opiids and narcotic analgesics Flashcards Preview

Yr 2 - Pharmacology > opiids and narcotic analgesics > Flashcards

Flashcards in opiids and narcotic analgesics Deck (51):
1

Which size/shape of axons have slower signal propogation?

Larger diameter

Unmyelinated

2

What underpins the gate control theory of pain in the dorsal horn?

Other sensory information (in greater amounts/ covering larger areas) such as touch and muscle joints) overrides pain due to modulation via inhibitory GABA pathways

N.B. The trigeminal pathway is still gated but in a different way

3

Which 7 types of drugs are used for analgesia?

  • Local anaesthetics
  • General anaesthetics
  • NMDA (glutamate) receptor antagonists
  • Voltage-gated calcium channel blockers (selective = into spinal cord) &
  • Anti epileptics (blocks overactive Ca channels)
  • NSAIDs - especially for low grade pain
  • Cannabinoid CB1 receptor agonists (animals)

4

What are NSAIDs used to treat? What is its method of action?

Inflammatory pain

Used to cleave cyclooxygenase (produces prostaglandins = pain, fever and inflammation)

5

What is an opiate?

Natural substance produced by opium poppy = binds and activates opioid receptors

6

What is an opioid?

Any drug (synthetic or natural) that binds and activated opioid receptors

7

What is a narcotic analgesic (narcotics)?

Any drug with the potential for abuse (traditionally opioids only) e.g. Cocaine

8

What are the 4 well defined classical opioid receptors?What are their classic names? (and their new names?)

μ (MOPr)

δ (DOPr)

κ (KOPr)

Opiod receptor like 1 ORL1 = (NOPr)

 

-> N.B. not relavent in analgesia

9

What type of receptors are opiod receptors?

GPCR

10

What is the principal transduction mechanism for Opioid receptors?

Gi/o= inhibits Ca= activates K= activates cAMP -> PKA = other mechanism (not the main pathway for analgesia)

11

What are the 3 consequences of opioid receptor activation?

  • Inhibit transmitter release
  • Inhibit neuronal firing
  • Disinhibition (removes inhibitory influence = excitation!)

12

What is the opioid structure similar to? 

Tyrosine

13

What is the terminal Amino acid for most opioid peptides?

Tyrosine

14

Name two μ opioid receptor agonists:

  • DAMGO
  • Morphine (partial)

15

Name two μ opioid receptor antagonists:

  • CTOP
  • Naloxone (all types of receptors but strongest with μ)

16

Name a δ opioid receptor agonist:

DPDPE

17

Name two δ opioid receptor antagonists:

  • Naltrindole
  • Naloxone

18

Name a κ opioid receptor agonist:

Enadoline

19

Name two κ opioid receptor antagonists:

  • nor-binaltrophimine
  • naloxone

20

Give an example of a drug that show mixed activity

Pentazocine (μ antagonist & κ agonist)

21

What are the 4 behavioural effects of μ opioid receptor agonists:

  • Analgesia
  • Euphoria
  • Respiratory depression
  • Constipation

22

What are the 4 behavioural effects of κ opioid receptor agonists:

Analgesia

Dysphoria/Hallucinations

No respiratory depression

Diuresis

23

What are the 2 behavioural effects of δ opioid receptor agonists:

Analgesia

Antidepressant/proconvulsant

24

What are the 5 desirable effects of opioids?

  • Analgesia
  • Euphoria
  • Constipation
  • Sedation (premed for surgery)
  • Cough suppression

25

What is the other effect of opioids?

Pupil constriction

26

What are the 8 undesirable effects of opioids?

  • Respiratory depression
  • Euphoria
  • Constipation
  • Sedation
  • Nausea and vomitting
  • Tolerance (need to increase dose over time)
  • Psychological dependence
  • Physical dependence

27

Which two neurotransmitters are found in the 1st synapse for pain to the CNS (A delta/c fibres)?

  • Substance P
  • Glutamate

28

Which membranes in the synapse are μ opioid receptors located?

On both the pre and post synaptic membrane

29

What is the effect of opioids on presynaptic μ opioid receptors?

Reduces transmitter release

30

What is the effect of opioids on postsynaptic μ opioid receptors?

Hyperpolarisation (activating potassium channels) = decreased size of action potential

31

What happens in disinhibition?

A decrease in GABA release (by decreasing Ca) = hyper polarisation of inhibitory interneurone = less inhibition and increased activity in projection neurones

32

In which pathways can disinhibition occur?

Descending inhibitory pathways

33

What causes Euphoria in Opioid users?

Disinhibition in ventral tegmental area (VTA) = enhanced dopamine release in nucleus accumbens

34

What are the 3 main problems with opioids?

- side effects

- Breakthrough pain (with chronic use)

- Neuropathic pain (doesn't treat all kinds of pain)

35

Why are drug combinations used?

To reduce side effects

Possibly due to synergy (binding to other drug used)

36

Which two drugs is co-codamol a mixture of?

Codeine

Paracetamol

37

Which two drugs is co-codaprin a mixture of?

Codeine

Aspirin

38

Which two drugs is co-proxamol a mixture of?

Dextroproxyphene

Paracetamol

 

N.B. this is not used as much now

39

Which two analgesic drugs are recommended for mild pain in the WHO pain ladder?

Non opioid drugs (ibuprofen & paracetamol)

40

Which analgesic drug is recommended for moderate pain in the WHO pain ladder?

Mild opioid e.g. codeine

41

Which analgesic drug is recommended for severe pain in the WHO pain ladder?

Opioid e.g. morphine

42

Which type of pain can be unresponsive to opioids?

Neuropathic pain

43

Which drugs are used as an alternative to opioids in neuropathic pain?

Antidepressants e.g. amitriptyline

Antiepileptics e.g. gabapentin & Carbamazepine

44

How does the anti epileptic drug gabapentine produce an analgesic effect?

Modulates Na and Ca Channels

45

Which 6 inflammatory mediators are released following tissue damage?

  • Histamine
  • Bradykinin
  • 5-HT
  • Prostaglandin
  • ATP
  • Acidosis (H)

46

What are collaterals?

Neurones that feedback to the area of tissue damage

47

Which chemicals are released by collaterals?

  • Substance P
  • CGRP (Calcitonin gene related peptide)

48

What effect does substance P have in the area of tissue damage?

  • Histamine release from mast cells (= pain and inflammation)
  • Vasodilation

49

What effect does CGRP have in the area of tissue damage?

Vasodilation

50

Which types of nerve fibres produce the sensation of pain?

Nociceptive fibres

51

Where do nociceptive fibres first synapse in the spinal cord?

The dorsal horn