{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,13]],"date-time":"2026-05-13T09:55:27Z","timestamp":1778666127253,"version":"3.51.4"},"reference-count":15,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2016,1,26]],"date-time":"2016-01-26T00:00:00Z","timestamp":1453766400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["accpjournals.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Pharmacotherapy"],"published-print":{"date-parts":[[2016,2]]},"abstract":"Pralatrexate (PDX<\/jats:styled-content>) is a folate antagonist structurally similar to methotrexate (MTX<\/jats:styled-content>). Unlike MTX<\/jats:styled-content>, it is currently not known whether PDX<\/jats:styled-content> exhibits delayed clearance and heightened toxicity in the setting of fluid overload. A specific serum assay for PDX<\/jats:styled-content> is not commercially available. To our knowledge, we report the first case using an MTX serum assay as a surrogate for PDX concentrations to avoid a potential drug\u2010drug interaction with pralatrexate. We describe a 76\u2010year\u2010old man with refractory cutaneous T\u2010cell lymphoma who began therapy with weekly PDX<\/jats:styled-content> 15 mg\/m2<\/jats:sup> intravenous infusions on days 1, 8, and 15 of a 28\u2010day cycle. He subsequently developed mucositis, a moderate right\u2010sided pleural effusion, and peripheral edema over the next 5 weeks. Aggressive diuresis with furosemide was initiated, which was then withheld the day before his next PDX<\/jats:styled-content> dose to avoid a potential drug\u2010drug interaction between PDX<\/jats:styled-content> and furosemide. His baseline MTX<\/jats:styled-content>\/PDX<\/jats:styled-content> concentration (measured prior to administration of the cycle 2, week 2 PDX<\/jats:styled-content> dose) was less than 0.20 \u03bcmol\/L (i.e., undetectable). After PDX<\/jats:styled-content> administration, his 1\u2010hour peak MTX<\/jats:styled-content>\/PDX<\/jats:styled-content> concentration increased to 0.58 \u03bcmol\/L. Aggressive diuresis was withheld until his MTX<\/jats:styled-content>\/PDX<\/jats:styled-content> concentration was undetectable, 43.5 hours later. PDX<\/jats:styled-content> is more potent than MTX<\/jats:styled-content> and displays similar pharmacokinetic properties. PDX<\/jats:styled-content> concentrations using the serum MTX<\/jats:styled-content> assay reflect lower values than those reported from PDX<\/jats:styled-content>\u2010specific assays in clinical studies. Because PDX<\/jats:styled-content> is approved by the U.S. Food and Drug Administration for the treatment of uncommon malignancies, it is unlikely that a specific assay will be commercially developed. We propose that the MTX<\/jats:styled-content> serum assay has merit for use in determining when to reinstate possible interacting drug therapies such as loop diuretics.<\/jats:p>","DOI":"10.1002\/phar.1699","type":"journal-article","created":{"date-parts":[[2016,1,26]],"date-time":"2016-01-26T00:35:08Z","timestamp":1453768508000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Pralatrexate Monitoring Using a Commercially Available Methotrexate Assay to Avoid Potential Drug Interactions"],"prefix":"10.1002","volume":"36","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4038-7951","authenticated-orcid":false,"given":"Jordan P.","family":"McPherson","sequence":"first","affiliation":[{"name":"Department of Pharmacy Huntsman Cancer Institute Salt Lake City Utah"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alaina","family":"Vrontikis","sequence":"additional","affiliation":[{"name":"Department of Pharmacy Huntsman Cancer Institute Salt Lake City Utah"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Courtney","family":"Sedillo","sequence":"additional","affiliation":[{"name":"Department of Nursing Huntsman Cancer Institute Salt Lake City Utah"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ahmad S.","family":"Halwani","sequence":"additional","affiliation":[{"name":"Division of Hematology and Hematologic Malignancies Huntsman Cancer Institute Salt Lake City Utah"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jeffrey A.","family":"Gilreath","sequence":"additional","affiliation":[{"name":"Department of Pharmacy Huntsman Cancer Institute Salt Lake City Utah"},{"name":"Department of Pharmacotherapy College of Pharmacy The University of Utah Salt Lake City Utah"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2016,1,26]]},"reference":[{"key":"e_1_2_5_2_1","unstructured":"Hospira 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