Rationale and design of a home-based trial using wearable sensors to detect asymptomatic atrial fibrillation in a targeted population: The mHealth Screening To Prevent Strokes (mSToPS) trial.

Efficient methods for screening populations for undiagnosed atrial fibrillation (AF) are needed to reduce its associated mortality, morbidity, and costs. The use of digital technologies, including wearable sensors and large health record data sets allowing for targeted outreach toward individuals at increased risk for AF, might allow for unprecedented opportunities for effective, economical screening. The trial's primary objective is to determine, in a real-world setting, whether using wearable sensors in a risk-targeted screening population can diagnose asymptomatic AF more effectively than routine care. Additional key objectives include (1) exploring 2 rhythm-monitoring strategies-electrocardiogram-based and exploratory pulse wave-based-for detection of new AF, and (2) comparing long-term clinical and resource outcomes among groups. In all, 2,100 Aetna members will be randomized 1:1 to either immediate or delayed monitoring, in which a wearable patch will capture a single-lead electrocardiogram during the first and last 2 weeks of a 4-month period beginning immediately or 4 months after enrollment, respectively. An observational, risk factor-matched control group (n = 4,000) will be developed from members who did not receive an invitation to participate. The primary end point is the incidence of new AF in the immediate- vs delayed-monitoring arms at the end of the 4-month monitoring period. Additional efficacy and safety end points will be captured at 1 and 3 years. The results of this digital medicine trial might benefit a substantial proportion of the population by helping identify and refine screening methods for undiagnosed AF.

Novel oral anticoagulants and reversal agents: Considerations for clinical development.

This white paper provides a summary of presentations and discussions that were held at an Anticoagulant-Induced Bleeding and Reversal Agents Think Tank co-sponsored by the Cardiac Safety Research Consortium and the US Food and Drug Administration (FDA) at the FDA's White Oak Headquarters on April 22, 2014. Attention focused on a development pathway for reversal agents for the novel oral anticoagulants (NOACs). This is important because anticoagulation is still widely underused for stroke prevention in patients with atrial fibrillation. Undertreatment persists, although NOACs, in general, overcome some of the difficulties associated with anticoagulation provided by vitamin K antagonists. One reason for the lack of a wider uptake is the absence of NOAC reversal agents. As there are neither widely accepted academic and industry standards nor a definitive regulatory policy on the development of such reversal agents, this meeting provided a forum for leaders in the fields of cardiovascular clinical trials and cardiovascular safety to discuss the issues and develop recommendations. Attendees included representatives from pharmaceutical companies; regulatory agencies; end point adjudication specialist groups; contract research organizations; and active, academically based physicians. There was wide and solid consensus that NOACs overall offer improvements in convenience, efficacy, and safety compared with warfarin, even without reversal agents. Still, it was broadly accepted that it would be helpful to have reversal agents available for clinicians to use. Because it is not feasible to do definitive outcomes studies demonstrating a reversal agent's clinical benefits, it was felt that these agents could be approved for use in life-threatening bleeding situations if the molecules were well characterized preclinically, their pharmacodynamic and pharmacokinetic profiles were well understood, and showed no harmful adverse events in early human testing. There was also consensus that after such approval, efforts should be made to augment the available clinical information until such time as there is a body of evidence to demonstrate real-world clinical outcomes with the reversal agents. No recommendations were made for more generalized use of these agents in the setting of non-life-threatening situations. This article reflects the views of the authors and should not be construed to represent FDA's views or policies.

Phase 0 study of the inhibition of cholesteryl ester transfer protein activity by JNJ-28545595 in plasma from normolipidemic and dyslipidemic humans.

OBJECTIVE: To assess and validate the application of a non-radioactive assay for cholesteryl ester transfer protein (CETP) activity in clinical samples. DESIGN AND METHODS: In this Phase 0 study, CETP activity was measured following addition of the CETP inhibitor JNJ-28545595 to plasma samples from normolipidemic and three subgroups of dyslipidemic subjects with differing lipid profiles. RESULTS: CETP activity was elevated in plasma samples from dyslipidemic subjects compared to normolipidemic subjects. Increased triglyceride levels correlated with decreased CETP inhibition. The assay was found to have good analytical precision and high throughput potential as required for clinical trial sample analysis. CONCLUSIONS: The results demonstrate that pharmacological inhibition of CETP is affected by the dyslipidemic nature of plasma samples. In addition, since the optimal degree of CETP inhibition for maximal cardiovascular benefit in patients is not known, this assay may be used to help define optimal dosing of CETP inhibitors.

Torcetrapib produces endothelial dysfunction independent of cholesteryl ester transfer protein inhibition.

OBJECTIVE: Torcetrapib, a prototype cholesteryl ester transfer protein (CETP) inhibitor with potential for decreasing atherosclerotic disease, increased cardiovascular events in clinical trials. The identified hypertensive and aldosterone-elevating actions of torcetrapib may not fully account for this elevated cardiovascular risk. Therefore, we evaluated the effects of torcetrapib on endothelial mediated vasodilation in vivo. METHODS AND RESULTS: In vivo endothelial mediated vasodilation was assessed using ultrasound imaging of acetylcholine-induced changes in rabbit central ear artery diameter. Torcetrapib, in addition to producing hypertension and baseline vasoconstriction, markedly inhibited acetylcholine-induced vasodilation. A structurally distinct CETP inhibitor, JNJ-28545595, did not affect endothelial function despite producing similar degrees of CETP inhibition and high-density lipoprotein elevation. Nitroprusside normalized torcetrapib's basal vasoconstriction and elicited dose-dependent vasodilation of norepinephrine preconstricted arteries in torcetrapib-treated animals, indicating torcetrapib did not impair smooth muscle function. CONCLUSIONS: Torcetrapib significantly impairs endothelial function in vivo, independent of CETP inhibition and high-density lipoprotein elevation. Given the well-documented association of endothelial dysfunction with cardiovascular disease and risk, this activity of torcetrapib may have contributed to increased cardiovascular risk in clinical trials.

Digital recruitment and enrollment in a remote nationwide trial of screening for undiagnosed atrial fibrillation: Lessons from the randomized, controlled mSToPS trial.

OBJECTIVES: The advent of large databases, wearable technology, and novel communications methods has the potential to expand the pool of candidate research participants and offer them the flexibility and convenience of participating in remote research. However, reports of their effectiveness are sparse. We assessed the use of various forms of outreach within a nationwide randomized clinical trial being conducted entirely by remote means. METHODS: Candidate participants at possibly higher risk for atrial fibrillation were identified by means of a large insurance claims database and invited to participate in the study by their insurance provider. Enrolled participants were randomly assigned to one of two groups testing a wearable sensor device for detection of the arrhythmia. RESULTS: Over 10 months, the various outreach methods used resulted in enrollment of 2659 participants meeting eligibility criteria. Starting with a baseline enrollment rate of 0.8% in response to an email invitation, the recruitment campaign was iteratively optimized to ultimately include website changes and the use of a five-step outreach process (three short, personalized emails and two direct mailers) that highlighted the appeal of new technology used in the study, resulting in an enrollment rate of 9.4%. Messaging that highlighted access to new technology outperformed both appeals to altruism and appeals that highlighted accessing personal health information. CONCLUSIONS: Targeted outreach, enrollment, and management of large remote clinical trials is feasible and can be improved with an iterative approach, although more work is needed to learn how to best recruit and retain potential research participants. TRIAL REGISTRATION: Clinicaltrials.govNCT02506244. Registered 23 July 2015.

Hemostatic effect of activated factor VII without promotion of thrombus growth in melagatran-anticoagulated primates.

INTRODUCTION: Pharmacological enhancement of coagulation using activated prothrombin complex concentrate (APCC) or activated factor VII (FVIIa) might be useful hemostatic approaches to bleeding emergencies during anticoagulant therapy. However, any such intervention should not increase thrombotic risk. We therefore investigated their hemostatic and prothrombotic potential during propagation of large arterial-type thrombin in anticoagulated baboons. MATERIALS AND METHODS: High dose melagatran, a competitive inhibitor of thrombin (0.6 mg/kg/h), or inactivated FVIIa (FVIIai), a competitive inhibitor of FVIIa (2 mg/kg) were used for anticoagulation. APCC or FVIIa were administered to melagatran-anticoagulated animals only. Primary hemostasis was assessed as template bleeding time (BT). Thrombus formation was quantified as fibrin deposition (FD) and platelet deposition (PLD) in synthetic vascular grafts that were deployed for 40 min into arteriovenous shunts. RESULTS: Melagatran (n=11) prolonged BT to 279% (95% CI +/-140%; P<0.019), reduced FD to 33% [+/-8%; P<0.001]; and PLD to 39% [+/-11%; P<0.001] of untreated controls. FVIIai (n=3) prolonged BT (222% [+/-51%; P<0.010]) without inhibiting thrombus propagation. APCC (n=10) reduced the antithrombotic effect of melagatran (FD 52% [+/-9%; P<0.002], PLD 61% [+/-17%; P=0.028] versus melagatran alone) at a dose (250 U/kg) that had no effect on the BT (327% [+/-150%; P=0.607]. Meanwhile, FVIIa (n=12) normalized the BT to 115% (+/-32%; P<0.05) at a dose (270 microg/kg) that was not yet prothrombotic (FD 26% [+/-4%; P<0.001], PLD 39% [+/-9%; P=0.970]). CONCLUSION: Administration of FVIIa during antithrombotic treatment with direct thrombin inhibitors might support hemostasis before promoting the intraluminal expansion of thrombi.

Antithrombotic effects of ximelagatran plus acetylsalicylic acid (ASA) and clopidogrel plus ASA in a human ex vivo arterial thrombosis model.

It was the objective of this study to compare the antithrombotic effects and bleeding profiles of the oral direct thrombin inhibitor ximelagatran, an anticoagulant, and the antiplatelet agent clopidogrel on top of steady-state acetylsalicylic acid (ASA) in a human arterial thrombosis model. Healthy male volunteers (n=62) received ASA (160 mg once daily), plus either clopidogrel for 6 days (loading dose 300 mg, then 75 mg once daily), or a single dose of ximelagatran (36 or 72 mg) on Day 6. Changes in total thrombus area (TTA) under low shear rate (LSR; 212 s(-1)) and high shear rate (HSR; 1690 s(-1)) conditions were measured, using the ex vivo Badimon perfusion chamber model pre-dose and 2 and 5 hours after dosing on Day 6, and capillary bleeding times (CBT) were determined. Ximelagatran plus ASA significantly reduced TTA under LSR and HSR, compared with ASA alone. Ximelagatran plus ASA reduced TTA more than clopidogrel plus ASA under LSR after 2 hours (36 mg, P=0.0011; 72 mg, P<0.0001) and 5 hours (72 mg, P=0.0057), and under HSR after 2 and 5 hours (72 mg, P<0.05). Compared with ASA alone, CBT was markedly prolonged by clopidogrel plus ASA (ratio 6.4; P<0.0001) but only slightly by ximelagatran plus ASA (72 mg ximelagatran, ratio 1.4; P=0.0010). Both drug combinations were well tolerated. Oral ximelagatran plus ASA has a greater antithrombotic effect in this human ex vivo thrombosis model and a less pronounced prolongation of bleeding time than clopidogrel plus ASA.

Effects of ximelagatran, an oral direct thrombin inhibitor, r-hirudin and enoxaparin on thrombin generation and platelet activation in healthy male subjects.

OBJECTIVES: The effects of ximelagatran, an oral direct thrombin inhibitor (DTI), recombinant hirudin (r-hirudin) and enoxaparin on thrombin generation and platelet activation were studied in humans. BACKGROUND: Recombinant hirudin (parenteral DTI) and enoxaparin (low molecular weight heparin) have been demonstrated to be clinically effective in acute coronary syndromes. Ximelagatran is currently under investigation for the prevention and treatment of thromboembolism. The shed blood model allows for the study of thrombin generation and platelet activation in humans in vivo. METHODS: This was an open-label, parallel-group study involving 120 healthy male volunteers randomized to receive one of three oral doses of ximelagatran (15, 30 or 60 mg), r-hirudin (intravenous) or enoxaparin (subcutaneous) at doses demonstrated to be clinically effective in acute coronary syndromes, or to serve as a control. Thrombin generation (prothrombin fragment 1+2 [F1+2] and thrombin-antithrombin complex [TAT]) and platelet activation (beta-thromboglobulin [beta-TG]) biomarkers were studied using a shed blood model involving blood collection from skin incisions made using standardized bleeding time devices. RESULTS: Oral ximelagatran, intravenous r-hirudin and subcutaneous enoxaparin rapidly and significantly (p < 0.05) decreased F1+2, TAT and beta-TG levels in shed blood, indicating inhibition of thrombin generation and platelet activation. Statistically significant concentration (melagatran, the active form of ximelagatran)-response relationships for F1+2 (p = 0.005), TAT (p = 0.005) and beta-TG (p < 0.001) levels, with IC(50)s of 0.376 (F1+2), 0.163 (TAT) and 0.115 (beta-TG) micromol/l, were detected. Melagatran showed dose-proportional pharmacokinetics with low variability. All drugs were well tolerated. CONCLUSIONS: Oral administration of the DTI ximelagatran resulted in a rapid inhibition of both thrombin generation and platelet activation in a concentration-dependent manner using a human shed blood model. The inhibition of thrombin generation by 60 mg ximelagatran was comparable to that observed with doses of r-hirudin and enoxaparin demonstrated to be effective for the treatment of acute coronary syndromes.

Inhibition of thrombin generation by the oral direct thrombin inhibitor ximelagatran in shed blood from healthy male subjects.

Ximelagatran, an oral direct thrombin inhibitor, whose active form is melagatran, was studied using a model of thrombin generation in humans. Healthy male volunteers (18 per group) received ximelagatran (60 mg p.o.), dalteparin (120 IU/kg s.c.) or a control (water p.o.). Shed blood, collected after incision of the forearm with standardised bleeding time devices at pre-dose, and at 2, 4 and 10 h post-dosing, was analysed for markers of thrombin generation. Statistically significant reductions (p < 0.05) in levels of prothrombin fragment 1+2 (F1+2) and thrombin-antithrombin complex (TAT) in shed blood were detected at 2 and 4 h post-dosing in both the ximelagatran and dalteparin groups. Shed blood F1+2 and TAT levels had returned to pre-dose levels at 10 h post-dosing. Using a shed blood model, we demonstrate that the reversible thrombin inhibitor melagatran and, therefore, oral administration of ximelagatran, inhibits thrombin generation in humans after acute activation of coagulation.

Effect of recombinant factor VIIa on melagatran-induced inhibition of thrombin generation and platelet activation in healthy volunteers.

The objectives were to investigate whether activation of the extrinsic coagulation cascade by recombinant factor VIIa (rFVIIa) reverses the inhibition of thrombin generation and platelet activation by melagatran, the active form of the oral direct thrombin inhibitor ximelagatran. In a single-blind, randomized, parallel-group study, volunteers (20 per group) received a 5-hour intravenous (i.v.) infusion to achieve steady-state melagatran plasma concentrations of approximately 0.5 micromol/L, with a single i.v. bolus of rFVIIa (90 microg/kg) or placebo at 60 minutes. Prothrombin fragment 1+2, thrombin-anti-thrombin complex, fibrinopeptide A, beta-thromboglobulin, and thrombin-activatable fibrinolysis inhibitor were quantified for venous and shed blood. Activated partial thromboplastin time (APTT), prothrombin time (PT), endogenous thrombin potential, thrombus precursor protein (TpP), and plasmin-alpha(2)-antiplasmin complex concentrations were determined in venous blood. Shed blood volume was measured. Melagatran reduced markers of thrombin generation and platelet activation in shed blood and prolonged APTT. rFVIIa increased FVIIa activity, PT, and TpP in venous blood. All other parameters were unaffected. In conclusion, rFVIIa did not reverse the anticoagulant effects of high constant concentrations of melagatran. However, the potential value of higher, continuous or repeated doses of rFVIIa or its use with lower melagatran concentrations has not been excluded.

No influence of obesity on the pharmacokinetics and pharmacodynamics of melagatran, the active form of the oral direct thrombin inhibitor ximelagatran.

BACKGROUND: Ximelagatran, an oral direct thrombin inhibitor, is currently in clinical development for the prevention and treatment of thromboembolic disease. Following oral administration, ximelagatran undergoes rapid bioconversion to its active form, melagatran, via two minor intermediates. Obesity, defined as body mass index (BMI) >30 kg/m(2), is a recognised risk factor for thrombosis. There is potential for differences in the pharmacokinetics and pharmacodynamics of drugs administered to obese versus non-obese patients, and some drugs may require alternative administration strategies in obese patients. OBJECTIVE: To investigate the effect of obesity on the pharmacokinetics and pharmacodynamics of melagatran after oral administration of ximelagatran. DESIGN AND PARTICIPANTS: This was an open-label, single-dose, group-matched study in which obese subjects (BMI 32-39 kg/m(2); six male and six female; age 21-40 years) were matched by sex and age (+/-2 years) with non-obese subjects (BMI 21-26 kg/m(2); six male and six female; aged 21-39 years). Each subject received a single oral dose of ximelagatran 24mg. Blood samples for determination of plasma concentrations of melagatran and activated partial thromboplastin times (APTT; a marker of melagatran pharmacodynamics) were collected up to 12 hours after administration. RESULTS: There were no statistically significant differences in the pharmacokinetic properties of melagatran between obese and non-obese subjects. Values of area under the melagatran plasma concentration-time curve, maximum plasma concentration (C(max)), time at which C(max) occurred and terminal elimination half-life were approximately 1 micromol. h/L, 0.2 micromol/L, 2 hours and 3 hours in both obese and non-obese subjects, respectively. In addition, there was no statistically significant difference between the obese and non-obese subjects in the amount of ximelagatran, melagatran or the minor intermediates ethyl-melagatran and melagatran hydroxyamidine excreted in urine. When relating the prolongation of APTT ratio to the square root of plasma concentration of melagatran and obesity status (no/yes), no statistically significant interaction between plasma concentration and obesity status was observed. Ximelagatran was well tolerated in both obese and non-obese subjects, and no bleeding events or serious adverse events occurred. CONCLUSIONS: No differences in the pharmacokinetics or pharmacodynamics of melagatran were detected between obese and non-obese subjects after oral administration of ximelagatran, suggesting that dose adjustment of ximelagatran in obesity (BMI up to 39 kg/m(2)) is not necessary.

No pharmacokinetic or pharmacodynamic interaction between digoxin and the oral direct thrombin inhibitor ximelagatran in healthy volunteers.

The interaction potential of digoxin and ximelagatran, an oral direct thrombin inhibitor being developed for the prevention and treatment of thromboembolic disease, was investigated in this randomized, double-blind, 2-way crossover study. On 2 separate occasions, healthy female and male volunteers (n = 16) received ximelagatran 36 mg or placebo twice daily for 8 days separated by a 4- to 14-day washout period. All volunteers received a single oral dose of digoxin 0.5 mg on day 4 of both study periods. No interaction between ximelagatran and digoxin was detected in the pharmaco-kinetic parameters (using a 90% confidence interval [CI] of least squares mean estimate ratios), including melagatran (the active form of ximelagatran) AUC(tau) and C(max) and digoxin AUC(t) and C(max). Digoxin did not alter the melagatran-induced prolongation of the activated partial thromboplastin time, and both drugs were well tolerated when administered in combination. In conclusion, no pharmacokinetic or pharmacodynamic interaction between digoxin and ximelagatran was observed in this study.

The pharmacokinetics and pharmacodynamics of ximelagatran, an oral direct thrombin inhibitor, are unaffected by a single dose of alcohol.

Ximelagatran-a direct thrombin inhibitor rapidly converted to its active form, melagatran, after oral administration-is being developed for the prevention and treatment of thromboembolic disease. The pharmacokinetics, pharmacodynamics, and tolerability/safety of ximelagatran following a single 36-mg oral dose of ximelagatran +/- a single oral dose of alcohol (0.5 and 0.6 g ethanol/kg to women and men, respectively) were assessed in a randomized, open-label, two-way crossover study (n = 26). The 90% confidence intervals (CIs) and least squares mean estimates for the ratio of ximelagatran plus alcohol to ximelagatran alone for melagatran AUC (1.04 [90% CI = 1.00-1.08]) and C(max) (1.08 [90% CI = 1.03-1.14]) fell within the bounds demonstrating no interaction. Alcohol did not alter the melagatran-induced prolongation of the activated partial thromboplastin time or the good tolerability/safety profile of ximelagatran. In conclusion, the pharmacokinetics, pharmacodynamics, and tolerability/safety of oral ximelagatran were not affected by alcohol.

No pharmacokinetic or pharmacodynamic interaction between atorvastatin and the oral direct thrombin inhibitor ximelagatran.

In this randomized, 2-way crossover study, the potential for interaction was investigated between atorvastatin and ximelagatran, an oral direct thrombin inhibitor. Healthy female and male volunteers (n = 16) received atorvastatin 40 mg as a single oral dose and, in a separate study period, ximelagatran 36 mg twice daily for 5 days plus a 40-mg oral dose of atorvastatin on the morning of day 4. In the 15 subjects completing the study, no pharmacokinetic interaction was detected between atorvastatin and ximelagatran for all parameters investigated, including melagatran (the active form of ximelagatran) area under the plasma concentration versus time curve (AUC) and maximum plasma concentration, atorvastatin acid AUC, and AUC of active 3-hydroxy-3-methyl-glutaryl-coenzyme-A (HMG-CoA) reductase inhibitors. Atorvastatin did not alter the melagatran-induced prolongation of the activated partial thromboplastin time, and both drugs were well tolerated when administered in combination. In conclusion, no pharmacokinetic or pharmacodynamic interaction between atorvastatin and ximelagatran was observed in this study.

A pharmacokinetic study of the combined administration of amiodarone and ximelagatran, an oral direct thrombin inhibitor.

The oral direct thrombin inhibitor ximelagatran is being developed for the prevention and treatment of thromboembolism. This single-blind, randomized, placebo-controlled, parallel-group study investigated the potential for the interaction of ximelagatran (36 mg every 12 hours for 8 days, measured as its active form melagatran in blood) and amiodarone (single 600-mg oral dose on day 4) in healthy male subjects (n = 26). For amiodarone + ximelagatran versus amiodarone + placebo, geometric mean ratios (90% confidence intervals for amiodarone AUC(0-120) and C(max) were 0.87 (0.69-1.08) and 0.86 (0.66-1.11), respectively. For desethylamiodarone, the principal metabolite of amiodarone, the corresponding ratios were 1.00 (0.89-1.12) for AUC(0-120) and 0.92 (0.77-1.09) for C(max). The geometric mean ratios (90% confidence intervals) for ximelagatran + amiodarone versus ximelagatran were 1.21 (1.17-1.25) for melagatran AUC(0-12) and 1.23 (1.18-1.28) for melagatran C(max). These confidence intervals were within or only slightly outside the interval, suggesting no interaction (0.8-1.25 for the effect of amiodarone on melagatran and 0.7-1.43 for the effect of melagatran on amiodarone or desethylamiodarone). Amiodarone did not affect the concentration-effect relationship of melagatran on activated partial thromboplastin time. Ximelagatran was well tolerated when coadministered with a single dose of amiodarone. Evaluation of the safety of the combination is needed to confirm that the relatively small pharmacokinetic changes in this study are of no clinical significance.

The inhibitory effect of melagatran, the active form of the oral direct thrombin inhibitor ximelagatran, compared with enoxaparin and r-hirudin on ex vivo thrombin generation in human plasma.

INTRODUCTION: The effect of the oral direct thrombin inhibitor (DTI) ximelagatran (Exanta, AstraZeneca) on the endogenous thrombin potential (ETP) of activated plasma was investigated ex vivo using a thrombin generation assay and compared with recombinant (r)-hirudin and enoxaparin. MATERIALS AND METHODS: 120 healthy male volunteers were randomized to one of six treatment groups (n=20 in each): oral ximelagatran (15, 30, or 60 mg), intravenous r-hirudin (0.4 mg/kg bolus, 0.15 mg/kg/h infusion for 2 h, followed by 0.075 mg/kg/h infusion for 2 h), subcutaneous enoxaparin (100 IU/kg), or control (tap water administered orally). Venous blood was collected predose and at 2, 4, and 10 h postdosing. Thrombin generation was triggered by the addition of tissue factor to platelet-poor plasma, and the ETP and time to peak thrombin generation were measured. RESULTS AND CONCLUSIONS: A significant and dose-dependent reduction in ETP was observed 2 and 4 h after the administration of ximelagatran 30 mg (70.3% of predose, 95% confidence intervals 63.0-78.5, P<0.0001 at 2 h) and 60 mg (49.8%, 43.2-57.4, P<0.0001 at 2 h), r-hirudin (19.5%, 10.1-37.6, P<0.0001 at 2 h), and enoxaparin (34.2%, 21.4-54.7, P<0.0001 at 2 h). Ximelagatran (30 mg, 3.79 min, 3.52-4.08 at 2 h), r-hirudin (6.23 min, 4.93-7.86 at 2 h), and enoxaparin (4.68 min, 3.30-6.64 at 2 h) also delayed the lag phase before the thrombin generation burst compared to placebo (2.92 min, 2.71-3.25 at 2 h). The oral DTI ximelagatran, in its active form melagatran, is a potent thrombin inhibitor that efficiently decreases ETP and delays the generation of thrombin in plasma in this ex vivo model.

Bioequivalence of ximelagatran, an oral direct thrombin inhibitor, as whole or crushed tablets or dissolved formulation.

OBJECTIVE: To investigate whether crushed or dissolved tablets of the oral direct thrombin inhibitor ximelagatran are bioequivalent to whole tablet administration. Ximelagatran is currently under development for the prevention and treatment of thromboembolic disorders. RESEARCH DESIGN AND METHODS: This was an open-label, randomised, three-period, three-treatment crossover study in which 40 healthy volunteers (aged 20-33 years) received a single 36-mg dose of ximelagatran administered in three different ways: I swallowed whole, II crushed, mixed with applesauce and ingested and III dissolved in water and administered via nasogastric tube. RESULTS: The plasma concentrations of ximelagatran, its intermediates and the active form melagatran were determined. Ximelagatran was rapidly absorbed and the bioavailability of melagatran was similar after the three different administrations, fulfilling the criteria for bioequivalence. The mean area under the plasma concentration-versus-time curve (AUC) of melagatran was 1.6 micromol.h/L (ratio 1.01 for treatment II/I and 0.97 for treatment III/I), the mean peak concentration (C(max)) was 0.3 micromol/L (ratio 1.04 for treatment II/I and 1.02 for treatment III/I) and the mean half-life (t(1/2)) was 2.8 h for all treatments. The time to C(max) (t(max)) was 2.2h for the whole tablet and approximately 0.5 h earlier when the tablet was crushed or dissolved (1.7-1.8 h), due to a more rapid absorption. The study drug was well tolerated as judged from the low incidence and type of adverse events reported. CONCLUSION: The present study showed that the pharmacokinetics (AUC and C(max)) of melagatran were not significantly altered whether ximelagatran was given orally as a crushed tablet mixed with applesauce or dissolved in water and given via nasogastric tube.

Effects of melagatran, the active form of the oral direct thrombin inhibitor ximelagatran, and dalteparin on the endogenous thrombin potential in venous blood from healthy male subjects.

The effect of the oral direct thrombin inhibitor ximelagatran and its active form, melagatran, on thrombin generation was investigated in vitro and ex vivo using a thrombin generation assay. In-vitro thrombin generation was triggered in human platelet-poor plasma by the addition of tissue factor, and the endogenous thrombin potential (ETP) was measured. The ETP IC(50) values for melagatran and the low-molecular-weight heparin dalteparin were 0.44 micromol/l and 0.06 IU/ml, respectively. In contrast to dalteparin, melagatran increased the time-to-thrombin peak in a concentration-dependent manner. ETP was also studied ex vivo in platelet-poor plasma collected from healthy male subjects (n = 54) at pre-dose and 2 h post-dose, with ximelagatran (60 mg) orally, dalteparin (120 IU/kg) subcutaneously, or control (water) orally. After ximelagatran or dalteparin administration, the time-to-thrombin peak was prolonged by 41 and 95%, and the ETP was decreased by 61 and 77%, respectively. Thus, melagatran, the active form of the oral direct thrombin inhibitor ximelagatran, efficiently delays and inhibits the generation of thrombin in plasma both in vitro and ex vivo.

Rivaroxaban crushed tablet suspension characteristics and relative bioavailability in healthy adults when administered orally or via nasogastric tube.

PURPOSE: Because some patients have difficulty swallowing a whole tablet, we investigated the relative bioavailability of a crushed 20 mg rivaroxaban tablet and of 2 alternative crushed tablet dosing strategies. METHODS: Stability and nasogastric (NG) tube adsorption characteristics of a crushed rivaroxaban tablet were assessed. Then, in 55 healthy adults, relative bioavailability of rivaroxaban administered orally as a whole tablet (Reference [Whole-Oral]), crushed tablet in applesauce suspension (Crushed-Oral), or crushed tablet in water suspension via NG tube (Crushed-NG) were determined. RESULTS: There were no significant changes in mean percent of non-degraded rivaroxaban recovered over 4 hours from crushed tablet suspensions (>98.4% recovery across all suspensions and time points) or after NG tube exposure (recovery: 99.1% for silicone and 98.9% for polyvinyl chloride NG tubes). Relative bioavailability was similar between Crushed-Oral and Reference dosing (Cmax and AUC∞ were within the 80-125% bioequivalence limits). Relative bioavailability was also similar between the Crushed-NG and Reference dosing (AUC∞ was within bioequivalence limits; Cmax [90% CI range: 78.5-85.8%] was only slightly below the 80% lower bioequivalence limit). CONCLUSIONS: A crushed rivaroxaban tablet was stable and when administered orally or via NG tube, displayed similar relative bioavailability compared to a whole tablet administered orally.

Rivaroxaban: a novel oral anticoagulant for the prevention and treatment of several thrombosis-mediated conditions.

The development of rivaroxaban (XARELTO®) is an important new medical advance in the field of oral anticoagulation. Thrombosis-mediated conditions constitute a major burden for patients, healthcare systems, and society. For more than 60 years, the prevention and treatment of these conditions have been dominated by oral vitamin K antagonists (such as warfarin) and the injectable heparins. Thrombosis can lead to several conditions, including deep vein thrombosis, pulmonary embolism, myocardial infarction, stroke, and/or death. Prevention and treatment of thrombosis with an effective, convenient-to-use oral anticoagulant with a favorable safety profile is critical, especially in an aging society in which the risk of thrombosis, and the potential for bleeding complications, is increasing. Rivaroxaban acts to prevent and treat thrombosis by potently inhibiting coagulation Factor Xa in the blood. Factor Xa converts prothrombin to thrombin, which initiates the formation of blood clots by converting fibrinogen to clot-forming fibrin and leads to platelet activation. After a large and novel clinical development program in over 75,000 patients to date, rivaroxaban has received approval for multiple indications in the United States, European Union, and other countries worldwide to prevent and treat several thrombosis-mediated conditions. This review will highlight some of the unique aspects of the rivaroxaban development program.