Vorapaxar in the Human Endotoxemia Model

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Medical University of Vienna

Status and phase

Phase 4


Healthy Volunteers


Other: LPS
Drug: Vorapaxar
Drug: Placebo

Study type


Funder types




Details and patient eligibility


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.

Full description

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.


16 patients




18 to 65 years old


Accepts Healthy Volunteers

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

Trial design

Primary purpose




Interventional model

Crossover Assignment


Quadruple Blind

16 participants in 2 patient groups, including a placebo group

Experimental group
subjects will be treated with 4x2,5mg vorapaxar in empty lactose-starch capsules
Drug: Vorapaxar
Other: LPS
Placebo Comparator group
subjects will be treated with 4 empty lactose-starch capsules
Drug: Placebo
Other: LPS

Trial contacts and locations



Data sourced from clinicaltrials.gov

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