B Ungar et al (Clin Gastroenterol Hepatol 2016; 14: 550-7) report median serum levels of infliximab (n=78) or adalimumab (n=67) in correlation with mucosal healing.
In this retrospective cross-sectional study of adult patients with IBD (median age ~35 years), the authors found a correlation with higher drug troughs and mucosal healing.
“Levels of infliximab above 5 mcg/mL…and levels of adalimumab above 7.1 mcg/mL identified patients with mucosal healing with 85% specificity. Increasing levels of infliximab above 8 mcg/mL produced only minimal increases in the rate of mucosal healing, whereas the association between higher level of adalimumab and increased rate of mucosal healing reached a plateau at 12 mcg/mL”
The authors propose a “therapeutic window” of 6-10 for infliximab and 8-12 for adalimumab.