IC17 Management of Gout Flashcards
What is gout?
Gout is a type of inflammatory arthritis that causes pain and swelling in your joints.
Gout flares often begin in your big toe or a lower limb.
What causes gout?
Gout is caused by:
1. Imbalances in purine metabolism
2. Purine is broken down into uric acid
3. Uric acid then precipitates out as uric acid crystals
4. Deposition of urate crystals in the articular & periarticular tissues (aka tophi)
What are the 5 risk factors of gout?
- Diet
- Obesity
- Male
- Genetics
- Kidney disease
What are the 2 main targets for pharmacotherapy management in gout?
- Xanthine oxidase
- Increasing uric acid excretion
What can cause hyperuricaemia?
- Overproduction of uric acid
- Under-excretion of uric acid
If pt has hyperuricaemia, but show no S&S, there is no need to treat.
What are the clinical presentations of gout?
- Redness
- Warmth
- Swelling & tenderness
- Often presents at the big toe
- Attack often occurs in the early morning after waking up
What is the criteria to diagnose a pt w gout?
We diagnose a pt w gout via testing of:
- Synovial fluid
- Tissue sections of tophaceous deposits
If urate crystals are present in the synovial fluid, we diagnose a pt with gout.
What would synovial fluid look like with and without urate crystals?
Without urate crystals, synovial fluid is:
- Colourless & translucent
- <200 WBCs/mm^3
- No crystals present
With urate crystals, synovial fluid is:
- Yellow & cloudy
- 2000-50,000 WBCs/mm^3
- Crystals present
What are the 5 treatment goals for gout?
- Provide rapid, SAFE, & effective pain relief
- Reduce future attacks
- Prevent joint destruction & tophi formation
- Increase QoL
- Address associated comorbidities
What is considered hyperuricaemia in men & women?
Men: Plasma uric acid >7mg/dL
Women: Plasma uric acid >6mg/dL
How to manage acute gout flares?
Treat pt w:
- Colchicine (within 24hrs) - 1st line
- Oral NSAIDs
- Oral glucocorticoids
If pt is already on Urate Lowering Therapy (ULT), continue ULT during flare.
What are the 2 ways to give colchicine for acute gout flares?
[DIFFERENT FROM PROPHYLAXIS TREATMENT]
- One-off treatment
- 1mg loading dose + 0.5mg 1hr later - Continuous treatment
- 0.5mg 2-3 times a day, until acute flares resolves
How is colchicine given for prophylaxis treatment?
Colchicine 0.5mg OD* for 3-6 months
Note that Colchicine is given OD and not 2-3 times daily as compared to acute treatment.
What are the ADRs of colchicine?
- N&V
- Diarrhoea
ADRs increase w higher dose or long term use.
Colchicine can be discontinued after gout attacks are gone.
What should we avoid if there is an acute gout flare?
We should avoid using ULT - (allopurinol, febuxostat & probenecid) in acute flare attacks.
Reason: They can cause mobilisation or uric acid. We should wait 2-4 weeks after the acute gout flare before giving ULT.
Colchicine toxicity is more likely to occur in renally impaired pts.
What should we do for renally-impaired pt with acute gout flares?
Lower the dose of colchicine to give.
Avoid giving oral NSAIDs to renally impaired pts.
Oral NSAIDs are CI in pt w CrCL<30ml/min.
What are the criteria to initiate ULT?
Pt is only eligible for ULT if:
1.Pt has ≥2 acute gout flares a year
2. Presence of tophi or tophus
3. Imaging showing joint damage
4. History of kidney stones (urolithiasis)
What are the treatment targets when using ULT?
Treatment target:
Non-tophaceous gout: <360µmol/L (6mg/dL)
Tophaceous gout: 300µmol/L (5mg/dL)
What is the MOA of allopurinol & febuxostat?
They inhibit xanthine oxidase.
What is the MOA of probenecid?
It increases the excretion of uric acid.
What is the ADR of allopurinol?
There is a risk of SCAR - subcutaneous adverse reactions, e.g SJS, TEN, DRESS.
We can conduct genetic testing for HLA-B*58:01 in pt at higher risk for SCAR.
We should lower the dose of allopurinol in renally impaired pts
What is the acronym for pt at higher risk of SCAR when taking allopurinol?
RASHES
R - renal impairment
A - Agent concomitant use of therapeutic agent, such as diuretics
S - Starting dose of allopurinol is high
H - HLA-B*5801 is present
E - Escalation of allopurinol dose is rapid
S - Seniority / older age
What are the 4 S&S of SCAR?
- Flu-like symptoms - fever, body aches
- Mouth ulcers or sore throat
- Red or sore eyes
- Rash
What should we be cautious of when using febuxostat?
- Cautious in pt w hepatic impairment.
- Use w caution in HF & CHD pts.
- Has risk of SCAR, but lower than allopurinol
What should we be cautious of when using probenecid?
- Not recommended in pt with renal impairment (CrCl<50ml/min)
- CI in urolithiasis (kidney stones)
- Not effective in CKD pt.
What is the dosing for allopurinol?
- Initiation dose
- Maintenance dose
Initiation dose: ≤100mg/day
Maintenance dose: >300mg/day
“Start low, go slow”
What is the dosing for febuxostat?
- Initiation dose
- Maintenance dose
Initiation dose: ≤40mg/day
Maintenance dose: 80mg/day
Febuxostat is given if pt is intolerant to allopurinol
When do we stop ULT?
We can choose to stop ULT if clinical remission is achieved.
Clinical remission = no flares for ≥1 year and no tophi.
If therapy is well-tolerated & not burdensome, pt can have preference to continue or stop treatment. Shared decision is needed.
What are non-pharmacological treatment for gout?
- Limit alcohol intake
- Limit purine-rich foods
- Limit high-fructose corn syrup
- Weight management
What are examples of high-purine food?
- Asparagus
- Cauliflower
- Mushroom
- Red meat
- Anchovies
- Durian
- Durian
- Peanuts
- Organ meat (e.g liver)
