Quantification of valproic acid in dried blood spots.
Author(s): Pohanka A, Mahindi M, Masquelier M, Gustafsson LL, Beck O
Publication: Scand J Clin Lab Invest, 2014, Vol. 74, Page 648-52
PubMed ID: 25059925 PubMed Review Paper? No
Purpose of Paper
The purpose of this paper was to compare levels of the antiepileptic drug valproic acid (VA) in plasma and dried blood spots (DBS) and to determine the effects of hematocrit and spot volume.
Conclusion of Paper
Plasma and DBS concentrations of VA were very strongly correlated, with an average bias of -27% for DBS compared with plasma. As hematocrit and spot volume increased, so did measured levels of VA, but a >15% difference was only noted between specimens with a hematocrit of ≤40% and those with a hematocrit of 70%.
Studies
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Study Purpose
The purpose of this study was to compare levels of the antiepileptic drug VA in plasma and DBS and to determine the effects of hematocrit and DBS volume on VA quantification. For each of 32 patients taking VA, triplicate DBS of 20µL were prepared on Whatman 903 paper before plasma isolation. The effects of hematocrit and blood volume were conducted by spiking 600 µL/mol VA into 4 leftover VA negative therapeutic drug monitoring blood specimens. DBS were stored at room temperature for up to 42 days.
Summary of Findings:
Plasma and DBS concentrations of VA were very strongly correlated (R2=0.9013), with an average bias of -27% for DBS compared with plasma. As hematocrit increased so did measured levels of VA, but a >15% difference was only noted between specimens with a hematocrit of ≤40% and those with a hematocrit of 70%. Measured VA concentrations increased with increasing DBS volume, but the effect was not significant.
Biospecimens
Preservative Types
- None (Fresh)
- Other Preservative
Diagnoses:
- Epilepsy
- Other diagnoses
- Not specified
Platform:
Analyte Technology Platform Small molecule LC-MS or LC-MS/MS Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Preaquisition Biomarker level Hematocrit 20%
Hematocrit 30%
Hematocrit 40%
Hematocrit 50%
Hematocrit 60%
Hematocrit 70%
Biospecimen Aliquots and Components Aliquot size/volume 20µL
30 µL
40 µL
50 µL
75 µL
100 µL
Biospecimen Preservation Type of fixation/preservation Air-dried
None (fresh)
Biospecimen Aliquots and Components Blood and blood products Plasma
Whole blood