title: Gas chromatography-electron ionization-mass spectrometry quantitation of valproic acid and gabapentin, using dried plasma spots, for therapeutic drug monitoring in in-home medical care.
abstract: A simple and sensitive gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) method using dried plasma spot testing cards was developed for determination of valproic acid and gabapentin concentrations in human plasma from patients receiving in-home medical care. We have proposed that a simple, easy and dry sampling method is suitable for in-home medical patients for therapeutic drug monitoring. Therefore, in the present study, we used recently developed commercially available easy handling cards: Whatman FTA DMPK-A and Bond Elut DMS. In-home medical care patients can collect plasma using these simple kits. The spots of plasma on the cards were extracted into methanol and then evaporated to dryness. The residues were trimethylsilylated using N-methyl-N-trimethylsilyltrifluoroacetamide. For GC-EI-MS analysis, the calibration curves on both cards were linear from 10 to 200 µg/mL for valproic acid, and from 0.5 to 10 µg/mL for gabapentin. Intra- and interday precisions in plasma were both ≤13.0% (coefficient of variation), and the accuracy was between 87.9 and 112% for both cards within the calibration curves. The limits of quantification were 10 µg/mL for valproic acid and 0.5 µg/mL for gabapentin on both cards. We believe that the present method will be useful for in-home medical care.
authors.affiliation: Department of Clinical Pharmacotherapy, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Kayo
authors.initials: K
authors.lastname: Ikeda
authors.forename: Kazuro
authors.initials: K
authors.lastname: Ikawa
authors.forename: Satoko
authors.initials: S
authors.lastname: Yokoshige
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yoshikawa
authors.forename: Norifumi
authors.initials: N
authors.lastname: Morikawa
mesh_terms: D000081:Acetamides; D000588:Amines / Q000097:blood* / Q000737:chemistry; D003509:Cyclohexanecarboxylic Acids / Q000097:blood* / Q000737:chemistry; D059788:Dried Blood Spot Testing / Q000379:methods*; D005463:Fluoroacetates; D000077206:Gabapentin; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D016014:Linear Models; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods; D014297:Trimethylsilyl Compounds; D014635:Valproic Acid / Q000097:blood* / Q000737:chemistry; D005680:gamma-Aminobutyric Acid / Q000097:blood* / Q000737:chemistry
chemical_list: D000081:Acetamides; D000588:Amines; D003509:Cyclohexanecarboxylic Acids; D005463:Fluoroacetates; D014297:Trimethylsilyl Compounds; C086665:N-methyl-N-(trimethylsilyl)trifluoroacetamide; D005680:gamma-Aminobutyric Acid; D014635:Valproic Acid; D000077206:Gabapentin
keywords: dried plasma spot testing; electron ionization; gabapentin; gas chromatography-mass spectrometry; valproic acid