Schedule H

Oral, Topical

• Tablets: 50 mg, 100 mg

• Topical gel: 5% w/w, 7.5% w/w

INDICATIONS + DOSING — FOR CLINICIAN USE ONLY

Primary Indications (Approved / Standard in India)

➤ Multibacillary (MB) Leprosy — WHO/NTLEP MDT Regimen

Parameter Recommendation

Starting dose 100 mg orally once daily

Titration Not applicable — fixed dose regimen

Usual maintenance dose 100 mg once daily

Maximum dose 100 mg/day

Key Clinical Notes:

• Must be used in combination with rifampicin (600 mg monthly supervised) and clofazimine (50 mg daily + 300 mg monthly supervised)

• Duration: 12 months as per NTLEP guidelines

• Never use as monotherapy — risk of resistance development

➤ Paucibacillary (PB) Leprosy — WHO/NTLEP MDT Regimen

Parameter Recommendation

Starting dose 100 mg orally once daily

Titration Not applicable — fixed dose regimen

Usual maintenance dose 100 mg once daily

Maximum dose 100 mg/day

Key Clinical Notes:

• Used in combination with rifampicin (600 mg monthly supervised)

• Duration: 6 months as per NTLEP guidelines

• Must be part of MDT; monotherapy contraindicated

➤ Dermatitis Herpetiformis

Parameter Recommendation

Starting dose 50 mg orally once daily

Titration Increase by 25–50 mg every 1–2 weeks based on clinical response and haematological tolerance

Usual maintenance dose 50–200 mg once daily

Maximum dose 300 mg/day (rarely required; significant toxicity risk)

Key Clinical Notes:

• Response typically seen within 1–2 weeks

• Gluten-free diet essential for long-term control

• Regular haematological monitoring mandatory

• Dose reduction attempted once disease controlled

➤ Pneumocystis jirovecii Pneumonia (PCP) Prophylaxis — HIV-positive patients intolerant to cotrimoxazole

Parameter Recommendation

Starting dose 100 mg orally once daily

Titration Not applicable

Usual maintenance dose 100 mg once daily OR 50 mg twice daily

Maximum dose 200 mg/day (or 200 mg once weekly as alternative regimen)

Key Clinical Notes:

• Reserved for confirmed sulfonamide-allergic or cotrimoxazole-intolerant patients

• Often combined with pyrimethamine and leucovorin for enhanced efficacy

• G6PD screening mandatory before initiation

• Continue until CD4 count sustained above 200 cells/μL for ≥3 months on ART

Secondary Indications – Adults (Off-label)

Indication Dose Duration Notes

Linear IgA Dermatosis 50–150 mg orally once daily Until remission, then gradual taper OFF-LABEL — Specialist only; Indian dermatology practice; monitor for haemolysis

Bullous Systemic Lupus Erythematosus 50–200 mg orally once daily Variable; based on disease activity OFF-LABEL — Specialist only; case series evidence; baseline G6PD mandatory

Subcorneal Pustular Dermatosis 50–100 mg orally once daily Until disease control OFF-LABEL — Specialist only; Indian dermatology practice

PAEDIATRIC DOSING (Specialist Only)

Primary Indications (Approved / Standard in India)

➤ Leprosy (PB and MB) — NTLEP Paediatric MDT

6–9 years 25 mg orally once daily PB: 6 months; MB: 12 months

10–14 years 50 mg orally once daily PB: 6 months; MB: 12 months

≥15 years 100 mg orally once daily (adult dose) PB: 6 months; MB: 12 months

Key Clinical Notes:

• Always use as part of age-appropriate WHO/NTLEP MDT regimen

• Never use as monotherapy

• G6PD screening recommended before initiation

➤ Dermatitis Herpetiformis (Paediatric)

Parameter Recommendation

Starting dose 0.5 mg/kg/day orally

Titration Increase by 0.5 mg/kg every 1–2 weeks based on response

Usual maintenance dose 1–2 mg/kg/day

Maximum dose 2 mg/kg/day or 100 mg/day (whichever is lower)

Secondary Indications – Paediatrics (Off-label)

Indication Dose Notes

PCP Prophylaxis in HIV-positive children (cotrimoxazole intolerant) <15 kg: 2 mg/kg once daily; 15–30 kg: 50 mg once daily; >30 kg: 100 mg once daily OFF-LABEL — Specialist only; MoHFW paediatric HIV guidelines; G6PD screening mandatory

Age Restrictions:

• Not recommended in children <4 years except under specialist supervision (paediatric dermatology, infectious disease, or leprosy specialist)

• Mandatory G6PD testing before initiation in all paediatric patients

Safety Monitoring:

• Complete blood count at baseline, then fortnightly for first 3 months

• Monitor for jaundice, pallor, cyanosis

• Watch for behavioural changes, feeding difficulties

Severe impairment (eGFR <30) Use with caution; monitor for accumulation and haematological toxicity

Haemodialysis Not effectively dialysed; avoid or use with extreme caution; enhanced monitoring required

Peritoneal dialysis Limited data; use with caution

• Known hypersensitivity to dapsone or other sulfone derivatives

• Confirmed G6PD deficiency (severe haemolysis risk)

• Severe anaemia (haemoglobin <8 g/dL)

• Congenital or acquired methemoglobin reductase deficiency

• Severe hepatic impairment

• Concurrent use with other drugs causing significant haemolysis in high-risk patients

• G6PD heterozygotes (partial deficiency) — increased haemolysis risk; close monitoring required

• Pre-existing anaemia or haematological disorders

• Cardiac or pulmonary disease (may not tolerate anaemia)

• Hepatic impairment

• Renal impairment

• Elderly patients — more susceptible to adverse effects

• Prolonged therapy — risk of peripheral neuropathy

• Concurrent use of other haemolytic agents or bone marrow suppressants

• Nutritional deficiencies (folate, vitamin B12)

Parameter Details

Risk Category Use with caution; crosses placenta

Concerns Potential neonatal haemolysis and hyperbilirubinaemia; theoretical teratogenicity not confirmed

When may be used Leprosy treatment during pregnancy — benefits of MDT generally outweigh risks; continuation advised by NTLEP

Preferred alternatives For dermatological indications — consider alternatives; for leprosy — no safer alternative; continue MDT

Monitoring Maternal haemoglobin monthly; fetal growth monitoring; neonatal observation for jaundice and anaemia at birth

Parameter Details

Compatibility Generally compatible with breastfeeding

Drug levels in milk Low concentrations excreted; infant receives approximately 6–14% of maternal dose

Infant concerns Haemolysis risk if infant is G6PD deficient; potential mild haemolysis even in normal infants

Preferred alternatives For PCP prophylaxis — consider alternatives if feasible; for leprosy — continue MDT

Infant monitoring Monitor for jaundice, pallor, poor feeding, irritability; G6PD testing of infant if symptomatic

Parameter Recommendation

Starting dose 50 mg once daily

Titration Increase slowly; weekly assessment recommended

Special risks Increased susceptibility to haemolysis, methemoglobinaemia, peripheral neuropathy; reduced renal clearance; cardiac compromise from anaemia

Monitoring More frequent CBC (weekly initially); baseline and periodic renal and hepatic function; neurological assessment

Interacting Drug Effect Recommendation

Rifampicin Induces CYP3A4 and CYP2C9; reduces dapsone levels by 7–10 fold Part of MDT regimen — continue together but monitor for reduced dapsone efficacy

Trimethoprim Increases hydroxylamine metabolite; enhanced haematological toxicity Avoid combination or monitor closely; increased methemoglobinaemia risk

Primaquine Additive haemolytic effect Avoid concurrent use, especially in G6PD-deficient patients

Didanosine (buffered formulation) Reduces dapsone absorption Separate administration by ≥2 hours; monitor for PCP prophylaxis failure

Probenecid Inhibits renal excretion of dapsone Increased dapsone toxicity; avoid or reduce dapsone dose

Interacting Drug Effect Recommendation

Clofazimine May delay dapsone absorption; additive GI effects Part of MDT — continue together; monitor GI tolerance

Warfarin Potential INR prolongation Monitor PT/INR regularly when initiating or stopping dapsone

Methotrexate Additive bone marrow suppression Monitor CBC closely if co-administered

Chloroquine/Hydroxychloroquine Additive haemolysis risk Monitor haemoglobin; caution in G6PD-borderline patients

Phenytoin/Carbamazepine May reduce dapsone levels via enzyme induction Monitor clinical response; may need dose adjustment

Sulfonylureas Potential hypoglycaemia Monitor blood glucose

Folic acid antagonists Enhanced haematological toxicity Consider folic acid supplementation

• Dose-dependent haemolysis (occurs in virtually all patients at high doses)

• Methemoglobinaemia (dose-related)

• Nausea, vomiting, anorexia

• Headache

• Dizziness

• Insomnia

• Skin rash

• Elevated liver enzymes

Adverse Effect Action Required

Dapsone Hypersensitivity Syndrome (fever, rash, hepatitis, lymphadenopathy — typically 3–6 weeks after initiation) Immediate discontinuation; hospitalisation; systemic corticosteroids may be required; potentially fatal

Agranulocytosis Immediate discontinuation; haematology referral; supportive care

Aplastic anaemia Discontinue; haematology referral

Severe haemolytic anaemia (especially in G6PD deficiency) Discontinue; transfusion may be required

Symptomatic methemoglobinaemia (cyanosis not responsive to oxygen) Discontinue; methylene blue if severe (1–2 mg/kg IV)

Peripheral neuropathy (predominantly motor; with prolonged use) Consider dose reduction or discontinuation; often partially reversible

Hepatotoxicity Discontinue; monitor LFTs; hepatology referral if severe

Stevens-Johnson Syndrome/TEN Immediate discontinuation; dermatology and ICU referral

Phase Parameters

Baseline Complete blood count with reticulocyte count; G6PD status (mandatory); liver function tests; renal function; methemoglobin level if available

During initial therapy (first 3 months) CBC every 2 weeks; LFTs monthly; clinical assessment for rash, fever, jaundice

After stabilisation CBC monthly for duration of therapy; LFTs every 3 months

Long-term therapy Neurological examination every 6 months (for peripheral neuropathy); annual comprehensive review

Symptomatic monitoring Methemoglobin level if cyanosis develops; reticulocyte count if haemolysis suspected

Single-agent formulations:

• Dapsone® (various generic manufacturers)

• Lepridone® (Unichem)

• Dapzone® (Zydus)

Topical formulations:

• Acnedap® Gel (Glenmark) — 5%

• Aczone® — 7.5% (limited availability)

Fixed-dose combinations (leprosy MDT kits):

Note: Included in NLEM 2022 for leprosy treatment — price controlled. Government supply through NTLEP is free of cost.

• G6PD testing is mandatory before initiation — haemolysis in G6PD-deficient patients can be life-threatening; do not assume normal status

• Never use dapsone as monotherapy for leprosy — always as part of WHO/NTLEP MDT regimen to prevent resistance

• Dapsone hypersensitivity syndrome typically manifests 3–6 weeks after starting therapy — educate patients about early warning signs (fever, rash, lymphadenopathy)

• In dermatitis herpetiformis, clinical response is usually evident within 1–2 weeks; gluten-free diet is essential for long-term disease control

• Some degree of haemolysis occurs in all patients at therapeutic doses — baseline anaemia should be corrected before initiation

• Topical dapsone (for acne) has minimal systemic absorption — haematological monitoring not required for topical use alone

Dapsone; sulfone; leprosy; MDT; NTLEP; dermatitis herpetiformis; PCP prophylaxis; G6PD deficiency; haemolysis; methemoglobinaemia; NLEM India

RxIndia v1.0 — 10 Jul 2025

• CDSCO approved product inserts — Dapsone

• Indian Pharmacopoeia 2022

• National Formulary of India (NFI) 2021

• NLEM 2022

• National Leprosy Eradication Programme (NTLEP) Guidelines — Government of India

• API Textbook of Medicine, 11th Edition

• AIIMS Antiretroviral Therapy Guidelines and Opportunistic Infection Management Protocol

• Indian Association of Dermatologists, Venereologists and Leprologists (IADVL) Guidelines

• MoHFW Paediatric HIV Guidelines

• WHO Guidelines on Leprosy Treatment (supportive reference)