Influence of volume and citrate on perceived pain in patients treated with adalimumab.

Background: Immune-mediated inflammatory diseases (IMIDs) are a group of disorders characterised by acute or chronic inflammation. Adalimumab and infliximab are the cornerstones of their pharmacotherapy. This study aimed to determine whether variations in the volume and citrate content of different subcutaneous adalimumab formulations result in differences in pain perception during administration.

Methods: A retrospective, cross-cohort study was conducted. Patients who had experienced a change in subcutaneous adalimumab formulation in the past year were recruited. Pain perception was evaluated using a visual analogue scale ranging from 1 to 10 points. Patients were assigned to three groups based on the type of formulation change they experienced: reduction in citrate and volume, reduction in volume only or reduction in citrate only. Data were analysed via ANOVA to determine if there were differences in perceived pain among the three patient groups.

Results: A total of 68 patients were included, of whom 39 (57.4%) experienced a reduction in both volume and citrate, 20 (29.4%) experienced only a reduction in volume and 9 (13.2%) experienced only a reduction in citrate. Analysis showed that all three groups experienced a reduction in perceived pain during administration: 2.46±0.24, 0.3±0.57 and 0.66±1.11 points, respectively (p<0.001).

Conclusions: Our results show that in all three scenarios, perceived pain was reduced. If both volume and citrate are reduced, this effect is greater. Therefore, it is recommended to use formulations with the lowest citrate buffer concentration and the lowest possible volume to minimise pain during adalimumab administration.