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Pharmacokinetics of oral and subcutaneous methotrexate in red and white blood cells in patients with early rheumatoid arthritis: the methotrexate monitoring trial
  1. Renske CF Hebing1,2,
  2. Marry Lin3,
  3. Maja Bulatovic Calasan3,4,
  4. Ittai B Muller3,
  5. Sohaila Mahmoud1,
  6. Sandra Heil5,
  7. Eduard A Struys3,
  8. Bart JF van den Bemt6,
  9. Jos WR Twisk7,
  10. Willem Lems1,2,
  11. Michael T Nurmohamed1,2,
  12. Gerrit Jansen2,
  13. Robert de Jonge3
  1. 1 Reade, Amsterdam Rheumatology and Immunology Center, Amsterdam, The Netherlands
  2. 2 Rheumatology, Amsterdam UMC VUMC Site, Amsterdam, The Netherlands
  3. 3 Clinical Chemistry, Amsterdam UMC VUMC Site, Amsterdam, The Netherlands
  4. 4 Rheumatology and Clinical Immunology, University Medical Centre Utrecht, Utrecht, The Netherlands
  5. 5 Clinical Chemistry, Erasmus Medical Center, Rotterdam, The Netherlands
  6. 6 Pharmacy, Sint Maartenskliniek, Nijmegen, The Netherlands
  7. 7 Methodology and Applied Biostatistics, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
  1. Correspondence to Renske CF Hebing, Reade, Amsterdam Rheumatology and Immunology Center, Amsterdam 1056AA, Netherlands; r.hebing{at}


Objective To investigate the pharmacokinetics of methotrexate polyglutamate (MTX-PG) accumulation in red blood cells (RBCs) and peripheral blood mononuclear cells (PBMCs) in patients with early rheumatoid arthritis (RA) after oral and subcutaneous MTX treatment.

Methods In a clinical prospective cohort study (Methotrexate Monitoring study), newly diagnosed patients with RA were randomised for oral or subcutaneous MTX. At 1, 2, 3 and 6 months after therapy initiation, blood was collected and RBCs and PBMCs were isolated. MTX-PG1-6 concentrations were determined by mass spectrometry methods using stable isotopes of MTX-PG1-6 as internal standards.

Results 43 patients (mean age: 58.5 years, 77% female) were included. PBMCs and RBCs revealed disparate pharmacokinetic profiles in both absolute MTX-PG accumulation levels and distribution profiles. Intracellular MTX-PG accumulation in PBMCs was significantly (p<0.001) 10-fold to 20-fold higher than RBCs at all time points, regardless of the administration route. MTX-PG distribution in PBMCs was composed of mostly MTX-PG1 (PG1>PG2>PG3). Remarkably, the distribution profile in PBMCs remained constant over 6 months. RBCs accumulated mainly MTX-PG1 and lower levels of MTX-PG2-5 at t=1 month. After 3 months, MTX-PG3 was the main PG-moiety in RBCs, a profile retained after 6 months of MTX therapy. Subcutaneous MTX administration results in higher RBC drug levels than after oral administration, especially shortly after treatment initiation.

Conclusions This is the first study reporting disparate MTX-PG accumulation profiles in RBCs versus PBMCs in newly diagnosed patients with RA during 6 months oral or subcutaneous MTX administration. This analysis can contribute to improved MTX therapeutic drug monitoring for patients with RA.

Trial registration number NTR 7149.

  • arthritis, rheumatoid
  • methotrexate
  • pharmacokinetics

Data availability statement

Data are available on reasonable request.

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Data availability statement

Data are available on reasonable request.

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  • GJ and RdJ are joint senior authors.

  • Handling editor Josef S Smolen

  • GJ and RdJ contributed equally.

  • Contributors Design of the study: RdJ, MTN, GJ, RCFH. Conduct of the study: RCFH (and ML, SM, IBM). Laboratory analyses: ML, IBM, EAS, SH. Statistical analyses: RCFH, SM, JWRT. First draft of the manuscript: RCFH, SM, ML. Final draft of the manuscript: all authors. Guarantor: RdJ.

  • Competing interests RCFH: grant/research support from: Pfizer, Amsterdam UMC (research school Amsterdam Infection & Immunology Institute) and NVKC (Dutch Society for Clinical Chemistry). ML, MBC, IBM, SM, SH, EAS, WL, BJFvdB, GJ: none declared. MTN: research support from Pfizer. RdJ: grant from Dutch Society of Clinical Chemistry (NVKC).

  • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.