Evaluation of coagulation assays versus LC-MS/MS for determinations of dabigatran concentrations in plasma
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Dabigatran is an oral direct thrombin inhibitor for which routine laboratory monitoring is currently not recommended. However, there are situations in which measurements of the drug and its effect are desirable. We therefore compared and validated different coagulation methods for assessments of dabigatran in clinical samples in relation to measurements of plasma dabigatran, without the purpose of establishing effective and safe concentrations of dabigatran in plasma.
Samples were obtained from 70 atrial fibrillation patients treated with dabigatran etexilate. Plasma concentrations were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and were compared with coagulation methods Hemoclot thrombin inhibitors (HTI) and Ecarin clotting assay (ECA), as well as with prothrombin time-international normalized ratio (PT-INR) and activated partial thromboplastin time (aPTT).
A wide range of dabigatran concentrations was determined by LC-MS/MS (<0.5–586 ng/mL). Correlations between LC-MS/MS results and estimated concentrations were excellent for both HTI and ECA overall (r2 = 0.97 and 0.96 respectively, p < 0.0001), but the precision and variability of these assays were not fully satisfactory in the low range of dabigatran plasma concentrations, in which ECA performed better than HTI. aPTT performed poorly, and was normal (<40 s) even with dabigatran levels of 60 ng/mL. PT-INR was normal even at supratherapeutic dabigatran concentrations.
LC-MS/MS is the gold standard for measurements of dabigatran in plasma. Alternatively, either HTI or ECA assays may be used, but neither of these assays is dependable when monitoring low levels or to infer total absence of dabigatran. The aPTT assay is relatively insensitive to dabigatran, and normal aPTT results may be observed even with therapeutic dabigatran concentrations.
KeywordsDabigatran Drug concentration LC-MS/MS Hemoclot ECA PT-INR aPTT
Conflicts of interest
JPA has received support for attendance at scientific meetings from Stago. None of the other authors declare any conflict of interest.
Contributions to the manuscript
JPA – responsible for the study design, data analysis and interpretation and writing the manuscript.
MS – providing samples, helped in research ethics application, data analysis and reviewing the manuscript.
JE – responsible for the technical installation and evaluation of the HTI assay in the laboratory, data analysis and reviewing the manuscript.
EEB – responsible for the technical installation and evaluation of the ECA assay in the laboratory, data analysis and reviewing the manuscript.
LS – responsible for laboratory analysis of HTI, handling of the study samples and reviewing the manuscript.
EMN – responsible for laboratory analysis of ECA, handling of the study samples and reviewing the manuscript.
LO – performing of some assays, data analysis and reviewing the manuscript.
YR – laboratory analysis of dabigatran concentration, handling of the study samples and reviewing the manuscript.
AP – performing of some assays, data analysis and reviewing the manuscript.
OB – responsible for the LC-MS/MS assay for determination of dabigatran concentration and reviewing of the manuscript.
PH – helped in the study design and interpretation of data and reviewed the manuscript.
REM – responsible for the study design, research ethics application, data analyses and interpretation, writing and reviewing of the manuscript.
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