Performance Characteristics of DOAC Dipstick in Determining Direct Oral Anticoagulants in Urine.

Testing for direct oral anticoagulants (DOACs) in patient urine may facilitate medical treatment decisions. The aim of this study was to investigate interobserver variability by 2 independent observers compared to laboratory staff in the visual interpretation of factor Xa (DXI) and thrombin inhibitors (DTI) using the DOAC Dipstick test. We also examined whether test pads reacted to other anticoagulants and abnormal urine colors. The colors of the DOAC Dipstick direct factor Xa inhibitor and thrombin inhibitor pads were interpreted with 100% accuracy (95% confidence interval 0.862 to 1.000) for urine samples from persons treated with apixaban (n = 26), rivaroxaban (n = 24), and dabigatran (n = 29) and without anticoagulant therapy (n = 29). The factor Xa and thrombin inhibitor pads did not interact with heparin, nadroparin, fondaparinux, or coumadin. One µg/mL r-Hirudin and 6 µg/mL argatroban interacted with the DTI pad; however, this is unlikely to cause clinical problems because dabigatran is unlikely to be administered together with r-Hirudin and argatroban in clinical circumstances. Abnormal urine color was reliably detected by the urine color pad, so can prevent false interpretation of the DOAC Dipstick pad colors. In conclusion, we have demonstrated that interobserver variability when interpreting the DOAC Dipstick test strip is low and that factor Xa and thrombin inhibitor pads do not react to other anticoagulants such as heparins and coumadin. R-Hirudin and argatroban can be detected by the thrombin inhibitor pad and abnormal urine colors can be detected by the urine color pad to prevent false interpretation of the results in patient urine samples.

Accuracy of a Rapid Diagnostic Test for the Presence of Direct Oral Factor Xa or Thrombin Inhibitors in Urine-A Multicenter Trial.

The rapid determination of the presence of direct oral anticoagulants (DOACs) in a patient remains a major challenge in emergency medicine and for rapid medical treatment decisions. All DOACs are excreted into urine. A sensitive and specific point-of-care test has been developed to determine whether they are present in patient urine samples. This prospective multicenter study aimed to demonstrate at least 95% correct positive and negative predictive results for factor Xa and thrombin inhibitors in urine samples using DOAC Dipstick pads compared with liquid chromatography-tandem mass spectrometry (LC-MS/MS) (NCT03182829). Nine hundred and fourteen subjects were included and 880 were evaluated per protocol (factor Xa inhibitors apixaban, edoxaban, and rivaroxaban: n = 451, thrombin inhibitor dabigatran: n = 429) at 18 centers. The sensitivity, specificity, accuracy, and predictive values and agreement between methods for determination of factor Xa inhibitors were at least noninferior to 95% with a 0.5% margin and of thrombin inhibitor superior to 97.5%. These results were compared with LC-MS/MS results in the intention-to-analyze cohort (all p < 0.05). The receiver operating curve showed c-values of 0.989 (factor Xa inhibitors) and 0.995 (thrombin inhibitor). Visual evaluation of the factor Xa and thrombin inhibitor pads was not different between centers. Qualitative determination of both types of DOACs was accurate using the DOAC Dipstick compared with using LC-MS/MS. The high predictive values may impact laboratory and clinical decision-making processes.

Liquid chromatographic methods for the determination of direct oral anticoagulant drugs in biological samples: A critical review.

Direct oral anticoagulants (DOACs) are first-line drugs used for the treatment of venous thromboembolism and prevention of stroke in patients with atrial fibrillation. These drugs do not require the regular biochemical monitoring that is mandatory for warfarin, and they exhibit shorter half-lives and have a faster onset of action. Since recent real-world studies evidence a higher prevalence of adverse side effects than what was anticipated in clinical trials, monitoring the plasma concentrations of DOACs is being used to personalize their pharmacotherapy, in accordance to the characteristics of the patient, and to evaluate the adherence to therapy. In order to fulfill the aforementioned clinical unmet needs, there are specific coagulation assays that indirectly assess the plasma concentrations of DOACs. Nevertheless, these assays are not sufficiently accurate or sensitive. For this reason, liquid chromatography techniques coupled to mass spectrometry detection, are considered the gold standard method to accurately determine plasma concentrations of DOACs. Therefore, the present paper provides the first comprehensive review of the current analytical methods that were developed and validated for the quantitative determination of apixaban, dabigatran, rivaroxaban and/or edoxaban and their main metabolites in biological samples. The chromatographic methods will be particularly highlighted and an emphasis will be placed on the major difficulties faced during optimization and development steps. In addition, the physicochemical, pharmacokinetic and pharmacodynamic characteristics of each drug will be critically related to chromatographic conditions. Their influence on the pre-treatment procedures and storage conditions of DOACs will be examined, suggesting strategies that should be applied to accurately quantify DOACs in biological samples.

Microdosed Cocktail of Three Oral Factor Xa Inhibitors to Evaluate Drug-Drug Interactions with Potential Perpetrator Drugs.

OBJECTIVES: The aim of this study was to prove the suitability of simultaneously administered microdoses of the factor Xa inhibitors (FXaIs) rivaroxaban, apixaban and edoxaban (100 µg in total). To evaluate drug-drug interactions, the impact of ketoconazole, a known strong inhibitor of cytochrome P450 3A4 and P-glycoprotein, was studied. METHODS: In a crossover clinical trial, 18 healthy volunteers were randomized to the two treatments using microdoses of rivaroxaban, apixaban and edoxaban alone and when coadministered with ketoconazole. Plasma and urine concentrations of microdosed apixaban, edoxaban and rivaroxaban were quantified using a validated ultra-performance liquid chromatography-tandem mass spectrometry assay with a lower limit of quantification of 2.5 pg/ml. RESULTS: The microdosed FXaI cocktail showed similar pharmacokinetic parameters compared with published data, using normal therapeutic doses of each FXaI. Ketoconazole significantly increased exposure, with geometric mean AUC ratios of 1.90 (apixaban), 2.35 (edoxaban) and 2.27 (rivaroxaban). CONCLUSION: The microdosed FXaI cocktail approach was able to precisely predict the drug interaction with ketoconazole. This is the first study that has been conducted to evaluate drug-drug interactions with a drug class, and the low administered doses also allow evaluation in vulnerable target populations. STUDY PROTOCOL: EudraCT 2016-003024-23.

Measurement of dabigatran, rivaroxaban and apixaban in samples of plasma, serum and urine, under real life conditions. An international study.

BACKGROUND: The utility of measuring non-vitamin K antagonist oral anticoagulants (NOACs) in plasma, serum and urine samples and with the point-of-care test (POCT) on urine samples should be analysed in an international laboratory study. METHODS: The study was performed to determine the inter-laboratory variance of data from two chromogenic assays each for the NOACs rivaroxaban, apixaban and dabigatran, and to analyse the sensitivity and specificity of the POCT assays for factor Xa- and thrombin inhibitors. Plasma, serum and urine samples were taken from six patients in each group on treatment with a NOAC. RESULTS: The inter-laboratory variances, which can be identified best by the coefficient of variation, ranged from 46% to 59% for apixaban, 63% to 73% for rivaroxaban and 39% to 104% for dabigatran using plasma, serum or urine samples and two chromogenic assays for each NOAC. The concentrations were about 20% higher in serum compared to plasma samples for apixaban and rivaroxaban, and 60% lower for dabigatran. The concentration in urine samples was five-fold (apixaban), 15-fold (rivaroxaban) and 50-fold (dabigatran) higher. Sensitivity and specificity of POCT for apixaban, rivaroxaban, and dabigatran were all >94%. CONCLUSIONS: The inter-laboratory study showed the feasibility of measurement of apixaban, rivaroxaban, and dabigatran in plasma, serum and urine samples of patients on treatment. Dabigatran was determined at far lower levels in serum compared to plasma samples. Concentrations of NOACs in urine were much higher compared to plasma. The POCT was highly sensitive and specific for all three NOACs.

Population pharmacokinetics of edoxaban and its main metabolite in a dedicated renal impairment study.

A model characterizing the population pharmacokinetics (PK) of edoxaban and its major metabolite, M4, following a single oral dose of 15 mg administered to subjects with varying kidney function was developed. Thirty-two subjects contributed with edoxaban plasma, edoxaban urine, and M4 plasma concentrations. Edoxaban urine concentrations allowed estimation of renal clearance, and high contribution of renal to total clearance enabled estimation of absolute oral bioavailability. A 2-compartment model with delayed absorption and elimination parameterized as renal clearance linearly related to creatinine clearance (CLcr ) and nonrenal clearance forming M4 described edoxaban PK. The PK of M4 was described with a 1-compartment model. For a typical subject (70 kg; CLcr , 100 mL/min) bioavailability, clearance, and central and peripheral volume of distribution for edoxaban was estimated to 72.3%, 21.0 L/h, 95.4 L, and 54.3 L, respectively. For both edoxaban and M4, the model predicted systemic exposure to increase 57.0%, 35.0%, and 11.6% in a subject having CLcr of 30, 50, and 80 mL/min, respectively, compared with a subject having a CLcr of 100 mL/min. Concentration ratios (M4 over edoxaban) were predicted to vary with time after dose, but with minor influence of kidney function and body weight. Results were in agreement with previous analyses.