Schedule H

Oral

Tablets: 100 mg, 300 mg

INDICATIONS + DOSING — FOR CLINICIAN USE ONLY

Primary Indications (Approved / Standard in India)

1. Chronic Gout / Hyperuricaemia (prophylaxis)

Step Dose Clinical Notes

Starting dose 100 mg once daily Use 50 mg in elderly or renal impairment

Titration Increase by 100 mg every 2–4 weeks Guided by serum uric acid target (<6 mg/dL)

Usual maintenance dose 200–300 mg once daily Divide doses >300 mg/day

Maximum dose 800 mg/day in divided doses Specialist supervision required

Key points:

• Do NOT initiate during acute gout flare — wait until attack fully resolves

• Maintain adequate fluid intake (≥2 L/day)

• Co-prescribe colchicine 0.5 mg OD or NSAID prophylaxis for first 3–6 months to prevent mobilisation flares

1. Tumour Lysis Syndrome (TLS) — Prophylaxis

Population Dose Duration

Adults 300 mg once daily (or 100 mg TDS) Start 2–3 days before chemotherapy; continue until uric acid normalises (typically 3–7 days)

Dose adjustment Mandatory in renal impairment See Renal Adjustment section

Key points:

• Rasburicase preferred over allopurinol in high-risk TLS patients

• Ensure adequate hydration and urine output

Secondary Indications — Adults (Off-label)

Indication Dose Duration Notes

Recurrent calcium oxalate nephrolithiasis (with hyperuricosuria) 100–300 mg once daily Long-term OFF-LABEL; Specialist only; Evidence: Indian nephrology practice, supportive RCT data

PAEDIATRIC DOSING (Specialist Only)

Primary Indications

1. Tumour Lysis Syndrome — Prophylaxis

Age/Weight Dose Maximum Notes

Children 10 mg/kg/day in 2–3 divided doses 400 mg/day Start 2–3 days before chemotherapy

1. Secondary Hyperuricaemia / Juvenile Gout Syndromes (rare)

Dose Maximum Notes

10–20 mg/kg/day in 2–3 divided doses 800 mg/day Rare indication; paediatric rheumatology or metabolic specialist supervision mandatory

Safety notes:

• Monitor serum uric acid, renal function, LFTs, and CBC

• Observe closely for hypersensitivity reactions (rash, fever)

• Minimum age: No specific cutoff; use only under specialist guidance

Secondary Indications — Paediatrics (Off-label)

Indication Dose Notes

Lesch–Nyhan syndrome and related genetic disorders 5–10 mg/kg/day in divided doses OFF-LABEL; Metabolic/genetic specialist only; Evidence: Case series, expert consensus

Notes:

• Allopurinol and active metabolite oxypurinol accumulate in renal impairment

• Increased risk of hypersensitivity and bone marrow suppression — monitor closely

• Known hypersensitivity to allopurinol

• Prior severe cutaneous adverse reaction (SCAR) to allopurinol (SJS, TEN, DRESS)

• Acute gouty arthritis (do NOT initiate during active flare)

• Asymptomatic hyperuricaemia without clinical indication (routine treatment not justified)

• Chronic kidney disease (accumulation risk; dose adjustment mandatory)

• Hepatic impairment (hepatotoxicity risk)

• Concurrent azathioprine or 6-mercaptopurine therapy (severe interaction)

• HLA-B*58:01 carriers (Han Chinese, Thai, Korean ethnicity) — consider genetic screening before initiation if available

• Elderly patients — higher susceptibility to adverse reactions

• Thiazide diuretic use — increased hypersensitivity risk

Parameter Recommendation

Safety category Not formally classified; Limited human data — avoid unless clearly necessary

Preferred alternatives Dietary modification; if pharmacotherapy essential, use under specialist guidance

When it may be used Only when benefit clearly outweighs fetal risk; specialist obstetric input required

Monitoring Maternal uric acid levels, renal function; fetal growth surveillance

Parameter Recommendation

Compatibility Not recommended — insufficient safety data

Drug levels in milk Allopurinol and oxypurinol excreted in breast milk; levels unknown

Preferred alternatives Avoid drug if possible; if essential, consider temporary cessation of breastfeeding

Infant monitoring If exposure occurs, observe for rash, irritability, feeding difficulties

• Recommended starting dose: 50 mg once daily

• Titration: Slower interval (every 3–4 weeks)

• Additional risks:

• Higher incidence of hypersensitivity reactions

• Renal function often reduced — dose adjustment essential

• Bone marrow toxicity risk increased

• Monitoring: Regular renal function, CBC, and clinical review for rash

Drug Interaction Management

Azathioprine / 6-Mercaptopurine Allopurinol inhibits xanthine oxidase, causing 3–4 fold increase in thiopurine levels → severe myelosuppression Reduce azathioprine/6-MP dose to 25% of usual OR avoid combination

Didanosine Increased didanosine exposure and toxicity Combination not recommended

Cyclophosphamide Additive bone marrow suppression Use with caution; monitor haematological parameters closely

Drug Interaction Management

Warfarin Enhanced anticoagulant effect possible Monitor INR more frequently; adjust warfarin dose as needed

Thiazide diuretics Increased risk of allopurinol hypersensitivity Use together with caution; observe for rash

Ampicillin / Amoxicillin Increased incidence of skin rash Warn patients; not a contraindication

Theophylline Reduced theophylline clearance Monitor theophylline levels if high doses used

Chlorpropamide Prolonged hypoglycaemic effect (especially in renal impairment) Monitor blood glucose

• Skin rash (maculopapular; 3–5%)

• Gastrointestinal upset (nausea, diarrhoea)

• Drowsiness, dizziness

• Transient elevation of liver enzymes

• Headache

Reaction Action Required

Stevens-Johnson Syndrome (SJS) / Toxic Epidermal Necrolysis (TEN) Discontinue immediately; hospitalise

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) Discontinue immediately; hospitalise

Bone marrow suppression (agranulocytosis, aplastic anaemia) Discontinue; specialist haematology referral

Hepatotoxicity (including granulomatous hepatitis) Discontinue; monitor LFTs; hepatology referral

Hypersensitivity vasculitis Discontinue immediately

Note: Risk of severe reactions higher in renal impairment, HLA-B*58:01 carriers, and with rapid dose escalation

2–4 weeks after initiation/dose change Serum uric acid, renal function; clinical review for rash or hypersensitivity

Long-term (every 3–6 months) Serum uric acid, renal function, LFTs, CBC

Clinical note: Discontinue immediately if any rash develops — may herald serious hypersensitivity

• Zyloric (GSK)

• Allozen (Sun Pharma)

• Zyloprim (Ranbaxy/Sun)

• Purinol (Cadila)

• Alloric (Micro Labs)

NLEM status: Allopurinol 100 mg tablet included in NLEM 2022 — ceiling price applicable under NPPA

• Never initiate during acute gout — can prolong or worsen the flare; wait until attack fully resolves

• Start low, go slow — begin with lowest dose and titrate gradually; rapid escalation increases SCAR risk

• Prophylaxis is essential — co-prescribe colchicine or NSAID for first 3–6 months to prevent mobilisation flares

• Stop at first sign of rash — early discontinuation may prevent progression to SJS/TEN

• Dose adjust in CKD — failure to reduce dose is a common cause of toxicity

• In high-risk TLS, rasburicase is preferred; allopurinol does not break down existing uric acid

gout; hyperuricaemia; uric acid; TLS prophylaxis; xanthine oxidase inhibitor; renal-adjusted; SJS-risk; NLEM India; rheumatology

RxIndia v1.1 — 14 Jun 2025

• CDSCO Approved Product Information

• Indian Pharmacopoeia 2022

• NLEM 2022 (National List of Essential Medicines)

• API Textbook of Medicine (11th Edition)

• Indian Rheumatology Association Guidelines

• Goodman & Gilman's The Pharmacological Basis of Therapeutics (13th Edition)

• Harrison's Principles of Internal Medicine (21st Edition)