Pharm
Allopurinol
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Allopurinol
, Zyloprim, Xanthine Oxidase Inhibitor
Indications
Uric Acid
Lowering Therapy
Gout
Prophylaxis (first-line agent)
Uric Acid
over-producers (
Uric Acid
> 750 mg/24h)
Used in
Uric Acid
under-excreters as well
Criteria
Recurrent episode of gout (>=2 attacks per year, and consider for 1 gout flare/year)
Tophaceous gout
Radiographic damage attributable to gout
Nephrolithiasis
Precautions
Avoid use with
Azathioprine
(causes toxic levels)
Avoid in
Renal Failure
(or use low dose)
Do not use for asymptomatic
Hyperuricemia
Genetic Test
ing (HLA B5801)
Obtain prior to use if risk of severe
Hypersensitivity
skin reaction
Risks include southeast asian (esp. Hans Chinese, Thai, Korean) and African American
Avoid in acute gout attack (wait at least 4-6 weeks after acute attack)
However, more recent data suggests safety in starting during acute attack (per email, Dr. John Rasor)
Eminaga (2016) Rheumatol Int 36(12):1747-52 +PMID:27761603 [PubMed]
Hill (2015) J Clin Rheumatol 21(3):120-5 +PMID:25807090 [PubMed]
Taylor (2012) Am J Med 125(11):1126-1134 +PMID:23098865 [PubMed]
Mechanism
Xanthine Oxidase Inhibitor
Inhibits
Uric Acid
formation
Dosing
Use concurrent antiinflammatory agent when starting to prevent triggering attack
Wait to start Allopurinol until at least 6-8 weeks symptom-free from last attack
However, see precautions above for recent data suggesting safety in starting with acute attack
Antiinflammatory agent options to start concurrently with Allopurinol (continue for first 3-6 months)
NSAID
S (avoid in
Chronic Kidney Disease
, heart disease or liver disease)
Aleve
220 mg (OTC) orally twice daily or
Naprosyn
250 mg orally twice daily or
Indomethacin
25 mg orally twice daily
Prednisone
(if
NSAID
s contraindicated)
Maintenance: 10 mg orally daily, then 5 mg orally daily for 3-6 months
Acute Exacerbation (start at first symptoms of gout recurrence): 40 mg orally for 1-3 days
Have available as emergency prescription
Colchicine
Colchicine
was a first line agent for Allopurinol initiation (but now too expensive)
Gene
ric preparations were removed from market
Colchicine
0.6 mg PO daily to twice daily
Allopurinol 100-300 mg/day
Use lowest dose to keep
Uric Acid
<6 mg/dl (<5 mg/dl if symptomatic)
Probenacid may be used with Allopurinol if GFR>50 ml/min and normal
Urine Uric Acid
normal
Duzallo
(Allopurinol with
Lesinurad
) is an expensive alternative to Probenacid and Allopurinol
Initiating dose
Start: 100 mg daily for 2 weeks
Next: 200 mg daily for 2 weeks
Next: 300 mg daily (most effective dose for most patients)
Some patients require higher doses (up to 800 mg/day) to maintain
Uric Acid
<6 mg/dl
Adjust starting dose for
Renal Function
GFR >90 ml/min: 300 mg daily
GFR 60-89 ml/min: 200 mg daily
GFR 30-59 ml/min: 100 mg daily
GFR 10-29 ml/min (or Cr >1.5): 50 mg daily (maximum dose 300 mg/day)
GFR <10 ml/minute: Avoid or use with caution
Monitoring
Obtain 6 weeks after starting Allopurinol
Complete Blood Count
(CBC)
Alanine Aminotransferase
(ALT)
Serum Creatinine
Serum
Uric Acid
Adverse effects (more common with renal dysfunction)
May precipitate acute gout attack (never start during active gout attack)
See Dosing above for protocol using
NSAID
s or
Colchicine
concurrently
Severe
Hypersensitivity
Syndrome (presents as dermatitis,
Pruritus
)
Varies from mild rash to
Stevens Johnson Syndrome
Genetic Test
ing (HLA B5801) prior to use if Hans Chinese, Thai or if CKD 3, Korean
Stop Allopurinol if this occurs
Toxic Hepatitis
Nausea
Diarrhea
Cytopenias
Drug Interactions
Azathioprine
(toxicity)
Warfarin
(Allopurinal increases INR)
References
(2018) Presc Lett 25(9):50-1
Eggebeen (2007) Am Fam Physician 76:801-12 [PubMed]
Hainer (2014) Am Fam Physician 90(12): 831-6 [PubMed]
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