Persistence of Infliximab in Circulation for 7 Years?

S. M. Kelting, D. L. Kimpel, D. E. Bruns
2015 Clinical Chemistry  
A 55-year-old man with ankylosing spondylitis presented with increasing symptoms despite treatment with adalimumab. The decreased therapeutic response raised concern that he had produced antibodies against the drug or that he had cross-reacting antibodies made against a similar drug, infliximab, with which he was treated 7 years earlier. Tests for antibodies against the drugs were negative, but the serum adalimumab and infliximab concentrations, reported automatically with results for antidrug
more » ... sults for antidrug antibodies, were 4.4 and 4.6 g/mL. QUESTIONS 1. What are adalimumab and infliximab? 2. How are such drugs measured? 3. What is the explanation for the reported finding in serum of a drug that had not been prescribed for the patient in Ͼ7 years? The answers are on the next page.
doi:10.1373/clinchem.2015.242024 pmid:26511353 fatcat:lo6frpkftbfjtkrqvg6qhbcvei