Analgesics and Sedative Drugs Flashcards
What is pain?
an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage
Anagesia
relieve pain by directly manipulating its physiological mechanisms
Pain cam be assessed using
unidimensional tools like scales/faces
multi-dimensional tools (more history)
What is an adjuvent?
Enhancing effect of a drug
WHO Analgesic Ladder:
- needs to be bidirectional
- step 4 = minimally invasive procedures
Principles of WHO Analgesic Ladder:
- by the mouth = oral administration
- by the clock = regular and at regular
intervals - by the ladder = according with the pain
intensity characterised by the patient - individualised therapy = dosing
- medication adherence
Analgesia can be complicated:
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NSAIDs:
- non-steroidal anti-inflammatory drug
- ibuprofen
- effects can be peripheral and central
- competitive inhibitors of COX
Three Effects:
- analgesics
- anti-inflammatory
- antipyretic
Core Drug: Ibuprofen: Mechanism of Action:
Competitive inhibitors of COX
(reversible action)
hence:
- reduce production of prostaglandins
- prostaglandins increase Na+/Ca2+
influx into nociceptors, hence
decreasing pain signalling
Core Drug: Aspirin: Mechanism of Action:
irreversible inhibitor of COX
lowers amount of time needs to be taken
COX1 in platelets, platelets have no nucleus so can not synthetise new COX1
Arachidonic Acid
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Effects of NSAIDs:
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Side Effects of Ibuprofen:
- perforation
- peptic ulcers
- renal failure
- fluid retention
- constipation
How to avoid gastric pain from taking NSAIDs?
Proton Pump Inhibitors PPIs
omneprazole
Is paracetamol an NSAID?
No only an analgesic and antipyretic not an anti-inflammatory
Core Drug: Paracetamol: Drug Class:
Analgesic
Core Drug: Paracetamol: Mechanism of Action:
- inhibition of COX
Core Drug: Paracetamol: Effects:
mainly central
benefit from regular full dosing
Core Drug: Paracetamol: Metabolised:
Liver
Core Drug: Paracetamol: Side Effects:
- patients with liver failure
- liver impairment
- adverse effects are rare
NO INJURY TO GASTRIC MUCOSA
What is the primary drug class for acute management of moderate to severe pain?
Opiods (agonist of opiod receptors)
What type of receptors are responsible for most analgesic effects of opiods?
mu opiod receptors
coupled to G alpha i
Opiod Receptors: Mechanism of Action:
- bind to opiod receptors
- activate G-alpha-i pathway
- inhibition of adenylate cyclase, decrease
in cyclic AMP, decreased
phosphorylation - inhibits Ca2+ voltage gated channels,
leading to decreased release of
neurotransmitters - activates K+ channels, which
hyperpolarise cell membranes, less APs
fired
An example of a weak opiod?
Core Drug: Codeine
Codeine: Ceiling Dose:
- pain relief will stop after a certain dose
- continuing will simply increase risk or
intensity of the adverse reactions
Does morphine have a ceiling dose?
No
Core Drugs:
How potent is codeine compared to morphine?
1/10th as potent as morphine
Core Drug: Codeine: Metabolism:
metabolised to morphine by the liver
Core Drug: Morphine: Metabolism:
- metabolised to active metabolites
- renally excreted
can cause renal impairment
Core Drug: Codeine: Side Effects:
- constipation = faecal softener +
stimulant laxative (no) - nausea and vomiting = antiemetics (yes)
- sedation
- confusion = reduce dose + monitor renal
function - respiratory depression = naloxone
Opiod Toxicity: Management:
- initial management:
- reduce dose
- hydrate
- relieve agitation with low dose of
haloperidol - if intolerant side effects with inadequate
pain relief switch to an alternative
analgesic - naloxone (with caution)
Naloxone
- opiod antagonist
- all opiod receptors (many side effects)
Sedation: Pharmacological Management:
- opiods
- propofol
- dexmedetomidine
- benzodiazepine: diazapam
- Z-drugs; Zopiclone
Core Drug: Diazepam: Mechanism of Action:
- GABA receptor modulator (ionotropic)
- bind in different site to GABA
- GABA still needed for effect
- simply facilitating the opening of
channel - Cl- channel
- hyperpolarise cell, stable and resting
- depressive effect on the nervous system
Core Drug: Diazepam: Side Effects:
- oversedation
- drowsiness
- light-headedness
- amnesia
- muscle weakness
- tolerance
- dependance (need withdrawal
management)
Core Drug: Zopiclone: Mechanism of Action:
- GABA receptor modulator (ionotropic)
- bind in different site to GABA
- GABA still needed for effect
- simply facilitating the opening of
channel - Cl- channel
- hyperpolarise cell, stable and resting
- depressive effect on the nervous system
Core Drug: Zopiclone: Side Effects:
- dry mouth***
- metallic taste in mouth***
- oversedation
- drowsiness
- light-headedness
- confusion
- amnesia
- muscle weakness
- tolerance
- dependence
