Thrombosis

Inclusion Criteria

- Children with an age ≥2 months and weight between 3 and <12 kg, who have completed anticoagulant treatment at least 10 days prior to the planned study drug administration.
 -- Gestational age at birth of at least 37 weeks
 -- Oral feeding/ nasogastric/ gastric feeding for at least 10 days
 - Normal PT and aPTT within 10 days prior to planned study drug administration
 - Written informed consent provided and, if applicable, child assent provided

Exclusion Criteria

- Active bleeding or high risk for bleeding, contraindicating anticoagulant therapy
 - Planned invasive procedures, including removal of central lines, within 24 hours before and after single dose intake
 - An estimate glomerular filtration rate (eGFR) < 30 mL/min/1.73m2
 - Hepatic disease which is associated either with:
 -- coagulopathy leading to a clinically relevant bleeding risk, or alanine aminotransferase (ALT) > 5x upper level of normal (ULN), or
 -- total bilirubin > 2x ULN with direct bilirubin > 20% of the total.
 - Platelet count < 50 x 10^9/L
 - Hypertension (defined as systolic and/or diastolic blood pressure >95th percentile for age)
 - Concomitant use of strong inhibitors of both CYP3A4 and P-glycoprotein, e.g., all human immunodeficiency virus protease inhibitors and the following azoleantimycotic agents: ketoconazole, itraconazole, voriconazole, and posaconazole,  if used systemically (fluconazole is allowed)
 - Concomitant use of strong inducers of CYP3A4, e.g., rifampicin, rifabutin, phenobarbital, phenytoin and carbamazepine
 - Inability to cooperate with the study procedures
 - Hypersensitivity to rivaroxaban
 - Participation in a study with an investigational drug other than rivaroxaban or a medical device within 30 days prior to treatment
 -  History of gastrointestinal disease or surgery associated with impaired absorption