L19 Flashcards

1
Q

Nociceptive pain

A

protective; response to the detection of noxious stimuli that can potentially cause tissue injury

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2
Q

Inflammatory pain

A

protective; caused by tissue damage; release of inflammatory mediators

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3
Q

Pathological pain

A

neuropathic pain
* caused by damage to the nervous system; e.g., spinal cord injury, diabetic neuropathy, multiple sclerosis

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4
Q

dysfunctional pain

A
  • abnormal function of the nervous
    system in the absence of damage or
    inflammation
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5
Q

Inflammatory pain sensitisation simple

A

Tissue injury

Production & release of a chemical soup

Peripheral sensitisation to pain

Central processing and sensitisation (Spinal cord)

Signal sent to brain for final processing

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6
Q

What does PGE2 do with peripheral excitability

A

PGE2 increased peripheral excitability; evoked many action potentials,
* cAMP/PKA-dependent modulation of the tetrodotoxin-resistant sodium channel

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7
Q

Cyclooxygenase and prostaglandin synthesis

A

Membrane phospholipids
↓ – Phospholipase A2
Arachidonic acid
↓ –cyclooxygenase activity (COX)
Prostaglandin G2
↓ –peroxidase activity (COX)
Prostaglandin H2

Prostaglandin E2

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8
Q

COX

A

Cyclooxygenase (COX)*

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9
Q

COX-1 stomach

A

COX-1 synthesises cytoprotective PGs (e.g., PGI2)→ protection on mucosal epithelium→ protection from peptic ulcer

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10
Q

Cox-1 Kidney

A

PGE2 production→ vasodilation and maintains renal blood flow

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11
Q

Cox-1 Platelet

A

production of thromboxane A2- platelet aggregation

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12
Q

COX1 CNS

A

distributed in neurons throughout the brain

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13
Q

COX-2 - inflam and CNS

A
  • Can be induced by stimuli that are associated with inflammation
  • CNS: restricted to parts of the CNS, e.g., spinal cord, hippocampus
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14
Q

What type of drugs inhibit COX

A
  • steroids
  • NSAID
  • Diclofenac
  • Aspirin
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15
Q

Diclofenac and COX

A
  • Drug inhibits COX
  • Compete with arachidonic acid for cyclooxygenase active site thereby blocking it
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16
Q

Aspirin and COX

A
  • Unique MoA
  • Acetyl group with acetylated the hydroxyl group serine → irreversible COX inhibition
  • antiplatelet effects from inhibition of thromboxane A2 formation
17
Q

Aspirin in asthma

A
  • bronchospasm in aspirin-sensitive asthmatics (leukotrienes - airway constriction)
18
Q

How aspirin produces leukotrienes

A
  • Arachidonic acid
  • 5-Lipoxygenase (5-LOX)
  • 5-HPETE
  • Leukotrienes
  • bc aspirin irreversibly blocks prostaglandin formation
19
Q

Reye’s Syndrome

A
  • affect children - use aspirin to treat fever after viral infection; first described in 1963
  • vomiting, hyperventilation→ hepatic failure, encephalopathy
  • high mortality
20
Q

Difference in structure of COX-1 and COX-2

A
  • isoleucine to valine substitution at position 523 - a side pocket to accommodate bulkier substrates
  • wider channel opening
  • Only COX-2 has the side pocket not COX-1 which make it easier to make selective inhibitors
21
Q

-coxibs are what type of drug

A

COX-2 selective inhibitors that fit into the side pocket of COX-2

22
Q

Non-steroidal anti-inflammatory drugs uses

A
  • analgesic effects - useful non-opioid analgesics
  • anti-inflammatory effects - painful conditions with an inflammatory component
  • anti-pyretic effects
23
Q

Effects of using Non-selective COX inhibitors

A
  • GI tract adverse effects
  • bleeding
  • acute renal dysfunction - ↓ renal blood flow
  • problems in the elderly
24
Q

Elderly patients and Non-selective COX inhibitors

A
  • elderly patients
  • history of previous GI ulcers
  • patients with CV risk factors
  • patients with renal risk factors
  • make side effects worse
25
Q

Effects of using selective COX-inhibitor compared to non-selective

A
  • lower GI adverse effects
  • reduced risk of bleeding
  • no bronchospasm in NSAID-sensitive asthmatics
26
Q

Paracetamol effects

A
  • analgesic effects
  • anti-pyretic effects
  • lacks anti-inflammatory effects
27
Q

Paracetamol deacetylation

A

By P-aminophenol to AM404
enzyme is a fatty acid amide hydrolase

28
Q

Paracetamol MoA proposed

A
  • COX-3 inhibition in dogs its different in humans
  • Interaction with the endocannabinoid system
    –AM404 inhibits endocannabinoid reuptake→ CB1 receptor activation → descending serotoninergic pathways→ inhibit pain sensitisation
  • Interaction with TRP (transient receptor potential) channels
    – Paracetamol and metabolites
  • Inhibition of NO formation
    – Inhibit NMDA receptor-mediated NO synthesis - NO conveys nociceptive information at the spinal level
29
Q

Paracetamol metabolites

A
  • NAPQI
  • AM404
30
Q

Paracetamol inactive at what sites

A
  • kidney - no renal impairment
  • GI tract - no peptic ulcer risk
  • lacks anti-inflammatory effect
31
Q

NAPQI is rapidly detoxified - how? (treatment of OD)

A
  • intrinsic drug-induced liver injury- NAPQI accumulation
  • antidote: N-acetylcysteine to replenish glutathione
32
Q

What is antidote to Paracetamol OD

A

N-acetylcysteine