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What is the MOA of morphine?
G protein coupled receptors which increase adenylate cyclase to reduce intracellular cAMP content.
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What is morphine metabolised to?
morphine-6-glucuronide which contributes to action
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what is the plasma half life of morphine and how is it excreted?
- Half life: 3-6hours
- Excreted: renally
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Give 6 SE of morphine
- 1. respiratory depression
- 2. N&V
- 3. constipation, reduce GI motility and so reduce absorption of other drugs
- 4. pupil constriction
- 5. mast cell release histamine so bronchoconstriction and hypotension
- 6. EUPHORIAAAAA
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What does tolerance mean?
Need higher dose to get the same effect
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What does dependance mean?
When come off it, get withdrawal symptoms and cant sleep, nausea…cravings
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Apart from morphine overdose, when else is naloxone needed?
Give to neonate im if pethidine used in labour
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What is the half life of naloxone, why is it important?
Only 2-4 hours so may need to be repeated or given by infusion as morphine half life is 3-6 hours.
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Apart from analgesia, what other property does codeine have?
Anti-tussive
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How does codeine work?
Converted to morphine
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What is codeine’s main SE?
Constipation
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What is the MOA of tramadol…careful!
- 2 MOA – one opioid agonist
- Also NA/5HT reuptake inhibitor
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What are the properties of fentanyl? And 2 main uses
- Highly potent and short acting
- Use: anaesthesia, palliative care (patches and lollipops)
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What are the main SE or unwanted effects of pethidine
- Restlessness (not sedation unlike morphine)
- Anti-muscarinic: dry mouth, blurred vision
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Why is pethidine used in labour?
Short acting so safer
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What is methadone used for?
Heroin and morphine addiction
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What is the half life of methadone?
Over 24 hours. Good as less sedative than morphine. It is a synthetic opioid
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Give 4 uses of NSAIDs
- 1. anti-inflammatory eg in arthritis
- 2. pain relief for orthopaedic pts – no evidence that NSAIDs reduce bone healing
- 3. opiate sparing
- 4. closure of patent ductus arteriosus
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what is MOA of NSAIDs?
COX inhibit so less PG and TXA2 made
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What is the difference between COX1 and COX2?
- COX1: constitutive – eg gastric mucosa protected by it
- COX2: inducible – formation of pro-inflammatory mediators
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What are 4 ‘a’ effects of NSAIDs?
- Anti-inflammatory
- Anti-pyretic
- Analgesic
- Anti-platelet
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Which 4 systems are affected by NSAIDs? (SE)
- GI: gastritis, bleeds
- Renal: reduced PG means less vascular tone so makes renal failure worse
- Respiratory: bronchoconstriction
- Cardiac: CCF, pedal oedema
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What is the MOA of aspirin?
IRREVERSIBLE COX 1 and 2 inhibitor
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What additional SE does aspirin have?
- Dizziness, deafness, tinnitus
- Reye’s syndrome (liver failure in children who take aspirin)
- Drug interactions as aspirin is highly protein bound so interacts with warfarin
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What is the MOA of paracetamol?
COX3 inhibitor
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What are the 2 main effects of paracetamol?
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What is the MOA of gabapentin?
- Anti-epileptic
- Binds VGCC, acts at glycine site of NMDA receptor, subsP
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What are the SE of amitryptiline?
- Anticholinergic
- Hypotensive
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