At what blood level is adalimumab (Humira) most effective on disease activity in rheumatoid arthritis (RA)?

Updated: Feb 07, 2020
  • Author: Howard R Smith, MD; Chief Editor: Herbert S Diamond, MD  more...
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A 5-year analysis of an open-label extension (OLE) study concluded that a delay of 52 weeks for adding adalimumab to concomitant MTX therapy contributed to inferior radiographic, functional, and clinical outcomes in patients with active RA. [82]

According to data from a study of 221 consecutive RA patients, adalimumab blood levels of 5 to 8 μg/mL have the greatest effect on disease activity. In the study, adalimumab trough levels greater than 8 μg/mL had no additional beneficial effect on disease activity. [83, 84] Study participants were treated with 40 mg adalimumab subcutaneously every other week for 28 weeks and stratified according to whether or not they were taking concomitant MTX. Patients treated with concomitant MTX reached recommended blood levels at lower adalimumab doses. At 28-week follow-up, mean adalimumab levels were 4.1 μg/mL in patients receiving monotherapy and 7.4 μg/mL in patients receiving concomitant MTX. MTX might contribute to increasing adalimumab blood levels by reducing inflammation and lowering the number of targets for adalimumab to bind to. [83]

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