Pain/MSK Flashcards
What drug class is Diclofenac?
NSAIDs
What are NSAIDs indicated for?
Mild to moderate pain Pain related to inflammation: -Osteoarthritis -Rheumatoid Arthritis -Gout
How do NSAIDs work?
Inhibit COX
COX -2 inhibition inhibits inflammation and pain
COX-1 inhibition causes side effects
What are the side effects of NSAIDs?
GI toxicity
Renal impairment
Increased risk of CV events
Fluid retention - can worsen hypertension and heart failure
What are the contraindications of NSAIDs?
Severe renal impairment Heart failure Liver failure NSAID hypersensitivity Peptic Ulcer disease/GI bleeding
Important drug interactions of NSAIDs?
Low-dose aspirin, corticosteroids - GI ulceration risk increased
ACEi - renal impairment
What drug class is Codeine?
Weak Opioids
What are Weak Opioids indicated for?
Mild to moderate pain
How do Weak Opioids work?
Metabolised in the liver to make morphine
The metabolites are stronger agonists of opioid
What are the side effects of Weak Opioids?
Nausea Constipation Dizziness Drowsiness Neurological and respiratory depression Not IV - get reaction similar to anaphylaxis
What are the contraindications of Weak Opioids?
Respiratory disease
Renal and hepatic impairment
Elderly
Tramadol - lowers seizure threshold
Important drug interactions of Weak Opiods?
Other sedating drugs - Benzos, TCAs, antipsychotics
Lower seizure threshold - SSRIs and TCAs
What drug class is Morphine?
Strong Opioids
What are Strong Opioids indicated for?
Acute severe pain
Chronic pain when - weak opioids are insufficient
Relief of breathlessness
Acute pulmonary oedema - relieves breathlessness and anxiety (oxygen, furosemide and nitrates)
How do Strong Opioids work?
Activation of opioid receptors in the CNS
Reduce sympathetic nervous system activity
What are the side effects of Strong Opioids?
Respiratory depression
Neurological depression
Can activate chemoreceptor trigger zone - nausea and vomiting
Pupillary constriction
Constipation - (think like loperamide - smooth muscle tone increased)
Tolerance
Withdrawal reaction (dependence)
What are the contraindications of Strong Opioids?
Hepatic failure
Renal impairment
Respiratory failure ( In less palliative)
Elderly
Biliary colic (spasm of sphincter of Oddi)
Important drug interactions of Strong Opiods?
Other sedating drugs - antipsychotics, benzos, TCAs
What drug class is Paracetamol?
Paracetamol
What is Paracetamol indicated for?
First line for acute and chronic pain
Antipyretic - can reduce fever
How does Paracetamol work?
Paracetamol is a weak inhibitor of COX
Specificity for COX-2
What are the side effects of Paracetamol?
Few side effects
In overdose causes liver failure
Metabolised by p450 to NAPQI
What are the contraindications of Paracetamol?
Dose should be reduced by people at increased risk of liver toxicity - NAPQI production (chronic alcohol
or with
Reduced glutathione stores (malnutrition, low body weight)
Important drug interactions of Paracetamol?
P450 inducers increase rate of NAPQI production after paracetamol overdose
What drug class is Allopurinol?
Xanthine oxidase inhibitor
What is Allopurinol indicated for?
Prevent acute attacks of gout
Prevent uric acid and calcium oxalate renal stones
Hyperuricaemia and tumour lysis syndrome
How does Allopurinol work?
Xanthine oxidase inhibitor
Xanthine oxidase metabolises xanthines (from purines) to uric acid
Lower plasma concentration of uric acid leads to less precipitation of uric acid in the joints or kidneys (explanation, do not need to learn)
What are the side effects of Allopurinol?
Skin rash
Stephen-Johnson, Toxic epidermal necrolysis
Starting can trigger or worsen an acute attack of gout
What are the contraindications of Allopurinol?
Do not start during acute attacks of gout
Recurrent skin rash/ severe hypersensitivity to allopurinol
Renal and hepatic impairment
Important drug interactions of Allopurinol?
Azathioprine requires xanthine oxidase for metabolism - so don’t give with allopurinol
Allopurinol with amoxicillin increases the risk of skin rash
