Vorapaxar in the Human Endotoxemia Model

Medical University of Vienna16 enrolled

Overview

Vorapaxar is a recently approved protease activated receptor - 1 (PAR-1) inhibitor. Platelet inhibition may also exert positive results on coagulation activation and may beneficially influence the inflammatory response. Since vorapaxar is the first available substance of a new class of platelet inhibitors its effects on the human coagulation system and the inflammatory response will be assessed in the well-established human endotoxemia model.

Vorapaxar is a novel platelet inhibitor inhibiting PAR-1. It is the first available substance of a new class of platelet inhibitors blocking the activation of platelets via thrombin or thrombin receptor activating peptides via PAR-1. As platelets contribute to the coagulation activation, i.e. by providing the surface for the assembly of the Tenase complex, and furthermore to the inflammatory response by releasing their stored granula containing promotors of both, inflammation and coagulation, we want to assess the effects of vorapaxar on these in the human endotoxemia model. Sixteen healthy volunteers will be included in this randomized, double-blind, placebo-controlled, single center, crossover trial with a washout period of 8 weeks. This wash out period was chosen based on the long elimination half-life of vorapaxar and to prevent any carry-over effects. After intake of 10mg vorapaxar (-24h) the degree of platelet inhibition will be assessed by whole bood aggregometry and, in case of insufficient platelet inhibition, subjects may receive another 10mg of vorapaxar. A bolus of 2ng/kg bodyweight lipopolysaccharide (LPS) will be infused and blood sampling will be performed at pre-defined time-points. After the washout-period the respective other treatment will be given to subjects.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

QUADRUPLE

Enrollment

Conditions

Healthy Volunteers

Interventions

VorapaxarDRUG

10mg-20mg vorapaxar to achieve \>80% thrombin-receptor activated peptide-6 (TRAP) induced platelet inhibition

PlaceboDRUG

LPSOTHER

2ng/kg Lipopolysaccharide as a bolus infusion

Eligibility

Sex: ALLMin age: 18 YearsMax age: 65 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * ≥18 years of age * ≥60 kg bodyweight * Normal findings in medical history and physical examination unless the investigator considers the abnormality to be clinically irrelevant * Normal laboratory values unless the investigator considers abnormalities to be clinically irrelevant * Willingness to comply with the trial's safety demands (to refrain from excessive sporting activities two weeks after Vorapaxar intake, i.e. full contact sports, climbing, mountain biking etc.) * Ability to understand the purpose and nature of the study, as well as the associated risks No planned surgeries or other medical interventions in the planned study period Exclusion Criteria: * Intake of any drugs that may interfere with the trial's endpoints or drugs (i.e. platelet inhibitors, anticoagulants, CYP3A4 inhibitors, NSAIDs, selective serotonin reuptake inhibitors, selective noradrenaline and serotonin reuptake inhibitors) * Positive results of HIV or hepatitis virology * Acute illness with systemic inflammatory reactions * Known allergies, hypersensitivities or intolerances to any of the used substances * Acute or recent bleeding episodes, increased risk of bleeding at the discretion of the investigator * History of stroke, transient ischemic attacks or intracerebral hemorrhage * Known coagulation or platelet disorders * Participation in an LPS trial within 6 weeks of the first study day * Severe liver or kidney dysfunction * Pregnancy or breastfeeding

Locations (1)

Department of Clinical Pharmacology, Medical University of Vienna

Vienna, Austria

Outcomes

Primary Outcomes

Changes in Prothrombin Fragments F1+2

prothrombin fragment F1+2 concentrations, individual maxima were compared between both study periods

Time frame: Time points for evaluation were: baseline, 0h, 2h, 4h, 6h, 24h

Secondary Outcomes

Protease Activated Receptor (PAR)-1 Expression on Platelets

Protease Activated Receptor (PAR)-1 expression on platelets was measured by flow cytometric analysis. The change in protease activated receptor (PAR)-1 expression over time was assessed. The ratio of protease activated receptor (PAR)-1 expression from baseline to 4h was the main parameter of interest and is presented here. Since the presented data are ratios, the arbitrary unit is "fold". Otherwise flow cytometric data is presented as "hits" during the analysis.

Time frame: Time points for evaluation were: baseline, 0h, 4h, 24h

Thrombin-Antithrombin Complexes

Thrombin-Antithrombin Complexes were quantified using commercially available "ELISA" assays. The individual maxima during the study periods were compared.

Time frame: Time points for evaluation were: baseline, 0h, 2h, 4h, 6h, 24h

Plasmin-Antiplasmin Complexes

Plasmin-Antiplasmin Complexes were quantified using commercially available "ELISA" assays. Individual maxima during both study periods were compared.

Time frame: Time points for evaluation were: baseline, 0h, 2h, 4h, 6h, 24h

E-Selectin

E-Selectin concentrations were quantified using commercially available "ELISA" assays, individual maxima were compared between both study periods

Time frame: Time points for evaluation were baseline, 2h, 4h, 6h, 24h after LPS administration

Von Willebrand Factor

Data from ClinicalTrials.gov

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