Related Experiment Video
Updated: May 16, 2026

Multi-Gene Single Nucleotide Polymorphism Detection in Gastric Cancer Based on Ion Semiconductor Sequencing Platform
Published on: May 10, 2024
Methotrexate polyglutamation in relation to infliximab pharmacokinetics in rheumatoid arthritis
Thierry Dervieux1, Michael E Weinblatt, Alan Kivitz
1R&D Department, Exagen Diagnostics, Vista, California 92081, USA. tdervieux@exagen.com
Objective:
The combination of methotrexate (MTX) with infliximab can modify infliximab pharmacokinetics and lower the incidence of antibodies against infliximab (ATIs). We hypothesised that the pharmacokinetic interaction between MTX and infliximab is related to activation of MTX to immunosuppressive MTX polyglutamates (MTXPGs).
Methods:
Adult patients with rheumatoid arthritis receiving weekly MTX with infliximab for more than 3 months were enrolled in a cross-sectional study. Blood was collected at trough before the infusion of infliximab. Red blood cell (RBC) MTXPGs were measured using liquid chromatography, and circulating levels of infliximab were measured using a cell-based assay. ATIs were measured using enzyme immunoassays. Statistical analyses consisted of multiple regression and Wilcoxon tests.
Results:
In the 61 patients enrolled in the study, ATIs were detected in 11 (18%). Regression analyses revealed that lower infliximab levels (median 3.3 µg/ml) were associated with the presence of ATIs and lower RBC MTXPG levels (median 28 nmol/l) (p<0.05). Logistic regression revealed that RBC MTXPG levels above 25 nmol/l were associated with a 4.7-fold lower likelihood of having ATIs (OR=4.7; 95% CI 1.1 to 20.8; p=0.02). None of the 12 patients with RBC MTXPG levels above 50 nmol/l tested positive for ATIs.
Conclusions:
These hypothesis-generating data indicate that MTXPGs are associated with infliximab pharmacokinetics and ATI formation.
More Related Videos
04:50Preliminary Study on Acupuncture Combined with Grain-sized Moxibustion for Treating Rheumatoid Arthritis with Finger Joint Pain
Published on: May 16, 2025
11:09An HS-MRM Assay for the Quantification of Host-cell Proteins in Protein Biopharmaceuticals by Liquid Chromatography Ion Mobility QTOF Mass Spectrometry
Published on: April 17, 2018
Related Concept Videos
Drugs for Treatment of Crohn's Disease in IBD Using Immunomodulatory Agents
Drugs for Treatment of Crohn's Disease in IBD Using Biologic Agents: Anti-TNF
Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase
Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase
Inflammatory Bowel Disease IV: Pharmacological Management
Pharmacologic...
Pharmacogenetic Phenotypes: Alterations in Pharmacokinetics, Drug Targets and Biologic Milieu