Dried plasma spots as an alternative sample collection technique for the quantitative LC-MS/MS determination of gabapentin

Dried plasma spots were employed as an alternative sample collection technique for the quantitative determination of gabapentin in human plasma, using an automated liquid chromatography tandem mass spectrometry method. After the methanolic extraction of single plasma, 1/8-in. disks which contained only 1.98 mu L plasma volume, were placed in 96-well format plates, then gabapentin and its internal standard, 4-aminocyclohexanecarboxylic acid, were derivatized with n-butanol/HCl (3 M) and detected as butyl esters. The assay exhibited excellent linearity over the concentration range of 40.0-10.0 x 10(3) ng/mL, which is suitable for the determination of gabapentin after per os administration of a single tablet. Variations in intra- and inter-assay accuracy and precision were within internationally accepted criteria. Homogeneity of plasma spots was proven, whilst butyl ester stability for both analytes was estimated and found very satisfactory. The quantitative analysis of Gabapentin with dried plasma spot specimens seems to be a prominent and advantageous technique, especially when applied to pharmacokinetic studies, where plasma sampling procedure becomes rapid and required plasma volumes negligible.