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BAY 59--7939 was well tolerated with predictable pharmacodynamics and pharmacokinetics across a wide range of doses in healthy male subjects. BAY 59--7939 was shown to be an effective and specific factor Xa inhibitor.

BAY 59-7939 was safe and well tolerated across the wide dose range studied, with predictable, dose-proportional pharmacokinetics and pharmacodynamics and no relevant accumulation beyond steady state. These results support further investigation of BAY 59-7939 in phase II clinical trials.

Rivaroxaban is an oral, direct Factor Xa inhibitor that targets free and clot-bound Factor Xa and Factor Xa in the prothrombinase complex. It is absorbed rapidly, with maximum plasma concentrations being reached 2–4 h after tablet intake. Oral bioavailability is high (80–100 %) for the 10 mg tablet irrespective of food intake and for the 15 mg and 20 mg tablets when taken with food. Variability in the pharmacokinetic parameters is moderate (coefficient of variation 30–40 %). The pharmacokinetic profile of rivaroxaban is consistent in healthy subjects and across a broad range of different patient populations studied. Elimination of rivaroxaban from plasma occurs with a terminal half-life of 5–9 h in healthy young subjects and 11–13 h in elderly subjects. Rivaroxaban produces a pharmacodynamic effect that is closely correlated with its plasma concentration. The pharmacokinetic and pharmacodynamic relationship for inhibition of Factor Xa activity can be described by an Emax model, and prothrombin time prolongation by a linear model. Rivaroxaban does not inhibit cytochrome P450 enzymes or known drug transporter systems and, because rivaroxaban has multiple elimination pathways, it has no clinically relevant interactions with most commonly prescribed medications. Rivaroxaban has been approved for clinical use in several thromboembolic disorders.

Aims The anticoagulant rivaroxaban is an oral, direct Factor Xa inhibitor for the management of thromboembolic disorders. Metabolism and excretion involve cytochrome P450 3A4 (CYP3A4) and 2J2 (CYP2J2), CYP‐independent mechanisms, and P‐glycoprotein (P‐gp) and breast cancer resistance protein (Bcrp) (ABCG2). Methods The pharmacokinetic effects of substrates or inhibitors of CYP3A4, P‐gp and Bcrp (ABCG2) on rivaroxaban were studied in healthy volunteers. Results Rivaroxaban did not interact with midazolam (CYP3A4 probe substrate). Exposure to rivaroxaban when co‐administered with midazolam was slightly decreased by 11% (95% confidence interval [CI] −28%, 7%) compared with rivaroxaban alone. The following drugs moderately affected rivaroxaban exposure, but not to a clinically relevant extent: erythromycin (moderate CYP3A4/P‐gp inhibitor; 34% increase [95% CI 23%, 46%]), clarithromycin (strong CYP3A4/moderate P‐gp inhibitor; 54% increase [95% CI 44%, 64%]) and fluconazole (moderate CYP3A4, possible Bcrp [ABCG2] inhibitor; 42% increase [95% CI 29%, 56%]). A significant increase in rivaroxaban exposure was demonstrated with the strong CYP3A4, P‐gp/Bcrp (ABCG2) inhibitors (and potential CYP2J2 inhibitors) ketoconazole (158% increase [95% CI 136%, 182%] for a 400 mg once daily dose) and ritonavir (153% increase [95% CI 134%, 174%]). Conclusions Results suggest that rivaroxaban may be co‐administered with CYP3A4 and/or P‐gp substrates/moderate inhibitors, but not with strong combined CYP3A4, P‐gp and Bcrp (ABCG2) inhibitors (mainly comprising azole‐antimycotics, apart from fluconazole, and HIV protease inhibitors), which are multi‐pathway inhibitors of rivaroxaban clearance and elimination.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Prior to the commencement of this study, it was already known that rivaroxaban is partially cleared via the kidneys and an influence of renal insufficiency on rivaroxaban pharmacokinetics and exposure was anticipated. WHAT THIS STUDY ADDS• As many patients in the target indications of rivaroxaban will be elderly, a precise quantitative knowledge of the influence of renal function on rivaroxaban pharmacokinetics and exposure is mandatory for adequate labelling recommendations (in the context of benefit/risk provided by phase III studies) to guide therapy. This study provided detailed insight on both rivaroxaban pharmacokinetics and pharmacodynamic behaviour in renal impairment including severely renally impaired subjects. AIMThis study evaluated the effects of impaired renal function on the pharmacokinetics, pharmacodynamics and safety of rivaroxaban (10 mg single dose), an oral, direct Factor Xa inhibitor. METHODSSubjects (n = 32) were stratified based on measured creatinine clearance: healthy controls (Ն80 ml min -1 ), mild (50-79 ml min -1 ), moderate (30-49 ml min -1 ) and severe impairment (<30 ml min -1 ). RESULTSRenal clearance of rivaroxaban decreased with increasing renal impairment. Thus, plasma concentrations increased and area under the plasma concentration-time curve (AUC) LS-mean values were 1.44-fold (90% confidence interval [CI] 1.1, 1.9; mild), 1.52-fold (90% CI 1.2, 2.0; moderate) and 1.64-fold (90% CI 1.2, 2.2; severe impairment) higher than in healthy controls. Corresponding values for the LS-mean of the AUC for prolongation of prothrombin time were 1.33-fold (90% CI 0.92, 1.92; mild), 2.16-fold (90% CI 1.51, 3.10 moderate) and 2.44-fold (90% CI 1.70, 3.49 severe) higher than in healthy subjects, respectively. Likewise, the LS-mean of the AUC for Factor Xa inhibition in subjects with mild renal impairment was 1.50-fold (90% CI 1.07, 2.10) higher than in healthy subjects. In subjects with moderate and severe renal impairment, the increase was 1.86-fold (90% CI 1.34, 2.59) and 2.0-fold (90% CI 1.44, 2.78) higher than in healthy subjects, respectively. CONCLUSIONSRivaroxaban clearance is decreased with increasing renal impairment, leading to increased plasma exposure and pharmacodynamic effects, as expected for a partially renally excreted drug. However, the influence of renal function on rivaroxaban clearance was moderate, even in subjects with severe renal impairment.

Anticoagulants are often dose adjusted, or their use restricted, in patients with extremes of body weight. Rivaroxaban (BAY 59-7939) is a novel, oral, direct factor Xa inhibitor in clinical development. This was a randomized, single-blind, placebo-controlled, parallel-group study in healthy male and female subjects to assess the effect of extreme body weight (< or = 50 kg and >120 kg), and gender, on the safety, tolerability, pharmacokinetics, and pharmacodynamics of rivaroxaban 10 mg, compared with subjects of normal weight (70-80 kg). Rivaroxaban was well tolerated. Cmax of rivaroxaban was unaffected in subjects >120 kg but was increased by 24% in subjects weighing < or = 50 kg, resulting in a small (15%) increase in prolongation of prothrombin time, which was not considered clinically relevant. The area under the curve was unaffected by body weight or gender. No other clinically relevant differences were observed, suggesting that rivaroxaban is unlikely to require dose adjustment for body weight or gender.

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