Evaluation of the chromogenic anti-factor IIa assay to assess dabigatran exposure in geriatric patients with atrial fibrillation in an outpatient setting

Assessing Direct Oral Anticoagulants in the Clinical Laboratory

Direct oral anticoagulants (DOACs) have significant advantages over vitamin K antagonists including lack of need for routine laboratory monitoring. However, assessment of DOAC effect and concentration may be important to guide clinical management including need for DOAC reversal, particularly in acute or emergent situations. In this manuscript, the authors describe tests to screen for DOAC presence and tests that have demonstrated equivalence to gold standard testing for quantifying DOAC exposure. They also discuss the effect of DOACs on other coagulation assays and strategies for monitoring unfractionated heparin in patients with concomitant DOAC exposure.

Direct oral anticoagulants (DOACs): From the laboratory point of view

Direct oral anticoagulants (DOACs) represent a new generation of drugs that have been increasingly used in the prevention and treatment of thromboembolic states. According to the mechanism of anticoagulant action, DOACs are divided into two groups: direct inhibitors of thrombin (dabigatran) and direct inhibitors of activated factor X (FXa) (rivaroxaban, apixaban, edoxaban, betrixaban). Compared to the vitamin K antagonists, DOACs are superior in terms of onset of action, pharmacokinetic and pharmacodynamics properties and fixed daily dose without the need for routine coagulation monitoring. Despite these advantages, there are clinical conditions in which laboratory measurement of DOACs should be performed. Although DOACs have an impact on screening haemostasis assays (prothrombin time, PT; activated partial thromboplastin time, aPTT; and thrombin time, TT), these tests are not appropriate for quantifying drug levels. Therefore, specific quantitative methods (LC-MS/MS as a gold standard method for all DOACs, coagulometric and chromogenic assays for dabigatran, and chromogenic anti-Xa assays with drug-specific calibrators for inhibitors of FXa) should only be used for determination of DOACs concentration. The aim of this review is to present all aspects of laboratory assessment of DOACs, including pre-analytical, analytical and post-analytical factors in the overall testing process with a special accent on the available specific quantitative methods for measurement of DOACs in circulation.

Gerinnungsdiagnostik im klinischen Alltag – Teil 2

Während bei einer Vitamin-K-Antagonisten-Therapie die Therapieüberwachung (International Normalized Ratio [INR]) obligat ist, gilt dies für direkte orale Antikoagulanzien (DOAK) oder niedermolekulares Heparin (NMH) nur in ausgewählten klinischen Szenarien. Bei DOAK steht die Bestimmung von Tal- und Spitzenspiegeln des Medikaments im Plasma im Vordergrund, bei NMH die Anti-Xa-Aktivität. Der Zeitpunkt der Probenabnahme in Relation zur Einnahme ist für die Bewertung essenziell. Eine neu aufgetretene Thrombozytopenie im Rahmen stationärer Behandlungen ist häufig. Einordnung der Grunderkrankung, Tag des Auftretens sowie Erfassung medikamentöser Einflüsse und ihrer Dynamik ermöglichen oft die Eingrenzung der Ursache. Die Thrombophilietestung nach venöser Thromboembolie wird aufgrund fehlender therapeutischer Konsequenz zunehmend seltener durchgeführt. Ein Antiphospholipidsyndrom darf aber nicht übersehen werden, da sowohl die Therapiedauer als auch die Wahl des Antikoagulans davon abhängen.

Bioequivalence and pharmacodynamics of a generic dabigatran etexilate capsule in healthy Chinese subjects under fasting and fed conditions

To assess bioequivalence of a generic dabigatran etexilate capsule in healthy Chinese subjects under fasting and fed conditions. This was an open-label, single-center, randomized four-period crossover study with a 7-day washout period. A single oral dose of 150 mg generic dabigatran etexilate capsule (test drug) or a commercial dabigatran etexilate capsule (Pradaxa® , reference drug) was given to healthy volunteers under the fasting and fed conditions. Plasma concentrations of total and free dabigatran were detected using a validated HPLC-MS/MS method. A noncompartmental method was used for pharmacokinetic analysis and established coagulation assays were applied for pharmacodynamic analysis. The 90% CIs of the test/reference ratios of Cmax , AUC0-t , and AUC0-∞ for the total dabigatran concentration were 92.57%-106.58%, 91.63%-106.32%, and 92.54%-106.17%, respectively, under fasting condition, and 99.30%-110.74%, 98.58%-105.37%, and 97.75%-103.99%, respectively, under fed conditions. The 90% CIs of the ratios of the parameters for the free dabigatran were 93.18%-106.98%, 92.13%-107.10%, 92.89%-106.48%, respectively, under fasting condition, and 100.05%-110.89%, 99.37%-106.23%, 97.59%-103.98%, respectively, under the fed condition. Additionally, the upper limit of the 90% CIs for σWT/σWR was below 2.5. There were no significant differences in the coagulation parameters including thrombin clotting time, activated partial thromboplastin time, and anti-IIa activity between the two preparations. The generic dabigatran etexilate capsule is bioequivalent to the brand-named product in healthy Chinese volunteers under fasting and fed conditions. The two products have comparable pharmacodynamic parameters, with a good safety profile. In addition, food intake influences absorption of both products in a similar way.

Laboratory testing in patients treated with direct oral anticoagulants: a practical guide for clinicians

Click to hear Dr Baglin's perspective on the role of the laboratory in treatment with new oral anticoagulants SUMMARY: One of the key benefits of the direct oral anticoagulants (DOACs) is that they do not require routine laboratory monitoring. Nevertheless, assessment of DOAC exposure and anticoagulant effects may become useful in various clinical scenarios. The five approved DOACs (apixaban, betrixaban, dabigatran etexilate, edoxaban and rivaroxaban) have different characteristics impacting assay selection and the interpretation of results. This article provides an updated overview on (i) which test to use (and their advantages and limitations), (ii) when to assay DOAC levels, (iii) how to interpret the results relating to bleeding risk, emergency situations and perioperative management, and (iv) what is the impact of DOACs on routine and specialized coagulation assays. Assays for anti-Xa or anti-IIa activity are the preferred methods when quantitative information is useful, although the situations in which to test for DOAC levels are still debated. Different reagent sensitivities and variabilities in laboratory calibrations impact assay results. International calibration standards for all specific tests for each DOAC are needed to reduce the inter-laboratory variability and allow inter-study comparisons. The impact of the DOACs on hemostasis testing may cause false-positive or false-negative results; however, these can be minimized by using specific assays and collecting blood samples at trough concentrations. Finally, prospective clinical trials are needed to validate the safety and efficacy of proposed laboratory thresholds in relation to clinical decisions. We offer recommendations on the tests to use for measuring DOACs and practical guidance on laboratory testing to help patient management and avoid diagnostic errors.

Application of a novel mass spectrometric (MS) method to examine exposure to Bisphenol-A and common substitutes in a maternal fetal cohort

The use of Bisphenol A (BPA) has widely been replaced in consumer products by analogs BPB, BPE, BPF, BPS, and BPAF. Recent studies have linked these substitutes to similar adverse health outcomes as BPA, including disruption of endocrine pathways in animal and human studies. We designed a novel MS method, developed specifically for this study, to capture the most relevant BPA alternatives, BPB, BPE, BPF, BPS, BPAF and 4-NP in human blood and urine to quantify potential in utero exposures. To our knowledge, this is the first study to explore in utero exposure to these BPA analogs and the first U.S. study to test for BPA in maternal/fetal pairs. The method was run on 30 paired maternal urine and fetal cord blood samples from mothers undergoing elective Caesarean sections. 90% of mothers and 77% of babies tested positive for at least one BP analog. 83% of mothers tested positive for BPAF, 60% for BPS, 57% for BPB, 17% for BPF and 7% for BPA. 57% of babies tested positive for BPAF and 50% for BPF. BPA and BPB were detected in one cord blood sample each. BPS was not detected in cord blood. BPE was not detected in any fetal cord blood or maternal urine samples. These findings demonstrate the pervasiveness of some BP analogs in pregnant women and their babies at birth.

Measurement and reversal of the direct oral anticoagulants

Direct oral anticoagulants (DOACs) offer noninferior efficacy and improved safety compared to vitamin K antagonists (VKAs) for the prevention and treatment of venous thromboembolism and for the prevention of stroke and systemic embolism in nonvalvular atrial fibrillation. Unlike VKAs, DOACs do not require routine laboratory monitoring of anticoagulant effect and dose adjustment. In certain situations, however, laboratory assessment of anticoagulant effect may be desirable. Here we review the utility of currently available assays for assessment of DOAC effect and recommend an optimal assessment strategy for each drug, including calibrated dilute thrombin time or ecarin-based assays for dabigatran and calibrated anti-Xa activity assays for the factor Xa inhibitors. We also discuss reversal strategies, both specific and nonspecific, for each drug, including the preferential use of idarucizumab for the reversal of dabigatran and two agents, andexanet and ciraparantag, currently under development for the reversal of rivaroxaban, apixaban, and edoxaban.