T1 L24 Analgesics, anaesthetic & sedation drugs Flashcards
What is pain?
Unpleasant sensory & emotional experience associated with actual or potential tissue damage
Describe gate theory
C fibres let pain through
AB fibres stimulate inhibitory neurons
Descending pathways prevent central passage
Describe pain modification
Nociceptor C
A delta fibes
Central interpretation
Not just drugs
How can pain be scored?
Linear
Smiley / sad faces
Mild, moderate, severe, excruciating
Describe the WHO analgesic ladder
Aspirin & NSAIDs
Add local anaesthetic & weak opioids
Add strong opioids
Describe the WFSA analgesic ladder
Aspirin & NSAIDs
Opioids by mouth
Strong opioids by injection, local anaesthesia
Where do opioids act?
On opioid receptor
What antagonises opioids?
Naloxone
What are examples of naturally occurring opioids?
Morphine
Codeine (weaker)
Give example of a semi-synthetic opioid
Diamorphine
Give an example of a synthetic opioid
Fentanyl
How can opioids be administered?
Intravenous / infusion Intramuscular Oral Intranasal / aerosol Epidural / spinal
Where are opioid receptors located?
Pons & midbrain Periaqueductal grey matter Nucleus raphe Magnus Spinal cord posterior horn 1 & 2 GI tract Peripheral tissues
What are the subtypes of opioid receptors?
MU 1 & 2
OP3
Delta - OP1
Kappa - OP2
What are the side effects of morphine?
Respiratory depression / airway loss
Nausea / vomiting
Constipation / pruritus
Miosis
Describe ketamine
NMDA antagonist Kappa & delta receptors Analgesic local / general Anaesthetic Sedative Side effects: emergence phenomena
Describe NSAIDs
Inhibit cyclooxyrgenase 1 & 2
Analgesic
Antipyretic
Anti-inflammatory
What are the side effects of NSAIDs?
Gastric irritation
Bronchospasm
Renal impairment
Platelet function - aspirin
Describe aspirin
Acetylsalicylic acid
Oxidative phosphorylation
Air hunger
Reyes syndrome
Describe paracetamol
Mechanism is unknown
Central prostaglandin effect
What are the effects of an overdose of paracetamol?
Hepatotoxicity
Glutathione depletion
What are some other methods of analgesia?
Anxiolysis Local anaesthetics Antidepressants, anti epileptics, tramadol Guanethadine, ketamine, clonidine Acupuncture Inhalation nitrous oxide Penthrox Magnesium
What is used as an anti-emetic?
Propofol Cyclizine Ondansetron Hyoscine Metoclopramide Steroids Prochlorperazine Cannabinoids
Describe the Ramsay sedation scale
Patient anxious Cooperative Responds only to commands Brisk response to Glabellar tap / shout Sluggish response No response
Give examples of some benzodiazepines
Midazolam
Diazepam
Lorazepam
Describe the physiology of benzodiazepines
GABA
Inhibitory neurotransmitter
Receptors A & B
Describe the side effects of benzodiazepines
Over-sedation
Loss of airway
Respiratory depression
What can be given to reduce side effects of benzodiazepines?
Flumazenil
Give examples of some other sedatives
Low dose vapours Ketamine Hyoscine Propofol at low dose Major tranquilisers Alpha 2 agonists
What are the categories of other sedatives?
Amides
Esters
Give an example of an amide sedative
Lignocaine
Prilocaine
Bupivacaine
Give an example of an ester sedative
Cocaine
Amethocaine
Give examples of the mechanisms of other sedatives
Na channel blockade
Un-ionised drug through membrane into axoplasm
Protonated
Blocks channel –> blocks action potential
Methods of administering sedatives
Anatomy local blocks / ultrasound Spinal epidural caudal skin Aerosol / nebulised Combination with GA
What are some cardiovascular symptoms of toxicity?
Dysrhythmias
Cardiac depression
What are some central nervous system symptoms of toxicity?
Fitting
Anxiety
Loss of consciousness
Circumoral numbness
What is the treatment for toxicity?
ABC
Oxygen
Lipid - 20%
Dysrhythmias / fitting
