title: Optimized high-performance liquid chromatographic method for determination of lamotrigine in serum with concomitant determination of phenytoin, carbamazepine, and carbamazepine epoxide.
abstract: Lamotrigine (LG), phenytoin (PY), carbamazepine (CM), and carbamazepine epoxide (CE) are measured with an optimized procedure that uses thin sorbent extraction disks and a highly selective, sterically protected bonded silica high-performance liquid chromatography (HPLC) column. Routinely, serum (200 microliters at pH 6.8 with cyheptamide as internal standard) is applied to an Empore octyl (C8) solid-phase extraction disk to isolate the drugs. a water wash removes interferences, and the retained drugs are eluted with a small volume of solvent. The eluate is directly injected onto a Zorbax Stable Bond cyanopropyl HPLC column with quantification at 214 nm. Evaporation-concentration steps are unnecessary. Overall, for all drugs, between-run precision coefficients of variation (n = 16 each) ranged from 2.1% to 4.9% at concentrations from 0.75 to 20.5 mg/l; extraction recoveries fell within a range of 96% to 110% at concentrations of 2, 10, and 30 mg/l tested for each drug; the lowest limit of detection was 0.15 to 0.35 mg/l. The analytical response was linear for each drug > 80 mg/l (LG) and > 50 mg/l (PY, CM, and CE). Optimization graphs are presented to illustrate the rationale for selection of test parameters for a robust method. In addition, a comparison study between two commercial laboratories demonstrates accuracy problems associated with LG testing.
authors.affiliation: Department of Pathology, School of Pharmacy, University of Wisconsin Hospital and Clinics, Madison 53792, USA.
authors.forename: G L
authors.initials: GL
authors.lastname: Lensmeyer
authors.forename: B E
authors.initials: BE
authors.lastname: Gidal
authors.forename: D A
authors.initials: DA
authors.lastname: Wiebe
mesh_terms: D000927:Anticonvulsants / Q000097:blood*; D002220:Carbamazepine / Q000031:analogs & derivatives* / Q000097:blood*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D000077213:Lamotrigine; D010672:Phenytoin / Q000097:blood*; D014227:Triazines / Q000097:blood*
chemical_list: D000927:Anticonvulsants; D014227:Triazines; D002220:Carbamazepine; D010672:Phenytoin; C012227:carbamazepine epoxide; D000077213:Lamotrigine