A phase I, single and continuous dose administration study on the safety, tolerability, and pharmacokinetics of neorudin, a novel recombinant anticoagulant protein, in healthy subjects.

The aim of this study was to evaluate the tolerability, safety, and pharmacokinetics of single and continuous dose administration of recombinant neorudin (EPR-hirudin, EH) by intravenous administration in healthy subjects, and to provide a safe dosage range for phase II clinical research. Forty-four subjects received EH as a single dose of between 0.2 and 2.0 mg/kg by intravenous bolus and drip infusion. In addition, 18 healthy subjects were randomly divided into three dose groups (0.15, 0.30, and 0.45 mg/kg/h) with 6 subjects in each group for the continuous administration trial. Single or continuous doses of neorudin were generally well tolerated by healthy adult subjects. There were no serious adverse events (SAEs), and all adverse events (AEs) were mild to moderate. Moreover, no subjects withdrew from the trial because of AEs. There were no clinically relevant changes in physical examination results, clinical chemistry, urinalysis, or vital signs. The incidence of adverse events was not significantly related to drug dose or systemic exposure. After single-dose and continuous administration, the serum EH concentration reached its peak at 5 min, and the exposure increased with the increase in the administered dose. The mean half-life (T1/2 ), clearance (Cl), and apparent volume of distribution (Vd) of EH ranged from 1.7 to 2.5 h, 123.9 to 179.7 ml/h/kg, and 402.7 to 615.2 ml/kg, respectively. The demonstrated safety, tolerability, and pharmacokinetic characteristics of EH can be used to guide rational drug dosing and choose therapeutic regimens in subsequent clinical studies. Clinical trial registration: Chinadrugtrials.org identifier: CTR20160444.

Production of a specific monoclonal antibody and a sensitive immunoassay for the detection of diphacinone in biological samples.

Diphacinone (DPN) is an extensively used anticoagulant rodenticide that is also considered a hazardous chemical, which poses a threat to nontarget species. DPN poisoning cases in humans or other species frequently occur, while rapid and sensitive detection methods are rarely reported. Thus, it is meaningful to develop an immunoassay for DPN detection with high sensitivity and specificity. In this study, a hapten was synthesized and then conjugated with carrier proteins to prepare the immunogens with different conjugation ratios for the preparation of antibody. After evaluation of the antisera using an indirect competitive enzyme-linked immunosorbent assay (icELISA) and statistical analysis, we found that the immunogen prepared using the N,N-dicyclohexylcarbodiimide (DCC) method with a conjugation ratio of 28.5 could elicit mice to generate antibodies with high performance. Using hybridoma technology, we obtained the specific monoclonal antibody (mAb) 4G5 with a half maximal inhibitory concentration (IC50) of 0.82 ng/mL in buffer solution. We initially explored the recognition mechanism of DPN/CLDPN and mAb from both conformational and electronic aspects. Then, mAb 4G5 was applied to develop icELISA for biological samples. The limits of detection (LODs) of icELISA were 0.28 µg/L, 0.32 µg/L, and 0.55 µg/kg for swine plasma, urine, and liver samples, respectively, and the recoveries ranged from 72.3 to 103.3% with a coefficient of variation (CV) of less than 12.3% in spiked samples. In summary, we developed a sensitive, specific, and accurate icELISA for the detection of DPN in biological samples, which showed potential in food safety analysis and clinical diagnosis. Graphical abstract.

Detecting Anti-IIa and Anti-Xa Direct Oral Anticoagulant (DOAC) Agents in Urine using a DOAC Dipstick.

The assessment of the anticoagulant effect of direct oral anticoagulants (DOACs) can be important for rapid medical decision-making, especially in patients needing immediate management. An assay that screens for the absence or presence of a DOAC would help accelerate treatment in these situations. Chromogenic and coagulation methods have several limitations, including limited accuracy, long turnaround time, and their need of specialized laboratories. Oral factor Xa and thrombin inhibitors are also eliminated by the kidneys and can be detected in patient urine samples using a single, rapid, sensitive, and patient-specific qualitative assay. In these tests, the presence or absence of a DOAC in urine can be identified by visually observing specific colors after a few minutes. Several studies have demonstrated the robustness and repeatability of these assays. The specific colors of the test strip also detect creatinine in the urine, which shows whether DOAC excretion is reduced, thus suggesting renal impairment. Persons with amblyopia may use a specific reader. Current indications for using the DOAC Dipstick test include emergency medical situations with severe bleeding and thrombotic events or before urgent major surgical interventions to accelerate medical decision-making.

Simultaneous determination of nine anticoagulant rodenticides by ultra-performance liquid chromatography-tandem mass spectrometry with ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction.

A sensitive determination method is developed for nine anticoagulant rodenticides (ARs) in urine samples by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction (UA-LDS-DLLME) pretreatment. The target analytes are brodifacoum, bromadiolone, warfarin, coumachlor, coumatetralyl, difenacoum, pindone, diphacinone and chlorophacinone. The parameters that influence the extraction recovery in the UA-LDS-DLLME were systematically investigated and optimized. With the optimized extraction parameters, recoveries ranging from 64.6%-124.2% were obtained for the target analytes. The linear range for all analytes was 0.1-100 ng/mL with correlation coefficients higher than 0.99. Very low LODs ranging in 0.003-0.03 ng/mL were obtained. LOQs were in the range of 0.01-0.1 ng/mL for the nine target analytes. The accuracy that was expressed as mean relative error was within ±5.8% while the precision expressed as relative standard error was less than 5.9%. The combination of UA-LDS-DLLME with UPLC-MS/MS is a feasible, sensitive and rapid analytical approach for the determination of ARs in urine matrix, which is particularly suitable for clinical and forensic purposes.

CYP2C9 Genotype-Dependent Warfarin Pharmacokinetics: Impact of CYP2C9 Genotype on R- and S-Warfarin and Their Oxidative Metabolites.

Multiple factors can impact warfarin therapy, including genetic variations in the drug-metabolizing enzyme cytochrome P450 2C9 (CYP2C9). Compared with individuals with the wild-type allele, CYP2C9*1, carriers of the common *3 variant have significantly impaired CYP2C9 metabolism. Genetic variations in CYP2C9, the primary enzyme governing the metabolic clearance of the more potent S-enantiomer of the racemic anticoagulant warfarin, may impact warfarin-drug interactions. To establish a baseline for such studies, plasma and urine concentrations of R- and S-warfarin and 10 warfarin metabolites were monitored for up to 360 hours following a 10-mg warfarin dose in healthy subjects with 4 different CYP2C9 genotypes: CYP2C9*1/*1 (n = 8), CYP2C9*1/*3 (n = 9), CYP2C9*2/*3 (n = 3), and CYP2C9*3/*3 (n = 4). Plasma clearance of S-warfarin, but not R-warfarin, decreased multiexponentially and in a CYP2C9 gene-dependent manner: 56%, 70%, and 75% for CYP2C9*1/*3, CYP2C9*2/*3, and CYP2C9*3/*3 genotypes, respectively, compared with CYP2C9*1/*1, resulting in pronounced differences in the S:R ratio that identified warfarin-sensitive genotypes. CYP2C9 was the primary P450 enzyme contributing to S-warfarin metabolism and a minor contributor to R-warfarin metabolism. In the presence of a defective CYP2C9 allele, switching of warfarin metabolism to other oxidative pathways and P450 enzymes for the metabolic elimination of S-warfarin was not observed. The 10-hydroxywarfarin metabolites, whose detailed pharmacokinetics are reported for the first time, exhibited a prolonged half-life with no evidence of renal excretion and displayed elimination rate-limited kinetics. Understanding the impact of CYP2C9 genetics on warfarin pharmacokinetics lays the foundation for future genotype-dependent warfarin-drug interaction studies.

Repeated Oral or Subcutaneous LMWH Has similar Antithrombotic Activity in a Rat Venous Thrombosis Model: Antithrombotic Activity Correlates With Heparin on Endothelium When Orally Administered.

Low-molecular-weight heparins (LMWHs) endure as important drugs for thromboprophylaxis. Although clinical use relies on the subcutaneous (SC) route, our previous studies show that single-dose orally administered LMWHs have antithrombotic activity. Since thromboprophylaxis requires long-term treatment, we examined antithrombotic effects of subacute oral LMWHs in a rat venous thrombosis model and compared results to SC or single-dose oral administration. We measured LMWH in endothelium and plasma, weight change and complete blood counts (CBC). Oral LMWH tinzaparin (3 × 0.1 mg/kg/12 or 24 hours) or reviparin (3 × 0.025 mg/kg/24 hours) significantly decreased thrombosis compared to saline. In the subacute study (60 × 0.1 mg/kg/12 hours), oral or SC tinzaparin significantly reduced thrombosis compared to saline but not to single or 3 × 0.1 mg/kg/12 hours oral tinzaparin. Antithrombotic effects were similar between oral and SC administration. LMWH was found on endothelium following oral but not SC administration. Endothelial concentrations were significantly correlated with incidence of stable thrombi ( P = 0.021 and 0.04 for aortic and vena cava endothelium respectively, χ2 test) and total thrombi ( P = 0.003 for vena cava endothelium). Anti-Xa activity was significantly greater for oral or SC LMWH than saline and significantly greater for SC versus oral LMWH. Values for CBCs were within normal ranges (mean ± 2 SD). There was no evidence of bleeding. Weight gain was similar between groups. In conclusion, subacute oral and SC LMWH have similar antithrombotic effects. Antithrombotic activity with oral administration is correlated with endothelial LMWH concentrations but not with plasma anticoagulant activity.

Antithrombotic activity of oral administered low molecular weight fucoidan from Laminaria Japonica.

INTRODUCTION: Fucoidans extracted from brown algae have been documented to have excellent antithrombotic activity when administered by either intravenous or subcutaneous route in animal models. However, it is unknown if the fucoidans also have antithrombotic activity when administered orally, a highly desirable feature of oral antithrombotic agents. In the present study, we compared the oral absorption, bioavailability and antithrombotic activity of two fucoidan fractions from Laminaria japonica with different molecular weight by oral administration in an electricity induced arterial thrombosis model and the underlying molecular mechanisms. RESULTS AND CONCLUSIONS: After a single dose of oral administration, the fucoidan content in plasma and urine in rats was assessed using the reverse-phased HPLC analysis of 1-phenyl-3-methyl-5-pyrazolone (PMP)-labeled fucose. The fucose content in the low molecular weight (LMW) fucoidan-treated rats increased up to 2-fold and peaked at 15h, indicating that the LMW fucoidan had much better absorption and bioavailability than the MMW fucoidan in vivo. Oral administration of the LMW fucoidan at 400 and 800mg/kg for 30days inhibited the arterial thrombosis formation effectively induced by electrical shock in rats, accompanied by moderate anticoagulation activity, regulation on TXB2 and 6-keto-PGF1α, significant antiplatelet activity and effective fibrinolysis. The LMW fucoidan showed better oral absorption and antithrombotic activity in addition to different antithrombotic mechanisms compared to those of the medium molecular weight (MMW) fucoidan. Thus, the LMW fucoidan has a potential to become an oral antithrombotic agent.

Validation and Application of a Simple UHPLC-MS-MS Method for the Enantiospecific Determination of Warfarin in Human Urine.

A simple and rapid liquid chromatographic-tandem mass spectrometric method has been developed and validated for the enantiospecific determination of R- and S-warfarin in human urine. Warfarin enantiomers were extracted from urine using methyl tert-butyl ether. Chromatographic separation of warfarin enantiomers and the internal standard d5-warfarin was achieved using a Astec Chirobiotic V column with gradient mobile phase at a flow rate of 400 µL/min over 10 min. Detection was performed on a TSQ Quantum Ultra triple quadrupole mass spectrometer equipped with a heated electrospray ionization source. Analytes were detected in negative ionization mode using selected reaction monitoring. Calibration curves were linear with a correlation coefficient of ≥0.996 for both enantiomers over a concentration range of 5-500 ng/mL. The intra- and interday accuracy and precision for both analytes were within ±9.0%. Excellent extraction efficiency and negligible matrix effects were observed. The applicability of the method was demonstrated by successful measurement of warfarin enantiomers in urine of patients with kidney disease. The method is simple, accurate and reproducible and is currently being used to support warfarin pharmacokinetic studies.

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.

[Simultaneous qualitative and quantitative determination of seven anticoagulant rodenticides in whole blood and urine samples using on-line solid phase extraction with liquid chromatography-linear ion trap mass spectrometry].

A new and sensitive analytical method has been developed for the simultaneous determination of seven anticoagulant rodenticides in whole blood and urine samples by liquid chromatography-linear ion trap mass spectrometry (LC-LIT/MS) with on-line solid phase extraction (on-line SPE). The samples were treated with acetonitrile, followed by dilution, centrifugation, and filtration. The resulting solution was injected into the LC system directly and processed by on-line SPE column for enrichment and purification. Separation was performed on a C18 column with mixed mobile phases of methanol and 0.02 mol/L ammonium acetate aqueous solution for gradient elution. The analytes were detected by the mass spectrometer with electrospray ionization (ESI) in negative mode. MS2 full scan signals of the target parent ions within the locked retention time window were recorded. Self-built database searching was performed for qualitative confirmation, and MS2 fragment ions with high sensitivity and specificity were selected for quantification. Simultaneous qualitative and quantitative analyses of the seven rodenticides were achieved in this way. Good linearities were obtained within the investigated mass concentration ranges of the seven rodenticides, with r2 ≥ 0.9958 in blood and r2 ≥ 0.9946 in urine. The LODs varied from 0.02 ng/mL to 1.00 ng/mL, and the LOQs varied from 0.10 ng/mL to 4.00 ng/mL. The recoveries at three spiked levels in blood and urine samples ranged from 81.0% to 113.9%, with RSDs of 0.1%-6.2% (n = 6). The developed method is simple, sensitive, and can be used for the rapid detection and accurate quantification of the seven anticoagulant rodenticides in whole blood and urine samples.

Rapid determination of rivaroxaban in human urine and serum using colloidal palladium surface-assisted laser desorption/ionization mass spectrometry.

RATIONALE: Rivaroxaban is a new anticoagulant drug that has recently been introduced for clinical applications. To ensure optimum efficacy while minimizing the risk of toxicity and other adverse effects, a simple and sensitive analytical procedure for monitoring the concentration of rivaroxaban in biological fluids is required. METHODS: Rivaroxaban was extracted from aqueous solutions by dispersive liquid-liquid microextraction (DLLME). Detection of rivaroxaban was achieved through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using colloidal palladium as the SALDI matrix. RESULTS: The calibration curve for rivaroxaban in aqueous solutions was linear over the concentration range from 5 to 500 nM. The limit of detection (LOD) for rivaroxaban at a signal-to-noise ratio of 3 was 2 nM. With a sample-to-extract volume ratio of 200, the enrichment factors were calculated to be 141. This method was successfully applied for the determination of rivaroxaban in human urine and serum samples. The LODs for rivaroxaban in urine and serum were calculated to be 6 nM and 60 nM, respectively. CONCLUSIONS: The analysis speed, together with the ease of operation and high sensitivity, allows SALDI-MS method to be particularly suitable for the high-throughput screening of rivaroxaban levels in human urine and serum samples.

Synthesis of molecularly imprinted polypyrrole as an adsorbent for solid-phase extraction of warfarin from human plasma and urine.

The aim of this work was to develop a method for the clean-up and preconcentration of warfarin from biological sample employing a new molecularly imprinted polymer (MIP) as a selective adsorbent for solid-phase extraction (SPE). This MIP was synthesized using warfarin as a template, pyrrole as a functional monomer and vinyl triethoxysilane as a cross-linker. The molar ratio of 1:4:20 (template-functional monomer-cross-linker) showed the best results. Nonimprinted polymers (NIPs) were prepared and treated with the same method, but in the absence of warfarin. The prepared polymer was characterized by Fourier transmission infrared spectrometry and scanning electron microscopy. An adsorption process (SPE) for the removal of warfarin using the fabricated MIPs and NIPs was evaluated under various conditions. Effective parameters on warfarin extraction, for example, type and volume of elution solvent, pH of sample solution, breakthrough volume and maximum loading capacity, were studied. The limits of detection were in the range of 0.0035-0.0050 µg mL(-1). Linearity of the method was determined in the range of 0.0165-10.0000 µg mL(-1) for plasma and 0.0115-10.0000 µg mL(-1) for urine with coefficients of determination (R(2)) ranging from 0.9975 to 0.9985. The recoveries for plasma and urine samples were >95%.

Pharmacokinetics, pharmacodynamics and food effect of LB30870, a novel direct thrombin inhibitor, after single oral doses in healthy men.

1. The safety, tolerability, pharmacokinetics, pharmacodynamics, and food effect of LB30870, a new selective thrombin inhibitor, were studied in 16 healthy men. 2. A double-blind, placebo-controlled single ascending dose study was done at oral doses of 5, 15, 30, 60, 120, and 240 mg under fasting conditions. An open, randomized, balanced cross-over food effect study was done at 60 mg dose. Plasma and urinary concentrations were measured up to 48 h post-dose. Coagulation and thrombin activity markers were measured at selected time points. 3. Cmax of LB30870 was at 1.3-3.0 h post-dose with a mean apparent terminal half-life (t1/2) of 2.8-4.1 h. AUC after doses above 15 mg appeared greater than dose-proportional. In fed state, AUC showed 80% reduction relative to fasting condition. 4. At doses 60 and 120 mg, peak activated partial thromboplastin time (aPTT) increased by 1.5- and 2-fold, respectively, from baseline. The aPTT and international normalized ratio (INR) were concentration-dependent, with less within-individual variability than ecarin clotting time (ECT), prothrombin time (PT), or thrombin time (TT). 5. Single oral doses of LB30870 up to 240 mg were well tolerated. The food effect must be overcome if LB30870 is to be used as an oral anti-coagulant.

Clinical factors associated with negative urinary antigen tests implemented for the diagnosis of community-acquired pneumococcal pneumonia in adult patients.

OBJECTIVE: This study investigated clinical factors associated with negative urinary antigen tests (UAT) implemented for the diagnosis of pneumococcal community-acquired pneumonia (CAP) in adult patients. SUBJECTS AND METHODS: We reviewed the medical records of 755 adult patients who completed the UAT in our hospital between 2009 and 2012. Of these, we evaluated 63 patients with bacteriologically confirmed definite pneumococcal CAP (33 were UAT-positive, and 30 were UAT-negative). RESULTS: There was no significant difference between the UAT-positive and the UAT-negative patients regarding age, dehydration, respiratory failure, orientation, blood pressure (ADROP) score (the CAP severity score proposed by the Japanese Respiratory Society), gender, white blood cell counts, liver/kidney function tests, or urinalysis. However, serum C-reactive protein (CRP) concentrations were 31% lower in the UAT-negative patients than in the UAT-positive patients (p = 0.02). Furthermore, the prothrombin time-international normalized ratio was 50% higher in the UAT-negative patients than in the UAT-positive patients, although the difference did not reach statistical significance (p = 0.06). The prevalence of comorbidities was similar in both UAT-positive and UAT-negative patients. However, warfarin had been prescribed in 8 (27%) of the UAT-negative patients compared to only 1 (3%) of the UAT-positive patients (odds ratio = 11.6; p = 0.01). CONCLUSIONS: These results suggested that low serum CRP concentrations and the use of warfarin increased the possibility with which false-negative UAT results occurred in these patients with pneumococcal CAP.

Association of the urine homocysteine/creatinine ratio to proinflammatory cytokine, natural anticoagulant, and nitric oxide levels in cerebrovascular disease.

This study investigated the relationship between the urine homocysteine/creatinine (uHcy/Cr) ratio and the levels of natural anticoagulants, proinflammatory cytokines, and nitric oxide (NOx) metabolites in cerebrovascular diseases. No significant differences were observed in protein C, protein S, and antithrombin III levels among subjects with serum Hcy (sHcy) >15.0 µmol/L and ≤15.0 µmol/L. However, subjects with a uHcy/Cr ratio >14.8 µmol/g Cr showed significant differences in the levels of the corresponding parameters than those with uHcy/Cr ratio ≤14.8 µmol/g Cr. The sensitivity and specificity of the sHcy level at a cutoff of 15.0 µmol/L were 32.6% and 85.7%, respectively, with a positive predictive value of 69.5%. In contrast, those values for the uHcy/Cr ratio at a cutoff of 14.8 µmol/g Cr were 55.1% and 91.4% with a positive predictive value of 86.5%. The uHcy/Cr ratio correlated more closely with protein C, antithrombin III, TNF-α, and NOx levels than did sHcy concentrations. In short, the uHcy/Cr ratio has a significant relationship with anticoagulation- and inflammation-related parameters. A measurement of the uHcy/Cr ratio may provide helpful information for assessing patients with cerebrovascular diseases.

Effect of oral administration of unfractionated heparin (UFH) on coagulation parameters in plasma and levels of urine and fecal heparin in dogs.

The effects of heparin administration, by the oral route, were evaluated in dogs. In single and multiple dose studies (single 7.5 mg/kg, multiple 3 × 7.5 mg/kg per 48 h), plasma, urine, and fecal samples were collected at various times up to 120 h after oral administration of unfractionated heparin. Changes in plasma and urine anti-Xa activity, plasma and urine anti-IIa activity, plasma activated partial thromboplastin time (APTT) and antithrombin (ATIII), and chemical heparin in urine and feces were examined with time. There was support for heparin absorption, with significant differences in APTT, heparin in plasma as determined by anti-Xa activity (Heptest) in the single dose study and plasma anti-Xa activity, anti-IIa activity and ATIII; and chemical heparin in urine in the multiple dose study. No clinical evidence of bleeding was detected in any dog during the studies. Oral heparin therapy may be applicable for thromboembolic disease in animals. Further studies are warranted to determine the effects of oral heparin at the endothelial level in the dog.

Les effets de l'administration d'héparine, par voie orale, furent évalués chez des chiens. Dans des études suite à une administration unique et à des administrations multiples (unique 7,5 mg/kg; multiples 3 × 7,5 mg/kg par 48 h), des échantillons de plasma, d'urine et de fèces furent prélevés à différents intervalles jusqu'à 120 h suivant l'administration orale d'héparine non-fractionnée. On examina dans le temps les changements de l'activité anti-Xa dans le plasma et l'urine, l'activité anti-IIa dans le plasma et dans l'urine, le temps de thromboplastine partielle (APTT) et d'antithrombine (ATIII) activé par le plasma, et l'héparine dans l'urine et les fèces. Il y a évidence d'absorption d'héparine, avec des différences significatives de l'APTT, de l'héparine plasmatique tel que déterminé par l'activité anti-Xa (Heptest) dans l'étude à dose unique et dans l'activité anti-Xa plasmatique, l'activité anti-IIa et l'ATIII; et de l'héparine chimique dans l'urine lors de l'étude à doses multiples. Aucune évidence clinique de saignement ne fut détectée chez les chiens au courant des études. Une thérapie orale à l'héparine pourrait être applicable pour des maladies thromboemboliques chez les animaux. Des études supplémentaires sont nécessaires afin de déterminer les effets d'administration d'héparine orale au niveau endothélial chez les chiens.(Traduit par Docteur Serge Messier).

Novel methods for assessing oral direct factor Xa and thrombin inhibitors: use of point-of-care testing and urine samples.

Rivaroxaban and dabigatran are new oral anticoagulants (NOACs) that inhibit directly factor Xa and thrombin, respectively. These NOACs effectively prevent thromboembolic complications using fixed doses without the need for dose adjustment according to laboratory results. About 60% of rivaroxaban is cleared from circulation by glomerular filtration, 30% of which is excreted as active drug. About 80% of dabigatran is excreted into urine as active compound. Accordingly, both NOACs can be determined in urine by means of chromatographic methods. Only a few laboratories are able to perform such methods, and results are not available within short time frames. New methods have to be developed to obtain results within minutes and possibly as point-of-care (POC) techniques. This testing may be useful for special patient populations such as those with acute deterioration of renal function due to any disease, before surgical interventions, during unexpected bleeding or thrombotic episodes while on therapy with NOACs, the oldest and youngest populations, pregnancy, suspicion of overdose and intoxication, and to determine adherence to therapy. Here we describe results of a POC qualitative assay using urine samples from patients on treatment with dabigatran and rivaroxaban.

Measurement of the new anticoagulants.

New oral anticoagulants are given at fixed daily doses without laboratory dose adjustment for prevention of venous thromboembolism following elective total knee- and hip replacement, for treatment and prevention of recurrent events of acute venous thromboembolism, and for prevention of embolic events in atrial fibrillation. However, it may be necessary to determine the anticoagulant effect of new oral anticoagulants in special patient populations such as in elderly, for renal impairment, before operation, bleeding or thrombotic episodes and to monitor self-compliance. Oral factor Xa and oral thrombin inhibitors influence dose dependently global and specific coagulation assays. Standardization of assays is currently undertaken. Determination of the new oral anticoagulants in serum samples would facilitate blood sampling and analysis from samples taken and stored for creatinine or other biochemical parameters. Point of care methods from plasma or urine for the new oral anticoagulants would improve patient care. First data demonstrate the feasibility of such assays in urine.