Anti-TNFa drug levels in patients with rheumatoid arthritis and spondyloarthritis

Background and objectives: Knowledge of the levels of anti-TNFa drugs can modify treatment in patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA).Objectives: To compare the levels of anti-TNF alpha in patients with RA vs SpA, in different clinical situations. Materials and methods: A retrospective, observational study was conducted. Levels of anti-TNF alpha and the presence of anti-drug antibodies were measured in consecutively selected patients, using the ELISA technique. Results: Fifty-three, 73 and 78 patients treated with infliximab, adalimumab and etanercept were studied, respectively. The median drug levels in patients using standard doses were infliximab 2.2 mu g/mL (1.4-5.2), adalimumab 4.9 mu g/mL (0.8-8.9) and etanercept 3.1 mu g/mL (2.3-4.4). There were no differences in drug levels according to disease activity but we found differences in etanercept and infliximab levels according to DMARD use. Conclusions: Levels of anti-TNF alpha drugs will change with DMARD treatment. (C) 2021 Elsevier Espana, S.L.U. and Sociedad Espanola de Reumatologi acute accent a y Colegio Mexicano de Reumatologi acute accent a. All rights reserved.