dimethyl fumarate: clinical use

Prescribing considerations

• Initiate under a clinician experienced in the relevant condition; multiple-sclerosis capsules and Skilarence tablets have different indications and safety instructions.
• Assess active or serious infection and previous or concurrent immunomodulatory treatment.
• Counsel patients and carers about PML, infection, flushing, gastrointestinal effects and scheduled monitoring.
• Review pregnancy intentions, breastfeeding and contraception using product-specific advice.

Contraindications and cautions

• All selected products: hypersensitivity to dimethyl fumarate or relevant excipients.
• Multiple-sclerosis capsules: suspected or confirmed PML.
• Skilarence: severe gastrointestinal disease, severe hepatic or renal impairment, pregnancy and breastfeeding.
• Skilarence contains lactose and should not be used in specified rare hereditary disorders of galactose metabolism.

Monitoring

• Obtain a baseline full blood count, including lymphocytes; continue product-specific monitoring and respond promptly to sustained lymphopenia.
• For multiple-sclerosis capsules, do not initiate with severe lymphopenia; maintain enhanced PML vigilance even with mild lymphopenia.
• Ensure an appropriate baseline MRI is available for multiple-sclerosis treatment and investigate suspected PML immediately.
• Assess renal and hepatic function before treatment and periodically according to the product; investigate possible Fanconi syndrome even if creatinine is not raised.
• Continue lymphocyte monitoring after discontinuation when counts are reduced, until recovery.

Clinical pharmacology

Dimethyl fumarate undergoes rapid presystemic esterase hydrolysis to active monomethyl fumarate. Metabolism does not depend on cytochrome P450, making CYP-mediated interactions unlikely. Activity involves immunomodulatory, antioxidant and inflammatory signalling pathways.

Formulation and product differences

• Selected multiple-sclerosis products are gastro-resistant hard capsules containing enteric-coated pellets and are licensed from age 13 years.
• Skilarence is a lactose-containing gastro-resistant tablet licensed for adult plaque psoriasis.
• The products have indication-specific contraindications, monitoring thresholds, pregnancy advice and administration instructions and are not interchangeable.

Capsule

Route: Oral

Strengths: 120 mg, 240 mg

Gastro-resistant capsule

Route: Oral

Strengths: 120 mg

Gastro-resistant tablet

Route: Oral

Strengths: 30 mg, 120 mg