Dapsone 50mg Tablets – Summary of Product Characteristics (SmPC) for healthcare professionals

1 NAME OF THE MEDICINAL PRODUCT

Dapsone 50mg Tablets

2 QUALITATIVE AND QUANTITATIVE COMPOSITION

Each tablet contains 50mg Dapsone

3 PHARMACEUTICAL FORM

White uncoated tablets.

White to off-white, uncoated, circular, biconvex tablets debossed "50" above and “D” below the score on one side and plain on the other side. Tablet size: 5.8 mm

The tablet can be divided into equal doses.

4 CLINICAL PARTICULARS

4.1 Therapeutic indications

Dapsone Tablets are indicated for:

• As part of a multi-drug regimen in the treatment of all forms of leprosy.
• Treatment of dermatitis herpetiformis and other dermatoses.
• Prophylaxis of malaria in combination with pyrimethamine.
• Prophylaxis of Pneumocystis carinii pneumonia in immunodeficient subjects, especially AIDS patients.

4.2 Posology and method of administration

Posology

Adults and children over 12 years of age:

Multibacillary leprosy (3-drug regimen): 100mg daily for at least two years.

Paucibacillary leprosy (2-drug regimen): 100mg daily for at least six months.

Malaria prophylaxis: 100mg weekly with 12.5mg pyrimethamine. Dermatitis herpetiformis: Initially 50mg daily, gradually increasing to 300mg daily if required. Once lesions have begun to subside, the dose should be reduced to a minimum as soon as possible, usually 25-50mg daily, which may be continued for a number of years. Maintenance dosage can often be reduced in patients receiving a gluten-free diet.

Pneumocystis carinii pneumonia: In combination with trimethoprim, 50-100mg daily; 100mg twice weekly or 200mg once weekly.

Paediatric population:

Children aged 6 years to 12 years:

Multibacillary leprosy (3-drug regimen): 50mg daily for at least two years.

Paucibacillary leprosy (2-drug regimen): 50mg daily for at least six months.

Children aged less than 6 years:

The safety and efficacy of Dapsone in children aged less than six years has not been established. No data are available.

Elderly population

Dosage should be reduced in the elderly where there is an impairment of hepatic function.

Method of Administration

For oral administration.

4.3 Contraindications

Dapsone Tablets are contraindicated in cases of:

• Hypersensitivity to dapsone, sulfonamides, sulfones, or any of the excipients listed in section 6.1.
• Severe anaemia.
• Porphyria.
• Severe glucose-6-phosphate dehydrogenase deficiency.

4.4 Special warnings and precautions for use

Dapsone should be used with caution in patients with cardiac or pulmonary disease.

It is recommended that regular blood counts be performed during treatment with dapsone. Patients deficient in glucose-6-phosphate dehydrogenase, or methaemoglobin reductase, or with haemoglobin M are more susceptible to the haemolytic effects of dapsone.

Dapsone should be used with caution in anaemia. Severe anaemia should be treated prior to initiation of dapsone therapy.

4.5 Interaction with other medicinal products and other forms of interaction

Excretion of dapsone is reduced and plasma concentrations are increased by concurrent administration of probenecid. Rifampicin has been reported to increase the plasma clearance of dapsone.

Increased dapsone and trimethoprim concentrations have been reported following concurrent administration in AIDS patients.

4.6 Fertility, pregnancy and lactation

Pregnancy

It is now generally considered that the benefits of dapsone in the treatment of leprosy outweigh any potential risk to the pregnant patient. Some leprologists recommend 5mg folic acid supplementation daily for leprosy patients receiving dapsone during pregnancy.

Breast-feeding

Dapsone diffuses into breast milk and there has been a report of haemolytic anaemia in a breast-fed infant. While some feel that dapsone should not be used in lactating mothers, in general therapy for leprosy is continued in such patients.

4.7 Effects on ability to drive and use machines

None known.

4.8 Undesirable effects

Dapsone should be discontinued or reduced in dosage, if severe lepra reactions affecting the eyes or nerve trunks occur.

The frequencies of undesirable effects are reported according to the following convention:

¹ these are the most frequently reported adverse effects of dapsone and are dose related; occurring in most subjects administered more than 200mg daily; doses of up to 100mg daily do not cause significant haemolysis, but subjects deficient in glucose-6-phosphate dehydrogenase are affected by doses above 50mg daily. ² this is rare when dapsone is used alone, reports are more common when dapsone has been used with other medicines for malarial prophylaxis.

³ this may occur following 3-6 weeks of therapy, symptoms include rash (always present), fever, and eosinophilia. If dapsone is not stopped immediately; the syndrome may progress to exfoliative dermatitis, hepatitis, albuminuria and psychosis. Deaths have been recorded. The majority of patients require steroid therapy for several weeks, this is possibly due to the prolonged elimination time of dapsone.

⁴ peripheral neuropathy may occur as part of leprosy reaction states and it is not an indication to discontinue dapsone.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme; website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.

4.9 Overdose

Symptoms are hypoxia, methaemoglobinaemia and haemolytic anaemia. In severe overdosage the stomach should be emptied by gastric lavage. Administration of activated charcoal by mouth has been shown to enhance the elimination of dapsone and its monoacetyl metabolite. Methaemoglobinaemia has been treated with slow IV injections of methylene blue 1-2mg/kg bodyweight, repeated after one hour if necessary. Methylene blue should not be administered to patients with glucose-6- phosphate dehydrogenase deficiency since it will not be effective. Haemolysis has been treated by infusion of concentrated human red blood cells to replace the damaged cells.

Supportive therapy should include oxygen to alleviate hypoxia, and administration of fluids to maintain renal flow and promote the elimination of dapsone.

5 PHARMACOLOGICAL PROPERTIES

5.1 Pharmacodynamic properties

Pharmacotherapeutic group: Anti-infectives for systemic use; anti-mycobacterials; drugs for treatment of lepra

ATC code: JO4B A02

Dapsone is a sulfone with activity against a wide range of bacteria.

Dapsone’s mechanism of action is probably similar to that of the sulfonamides which involves inhibition of folic acid synthesis in susceptible organisms. It is usually considered bacteriostatic against M. leprae, although it may also possess weak bactericidal activity. Itis also active against Plasmodium and Pneumocystis carinii. As with sulfonamides, antibacterial activity is inhibited by p-aminobenzoic acid.

5.2 Pharmacokinetic properties

Absorption:

Following oral administration, dapsone is almost completely absorbed from the gastrointestinal tract, with reported bioavailability exceeding 86 %. Peak serum concentrations are reached within 2 h - 8 h. Post ingestion of a single 50 mg – 300 mg dose of dapsone, maximum serum concentrations range from 0.63 mg/L to 4.82 mg/L. Under steady state conditions, the most frequently used dose of 100 mg/day, results in serum concentrations of maximum 3.26 mg/L, and a minimum, at 24 h, of 1.95 mg/L. Steady state concentrations are not achieved until after at least 8 days daily administration.

Distribution:

Dapsone is 50-80% bound to plasma proteins, whereas the principal metabolite, monoacetyldapsone is almost completely bound to plasma proteins. Dapsone is distributed to almost all organs and is retained in the skin, muscle, kidneys and liver, with trace concentrations present in these tissues up to 3 weeks post discontinuation. Dapsone is distributed into sweat, saliva, sputum, tears and bile. It crosses the blood-brain barrier and the placenta, and is excreted in breast milk. The half-life ranges from 10 h - 80 h.

Biotransformation:

Post absorption, dapsone undergoes enterohepatic recirculation. It is metabolised by the liver, and additionally by activated polymorphonuclear leukocytes and mononuclear cells. In the liver dapsone is primarily metabolised via acetylation by N- acetyltransferase to monoacetyldapsone and through hydroxylation by cytochrome P-450 enzymes, resulting in the generation of dapsone hydroxylamine. Dapsone hydroxylamine may be responsible for dapsone associated methaemoglobinaemia and haemolysis. Acetylation exhibits genetic polymorphism, with both rapid and slow acetylators.

Elimination:

Around 20 % of dapsone is excreted, unchanged, via urine, with 70 % – 80 % of the dose being eliminated as water soluble metabolites following conjugation with glucuronic acid. A small amount of the dose may be excreted in faeces, including some unidentified metabolites.

Linearity/non – linearity:

The drug shows linear pharmacokinetics within the therapeutic range.

5.3 Preclinical safety data

There are no pre-clinical data of relevance to the prescriber which are additional to that already included in other sections of the SPC.

6 PHARMACEUTICAL PARTICULARS

6.1 List of excipients

Cellulose, microcrystalline (Grade – 102)

Maize starch

Silica colloidal anhydrous

Magnesium stearate

6.2 Incompatibilities

None known.

6.3 Shelf life

3 years

6.4 Special precautions for storage

This medicinal product does not require any special storage condition.

6.5 Nature and contents of container

Dapsone 50mg tablets are available in White opaque PVC-Aluminium foil blister pack

Blister pack sizes: 28 tablets

6.6 Special precautions for disposal

Not applicable.

7 MARKETING AUTHORISATION HOLDER

Milpharm Limited

Ares Block,

Odyssey Business Park,

West End Road,

Ruislip, HA4 6QD

United Kingdom

8 MARKETING AUTHORISATION NUMBER(S)

PL 16363/0645

9 DATE OF FIRST AUTHORISATION/RENEWAL OF THE

AUTHORISATION

13/08/2026

10 DATE OF REVISION OF THE TEXT

13/08/2026