Background The first biosimilar anti-NTF (infliximab) approved by the EMA (European Medicines Agency) began to be used throughout Europe in 2015. Since then, it has been widely used throughout the world, even replacing the original treatment approved in 1999 Remicade® with Remsima®, a biosimilar drug. This medicine is currently approved to treat people who have been diagnosed with rheumatoid arthritis, ankylosing spondylitis or psoriatic arthritis in the field of reheumatology, in addition to ulcerative colitis (UC) or Crohn's disease (EC) in gastroenterology. However, safety data of the use of Remsima® infliximab in a medical day hospital (MDH) are lacking.

Objectives To report intrainfusion and postinfusion adverse events related to intravenous Remsima® use in a medical day hospital. Besides, we will describe the rehospitalizations and continuity of treatment in the follow up.

Methods We designed a prospective uncontrolled case-series study. Patients referred from March 2015 to October 2016 to our MDH to receive intravenous Remsima® were consecutively enrolled. Demographic data were collected, and a harmonised active monitoring strategy was applied. We recorded the indication for treatment, the doses administered and the number and symptoms of acute transfusion reactions (ATR) occurring both in the infusion period and during the 3 hour postinfusion observation interval

Results 2828 doses were administered, 0.67% presented ATR, all of them during the infusion and reported to the Regional Pharmacovigilance Center. 53% of those ATR were women and they were on average 35.78 years (SD 14.71). The mean dose used was 4,809 mg/kg (SD 0.47). The indications for treatment in patients suffering ATR were: EC (47%), CU (26%), Spondylitis (21%) and Psoriasis (5%). As a predominant symptom during ATR we found: shortness of breath (36.89%), pruritus (15.75%), flushing sensation (15.75%), urticaria (10.4%), alopecia (5.2%), chest pain (5.2%), paresthesia (5.2%) and nausea (5.2%). 95% of ATR showed complete recovery of the symptoms, 47% disappeared with the pause of infusion. However, they had prolonged in MDH stay, the infusion was stopped for 30 minutes and restarted at a lower rate according to the protocol. 21% of patients presenting ATR dropped out because of the symptomatology, which represents 0.14% of the total infusions.

Conclusions Biosimilar Inflliximab seems to be safe in a MDH setting, given the low rate of adverse transfusion reactions during the 18 months analyzed. The most frequent adverse reaction was shortness of breath.

Disclosure of Interest None declared