It has been shown that patients on maintenance therapy having sustained trough concentrations, are more likely to remain in remission than patients with undetectable trough concentrations. Thus, regularly checking IFX trough concentrations during maintenance therapy may be useful to evaluate the IFX treatment schedule and make adjustments when necessary. On top, it has been shown that patients on maintenance therapy who lost response to infliximab have more benefit from individualized treatment based on the measured IFX serum concentrations than from an empirical strategy that uses all other available therapeutic options.
Due to the dosing regimen, trough concentrations during induction week 2 and week 6 are higher and serum samples need to be diluted more compared to the maintenance phase in which trough concentrations between 0.5-12 μg/ml are common.