Analgesics Flashcards
What are the major classes of drugs used for acute pain?
NOPLAN NSAIDs Opioids Paracetamol Local anaesthetics Alpha 2 agonists NMDA agonists
What are the 3 effects of NSAIDs?
Anti-pyrexic
Anti-inflammatory
Analgesia
NSAIDs work by inhibiting COX. Is COX 1 or 2 ‘good’ or ‘bad’? Which one causes side effects when inhibited?
COX 1 - physiological, good. Side effects when inhibited
COX 2 - inflammatory, little side effects when inhibited
What are some side effects of NSAIDs?
GI ulceration
Clotting
Photosensitisation
Hypersensitivity
What are opioids used for? (2 effects)
Analgesia
Sedation
Where are opioid receptors found?
Throughout body
In CNS - mainly dorsal horn of spinal cord
What are the 2 ways of how opioids work?
Reduce excitatory neurotransmiter in nociceptors
Reduce neuronal response to nociceptive input
What are the 3 main types of opioid? What do the 2 main types do?
Mu - analgesia and narcosis (loss of consciousness)
Kappa - sedation and visceral analgesia
Delta
Give examples of opioids that are full mu agonists?
Methadone
Morphine
Give an example of a partial mu agonist?
Buprenorphine
What type of receptors does butorphanol effect?
Mu antagonist
Kappa agonist
How do opioids tend to be administered?
Parenterally
Poor bioavailability orally
What are the side effects of opioids?
Bradycardia
Respiratory depression
Reduced GI motility
What are the effects of paracetamol?
Analgesia
Antipyrexia
(Not anti-inflammatory)
Paracetamol MOA is unsure but could work via cannabinoid, serotonin receptors or COX 3 inhibition. How is paracetamol administered? Can it be given to all species?
IV or orally
NOT CATS - toxic, causes haemolysis
What are the side effects of paracetamol?
Hepatoxicity
Hypotension (IV formula)
What are the 4 effects of local anaesthetics?
Analgesia
Anti-inflammatory
Anti-arrhythmmic
Prokinetic (increases GI motility)
How do local anaesthetics work?
Act on sodium channels in cell membrane
Stop propagation of AP in neurones
What are the 2 main classes of local anaesthetics? Where are they metabolised? Are they long or short lasting?
Amides - liver metabolism longer acting
Esters - tissue metabolism, shorter acting
Give an example of each of the 2 types of local anaesthetics
Amide - lidocaine
Ester - procaine
What is pKA in terms of pharmacological properties? What does a high pKA mean?
Degree of ionisation
Affects ability to cross membrane (amount of active drug)
High pKA - great amount of ionised drug, faster onset
How does protein binding of a drug effect duration?
Greater protein binding = longer duration
How does vessel diameter affect drug duration?
Vasodilated drug = shorter duration
What are the side effects of local anaesthetics?
Effects other nerves except nociceptors - loss of motor function
CNS toxicity
Cardiac toxicity
What are the 2 effects of alpha 2 adrenoreceptor agonists?
Sedation Analgesia (shorter than sedation length)
What are the 2 effects of NMDA antagonists?
Analgesia
Anaesthesia
Give an example of a NMDA antagonist
Ketamine
Blocks NMDA receptor - anaesthesia
How can ketamine be administered? Is it long are short acting?
IV, IM, SC, transmucosally
Short acting
What are the side effects of ketamine?
Hypertonicity
Excitement
Myocardial depression
Increased peripheral sympathetic tone
For chronic pain, acute analgesic drugs are given along with others. Give examples of drugs additionally given
Gabepentin Amantadine Antidepressants Capsaicin Elk velvet antler
