title: Rivaroxaban (BAY 59-7939)--an oral, direct Factor Xa inhibitor--has no clinically relevant interaction with naproxen.
abstract: OBJECTIVE
  Rivaroxaban (BAY 59-7939) is in advanced clinical development for the prevention and treatment of thromboembolic disorders. Frequent co-medications in the patient populations likely to receive rivaroxaban include NSAIDs. This randomized, two-way crossover study, with a naproxen run-in period, was performed to determine whether naproxen influences the tolerability, pharmacodynamics and pharmacokinetics of rivaroxaban.
  
  
  METHODS
  Eleven healthy, young males received naproxen 500 mg on two consecutive days, a single dose of rivaroxaban 15 mg, or both.
  
  
  RESULTS
  Treatments were well tolerated: adverse events (eight in total), reported by three subjects, were mild and not drug related. Rivaroxaban inhibited Factor Xa activity by 35% and prolonged prothrombin time [by 1.4 times baseline (tb)], activated partial thromboplastin time (1.3 tb) and the HepTest (1.9 tb). Naproxen had no influence on these measures and the combination of rivaroxaban and naproxen did not affect platelet aggregation. Rivaroxaban and naproxen given together significantly increased bleeding time compared with rivaroxaban alone (P = 0.017). However, this difference was small compared with the effect of naproxen given alone, except in one subject. Least squares-means ratios for the AUC and C(max) of rivaroxaban after administration alone and with naproxen were 1.125 [90% confidence interval (CI) 0.995, 1.271] and 1.095 (90% CI 0.905, 1.325), respectively.
  
  
  CONCLUSIONS
  There appeared to be no clinically relevant interaction between rivaroxaban and naproxen in healthy subjects, although some individuals may be more sensitive to the combination. Large-scale Phase III clinical studies will be required to confirm whether there is an increased risk of bleeding during treatment with rivaroxaban and concomitant NSAIDs.
authors.affiliation: Clinical Pharmacology, Pharmacometry, Bayer HealthCare AG, Wuppertal, Germany.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Kubitza
authors.forename: Michael
authors.initials: M
authors.lastname: Becka
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Mueck
authors.forename: Michael
authors.initials: M
authors.lastname: Zuehlsdorf
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism*; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects / Q000378:metabolism*; D018592:Cross-Over Studies; D004347:Drug Interactions; D006801:Humans; D008297:Male; D008875:Middle Aged; D009025:Morpholines / Q000008:administration & dosage / Q000009:adverse effects / Q000378:metabolism*; D009288:Naproxen / Q000378:metabolism*; D000069552:Rivaroxaban; D013876:Thiophenes / Q000008:administration & dosage / Q000009:adverse effects / Q000378:metabolism*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D000925:Anticoagulants; D009025:Morpholines; D013876:Thiophenes; D009288:Naproxen; D000069552:Rivaroxaban