title: Quantitation of Teriflunomide in Human Serum/Plasma Across a 40,000-Fold Concentration Range by LC/MS/MS.
abstract: Leflunomide is a prodrug used primarily for treatment of rheumatoid arthritis. The active metabolite, teriflunomide (A77 1726), inhibits the enzyme dihydroorotate dehydrogenase and thereby reduces the synthesis of pyrimidine ribonucleotides. Teriflunomide is also administered directly and finds use in treating multiple sclerosis. Therapeutic concentrations are generally in the tens of μg/mL serum or plasma and, due to adverse effects and the time required to reach steady state, therapeutic drug monitoring is beneficial. The drug is also a potential teratogen. A method was developed and validated to quantify the drug teriflunomide over a 40,000-fold concentration range of 5 ng/mL to 200 μg/mL in serum or plasma. This is accomplished by dividing the quantitative range into two separate but overlapping regions; a high curve and a low curve range. Samples are evaluated first against the high curve after a 100-fold dilution of the sample extract. Samples falling below the upper curve region are evaluated again without dilution and quantified, if possible, against the low curve calibration standards. Appropriate choice of a concentration for the deuterated internal standard (D4-teriflunomide) allows for a single, identical, extraction procedure to be performed for both curve regions but with the dilution performed for high curve samples. The method is rugged and reliable with good accuracy and precision statistics.
authors.affiliation: Institute for Clinical and Experimental Pathology, ARUP Laboratories, 500 Chipeta Way, Salt Lake City, UT, 84108, USA. geoffrey.s.rule@aruplab.com.
authors.forename: Geoffrey S
authors.initials: GS
authors.lastname: Rule
authors.affiliation: Department of Pathology, University of Utah School of Medicine, Salt Lake City, 84108, UT, USA.
authors.forename: Alan L
authors.initials: AL
authors.lastname: Rockwood
authors.affiliation: Department of Pathology, University of Utah School of Medicine, ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, 84108, UT, USA.
authors.forename: Kamisha L
authors.initials: KL
authors.lastname: Johnson-Davis
mesh_terms: D001172:Arthritis, Rheumatoid / Q000188:drug therapy; D002853:Chromatography, Liquid / Q000379:methods*; D003437:Crotonates / Q000097:blood*; D000090722:Dihydroorotate Dehydrogenase; D016903:Drug Monitoring / Q000379:methods*; D006801:Humans; D006885:Hydroxybutyrates; D007555:Isoxazoles / Q000097:blood; D000077339:Leflunomide; D057230:Limit of Detection; D009570:Nitriles; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000037:antagonists & inhibitors; D011355:Prodrugs / Q000493:pharmacokinetics*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014052:Toluidines / Q000097:blood*
chemical_list: D003437:Crotonates; D000090722:Dihydroorotate Dehydrogenase; D006885:Hydroxybutyrates; D007555:Isoxazoles; D009570:Nitriles; D011355:Prodrugs; D014052:Toluidines; C527525:teriflunomide; D044925:Oxidoreductases Acting on CH-CH Group Donors; D000077339:Leflunomide
keywords: Arthritis; Dynamic range; LC/MS/MS; Leflunomide; Teriflunomide