Allopurinol

Xanthine Oxidase Inhibitor·Musculoskeletal & Rheumatology

Prevention of gout flares, uric acid nephropathy, tumor lysis syndrome

PBSURATE LOWERINGZyloprim, Progout100 mg tabletS4+1

Max Dose

900 mg/day

Half-life

15 h (Act: 15h)

Acute Gout

FLARE RISK

SJS/TEN

HLA-B*5801

Rapid Summary

Overview

Xanthine oxidase inhibitor. The first-line urate-lowering therapy (ULT) to shrink tophi and prevent recurrent gout attacks.

Maximum Dose

Max 900 mg/day (Requires specialist oversight. Standard is 100-300 mg/day).

Clinical Focus

Starting allopurinol dissolves crystal stores, which causes *massive* acute gout flares. Must co-prescribe colchicine/NSAIDs for the first 3-6 months.

Bottom Line

Allopurinol is first-line urate-lowering therapy for chronic gout prevention. Start low, titrate to serum urate target, and use flare prophylaxis when initiating.

Formulation & Access

Brand Names

Zyloprim, Progout

Oral Routes

Tablets (100 mg, 300 mg).

Prescribing & PBS

Unrestricted General Benefit (S4).

Indications & Use

Primary

PBSTGA

Prevention of gout flares, uric acid nephropathy, tumor lysis syndrome.

Clinical Place

The foundational chronic therapy for gout. Stops uric acid production at the source.

Quick reference

Class & Role

Xanthine Oxidase Inhibitor — Xanthine oxidase inhibitor.

Route / Formulation

Tablets (100 mg, 300 mg). (Zyloprim, Progout)

Usual Dose & Max

Start PO 100 mg OD. Titrate up by 100 mg every 2-4 weeks until serum urate < 0.36 mmol/L. Max 900 mg/day (Requires specialist oversight. Standard is 100-300 mg/day).

Key Indication Doses

Chronic Gout Prophylaxis: Start PO 100 mg OD. Titrate up by 100 mg every 2-4 weeks until serum urate < 0.36 mmol/L. Renal Impairment: Start at PO 50 mg OD or alternate days if eGFR < 30. Very slow titration required.

Best Uses

Allopurinol is first-line urate-lowering therapy for chronic gout prevention. Start low, titrate to serum urate target, and use flare prophylaxis when initiating; do not stop established allopurinol during an acute flare.

Avoid / Cautions

Known HLA-B*58:01 allele (Massive risk of SJS/TEN).

Key Risks

Dermatological / Immuno: Allopurinol Hypersensitivity Syndrome (AHS), severe rash, Stevens-Johnson Syndrome (SJS), Toxic Epidermal Necrolysis (TEN). Musculoskeletal: Paradoxical acute gout flares upon initiation. Hepatic: Transaminitis, hepatotoxicity.

Key Interactions

Azathioprine and 6-Mercaptopurine. Xanthine oxidase breaks down these immunosuppressants. Allopurinol blocks this, causing 1000x fatal bone marrow toxicity. Do NOT combine without oncology oversight. Amoxicillin/Ampicillin (massive increase in non-allergic maculopapular rash).

Monitoring

Serum uric acid (target < 0.36 mmol/L or < 0.30 if tophi present). Baseline eGFR and LFTs. Educate the patient to stop the drug immediately and present to ED if ANY skin rash or oral blisters develop.

Clinical Pearl

If you give a patient Allopurinol without Colchicine cover, they will get a horrific gout flare in week 2, assume the drug is making them worse, and stop taking it forever. Always cover them.

Access

Zyloprim, Progout100 mg tablet

Brand: Zyloprim, Progout
Formulation: Tablets (100 mg, 300 mg)