Leflunomide Metabolite-994
Test info
Arava
Teriflunomide
DMARD
Leflunomide (Arava®) is a pyrimidine synthesis inhibitor used in the treatment of active rheumatoid arthritis. The drug is available in oral doses containing 10, 20, or 100 mg of active drug. Arava® is an isoxazole immunodulatory agent which inhibits dihydroorotate dehydrogenase (an enzyme involved in de novo pyrimidine synthesis) and has antiproliferative activity. Following oral administration, leflunomide is metabolized to an active metabolite, A77-1726 (teriflunomide), which is responsible for essentially all of its activity in vivo. Peak levels of this metabolite occurred 6 to 12 hours after dosing, with a long half-life (about two weeks).
Specimen
Submission of the minimum volume does not allow for repeat testing
- Allow sample to clot
- Spin and transfer serum or plasma to a Transfer vial/tube with cap - 12mL (LabCorp), labelled as serum or plasma, within 45 minutes of specimen collection.
Ambient (preferred) - 30 days
Refrigerated - 30 days
Frozen - 24 months
Polymer gel separation tube (SST or PST)
Performance
High Performance Liquid Chromatography/Tandem Mass Spectrometry(LC-MS/MS)
Clinical and Interpretive info
Reporting Limit 500 ng/mL