Pharmacology of Pain

Question 1

What is acetaminophen used for?

Answer 1

• Acetaminophen is an analgesic drug used alone or in combination with opioids for pain management (including GORD / Peptic Ulcer Disease), and as an antipyretic agent
  
  • Not an NSAID → little anti-inflammatory activity

Question 2

What is the primary drug target of acetaminophen?

Answer 2

• Not well defined. Possible targets:
  
  • COX-3 isoform
  • Cannabinoid receptors
  • Endogenois opioids
  • 5HT3 receptors

Question 3

What is the drug target type of acetaminophen?

Answer 3

• Probably inhibitor / antagonist

Question 4

What is the location of action of acetaminophen?

Answer 4

• Peripheral & Central Nervous System

Question 5

What is the mechanism of action of acetaminophen?

Answer 5

• Unknown

Question 6

What are the main adverse effects of acetaminophen (2)?

Answer 6

• Rare: Allergic skin reaction
• In case of overdose: Hepatotoxicity

Question 7

Give 1 example of acetaminophen.

Answer 7

• Paracetamol

Question 8

What are the symptoms of of paracetamol overdose (common method of suicide) (3)?

Answer 8

• Nausea
• Vomiting
• Onset of right subcostal pain after 24 hours indicate hepatic necrosis

Question 9

How is paracetamol overdose (common method of suicide) managed?

Answer 9

• < 8 hours: Activated charcoal + Acetylsteine + Antiemetic
• 8 - 24 hours: Acetylsteine + Antiemetic
• > 24 hours: Acetylsteine + Antiemetic

Question 10

What are opioids used for?

Answer 10

• Opioids are used for the relief of moderate to severe acute and chronic pain

Question 11

What is the primary drug target of opioids?

Answer 11

• Opiod receptor

Question 12

What is the drug target type of opioids?

Answer 12

• Receptor agonist

Question 13

What is the location of action of opioids?

Answer 13

• Central Nervous System (CNS)

Question 14

What is the mechanism of action of opioids?

Answer 14

• Over-arching mechanism at a cellular level is a depressant effect on cellular activity. Multiple sites within pain pathway, where activation of the opioid receptor leads to decreased perception or increased tolerance of pain. Antitussive effect due to decreased activation of afferent nerves relaying cough stimulus from airway to brain.

Question 15

What are the main adverse effects of opioids (3)?

Answer 15

• Nausea (Increased activity in chemoreceptor trigger zone)
• Vomiting (Increased activity in chemoreceptor trigger zone)
• Constipation (Opioid receptor in GIT can reduce gut mobility)

Question 16

Give 2 examples of weak opioids.

Answer 16

• Codeine
• Tramadol

Question 17

Give 3 examples of strong opioids.

Answer 17

• Morphine
• Fentanyl
• Diamorphine (Heroin)

Question 18

What are the symptoms of opioid overdose?

Answer 18

• Respiratory depression (Direct & Indirect inhibition of respiratory control centre)

Question 19

What is the management of opioid overdose?

Answer 19

• Ventilation
• Naloxone

Question 20

What is co-amoxiclav a combination of?

Answer 20

• Amoxicillin
• Clavulanic acid

Question 21

What is amoxicillin used for?

Answer 21

• Amoxicillin is a penicillin derivative used for the treatment of infections caused by gram-positive bacteria, in particular streptococcal bacteria causing upper respiratory tract infections

Question 22

What is clavulanic acid used for?

Answer 22

Clavulanic acid is a beta lactamase inhibitor used to enhance the effectiveness of beta lactam antibiotics

Question 23

What is the primary drug target of amoxicillin?

Answer 23

• Penicillin binding proteins

Question 24

What is the primary drug target of clavulanic acid?

Answer 24

• Beta-lactamase

Question 25

What is the drug target type of amoxicillin?

Answer 25

• Protein inhibitor

Question 26

What is the drug target type of clavulanic acid?

Answer 26

• Enzyme inhibitor

Question 27

What is the location of action of amoxicillin?

Answer 27

• Bacteria

Question 28

What is the location of action of clavulanic acid?

Answer 28

• Bacteria

Question 29

What is the mechanism of action of amoxicillin?

Answer 29

• Amoxicillin binds to bacterial penicillin binding proteins
• This prevents transpeptidation (the cross-linking process for bacterial cell wall synthesis

Question 30

What is the mechanism of action of clavulanic acid?

Answer 30

• Clavulamate is an inhibitor of beta lactamase
  
  • Beta lactamase is a bacterial enzyme that can degrade beta lactam antibiotics and thus confer resistanse to these antibiotics

Question 31

What are the main adverse effects of co-amoxiclav (2)?

Answer 31

• Nausea
• Vomiting

Question 32

What is lactulose used for?

Answer 32

• Lactulose is a disaccharide derivative of lactose used to treat constipation, portal systemic encephalopathy and pain

Question 33

What is the primary drug target of lactulose?

Answer 33

• No primary drug target

Question 34

What is the drug target type of lactulose?

Answer 34

• No drug target type

Question 35

What is the location of action of lactulose?

Answer 35

• Large bowel

Question 36

What is the mechanism of action of lactulose?

Answer 36

• Lactulose is a non-absorbable disaccharide
• It reaches the large bowel unchanged
• This causes water retention via osmosis & an easier to pass stool
• It can also be metabolised by colonic bacteria
• The colonic metabolism of of sugars has an additional laxative effect

Question 38

What are the main adverse effects of lactulose (4)?

Answer 38

• Abdominal pain
• Diarrhoea
• Flatulence
• Nausea