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Flashcards in Leffler-1 Deck (24)
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1

Non-opioid analgesics vs Opioid Analgesics

  • Non-opioid Analgesics:
    • act in:
      • peripheral tissues (primarily)
        • inhibit formation of pain producing substances
          • prostaglandins 
      • Act In the CNS:
        • reduce prostaglandin production involved in temperature regulation
        • Anti-inflammatory
  • Opioid Analgesics
    • Acts primarily in the CNS (Spinal cord and brain)
    • inhibit Neurotransmission of pain

2

Opioids differs from NSAIDs:

Opioids:

  • Significant:
    • abuse potential
      • tolerance, physical and psychological dependence 
    • First pass metabolism
      • oral has less analgesic effect than parenteral doses
      • Have to be injected
  • More powerful analgesic
  • Lack anti-inflammatory and antipyretic effects
    • Antipyretic (reduce fever)
  • Site of action: CNS

3

Opiate

  • Drug derived from the alkaloids of the opium poppy

4

Opioid

  • Classs of drugs
  • includes:
    • opiates
    • Opiopeptins
    • all synthetic and semisnthetic drugs
      • mimic action of opiates

5

Opioid peptides

  • Endogenous peptides that act on opioid receptors

6

Narcotic

  • Any psychoactive compound with sedative properties 
  • used in legal context to refer to substances with abuse or addictive potential
  • applies to more than just opioids 

7

Endogenous Opioid Peptides

  • 3 famillies of peptides:
    • Enkephalins
    • Endorphins
    • Dynorphins
  • Opioid receptors have overlapping affinities for these 3 peptides
  • All implicated in pain modulation
  • Analgesic role
    • Released upon stressful stimuli and diminish sensation
  • Dynorphin A
    • may increase pain
    • Pronociceptive action

8

Source of Opium

  • Poppy plant

9

What is the principle alkaloid?

  • Morphine

10

Opioid Receptors

  • Inhibitory G-coupled protein receptor (Gi)
  • Limbic System
  • 3 types:
    • Mu 
    • Kappa
    • Delta
  • Binding site for endogenous ligans and opioid drugs
  • all 3 coupled to adenylyl cyclase:
    • inhibition=Inhibition of NT release

11

Where are opioid receptors expressed?

  • Expressed in pain-modulating descending pathway
    • Periaqueductal gray area
  • Also expressed in limbic, midbrain, and cortical structures

12

When opioid receptors are activated what happens?

  • Direct inhibition of:
    • neurons
    • spinal cord pain transmission

13

Opioid Receptors: Mechanism of Action

  • Modulate Ca2+ and K+ ion channels
  • actions can occur at the level of the:
    • spinal cord (spinal analgesia)
    • CNS (supraspinal analgesia)
  • Net Result:
    • Raise the threshold to pain

14

Mu receptor: 

 

  • Function:
    • Supra spinal and spinal analgesia
    • sedation
    • inhibition of respiration
    • slowed GI transit (constipation)
  • High affinity for Endorphins (primary opioid peptide)
  • Primary receptor for opioid drugs

15

Kappa receptor

  • Function:
    • psychotomimetic effects

16

Delta Receptor

  • Function:
    • Supraspinal and spinal analgesai

17

Physiological effects to receptor types:

-Mu Receptors

-Kappa Receptors

-Delt Receptors

  • Mu Receptor:
    • Analgesia
    • Respiratory Depression
    • Euphoria (pleasure, well-being, elation)
    • Sedation
    • Physical Dependence
    • Slowed GI Transit (Constipation)
    • Miosis
    • Modulation of Hormone and NT release
  • Kappa Receptor:
    • Analgesia
    • Dysphoria (unease, Dissatsifaction)
    • Sedation (some to little)
    • Slowed GI transit 
    • Miosis
    • Psychomimetic effects
  • Delta receptor:
    • Modulation of Hormone and NT release

18

Overall systemic effects of opioid receptor activation:

CNS vs Periphery

Some are desired effects, some are undesired

Overdose can lead to death

CNS:

  • Analgesia
  • Euphoria
  • Sedation
  • Respiratory depression
  • Cough Suppresion
  • Miosis
  • Truncal rigidity 
  • Nausea and Vomiting
  • Body temperature-reduce shivering
  • May increase ICP

 

Periphery:

  • Bradycardia 
  • Hypotension (in cardiovascular-stressed patients)
  • Constipation
  • Biliary colic (contraciton of biliary smooth muscles)
  • Decreased renal function (or urinary retention)
  • Prolong labor (reduce uterine tone)
  • Stimulate release of ADH, prolactin, somatotropin and inhibit release of LH
  • Pruritus (hives)

19

Clinical uses for opioids

  • Analgesia
    • moderate to severe pain
    • refractory pain
  • Acute Pulmonary Edema
    • relieves pain associated with dyspnea
  • Cough Suppression
  • Ciarrhea
  • Shivering (Reduced by meperidine)
  • Applications in Anesthesia
    • Pre-op
    • Intraoperativiely 
    • Anesthetic regimen

20

Clinical Uses: Opioids for specific types of pain

  • Postoperative pain
    • effective in post-op
    • can facilitate early movement (positive outcomes)
  • Obstetric pain
    • Monitor respiration in neonate
    • can use naloxone if necessary
  • Myocardial infarction
    • Morphine=drug of choice
  • Head Injury
    • use with caution
    • opioids can incrase ICP
  • Cancer-related pain
    • Patient should be given as much meds as need for analgesia
  • Chronic Non-Cancer pain

21

Tolerance

 

  • compensatory changes in number and sensitivity of CNS receptors
  • Need more of the drug to achieve the same effect
  • time it takes-varies

22

Minimal or no degree of tolerance to opioid effects

  • Miosis

23

Dependence

  • Can develop dependence without addiction
  • Occurs with the development of tolerance
  • physical dependence
    • ​abstinence syndrome (withdrawal) will occur if drug is discontinued or antagonist if administered
  • Once dependence develops, the desire to avoid withdrawal becomes motivator for continued drug use

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