Induction Meds: Opioids Agonists Concepts

Question 1

What are opioids effects on the CO₂ medullary center?

Answer 1

• Opioids inhibit the CO₂ medullary center.

Question 2

Differentiate opioids from narcotics.

Answer 2

• Opioids = all exogenous substances that bind to endogenous opioid receptors.
• Narcotic = any substance that can produce dependence (stupor)

S7

Question 3

What two types of opioid chemical structures are there?

Answer 3

• Phenanthrenes
• Benzylisoquinolines

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Question 4

What types of drugs are Phenanthrenes?

Answer 4

Morphine & codeine

S8

Question 5

What is Papaverine mostly used for?

Answer 5

Treating intra-arterial barbiturate administration
(dilates the highly constricted artery).

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Question 6

What portions of the brain are the source of Descending Inhibitory Signals?

Answer 6

• Thalamus
• PAG
• Locus Coeruleus

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Question 7

What endogenous substances have the same effect on receptors as Opioids?

Answer 7

Endorphins, Enkephalins, and Dynorphines.

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Question 8

Presynaptic inhibition of what neurotransmitters occurs with Opioid administration?

Answer 8

• Substance P
• ACh
• NE
• Dopamine

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Question 9

How do Opioids modulate pain at the cellular level?

Answer 9

• ↑ K⁺ conductance (hyperpolarization)
• Ca⁺⁺ channel inactivation

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Question 10

Where are Opioid receptors located in the brain?

Answer 10

• PAG
• Locus Ceruleus
• RVM (rostral ventral medulla)
• Hypothalamus

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Question 11

Where is the primary site of Opioid receptors in the spinal cord?

Answer 11

Substantia gelatinosa (aka Laminae 2)

where local anesthetics work

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Question 12

Where is/are Opioid receptors found outside the CNS?

Answer 12

Sensory neurons & immune cells

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Question 13

What are the four (most important) types of opioid receptors?

Answer 13

• Μu₁ (μ₁)
• Μu₂ (μ₂)
• Κappa (κ)
• Delta (δ)

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Question 14

Which opioid receptor(s) is/are responsible for respiratory depression & physical dependence?

Answer 14

• Μu₂
• δ

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Question 15

Which receptors are responsible for constipation?

Answer 15

• Μu₂ (primarily)
• δ (less)

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Question 16

Which receptors can cause urinary retention?

Answer 16

• Μu₁
• δ (delta)

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Question 17

All opioid receptors induce analgesia at both the brain the spinal cord. T/F?

Answer 17

• False. Μu₂ receptors only cause at analgesia at the spinal cord level.

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Question 18

What opioid receptors have low abuse potential when bound?

Answer 18

Μu₁ and κ

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Question 19

Which opioid receptor is responsible for euphoria, bradycardia, hypothermia, and miosis when bound?

Answer 19

Mu1

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Question 20

What agonists bind to the four opioid receptors?

Answer 20

• Mu1 & Mu2 = endorphins, morphine, synthetics.
• κ = dynorphins.
• δ = enkephalins.

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Question 21

Describe the adverse side effects of Opioids on the cardiovascular system.

Answer 21

• ↓SNS tone = ↓BP, VR, and CO & Orthostatic hypotension and sycope
• ↓HR + histamine release = ↓BP

+ N2O or Benzo = CV depression

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Question 22

What possible cardiovascular benefits do Opioids provide?

Answer 22

Myocardial ischemia protection
(won’t cause myocardial depression)

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Question 23

What are the respiratory effects of Opioids?

Answer 23

• Depressed CNS response to CO₂ causing a right shift of PaCO₂ (↑)

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Question 24

What drug would treat opioid ventilatory depression but not reverse analgesia?
How?

Answer 24

Physostigmine would by increasing CNS levels of ACh

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Question 25

What is normal PaO₂?

Answer 25

Normal PaO₂ is **80 mmHg** ## Footnote S15

Question 26

What would cause a leftward shift in PaO₂? What would cause a rightward shift?

Answer 26

- Leftward: Metabolic acidosis (to breathe off all that CO₂) - Rightward: sleep → opiates → anesthesia (need higher CO2 to make them breath) ## Footnote S15

Question 27

Why should caution be used when administering opioids to *head trauma patients*?

Answer 27

Opioids **↓CBF** and **possibly ↓ICP** ## Footnote S16

Question 28

What musculoskeletal abnormality occurs with Opioid administration? What makes this condition worse? How is it treated?

Answer 28

**-Skeletal chest wall and abdominal muscle rigidity** - Mechanical ventilation makes it worse - *treat* with **Muscle relaxants and/or naloxone** ## Footnote S16

Question 29

What are Sphincter of Oddi spasms? Which drugs can cause this?

Answer 29

- Biliary smooth muscle spasm caused by: - **Fentanyl** (99%), - Morphine (53%) - Meperidine (61%). *I think maybe all opioids can cause this but these are the primary culprits* ## Footnote S17

Question 30

What drugs should be used for ERCP cases?

Answer 30

- Non-opioids (multimodal approach w/ NSAIDs, gabapentin, etc.)

Question 31

How are opioid-induced Sphincter of Oddi spasm's treated?

Answer 31

- **Naloxone** - **Glucagon** (2mg IV given incrementally) and causes no opioid antagonism.

Question 32

How long does it take (generally) to develop tolerance to Opioids? What causes tolerance?

Answer 32

- **2-3 weeks** - 25 days with Morphine - Downregulation (↓ opioid receptors) causes tolerance ## Footnote S20

Question 33

What types of drugs are Benzylisoquinolines?

Answer 33

**Papaverine** ## Footnote S8

Question 34

Are there any receptors that cause diuresis when bound?

Answer 34

κ (Kappa) ## Footnote S12

Question 35

What are the syptoms of Opioid overdose?

Answer 35

**- apnea** - miosis - hypoventilation - coma ## Footnote S14

Question 36

What can happen when large doses of Opioid is given?

Answer 36

Myoclonus ## Footnote S16

Question 37

What is the side effect on GU with Opioids?

Answer 37

urinary urgency ## Footnote S19

Question 38

What are the effects on cutaneous with Opioid?

Answer 38

flushed face, neck, & upper chest d/t Histamine release ## Footnote S19

Question 39

What are the side effects on the placenta with Opioids?

Answer 39

- neonate depression - dependence (chronic) ## Footnote S19

Question 40

What negative change can develop between all opioids?

Answer 40

Cross-tolerance ## Footnote S20