Leflunomide (ARAVA)
Leflunomide (ARAVA) | | | |
| Number | | 070021 |
| CPT | | 82542 |
| Synonyms | | Teriflunomide; A77/1726 |
| Specimen | | Serum |
| Volume | | 1 mL |
| Minimum Volume | | 0.5 mL (Note: This volume does not allow for repeat
testing) |
| Container | | Red top tube. Do not use a gel-barrier tube. The use
of gel-barrier tubes is not recommended due to slow
absorption of the drug by the gel. Depending on the
specimen volume and storage time, the decrease in drug
level due to absorption may be clinically significant. |
| Collection | | Serum must be separated from cells within 45 minutes of
collection and transferred to a plastic transport tube. |
| Storage Instructions | | Freeze. Stable for up to 3 months. |
| Causes for Rejection | | Serum separator tubes (SST); non-frozend sample; use of
gel-barrier tube |
| Use | | Arava or Leflunomide 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
anti-proliferative activity. Following oral administration,
Arava 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 between 6 to 12 hours after dosing, with a long
half-life (about 2 weeks).
|
| Methodology | | Liquid Chromatography Tandem Mass Spectrometry (LCMSMS) |
| References | | Brent, Robert L., Teratogen Update:
Reproductive Risks of Leflunimide (ARAVA); A Pyrmidine
Synthesis Inhibitor: Counseling Women Taking Leflunomide
Before or During Pregnancy and Men Taking Leflunomide Who
are Contemplating Fathering a Child, Teratology
(2001)63:106-112.
Physicians Desk Reference, 55th Edition, Thompson
Healthcare 2001, pages 685-689. |
|