title: Performance characteristics of the ARK diagnostics gabapentin immunoassay.
abstract: BACKGROUND
  Gabapentin is an antiepileptic drug used as adjunct therapy in the treatment of seizures. Absorption is saturable, and drug clearance can be reduced if patients have impaired renal function. Therapeutic drug monitoring can be useful for optimizing the dose in patients with impaired renal function, for evaluating individual patient absorption thresholds, and for monitoring compliance. Although chromatographic techniques have historically been used to support gabapentin monitoring, an immunoassay was recently introduced by ARK Diagnostics, for use with open channel chemistry analyzers. Here, we evaluated the immunoassay on a random access instrument.
  
  
  METHODS
  The ARK gabapentin assay was validated using a Beckman AU400e automated chemistry analyzer. Imprecision was assessed with 5 replicates of 3 concentrations (2.5, 8.0, and 25.0 mg/L), analyzed for 4 days. The analytical measurement range was evaluated with duplicate measurements of a prepared sample (40.0 mg/L) that was serially diluted. Patients' results were compared with the results generated with a previously validated ultra-high performance liquid chromatography coupled to tandem mass spectrometry method (n = 45, range, 1.5-45.6 mg/L).
  
  
  RESULTS
  The within-run and between-run coefficients of variation were ≤8.1%. The analytical measurement range was confirmed to be 1.5-40.0 mg/L, as stated by the manufacturer. The Deming regression for the results of 45 patients produced a correlation coefficient of 0.9987, a linear regression slope of 1.01, and an intercept of 0.24 when compared with the ultra-high performance liquid chromatography coupled to tandem mass spectrometry assay.
  
  
  CONCLUSIONS
  The ARK immunoassay is suitable for the clinical use of monitoring gabapentin in serum or plasma on the Beckman AU400e.
authors.affiliation: ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories Inc, Salt Lake City, UT, USA. juenkejm@aruplab.com
authors.forename: JoEtta M
authors.initials: JM
authors.lastname: Juenke
authors.forename: Kavina A
authors.initials: KA
authors.lastname: Wienhoff
authors.forename: Brent L
authors.initials: BL
authors.lastname: Anderson
authors.forename: Gwendolyn A
authors.initials: GA
authors.lastname: McMillin
authors.forename: Kamisha L
authors.initials: KL
authors.lastname: Johnson-Davis
mesh_terms: D000588:Amines / Q000008:administration & dosage* / Q000097:blood*; D000927:Anticonvulsants / Q000008:administration & dosage* / Q000097:blood*; D001774:Blood Chemical Analysis / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003509:Cyclohexanecarboxylic Acids / Q000008:administration & dosage* / Q000097:blood*; D016903:Drug Monitoring / Q000379:methods*; D000077206:Gabapentin; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D012640:Seizures / Q000097:blood / Q000188:drug therapy; D053719:Tandem Mass Spectrometry / Q000379:methods; D005680:gamma-Aminobutyric Acid / Q000008:administration & dosage* / Q000097:blood*
chemical_list: D000588:Amines; D000927:Anticonvulsants; D003509:Cyclohexanecarboxylic Acids; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin