Podcast
Questions and Answers
Which gene encodes the precursor peptide Proenkephalin?
Which gene encodes the precursor peptide Proenkephalin?
Where are the enkephalin peptides widely distributed?
Where are the enkephalin peptides widely distributed?
What receptors do enkephalins bind with high affinity?
What receptors do enkephalins bind with high affinity?
Which peptide has a limited distribution, with cell bodies in the intermediate lobe of pituitary and in hypothalamus, and axons projecting to amygdala, PAG, brainstem, and spinal cord?
Which peptide has a limited distribution, with cell bodies in the intermediate lobe of pituitary and in hypothalamus, and axons projecting to amygdala, PAG, brainstem, and spinal cord?
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Which peptide is distributed throughout the brain and spinal cord and functions as neurotransmitters?
Which peptide is distributed throughout the brain and spinal cord and functions as neurotransmitters?
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Which peptide has high affinity for mu and delta receptors and is released in response to stress?
Which peptide has high affinity for mu and delta receptors and is released in response to stress?
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Which opioid receptor is associated with diuresis and dysphoria?
Which opioid receptor is associated with diuresis and dysphoria?
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Which opioid receptor is associated with constipation and respiratory depression?
Which opioid receptor is associated with constipation and respiratory depression?
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Which opioid receptor is associated with reward and emotion?
Which opioid receptor is associated with reward and emotion?
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Which cellular mechanism is targeted by opioids to reduce neurotransmitter release?
Which cellular mechanism is targeted by opioids to reduce neurotransmitter release?
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What is the effect of opioids on postsynaptic neurons?
What is the effect of opioids on postsynaptic neurons?
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How do opioids reduce the formation of cAMP?
How do opioids reduce the formation of cAMP?
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Which of the following is a peripheral effect of opioids?
Which of the following is a peripheral effect of opioids?
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Which of the following is true about the tolerance to constipating effects of opioids?
Which of the following is true about the tolerance to constipating effects of opioids?
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Which receptor does morphine primarily act on?
Which receptor does morphine primarily act on?
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What is the major route of metabolism for morphine?
What is the major route of metabolism for morphine?
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Which active metabolite of morphine has high affinity for mu opioid receptors?
Which active metabolite of morphine has high affinity for mu opioid receptors?
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What is the main indication for morphine use?
What is the main indication for morphine use?
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Which route is used for the elimination of conjugated morphine?
Which route is used for the elimination of conjugated morphine?
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What condition contraindicates the use of opioids?
What condition contraindicates the use of opioids?
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Which opioid is used as an analgesic and an antitussive?
Which opioid is used as an analgesic and an antitussive?
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Which opioid is formulated with aspirin or acetaminophen?
Which opioid is formulated with aspirin or acetaminophen?
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Which opioid is more potent than morphine?
Which opioid is more potent than morphine?
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Which opioid has no active metabolites?
Which opioid has no active metabolites?
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Which opioid is a mu receptor agonist and also has antimuscarinic properties?
Which opioid is a mu receptor agonist and also has antimuscarinic properties?
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Which opioid is used for relief of mild to moderate pain in ambulatory persons?
Which opioid is used for relief of mild to moderate pain in ambulatory persons?
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Which opioid is metabolized by the liver and some of it is converted to morphine and is excreted in the urine?
Which opioid is metabolized by the liver and some of it is converted to morphine and is excreted in the urine?
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Which opioid is more lipid soluble than morphine?
Which opioid is more lipid soluble than morphine?
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Which opioid is used as an analgesic and an antitussive?
Which opioid is used as an analgesic and an antitussive?
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Which opioid has indications for severe pain?
Which opioid has indications for severe pain?
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Which opioid has little effect on the gastrointestinal system, pupil, and cough reflex?
Which opioid has little effect on the gastrointestinal system, pupil, and cough reflex?
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Which opioid is 80-100 times more potent than morphine?
Which opioid is 80-100 times more potent than morphine?
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Which opioids are considered high-efficacy analgesics?
Which opioids are considered high-efficacy analgesics?
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Which opioids are considered lower efficacy analgesics?
Which opioids are considered lower efficacy analgesics?
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Which drug is an agonist at kappa receptors and a weak antagonist at mu receptors?
Which drug is an agonist at kappa receptors and a weak antagonist at mu receptors?
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Which drug is a kappa receptor agonist and a weak partial mu receptor agonist?
Which drug is a kappa receptor agonist and a weak partial mu receptor agonist?
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Which drug is a partial mu receptor agonist with kappa receptor antagonist actions?
Which drug is a partial mu receptor agonist with kappa receptor antagonist actions?
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Which drug is a kappa receptor agonist and a mu receptor antagonist?
Which drug is a kappa receptor agonist and a mu receptor antagonist?
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Which drug is metabolized by glucuronidation?
Which drug is metabolized by glucuronidation?
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Which drug can precipitate a withdrawal syndrome in a person physically dependent on opioids?
Which drug can precipitate a withdrawal syndrome in a person physically dependent on opioids?
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Which drug has high abuse liability and can cause psychotomimetic effects, dysphoria, increased heart rate, and blood pressure at high doses?
Which drug has high abuse liability and can cause psychotomimetic effects, dysphoria, increased heart rate, and blood pressure at high doses?
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Which drug has low abuse liability and less respiratory depression compared to full agonists?
Which drug has low abuse liability and less respiratory depression compared to full agonists?
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Which drug can be used to reverse respiratory depression produced by other opioids while maintaining analgesia?
Which drug can be used to reverse respiratory depression produced by other opioids while maintaining analgesia?
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Which opioid has the highest affinity for mu receptors followed by kappa and delta receptors?
Which opioid has the highest affinity for mu receptors followed by kappa and delta receptors?
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Which opioid is a weak mu receptor agonist and inhibits the re-uptake of 5-HT and norepinephrine?
Which opioid is a weak mu receptor agonist and inhibits the re-uptake of 5-HT and norepinephrine?
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Which opioid is more effective in neuropathic pain and hyperalgesia than others?
Which opioid is more effective in neuropathic pain and hyperalgesia than others?
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Which drug is indicated for moderate to severe pain and the treatment of opioid use disorder?
Which drug is indicated for moderate to severe pain and the treatment of opioid use disorder?
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Which opioid has analgesic actions that are only partially antagonized by naloxone?
Which opioid has analgesic actions that are only partially antagonized by naloxone?
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Which opioid is contraindicated in patients with pre-existing seizure disorders?
Which opioid is contraindicated in patients with pre-existing seizure disorders?
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Which medication is indicated for the treatment of acute opioid toxicity?
Which medication is indicated for the treatment of acute opioid toxicity?
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Which medication is used for the treatment of opioid use disorder and alcohol use disorder?
Which medication is used for the treatment of opioid use disorder and alcohol use disorder?
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Which medication is a peripherally-acting mu receptor antagonist for the treatment of opioid-induced constipation or pruritus?
Which medication is a peripherally-acting mu receptor antagonist for the treatment of opioid-induced constipation or pruritus?
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Which medication is a peripherally-acting mu receptor antagonist for bowel recovery post-surgery?
Which medication is a peripherally-acting mu receptor antagonist for bowel recovery post-surgery?
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What is the potential risk of combining CNS depressants with antipsychotics, sedative-hypnotics, alcohol, and other CNS depressants?
What is the potential risk of combining CNS depressants with antipsychotics, sedative-hypnotics, alcohol, and other CNS depressants?
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What effect does naloxone have in an opioid-dependent patient?
What effect does naloxone have in an opioid-dependent patient?
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Which of the following is NOT a physiological effect of naloxone?
Which of the following is NOT a physiological effect of naloxone?
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Which opioid receptor does naloxone primarily target?
Which opioid receptor does naloxone primarily target?
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What is the main purpose of naloxone administration?
What is the main purpose of naloxone administration?
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Which of the following reactions can occur when meperidine is co-administered with MAO inhibitors?
Which of the following reactions can occur when meperidine is co-administered with MAO inhibitors?
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Which opioids can have adverse reactions when co-administered with MAO inhibitors?
Which opioids can have adverse reactions when co-administered with MAO inhibitors?
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What is a potential adverse effect of opioids on the fetus during obstetric labor?
What is a potential adverse effect of opioids on the fetus during obstetric labor?
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What is a paradoxical effect that opioids can have on renal and biliary colic?
What is a paradoxical effect that opioids can have on renal and biliary colic?
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Which of the following is an adverse effect of opioids except for meperidine?
Which of the following is an adverse effect of opioids except for meperidine?
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Which medication is used to treat acute opioid toxicity?
Which medication is used to treat acute opioid toxicity?
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Study Notes
Opioid Receptors and Peptides
- The precursor peptide Proenkephalin is encoded by the PENK gene.
- Enkephalin peptides are widely distributed throughout the brain and spinal cord.
Enkephalin Peptides
- Met-enkephalin is a peptide with a limited distribution, found in the intermediate lobe of the pituitary and hypothalamus, with axons projecting to the amygdala, PAG, brainstem, and spinal cord.
- Leu-enkephalin is distributed throughout the brain and spinal cord, functioning as a neurotransmitter.
Opioid Receptors
- Enkephalins bind to opioid receptors with high affinity, specifically mu and delta receptors.
- Mu receptors are associated with reward and emotion, and are also involved in constipation and respiratory depression.
- Delta receptors are associated with analgesia and mood elevation.
- Kappa receptors are associated with diuresis and dysphoria.
Cellular Mechanism of Opioids
- Opioids target the cellular mechanism of reducing neurotransmitter release by inhibiting the release of GABA and glutamate.
- Opioids have a hyperpolarizing effect on postsynaptic neurons, reducing the formation of cAMP.
Peripheral Effects of Opioids
- Opioids can cause constipation, respiratory depression, and diuresis.
- Tolerance to the constipating effects of opioids develops over time.
Morphine
- Morphine primarily acts on mu opioid receptors.
- Morphine is metabolized by the liver and conjugated with glucuronic acid, then excreted in the urine.
- The active metabolite of morphine, morphine-6-glucuronide, has high affinity for mu opioid receptors.
- Morphine is indicated for the relief of severe pain.
Other Opioids
- Codeine is an opioid used as an analgesic and an antitussive, and is often formulated with aspirin or acetaminophen.
- Hydrocodone is an opioid used for the relief of mild to moderate pain in ambulatory persons.
- Fentanyl is an opioid that is more lipid soluble than morphine and is used for the relief of severe pain.
- Sufentanil is an opioid that is 80-100 times more potent than morphine.
- Butorphanol is an opioid with agonist activity at kappa receptors and weak antagonist activity at mu receptors.
Opioid Agonists and Antagonists
- Naloxone is a mu receptor antagonist used to reverse respiratory depression produced by other opioids.
- Buprenorphine is a partial mu receptor agonist with kappa receptor antagonist actions.
- Pentazocine is a kappa receptor agonist and a weak partial mu receptor agonist.
Opioid Use Disorders and Treatment
- Naloxone is indicated for the treatment of acute opioid toxicity.
- Methadone is used for the treatment of opioid use disorder and alcohol use disorder.
- Alvimopan is a peripherally-acting mu receptor antagonist used for the treatment of opioid-induced constipation or pruritus.
- Naldemedine is a peripherally-acting mu receptor antagonist used for bowel recovery post-surgery.
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Description
Test your knowledge on endogenous opioid peptides and their functions with this quiz. Learn about the genes that encode these peptides and their distribution in the body. Discover how enkephalin acts as a neurotransmitter and the receptors it binds to.
