ARTHRITIS Flashcards
First line analgesia for OA?
Step 1 - Topical NSAIDs
Step 2 - oral NSAIDs +/- PPI
Step 3 - weak opioids or paracetamol - infrequently or short-term
Adjuncts: topic capsaicin cream or intra-articular steroid injection
how does topical capsaicin relieve pain?
Capsaicin is taken from chilli peppers
It works by reducing the amount of substance P associated with inflammation. It also defunctionalises nociceptor fibres by inducing a topical hypersensitivity reaction of the skin
What is the MOA of NSAIDs?
Non-selectively inhibit COX 1 and COX 2
COX 2 inhibition decreases the synthesis of prostaglandins involved in mediating inflammation, pain, fever and swelling
COX1 inhibition leads to the SE
Side efefcts of NSAIDs?
GI disturbance - indigestion + stomach ulcers
Renal insufficiency
Salt and water retention
Hyponatraemia and hyperkalaemia
cardiovascular events
Hypersensitivity reactions
Headaches
Dizziness
Skin reactions
Bronchospasm in asthmatics
Why does the side effect profile of NSAIDs vary?
Different selectivity for COX-1 or COX-2
More side effects for those with greater inhibitory selectivity for COX-1 than COX-2
What is an example of NSAIDs that have are selective for COX-2?
Celecoxib
whats the problem with celecoxib?
It can increase the risk of serious cardiovascular problems because COX-1 pathway is not inhibited at all
When prescribing NSAIDs, how can you attempt to reduce the GI side effects?
Use a COX-2 inhibitor e.g. celecoxib
Prescribe a PPI alongside
Contra-indications for NSAIDs?
Active GI bleeding or ulcer
History of GI bleeds or GI perf related to previous NSAID therapy
History of recurrent GI haemorrhage or ulceration
History of hypersensitivity or severe allergic reaction
Severe HF
Severe hepatic impairment
Severe renal impairment
Third trimester of pregnancy
Varicella infection
Why are NSAIDs contraindicated in the 3rd trimester of pregnancy?
May be associated with increased risk of oligohydramnios and premature closure of the ductus arteriosus
Drug-drug interactions for NSAIDs?
Alendronate - risk of GI bleed
ACEi - increase bp, renal impairment risk, rarely hypokalaemia
Anticoagulants - worsen bleeding
SSRIs and SNRIs - risk of GI bleed
Antiplatelets - increase risk of GI bleed
Beta blockers - may reduce efficacy
Corticosteroids - GI bleed
Cisplatin - nephrotoxicity
Ciclosporin - reduce renal function
Lithium - can increase risk of toxicity
Loop and thiazide diuretics - may reduce Antihypertensive effects
Methotrexate - risk of toxicity
Nicorandil - GI bleed
Potassium sparing diretics - acute renal impairment
Does a normal uric acid value rule out gout?
No - you can have drops in uric acid levels in acute flares of gout
XR findings in pseudogout?
Chondrocalcinosis in the joint space
Joint aspiration findings in gout?
Negatively birefringent, needle-shaped monosodium urate crystals
No mirobial growth
What medications can increase the risk of gout?
Diuretics
Low dose aspirin
Immunosuppressants e.g. cyclosporin
Management of an acute flare of gout?
NSAIDs or colchicine
(Continue the allopurinol if already taking it)
If both contraindicated then oral steroids can be considered
Moa of colchicine?
Inhibits microtubule polymerization by binding to tubulin and interfering with mitosis of neutrophils = prevention of activation, migration and action of neutrophils within the joint space
Side effects of colchicine?
GI disturbance - abdominal pain, diarrhoea, n&v
Blood disorders
GI haemorrhagic
Hepatic or renal impairment
Myopathy
Contraindications of colchicine?
Blood diorders
Interactions with colchicine?
The following drugs can increase toxicity risk due to CYP3A4 inhibition:
Macrolides
Antivirals
Antifungals
CCB
Grapefruit juice
Lipid lowering therapies e.g. simvastatin - increase risk of myopathy
What is the length of the colchicine course?
500 micrograms 2-4 times a day until sympotms resolved (max 6mg per course)
Lifestyle advice for a pt with gout?
Healthy, balanced diet - avoid food high in purines e.g. liver, seafood, oily fish
Reduce weight
Reduce alcohol consumption