Opioids Lecture

Question 1

What is the mechanism of action of opioids?

Answer 1

Binds to G-protein-coupled opioid receptors in brain, spinal cord, and peripherals.

Question 2

how do opioids inhibit PREsynaptic neurons?

Answer 2

Opioids close presynaptic Ca²⁺ channels → ↓ neurotransmitter release

Question 3

how do opioids inhibit POSTsynaptic neurons?

Answer 3

Opioids open K⁺ channels → hyperpolarization and inhibition of postsynaptic neurons.

Question 4

what are the opioid receptor types and their actions?

Answer 4

Mu: Analgesia, euphoria, respiratory depression, dependence.

Delta: Analgesia, dopamine release, reward center activation.

Kappa: Analgesia, dysphoria, psychomimetic effects.

Question 5

What is first-pass metabolism in opioids?

Answer 5

Oral opioids undergo extensive first-pass metabolism, reducing bioavailability and causing patient variability.

distributes well into highly perfused areas (brain, kidney, liver, lungs, spleen)

Question 6

what is the significance of fentanyl’s potency?

Answer 6

50-100x more potent than morphine

**heat increases transdermal absorption - avoid applying heat to patch areas

Question 7

what are common opioid-induced side effects?

Answer 7

Acute: Respiratory depression, sedation, nausea/vomiting, miosis*

Chronic: Constipation*, tolerance, dependence.

*does not subside

Question 8

what is the treatment for opioid-induced constipation?

Answer 8

1st-line: Stimulant laxative (Senna) + stool softener (Docusate).
2nd-line: Lactulose.
3rd-line: Methylnaltrexone

Question 9

What is Naloxone (Narcan) used for?

Answer 9

Pure opioid antagonist for opioid overdose - reverses the effects

Question 10

What are strategies to reduce opioid misuse?

Answer 10

Use immediate-release opioids first.
Assess risk of substance use disorder.
Consider multimodal pain management.
Provide naloxone for at-risk patients.

Question 11

How do opioids contribute to addiction?

Answer 11

Mu and delta receptor agonism release dopamine → euphoria → activation of reward pathways.

Question 12

What are signs of opioid withdrawal?

Answer 12

Insomnia, anxiety, GI distress, diaphoresis, hypertension, tremors, muscle spasms.

Question 13

What are opioid-induced adverse effects requiring monitoring?

Answer 13

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.

Question 14

What is opioid tolerance?

Answer 14

A decreased response to repeated opioid doses, requiring higher doses for the same effect.

Question 15

What are the risks of long-term opioid use?

Answer 15

Tolerance, physical dependence, addiction, and potential for opioid-induced hyperalgesia (increased pain sensitivity).

Question 16

What are signs of opioid allergy vs histamine release?

Answer 16

Allergy: True anaphylaxis (difficulty breathing, swelling, hypotension). avoid all opioids in same class.

Histamine release: Dose-dependent itching or rash; treat with antihistamines.

Question 17

Does Oxycodone or Morphine have a higher addiction potential?

Answer 17

Oxycodone

Question 18

What is the most popularly abused opiate and why?

Answer 18

Hydrocodone

Widely prescribed (e.g., Vicodin).
Produces euphoria.
Seen as less risky than stronger opioids.
Easy to access, leading to dependence.

Question 19

which opioid is primarily used for chronic cancer pain?

Answer 19

Methadone

Question 20

main drug interaction with opioids?

Answer 20

other psych meds – serotonin syndrome

Question 21

difference between Naloxone and Naltrexone?

Answer 21

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

Question 22

What are the 5 A’s of monitoring opioid use?

Answer 22

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.

Question 23

Associated Opioid Abuse Risk Factors?

Answer 23

Males
Age > 50 years
Preoperative history of drug abuse, alcohol abuse
Depression
Benzodiazepine use
Antidepressant use