Background Glatiramer acetate (GA) is a firstline therapy approved for the treatment of relapsing remitting multiple sclerosis (RRMS). GA 20 mg/mL (GA20) administered once daily by subcutaneous injection has been used since 2009. In 2014, modified treatment regimens–alternative dosages and low frequency administration schedules were introduced—GA 40 mg/mL (GA40) three times weekly.

Purpose To analyse injection related adverse events (IRAEs) reported for GA20 and GA40 in our clinical practice.

Material and methods This was a retrospective observational study of patients diagnosed with RRMS, receiving treatment with GA for at least for 6 months (January—June 2016). We studied all patients who started on GA40 three times weekly, as well as those converting from GA20 once daily to GA40, including naive and further lines of treatment. We excluded patients who wanted to get pregnant. The IRAEs analysed according to the System Organ Class were general disorders and administration site conditions, including local injection site reactions (ISRs), and symptoms or events related to immediate post-injection reactions (IPIRs).

Results 52 patients were included: 23 patients (14 women, 9 men; mean age 43 years) were receiving treatment with GA40, 15 (7 women, 8 men) had converted from GA 20 and 10 patients were naive for GA. Five moderate/severe IRAEs related to ISRs and IPIRs were reported (21.7%), 2 of which were in patients who had converted from GA20. 29 patients (19 women, 10 men; mean age 46 years) were receiving treatment with GA20 for at least 6 months. One moderate IRAE associated with IPIR (3.4%) was reported in this group.

Conclusion To our knowledge, post hoc analyses showed that patients receiving GA40 demonstrated a 60% reduction in the annualised event rate of moderate/severe IRAEs compared with GA20. In our study, from the total number of ISRs and IPIRs reported, GA40 had a significantly increased rate compared with GA20 (p<0.04). These outcomes suggest that moderate or severe reactions related to general disorders and administration site conditions were less frequent in GA20 treated patients. Due to the size of group, these results should be interpreted with caution; future analysis in clinical practice is necessary.

References and/or acknowledgements Wolinsky JS, et al. Mult Scler Relat Disord2015;4:370–6. Available at http://dx.doi.org/10.1016/j.msard.2015.06.005

No conflict of interest