosine kinases
G-protein coupled receptors
Nuclear receptors
Explanation:
Opioid receptors are Gi/o-coupled GPCRs.
4. Activation of μ-opioid receptors produces all EXCEPT:
Analgesia
Euphoria
Respiratory depression
Dysphoria
Explanation:
Dysphoria is mainly mediated by κ-opioid receptors.
5. Opioid-induced analgesia occurs primarily by:
Stimulating NMDA receptors
Inhibiting Ca²⁺ channels and activating K⁺ channels
Increasing cAMP
Blocking sodium channels
Explanation:
Opioids reduce neurotransmitter release and hyperpolarize neurons.
6. Which opioid receptor is most responsible for respiratory depression?
μ (mu)
κ (kappa)
δ (delta)
σ (sigma)
Explanation:
μ-receptor activation depresses the respiratory center.
7. Morphine provides better relief of which type of pain?
Neuropathic pain
Psychogenic pain
Visceral pain
Referred pain
Explanation:
Opioids are more effective for visceral than somatic or neuropathic pain.
8. Morphine is CONTRAINDICATED in acute head injury because it:
Causes hypotension
Causes seizures
Decreases cerebral blood flow
Increases intracranial pressure
Explanation:
Respiratory depression → CO₂ retention → cerebral vasodilation → ↑ ICP.
9. Which opioid effect does NOT develop tolerance?
Constipation
Sedation
Respiratory depression
Euphoria
Explanation:
Tolerance does NOT develop to constipation and miosis.
10. The hallmark sign of opioid overdose is:
Mydriasis
Hypertension
Miosis
Hyperthermia
Explanation:
Pinpoint pupils (miosis) are classic for opioid overdose.
11. Which opioid is MOST potent?
Morphine
Fentanyl
Codeine
Tramadol
Explanation:
Fentanyl is a highly potent synthetic opioid.
12. Which opioid does NOT cause miosis?
Morphine
Fentanyl
Heroin
Meperidine (Pethidine)
Explanation:
Meperidine uniquely does not cause miosis.
13. Methadone is useful in opioid dependence because it:
Has long duration of action
Has no withdrawal symptoms
Is a partial agonist
Is an opioid antagonist
Explanation:
Long duration prevents withdrawal and reduces cravings.
14. Buprenorphine is classified as a:
Full agonist
Pure antagonist
Partial agonist
Inverse agonist
Explanation:
Buprenorphine is a partial μ-agonist used in detoxification.
15. Naloxone reverses opioid overdose by:
Blocking serotonin receptors
Competitively antagonizing opioid receptors
Enhancing opioid metabolism
Increasing cAMP production
Explanation:
Naloxone is a short-acting opioid receptor antagonist.
16. Naltrexone differs from naloxone because it:
Is used only in acute overdose
Is inactive orally
Has shorter duration
Is used in opioid and alcohol dependence
Explanation:
Naltrexone has long duration and is used for maintenance therapy.
17. Loperamide is preferred as an antidiarrheal because it:
Acts peripherally with minimal CNS effects
Is highly addictive
Causes euphoria
Crosses BBB easily
Explanation:
Loperamide has minimal CNS penetration and low abuse potential.
18. Tramadol produces analgesia partly by:
NMDA antagonism
Pure μ-agonism
Inhibiting serotonin and norepinephrine reuptake
Blocking sodium channels
Explanation:
Tramadol has a mixed opioid and monoamine reuptake inhibition mechanism.
19. Why is naloxone combined with buprenorphine?
To increase analgesic potency
To prevent IV abuse by precipitating withdrawal
To prolong duration of action
To reduce constipation
Explanation:
Naloxone is inactive orally but precipitates withdrawal if injected.
20. The MOST common cause of death in opioid overdose is:
Arrhythmia
Renal failure
Seizures
Respiratory depression
Explanation:
Respiratory center depression is the main fatal complication.