Pharmacology Analgesic Agents Flashcards
What is pain?
Unpleasant sensory and emotional experience - primarily associated w/ tissue damage
Pain modulation?
Amount of pain not always relate severity of tissue damage
Anxiety, cultural and contextual factors can increase pain
What are some tx of dental pain?
NSAIDS, nerve block, option, physiological factors
What is a placebo?
Pharmacologically and physiologically inter
- Not ineffective can have measurable effect
What is step 1 on pain ladder - what does it tx and what is used?
Used for mild pain
Use paracetamol/NSAIDS - non opioid
Explain mechanism of paracetamol and dosing
Inhibit synthesis of prostaglandins
Analgesics, antipyretic, not anti-infam
Ig every 4-6 hours - max dose 4g 24 hrs
Explain mechanism of NSAID
Irreversible inhibition of cyclo-oxygenase
Inhibitor of prostaglandins and thromboxane
Explain side effects of NSAIDs
GI - cause GI bleed and ulceration
Renal - decrease intra-renal blood flow
Platelet - COX inhib = bleeding tendency
Resp - aspirin sensitivity in asthmatic
What is step 2 on pain ladder - what does it tx and what is used?
Used for moderate pain
Use weak option +/- non-opioid
What opiod would you use for moderate pain?
Codeine/ di-hydrocodiene
–> both metabolised into morphine (variable depending on person dependent enzyme)
Effect of weak opioid (codeine)
CV: reduced sympathetic outflow and increased vagal tone (bradycardia, hypotension)
Resp: resp depression - inhibit cough relex
GI: decreased motility - constipation and nausea
What effect do opioid have on CNS - what negative effect can this have?
Sedation and euphoria
Spinal cord: reduce pain fibre transmission at kappa opioid receptor
Brainstem: reduce pain projection at mu opioid receptor
- cause reduced brainstorm response - hypoxia
How to reverse opioids?
Naloxone 400mg I.V - reversal Mu receptors
Problem w/ opioid dependency and how occurs?
Chronic opioid use - decrease effect as CNS becomes more tolerant
Withdrawal - hypertension, tachycardia, anxiety, diarrhoea
What is tramadol?
Newer oral opioid - as effective as codeine with less variability
What is example of weak opioid + non-opioid
Co-codamol
What is step 3 on pain ladder and what would you use to tx?
Step 3 is management of severe pain
Tx w/ strong opioid +/- non-opioid
Give example of strong opioid
Morphine, diamorphine, fentanyl patch
How would you give post-op analgesia?
IV in recovery - 2mg increment every 3 min until comfortable - 10-20mg
Ward care - 10mg morphine SC 3 hourly w/ antiemetic
What is step 4 on pain ladder and how would you tx?
Step 4 is management of severe chronic pain
Tx = oral morphine, S.C infusion of morphine or diamorphine and fentanyl patch
Other: antidepressant, physiological support and pain management
Use of gabapentin and pregabalin?
Effective neurogenic pain - decrease central transmission and pain projection
Use of antidepressants in chronic pain?
Useful for neurogenic pain
