Pharmacokinetics of Rivaroxaban After Bariatric Surgery

Inclusion Criteria: * Creatinine clearance measured by the Cockroft formula ≥ 60 mL / min * Patient meeting the specific criteria of one of the 4 groups: * morbidly obese patients with BMI ≥ 40 * Patients operated by gastric bypass for over a year and with stable weight * Patients operated by sleeve gastrectomy for over a year and with stable weight * Control group: non-operated subjects but with an age and a BMI corresponding to those of the patients of the 2 operated groups. Exclusion Criteria: * Indication for anticoagulant therapy, antiplatelet therapy or long-term nonsteroidal anti-inflammatory drugs * Clinically significant bleeding in progress * Taking oral or parenteral anticoagulants, or taking platelet antiaggregants within 4 weeks before inclusion * Congenital or acquired hemorrhagic disorders (eg von Willebrand disease, hemophilia) * Injury or disease, at significant risk of major bleeding (gastrointestinal ulceration, presence of malignant tumors with a high risk of bleeding, recent brain or spinal cord injury, recent cerebral, spinal or ophthalmic surgery, recent intracranial hemorrhage, known or suspected oesophageal varices , arteriovenous malformations, vascular aneurysms or major intraspinal or intracerebral vascular abnormalities) * Severe uncontrolled arterial hypertension * Active gastrointestinal disease potentially leading to bleeding disorders (esophagitis, gastritis, gastroesophageal reflux disease, chronic inflammatory bowel disease) * Vascular retinopathy * Bronchiectasis or history of pulmonary bleeding * Hypersensitivity to the active substance or to any of the excipients of rivaroxaban * Hepatic involvement associated with coagulopathy and clinically significant bleeding risk, including cirrhotic patients with Child Pugh Grade B or C score * Concomitant use of potent inhibitors or inducers of CYP3A4 and / or P-gp (azole antifungal or HIV protease inhibitor) * Participation in a paid and / or therapeutic study in the previous 3 months * Pregnant or lactating women, * Women of childbearing potential not using effective contraception