title: Measuring dabigatran concentrations using a chromogenic ecarin clotting time assay.
abstract: BACKGROUND
  Clinicians managing patients receiving the direct thrombin inhibitor dabigatran may benefit in being able to determine the amount of drug present in selected situations. This may include assessment of accumulation, concurrent drug interactions, or adequate removal from circulation. The ability to estimate the amount of dabigatran present using the chromogenic ecarin assay (ECA) requires further clarification.
  
  
  OBJECTIVE
  To describe the reliability of dabigatran measurements using a chromogenic ECA.
  
  
  METHODS
  This was an evaluation of the ECA method that incorporated assessment of imprecision, linearity, accuracy, carryover, and lower limits of detection or blank. Pooled normal plasma enriched with dabigatran at concentrations of 0, 25, 50, 75, 100, 125, 150, 200, 300, 400, and 500 ng/mL were sent blinded to 3 laboratories in the United States to compare our ECA results with those of laboratories reporting dilute thrombin time methods (HEMOCLOT thrombin inhibitor assay) for measuring dabigatran. Trough and peak levels from 35 patients were also compared with mass spectrophotometry for assessing ECA accuracy.
  
  
  RESULTS
  The within-run or day-to-day imprecision was less than 10%, with high linearity (R (2) = 0.989) and high degree of accuracy (R (2) = 0.985; slope = 0.908) for levels ranging between 18 and 470 ng/mL and no carryover at 0 ng/mL noted. The ECA approach appeared to be more reliable at lower dabigatran concentrations.
  
  
  CONCLUSIONS
  The chromogenic ECA appears to be an effective approach to determine the amount of dabigatran present. Further insights are necessary to determine how it can be used to reduce thromboembolic or bleeding complications in patients receiving dabigatran.
authors.affiliation: University of California-Davis Health System, Sacramento, CA, USA.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Gosselin
authors.forename: Denis M
authors.initials: DM
authors.lastname: Dwyre
authors.forename: William E
authors.initials: WE
authors.lastname: Dager
mesh_terms: D000991:Antithrombins / Q000097:blood* / Q000737:chemistry; D001562:Benzimidazoles / Q000097:blood* / Q000737:chemistry; D001681:Biological Assay; D001777:Blood Coagulation; D002863:Chromogenic Compounds / Q000737:chemistry*; D000069604:Dabigatran; D010450:Endopeptidases / Q000737:chemistry*; D006801:Humans; D059021:Laboratory Proficiency Testing; D057230:Limit of Detection; D013058:Mass Spectrometry; D015091:beta-Alanine / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry
chemical_list: D000991:Antithrombins; D001562:Benzimidazoles; D002863:Chromogenic Compounds; D015091:beta-Alanine; D010450:Endopeptidases; C020097:ecarin; D000069604:Dabigatran
keywords: chromogenic ecarin assay; dabigatran; laboratory