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AVISE PG - MTX test

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AVISE PG, the first and only test to measure methotrexate polyglutamates, the active metabolites of methotrexate.

As a prodrug, methotrexate (MTX) requires enzymatic conversion to MTX polyglutamates to exert sustained anti-inflammatory and immunomodulatory effects in rheumatoid
arthritis (RA) [1].

Methotrexate polyglutamation illustration

However, MTX absorption, metabolism, and excretion vary widely among individuals, leading to marked variability in the conversion of MTX to its active, polyglutamated forms [2, 3].

methotrexate abosorption

Research has demonstrated that patients with a methotrexate polyglutamates (MTXPGs) level over 60 nmol/L are more than 5-fold more likely to have a good response to MTX than those with levels ≤ 60 nmol/L [4, 5].

MTXPGs Levels

*response was evaluated using physician's assessment of patient response to MTX, a measure concordant with the EULAR response criteria.

Because of this interpatient variability, dose and response do not always correlate, making it challenging to optimize MTX therapy without insight into an individual's polyglutamates levels. But now there is Avise PG, a test that can help you determine whether partial or nonresponders to MTX may benefit from continued dose escalation or may need a change in therapy.

MTXPG level interpretation

Results from the Avise PG test are provided on a color graph to facilitate easy interpretation and dialogue with patients if desired. The example below illustrates a series of three test results; the result of 74 nmol/L indicates a therapeutic level of MTX PGs has been achieved.

Avise PG test result form

Find out how well your RA patients are metabolizing MTX with Avise PG. For information on how to request the Avise PG test visit our test procedure page.

References:

  1. Kremer JM. Toward a better understanding of methotrexate. Arthritis Rheum. 2004;50(5):1370-1382 (review abstract)
  2. Hoekstra M, Haagsma C, Neef C, Proost J, Knuif A, van de Laar M. Bioavailability of higher dose methotrexate comparing oral and subcutaneous administration in patients with rheumatoid arthritis. J Rheumatol. 2004;31(4):645-648 (review abstract)
  3. Chládek J, Martínková J, Simková M, Vanecková J, Koudelková V, Nozicková M. Pharmacokinetics of low doses of methotrexate in patients with psoriasis over the early period of treatment. Eur J Clin Pharmacol. 1998;53(6):437-444 (review abstract)
  4. Dervieux T, Furst D, Lein DO, et al. Polyglutamation of methotrexate with common polymorphisms in reduced folate carrier, aminoimidazole carboxamide ribonucleotide transformylase, and thymidylate synthase are associated with methotrexate effects in rheumatoid arthritis. Arthritis Rheum. 2004;50(9):2766-2774 (review abstract)
  5. Dervieux T, Kremer J. Drug monitoring of methotrexate in rheumatoid arthritis: efficacy profile using red cell methotrexate polyglutamate measurements. Poster presented at: ACR/ARHP Annual Scientific Meeting; October 24-29, 2008; San Francisco, CA. Poster 386