Pharmacology of Pain Flashcards
Acetaminophen Opioids Co-amoxiclav Lactulose
What is acetaminophen used for?
- 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
What is the primary drug target of acetaminophen?
- Not well defined. Possible targets:
- COX-3 isoform
- Cannabinoid receptors
- Endogenois opioids
- 5HT3 receptors
What is the drug target type of acetaminophen?
- Probably inhibitor / antagonist
What is the location of action of acetaminophen?
- Peripheral & Central Nervous System
What is the mechanism of action of acetaminophen?
- Unknown
What are the main adverse effects of acetaminophen (2)?
- Rare: Allergic skin reaction
- In case of overdose: Hepatotoxicity
Give 1 example of acetaminophen.
- Paracetamol
What are the symptoms of of paracetamol overdose (common method of suicide) (3)?
- Nausea
- Vomiting
- Onset of right subcostal pain after 24 hours indicate hepatic necrosis
How is paracetamol overdose (common method of suicide) managed?
- < 8 hours: Activated charcoal + Acetylsteine + Antiemetic
- 8 - 24 hours: Acetylsteine + Antiemetic
- > 24 hours: Acetylsteine + Antiemetic
What are opioids used for?
- Opioids are used for the relief of moderate to severe acute and chronic pain
What is the primary drug target of opioids?
- Opiod receptor
What is the drug target type of opioids?
- Receptor agonist
What is the location of action of opioids?
- Central Nervous System (CNS)
What is the mechanism of action of opioids?
- 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.
What are the main adverse effects of opioids (3)?
- Nausea (Increased activity in chemoreceptor trigger zone)
- Vomiting (Increased activity in chemoreceptor trigger zone)
- Constipation (Opioid receptor in GIT can reduce gut mobility)
Give 2 examples of weak opioids.
- Codeine
- Tramadol
Give 3 examples of strong opioids.
- Morphine
- Fentanyl
- Diamorphine (Heroin)
What are the symptoms of opioid overdose?
- Respiratory depression (Direct & Indirect inhibition of respiratory control centre)
What is the management of opioid overdose?
- Ventilation
- Naloxone
What is co-amoxiclav a combination of?
- Amoxicillin
- Clavulanic acid
What is amoxicillin used for?
- 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
What is clavulanic acid used for?
Clavulanic acid is a beta lactamase inhibitor used to enhance the effectiveness of beta lactam antibiotics
What is the primary drug target of amoxicillin?
- Penicillin binding proteins
What is the primary drug target of clavulanic acid?
- Beta-lactamase
What is the drug target type of amoxicillin?
- Protein inhibitor
What is the drug target type of clavulanic acid?
- Enzyme inhibitor
What is the location of action of amoxicillin?
- Bacteria
What is the location of action of clavulanic acid?
- Bacteria
What is the mechanism of action of amoxicillin?
- Amoxicillin binds to bacterial penicillin binding proteins
- This prevents transpeptidation (the cross-linking process for bacterial cell wall synthesis
What is the mechanism of action of clavulanic acid?
- 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
What are the main adverse effects of co-amoxiclav (2)?
- Nausea
- Vomiting
What is lactulose used for?
- Lactulose is a disaccharide derivative of lactose used to treat constipation, portal systemic encephalopathy and pain
What is the primary drug target of lactulose?
- No primary drug target
What is the drug target type of lactulose?
- No drug target type
What is the location of action of lactulose?
- Large bowel
What is the mechanism of action of lactulose?
- 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
What are the main adverse effects of lactulose (4)?
- Abdominal pain
- Diarrhoea
- Flatulence
- Nausea
