Background Multiple sclerosis (MS) is a chronic demyelinating CNS disease. The recent commercialisation of new drugs for its treatment can change prescriber and patient treatment preferences.

Purpose To determinate the most prescribed drugs at the beginning of the disease and to observe if the emergence of new drugs for MS (dimethyl fumarate, alemtuzumab, pegylated interferon and teriflunomide) has changed the prescription tendency, or if they are preserved as a secondline treatment. Also, to quantify the outbreaks/year, reasons for discontinuation and adverse events of treatment.

Material and methods This was a retrospective observational study including all treated MS patients (January 2004–March 2016). The data were obtained from their medical records and dispensation register.

Results 55 patients were included in the study, 69% women. Average age was 36±9 years. The most prescribed drugs after diagnosis were: interferon-β1b (25%), interferon-β1a 30 µg (20%), interferon-β1a 44 µg (18%), glatiramer acetate (GA) (18%), natalizumab (7%), fingolimod (7%) and dimethyl fumarate (5%). Among these, there were 8 prescriptions after the commercialisation of the new MS drugs: 3 dimethyl fumarate, 2 interferon-β1a 44 µg, 1 GA, 1 fingolimod and 1 natalizumab. With those initial treatments, 27 (49%) patients did not have outbreaks, 17 (31%) had 1 outbreak/year, 8 (15%) had 2 outbreaks/year and 3 (6%) had 3 outbreaks/year. 69% of patients were treated with 1 drug, 20% with 2 different drugs and 11% were treated with ≥3 drugs. The reasons for the change were: disease progression (52%), adverse events (47%) and patient’s decision (1%).

27 patients did not present adverse events, 15 had flu-like syndrome, 5 redness, 5 discomfort at the injection site, 2 lymphopenia, 2 paresthesias, 2 mood disturbance, 1 transaminase elevation and 1 palpitations.

Conclusion MS affects young adults, especially women. Interferon and GA are the most common initial treatments but with the appearance of new MS drugs, the use of dimethyl fumarate has increased. New MS drugs are mostly used as a secondline treatments but natalizumab is still the most used when there is no response to initial treatment. 85% of patients tolerated the treatment and no medication change was necessary. This drug has been demonstrated to be effectives because 69% of patients needed one treatment line to control their illness.

No conflict of interest