Therapeutic Drug Monitoring
Antieleptics
Gabapentin
Lacosamide
Lamotrigine
Levetiracetam
Oxcarbazepine Metabolite
Topiramate
Zonisamide
NEW! ARK™ Methotrexate II Assay
Faster. Safer. More confident decisions in high-dose methotrexate therapy.
Deliver rapid, reliable MTX results at critical decision points — supporting safer rescue therapy, earlier discharge, and reduced cost of care.
How are MTX lab results used in HD-MTX Therapy?
High-dose methotrexate (HD-MTX) is a chemotherapy used in lymphoma, osteosarcoma, and leukemia. Because MTX has dose-dependent renal clearance and a narrow safety window, treatment decisions rely on serial plasma MTX measurements (typically 24, 48, 72 hours, and beyond).
The MTX result is the primary guide for leucovorin rescue, escalation, and discharge decisions. Delayed or unreliable results increase toxicity risk and length of stay.
ARK™ Methotrexate II – brings greater confidence to every HD-MTX decision.
Best-in-class analytical performance where it matters most — at low clinical decision levels — with fast turnaround on routine chemistry analyzers.
Key benefits
Unmatched Precision, Specificity and Accuracy
- LOQ 0.03 μmol/L = More confident decisions at <0.05 μmol/L for safe discharge
- High specificity = ≤ 0.01% cross-reactivity with 7-OH-MTX
- Avoids falsely elevated late-phase results and unnecessary prolonged monitoring
Short Turnaround Time
- Runs on most routine chemistry analyzers = ~1 hour results from stat labs, supporting 24/7 oncology workflows
Shorter Leucovorin Rescue Therapy
- Earlier optimization of leucovorin rescue
- Fewer inpatient days, lower overall cost, improved patient experience
A final note on Glucarpidase administration
Glucarpidase is a rare emergency intervention to reverse MTX toxicity (~1–4% of cases), extremely costly and not universally available. Optimized MTX monitoring incorporating rapid, reliable results helps reduce progression to this stage.
After glucarpidase administration, LC-MS/MS should be used for ~48 h, as all immunoassays cross-react with DAMPA, causing elevated results. Place a note on the LIMS so that the laboratory is aware of this fact.