Background and importance The therapeutic arsenal of multiple sclerosis has expanded in recent years. From the hospital perspective, we need to know what place these drugs should occupy in therapeutics.

Aim and objectives To study the use of dimethyl fumarate (DF) in relapsing–remitting multiple sclerosis (RRMS) and the adequacy of clinical practice guidelines in our hospital. We decided to focus our research on DF because it is the most prescribed recently marketed drug in our hospital.

Material and methods This was an observational, retrospective study and all patients who received at least one DF prescription from the outpatient pharmaceutical care unit between 2015 and 2019 were included. Data collected were age, sex, continuation or suspension of treatment, treatment line, pharmacological treatment before and after and duration of treatment. In the case of a change in treatment, the reason for the change was registered (ie, adverse events (AE) or inefficacy).

Results Thirty patients were included, 87% women, with a median age of 36.5 years (19–59) and 46.7% of patients were being treated with DF at the time of the study.

• DF was used as firstline treatment in 53% of patients and as secondline in 30% with the majority prior treatment being glatiramer acetate in 67%.

• Treatment changes were recorded in 53% of patients, of which 50% were due to AE and 50% to inefficacy. The most common AE was gastrointestinal disorder.

• Change in treatment for AE (n=8): the changes registered were for teriflunomide (5), glatiramer acetate (2) and beta interferon (1).

• Change in treatment due to inefficacy (n=8): cladribine (4), alemtuzumab (2), natalizumab (1) and teriflunomide (1).

• The average duration of treatment was 15 months.

Conclusion and relevance In conclusion, DF was used as a firstline treatment for RRMS in 53% of patients. The average duration of treatment in our centre was short considering that it is a progressive disease. In patients who suffered a change in treatment due to AE, it was mostly decided to switch to another firstline drug, generally teriflunomide. In patients who underwent a change in treatment due to inefficacy after firstline treatment, it was decided to go with secondline treatment, usually in patients with very active disease.

References and/or acknowledgements No conflict of interest.