Pain I: Opioids - McDougall 1 Flashcards Preview

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Flashcards in Pain I: Opioids - McDougall 1 Deck (46)
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1

What is pain?

An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage

2

Nociception

Physiological processes in response to noxious stimuli

3

Allodynia

Pain in response to a normally innocuous stimuli
Enhanced pain repsonse

4

Hyperalgesia

Enhanced pain to a normally painful stimuli

5

Nociceptive pain

Direct activation of nociceptors by noxious stimuli
Ie. Touching something hot

6

Inflammatory pain

Activation by inflammatory mediators

7

Neuropathic pain

Pain arising from nerve damage

8

Pain pathway

Ascending processes
Nociceptor - Primary afferent - Dorsal root ganglion (cell body) - Second order neuron in SC - Brain

Pain sensation, cognitive interpretation, affective behaviour

9

Normal movement pathway

Ascending processes
Mechanosensors - Primary afferent - Dorsal root ganglion (cell body) - Second order neuron in SC - Brain

10

Peripheral sensitization pathway

Ascending processes
Nociceptor - Primary afferent - Dorsal root ganglion (cell body) - Second order neuron in SC - Brain

11

Central sensitization pathway

Ascending processes
Nociceptor - Primary afferent - Dorsal root ganglion (cell body) - Second order neuron - brain

12

Referred pain

Pain at a point in the body
Nerves in areas surrounding synapse onto the same projection neutron, giving feeling of pain in those areas too
Because of development of fetus and different derm layers

13

Glyco-heroin

To be used as cough suppressant

14

Mrs. Winslows Soothing Syrup

Opium and alcohol for soothing teething children

15

Opium

c. 3400 BC, lower Mesopotamia
1806: isolated morphine

16

Morphine

10% of opium
High analgesia, addictive

17

Codeine

0.3-2% opium
Less powerful analgesia, less addictive

18

Heroin

Bayer and Co synthetically modified morphine to reduce negative side-effects
Replaced 2H with 2CH3CO to make diacetylmorphine
Made heroin: highly potent analgesic but extremely addictive
Passes BBB better than morphine

19

Opiate

Drugs derived from opium

20

Opioid

Agents with opiate-like actions
Synthetic
Proteins that mimic opiate actions
Endorphins

21

Narcotic

Sleep inducing (pharmacological)
Producing dependence (legal)

22

Opioid receptor subtypes

mu, delta, kappa, NOP

23

Mu opioid receptor

Endogenous ligand: endomorphin
Exogenous ligand: morphine, codeine, heroin
Antagonist: CTOP, DAMGO

24

Delta opioid receptor

Endogenous ligand: enkephalin
Exogenous ligand: diprenorphine
Antagonist: Naltrindole

25

Kappa opioid receptor

Endogenous ligand: dynorphin
Exogenous ligand: etorphine
Antaongist: nor-BNI

26

NOP opioid receptor

Endogenous ligand: nociception
Exogenous ligand: orphanin FQ(1-11)
Antagonist: nocistatin

27

Naloxone

Not-specific antagonist for opioid receptors

28

Site of action of opioids: Periphery

Receptors in periphery
Reduction in production of pain causing chemicals
Reduction in release of algogenic agents
Desensitize peripheral nerve

29

Site of action of opioids: SC

Mu opioid receptors on presynaptic terminal
Binding causes reduction of release of excitatory NT, resulting in reduction of CIP, Glu and SP, and reducing Ca influx
Postsynaptically, increasing K to cause hyperpolarization

30

Site of action of opioids: Supraspinal

Periaqueductal grey, insular cortex, dorsal raphe nucleus, nucleus raphe magnus
Opioids bind to receptors activating descending inhibitory pathways
Spinal release of 5-HT and NA
Inhibitory nerves activated
Receptors close to respiratory centres can cause respiratory depression