Podcast
Questions and Answers
Which opioid is primarily metabolized to its active form morphine?
Which opioid is primarily metabolized to its active form morphine?
What is the metabolic consequence of CYP3A4 inhibitors on opioid medications?
What is the metabolic consequence of CYP3A4 inhibitors on opioid medications?
Which opioid receptor is primarily associated with mediating analgesia and sedation?
Which opioid receptor is primarily associated with mediating analgesia and sedation?
What is a distinctive characteristic of methadone compared to other opioids?
What is a distinctive characteristic of methadone compared to other opioids?
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Which opioid is classified as a mixed agonist-antagonist?
Which opioid is classified as a mixed agonist-antagonist?
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Which of the following opioids is selective for µ receptors?
Which of the following opioids is selective for µ receptors?
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Which opioid undergoes glucuronidation to yield both active and inactive metabolites?
Which opioid undergoes glucuronidation to yield both active and inactive metabolites?
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What pharmacological action does a full agonist opioid have?
What pharmacological action does a full agonist opioid have?
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Which of the following peptides is produced endogenously in the brain?
Which of the following peptides is produced endogenously in the brain?
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What effect does caffeine have on opioid metabolism?
What effect does caffeine have on opioid metabolism?
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Which opioid is considered to have the highest permeability across the blood-brain barrier compared to morphine?
Which opioid is considered to have the highest permeability across the blood-brain barrier compared to morphine?
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Which statement accurately describes the pharmacokinetics of morphine in terms of oral administration?
Which statement accurately describes the pharmacokinetics of morphine in terms of oral administration?
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Which factor is most responsible for the long half-life of lipophilic opioids like fentanyl?
Which factor is most responsible for the long half-life of lipophilic opioids like fentanyl?
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Which of the following opioids has zero percent protein binding, allowing for rapid brain distribution?
Which of the following opioids has zero percent protein binding, allowing for rapid brain distribution?
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What type of formulations do extended-release opioids use to control the release of the active ingredient?
What type of formulations do extended-release opioids use to control the release of the active ingredient?
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Which phase of opioid metabolism is primarily responsible for modifying the drug molecule by cytochrome P450 enzymes?
Which phase of opioid metabolism is primarily responsible for modifying the drug molecule by cytochrome P450 enzymes?
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In which of the following scenarios would a parenteral administration of an opioid be preferred over oral administration?
In which of the following scenarios would a parenteral administration of an opioid be preferred over oral administration?
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Which opioid is least affected by first-pass metabolism and thus allows better absorption from the gastrointestinal tract?
Which opioid is least affected by first-pass metabolism and thus allows better absorption from the gastrointestinal tract?
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Which of the following opioids is commonly used in the treatment of opioid addiction?
Which of the following opioids is commonly used in the treatment of opioid addiction?
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Which opioids have predominantly shorter durations of action due to lower protein binding?
Which opioids have predominantly shorter durations of action due to lower protein binding?
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Which of the following is a common synthetic opiate?
Which of the following is a common synthetic opiate?
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What is the primary medical use of methadone in addiction therapy?
What is the primary medical use of methadone in addiction therapy?
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Which opiate is known for having the highest potency per dose?
Which opiate is known for having the highest potency per dose?
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How is buprenorphine primarily administered in medical settings?
How is buprenorphine primarily administered in medical settings?
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What is the mechanism of action for most opiates in the central nervous system?
What is the mechanism of action for most opiates in the central nervous system?
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Which factor primarily influences the metabolism rate of opioids?
Which factor primarily influences the metabolism rate of opioids?
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Which of the following statements about the kappa opioid receptor is true?
Which of the following statements about the kappa opioid receptor is true?
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Which opioid acts as a partial agonist at the µ receptor and a full agonist at δ receptors?
Which opioid acts as a partial agonist at the µ receptor and a full agonist at δ receptors?
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Which opiate is most commonly used in the treatment of severe acute pain?
Which opiate is most commonly used in the treatment of severe acute pain?
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What is the primary mechanism of action for naloxone?
What is the primary mechanism of action for naloxone?
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What is a common side effect associated with opioid analgesics?
What is a common side effect associated with opioid analgesics?
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Which of the following opioids primarily acts as a serotonin-norepinephrine reuptake inhibitor?
Which of the following opioids primarily acts as a serotonin-norepinephrine reuptake inhibitor?
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What type of administration is most likely to enhance the reinforcing effects of opioids?
What type of administration is most likely to enhance the reinforcing effects of opioids?
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What is the primary metabolite of codeine that contributes to its analgesic effects?
What is the primary metabolite of codeine that contributes to its analgesic effects?
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Which of these is a key characteristic of opioid tolerance?
Which of these is a key characteristic of opioid tolerance?
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All of the following are methods to manage opioid overdose except:
All of the following are methods to manage opioid overdose except:
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Which receptor does naltrexone act on as a non-selective antagonist?
Which receptor does naltrexone act on as a non-selective antagonist?
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What is a potential consequence of opioid abuse?
What is a potential consequence of opioid abuse?
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Which of the following is true regarding methadone's pharmacological actions?
Which of the following is true regarding methadone's pharmacological actions?
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What effect does rapid onset of opioid action generally have?
What effect does rapid onset of opioid action generally have?
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Study Notes
Opioid Analgesics
- Opioids are cornerstone analgesics for moderate to severe pain.
- Their potency, onset, duration, metabolism, and interactions with other drugs vary.
- Individual responses differ due to genetics, medical conditions, and prior opioid use.
- Pharmacokinetics (absorption, distribution, metabolism, and excretion) and pharmacodynamics (effects on the body) influence effectiveness.
Absorption
- Opioids are less effective when taken orally due to their basic nature (pH).
- Oral absorption is slower, with significant first-pass metabolism (destruction in stomach, intestines, and liver) reducing bioavailability.
- Bioavailability is typically 15-40% for oral morphine.
- Extended-release formulations have multiple layers to improve absorption rates.
- Lipid solubility and decreased enzymatic degradation in the gastrointestinal tract improve bioavailability.
- Codeine has approximately 90% bioavailability orally.
- Hydrocodone is also well-absorbed from the gastrointestinal tract and reaches peak blood levels in ~80 minutes.
- Oxycodone bioavailability varies between immediate-release (60-87%) and extended-release (up to 100%).
Distribution
- Opioids distribute to major organs: heart, lungs, kidneys, liver, spleen, and muscles, with some concentration in the brain (basal ganglia, amygdala, periaqueductal gray).
- Highly lipophilic opioids (e.g. buprenorphine, fentanyl, methadone) are more likely to bind to proteins.
- This results in longer half-lives due to slower release of the drugs from initial distribution sites.
- Opioids cross the placental barrier and enter breast milk.
Elimination
- Opioids are metabolized in the liver and intestines.
- Metabolites are actively excreted by the kidneys and other fluids like urine, feces, and sweat.
- Cytochrome P450 enzymes (primarily CYP3A4 and CYP2D6) play a crucial role in metabolism.
- Phase 1 metabolism involves enzymatic modification of the opioid molecule.
- Phase 2 metabolism involves conjugation with hydrophilic substances (e.g., glucuronic acid).
- Some metabolites are inactive; others are more potent than the parent molecule.
- Opioid metabolites are excreted in urine, feces, and other bodily fluids.
Neuropharmacology
- Opioid receptors (μ, κ, δ, ORL1) are found throughout the brain and spinal cord.
- Endogenous opioid peptides (endorphins, enkephalins, dynorphins, and nociceptin) interact with these receptors.
- Opioid receptors are metabotropic and exert their effects via intracellular signaling pathways.
- Activation influences mood, behavior, pain, stress, and reward.
- Different opioid receptors have varying effects, with μ receptors playing a key role in analgesia and reward.
Opioid Agonists, Antagonists, and Mixed Agonist-Antagonists
- Opioid agonists activate opioid receptors to produce effects.
- Mixed agonist-antagonists exert both agonist and antagonist effects.
- Some opioids are mixed agonists, meaning that they act as agonists on some receptors and as antagonists on others.
- Opioid antagonists block opioid receptors, preventing agonist effects.
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Description
This quiz explores opioid analgesics, focusing on their use for moderate to severe pain. It covers factors influencing potency, absorption methods, and the impact of first-pass metabolism on bioavailability. Test your knowledge on pharmacokinetics and pharmacodynamics as they relate to opioid medications.
