Opioids Lecture Flashcards
What is the mechanism of action of opioids?
Binds to G-protein-coupled opioid receptors in brain, spinal cord, and peripherals.
how do opioids inhibit PREsynaptic neurons?
Opioids close presynaptic Ca²⁺ channels → ↓ neurotransmitter release
how do opioids inhibit POSTsynaptic neurons?
Opioids open K⁺ channels → hyperpolarization and inhibition of postsynaptic neurons.
what are the opioid receptor types and their actions?
Mu: Analgesia, euphoria, respiratory depression, dependence.
Delta: Analgesia, dopamine release, reward center activation.
Kappa: Analgesia, dysphoria, psychomimetic effects.
What is first-pass metabolism in opioids?
Oral opioids undergo extensive first-pass metabolism, reducing bioavailability and causing patient variability.
distributes well into highly perfused areas (brain, kidney, liver, lungs, spleen)
what is the significance of fentanyl’s potency?
50-100x more potent than morphine
**heat increases transdermal absorption - avoid applying heat to patch areas
what are common opioid-induced side effects?
Acute: Respiratory depression, sedation, nausea/vomiting, miosis*
Chronic: Constipation*, tolerance, dependence.
*does not subside
what is the treatment for opioid-induced constipation?
1st-line: Stimulant laxative (Senna) + stool softener (Docusate).
2nd-line: Lactulose.
3rd-line: Methylnaltrexone
What is Naloxone (Narcan) used for?
Pure opioid antagonist for opioid overdose - reverses the effects
What are strategies to reduce opioid misuse?
Use immediate-release opioids first.
Assess risk of substance use disorder.
Consider multimodal pain management.
Provide naloxone for at-risk patients.
How do opioids contribute to addiction?
Mu and delta receptor agonism release dopamine → euphoria → activation of reward pathways.
What are signs of opioid withdrawal?
Insomnia, anxiety, GI distress, diaphoresis, hypertension, tremors, muscle spasms.
What are opioid-induced adverse effects requiring monitoring?
Adverse effects: Respiratory depression, sedation,
*constipation, *miosis, nausea.
Monitoring: Pain scores, respiratory rate, bowel movements, mental status
*these ADRs will NOT subside with tolerance to opioids.
What is opioid tolerance?
A decreased response to repeated opioid doses, requiring higher doses for the same effect.
What are the risks of long-term opioid use?
Tolerance, physical dependence, addiction, and potential for opioid-induced hyperalgesia (increased pain sensitivity).
What are signs of opioid allergy vs histamine release?
Allergy: True anaphylaxis (difficulty breathing, swelling, hypotension). avoid all opioids in same class.
Histamine release: Dose-dependent itching or rash; treat with antihistamines.
Does Oxycodone or Morphine have a higher addiction potential?
Oxycodone
What is the most popularly abused opiate and why?
Hydrocodone
Widely prescribed (e.g., Vicodin).
Produces euphoria.
Seen as less risky than stronger opioids.
Easy to access, leading to dependence.
which opioid is primarily used for chronic cancer pain?
Methadone
main drug interaction with opioids?
other psych meds – serotonin syndrome
difference between Naloxone and Naltrexone?
Naloxone = used for acute emergencies, rapid onset
Naltrexone = longer acting than Naloxone, used primarily for curbing dependence and cravings and not used in acute emergencies
What are the 5 A’s of monitoring opioid use?
Analgesia: Is the pain relief adequate?
Affect: Mood and depression scores.
Activities: Function and ability to perform daily tasks.
Adverse Effects: Any side effects from the therapy.
Aberrant Behaviors: Signs of misuse or addiction.
Associated Opioid Abuse Risk Factors?
Males
Age > 50 years
Preoperative history of drug abuse, alcohol abuse
Depression
Benzodiazepine use
Antidepressant use
