PCOL 7-1 Opioids and Pain

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Questions and Answers

What are the actions of opioids?

Improved digestion

Respiratory depression (correct)

Increased heart rate

Lowered blood pressure

Which opioid receptor type is responsible for strong analgesia?

MOR (correct)

ENK

DOR

KOR

Which type of pain do opioids mainly act on?

Nerve pain

Sharp, initial pain (correct)

Muscle pain

Longer, less intense pain

Where are opioid receptors present in the pain pathway?

At all levels of the pain pathway Signup and view all the answers

What do descending NA and 5-HT neurons do in relation to pain relief?

Modulate sensory synapses Signup and view all the answers

What is the role of enkephalin (ENK) neurons in pain relief?

Inhibit sensory synapses Signup and view all the answers

What type of drugs provide pain relief by inhibiting sensory synapses?

Antidepressants Signup and view all the answers

Which opioid receptor type is responsible for spinal analgesia?

DOR Signup and view all the answers

What is the major cause of death related to opioids?

Respiratory depression Signup and view all the answers

Which of the following is NOT an endogenous opioid?

Morphine Signup and view all the answers

Which opioid is inactive until esterases of CYP2D6 enzymes metabolize it into morphine?

Codeine Signup and view all the answers

Which synthetic opioid is a partial agonist?

Buprenorphine Signup and view all the answers

Which opioid receptor antagonist is commonly used to reverse opioid overdose?

Naloxone Signup and view all the answers

Which factors affect the strength of opioid signaling?

Intrinsic efficacy Signup and view all the answers

What is the mechanism of action of buprenorphine?

It binds tightly enough to prevent other agonists or antagonists from binding Signup and view all the answers

Why is low efficacy of opioids considered safer?

It reduces the maximum possible response Signup and view all the answers

What is the theorized benefit of signaling bias in opioids?

It could result in fewer side effects Signup and view all the answers

Which effects of opioids can develop tolerance within days?

Analgesia and euphoria Signup and view all the answers

What is the usual dose escalation for opioids in cases of tolerance?

10 – 30 times Signup and view all the answers

How do NSAIDs synergize with opioids?

They enhance opioid action on nerve endings Signup and view all the answers

What is the role of prostaglandins in pain sensitization?

They sensitize nociceptive sensory nerves Signup and view all the answers

Which effects of opioids are not affected by tolerance?

Constipation and pupil constriction Signup and view all the answers

What do NSAIDs inhibit to prevent prostaglandin synthesis?

COX Signup and view all the answers

Study Notes

Opioid Actions and Pain Relief

Opioids act on nociceptive pain, which is a type of pain that is caused by tissue damage or inflammation.
Opioid receptors are present in the pain pathway, particularly in the spinal cord and brain.
The mu (μ) opioid receptor type is responsible for strong analgesia and spinal analgesia.
Descending NA and 5-HT neurons inhibit pain transmission, thereby providing pain relief.
Enkephalin (ENK) neurons release endogenous opioids, which bind to opioid receptors, providing pain relief.

Opioid Receptors and Signaling

The delta (δ) opioid receptor type is responsible for spinal analgesia.
The strength of opioid signaling is affected by factors such as receptor density, ligand binding affinity, and receptor internalization.
Buprenorphine is a partial agonist at the mu opioid receptor, which means it has a lower efficacy than full agonists like morphine.
The mechanism of action of buprenorphine involves binding to the mu opioid receptor, which activates a signaling pathway that inhibits pain transmission.

Opioid Effects and Tolerance

Opioids can cause euphoria, sedation, and constipation, which can develop tolerance within days.
The usual dose escalation for opioids in cases of tolerance is to increase the dose by 10-20% every 2-3 days.
Tolerance does not affect the opioid-induced respiratory depression and constipation.

NSAIDs and Prostaglandins

NSAIDs synergize with opioids by inhibiting the synthesis of prostaglandins, which are involved in pain sensitization.
Prostaglandins are produced in response to tissue damage and inflammation, and they sensitize nociceptors, leading to increased pain transmission.
NSAIDs inhibit cyclooxygenase enzymes, which are necessary for prostaglandin synthesis.

Opioid Overdose and Antagonists

The major cause of death related to opioids is respiratory depression.
Naloxone is a commonly used opioid receptor antagonist to reverse opioid overdose.
Codeine is an inactive opioid that requires esterases of CYP2D6 enzymes to metabolize it into morphine.

Endogenous Opioids

Endogenous opioids, such as enkephalins and endorphins, are produced by the body and bind to opioid receptors, providing pain relief.
Dynorphin is NOT an endogenous opioid.
The theorized benefit of signaling bias in opioids is that it may lead to the development of safer and more effective opioids.

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Description

Test your knowledge on opioids and their actions with this quiz! Explore the various effects of opioids, such as analgesia, respiratory depression, tolerance, constipation, and more. Challenge yourself and learn about the complexities of these pain relief drugs.