These are exciting times in the treatment of multiple sclerosis, says Lesley Murray, advanced pharmacist for neurosciences at the Southern General Hospital in Glasgow

For several years, the only disease modifying therapies for MS required administration by either subcutaneous or intramuscular injection but in recent years, three oral drugs have been licensed for the treatment of relapsing-remitting multiple sclerosis (RRMS). This article will focus on dimethyl fumarate, which is accepted for use in NHS Scotland for adult patients with RRMS and is recommended by NICE as a possible treatment of active RRMS (normally defined as two clinically significant relapses in the previous two years) that isn’t highly active or rapidly evolving severe RRMS. This advice is dependent on the continued availability of a patient access scheme (PAS) that improves the cost-effectiveness of dimethyl fumarate.

Clinical evidence

The exact mechanism of action of dimethyl fumarate in MS is not known, but it is thought to involve the nuclear factor (erythroid-derived 2)-like (Nfr2) transcriptional pathway. Two phase 3 clinical trials evaluating the effect of dimethyl fumarate found that it reduces relapse rates by approximately 50 per cent. Existing first-line therapies beta-interferon and glatiramer acetate reduce relapse rates by around onethird. Although no direct comparison has been undertaken in a clinical trial setting, this suggests dimethyl fumarate may offer improved efficacy. Where the PAS is available, it is likely that prescribing dimethyl fumarate will remain, at least initially, in specialist centres. Community pharmacists may therefore be unaware that a patient is receiving dimethyl fumarate as this will not necessarily appear on the PMR. However the patient may still seek advice regarding common side-effects.

Points for practice

The main side-effects with dimethyl fumarate are flushing and gastrointestinal (GI) disturbance, which are commonest in the first month, but may continue to occur intermittently. GI side-effects were experienced by 10-12 per cent and flushing by up to 34 per cent of patients in clinical trials. It is recommended that dimethyl fumarate is taken with food. Patients have reported that taking with eggs, cheese, ham, peanut butter or a similar fat/protein-based meal lessens these side-effects. It has also been reported that non-enteric coated aspirin can help with the flushing (described as hot flushes, itchiness or burning of the skin). The optimal dose may vary between specialist centres, so the patient should speak to his/her MS nurse specialist, who can advise and ensure there are no contraindications to aspirin. Non-sedating antihistamines (e.g. cetirizine or loratadine 10mg daily) may help the itch. If these measures fail, some patients may require a temporary dose reduction of dimethyl fumarate and should seek advice from their MS nurse specialist.