Dabigatran etexilate (Pradaxa^®) is an oral anticoagulant licensed in multiple countries, Europe and Canada, for the prevention of venous thromboembolic events (VTE) in patients undergoing total hip replacement surgery (THR) or total knee replacement surgery (TKR). The label recommendation for therapy initiation of dabigatran etexilate is a half dose given 1–4 hours after surgery. If this is not possible, then dabigatran etexilate should be started the day following surgery with the full dose. In the European pivotal Phase III clinical trials, this initial dosing was delayed until the day after surgery in 14% of the cases. This prompted a post hoc study to analyze if these patients received adequate thromboprophylaxis. Pooled efficacy data of major VTE events (composite of proximal DVT, symptomatic DVT, pulmonary embolism and VTE-related death) from the two European pivotal trials (RE-MODEL; Eriksson BI et al. J Thromb Haemost2007;5:2178–2185, and RENOVATE; Eriksson BI et al. Lancet2007;370:949–956) where analyzed. The group with delayed dosing was compared to the group that received therapy initiation on the day of surgery to determine if there was any significant effect on clinical outcome. The final decision on the timing of the administration of the first dose required sometimes clinical judgment, and in particular good haemostasis had to be present. Therefore, the bleeding rate and the timing of the first dose are confounded and an analysis of bleeding events was not performed. The major VTE rate in the group with delayed treatment initiation compared with the 1–4 hour post surgery treatment initiation group were 2.2% (95% CI: 0.1–4.4) vs. 3.0% (95% CI: 2.0–3.9) for 220 mg dabigatran etexilate, 8.3% (95% CI: 4.3–12.4) vs. 3.5% (95% CI 2.5–4.5) for 150 mg dabigatran etexilate, and 4.3% (95% CI 1.2–7.4) vs. 3.7% (95% CI 2.7–4.8) for 40 mg enoxaparin. As the confidence intervals overlap markedly, no statistically significant differences where found. In conclusion, no difference in the rates of major VTE and VTE related mortality was seen when the doses of dabigatran etexilate were postponed to the first postoperative day. These data need to be interpreted carefully due to the low number of patients in the delayed treatment group. As recommended in the current labelling of dabigatran etexilate, treatment should be initiated 1–4 hours post-surgery.

The oral direct thrombin inhibitor dabigatran etexilate (Pradaxa^®) was recently approved in Europe for the prevention of venous thromboembolism (VTE) in patients undergoing elective total knee or total hip replacement surgery. In the Phase III RE-MODEL (Eriksson BI et al. J Thromb Haemost2007; 5: 2178–2185) and RENOVATE (Eriksson BI et al. Lancet2007; 370: 949–956) clinical trials the safety and efficacy of 220 mg and 150 mg dabigatran etexilate once daily were studied. In both trials these doses were compared with 40 mg subcutaneous enoxaparin. A post hoc pooled analysis was performed in patients with moderate renal impairment (glomerular filtration rate ≥ 30 and < 50 ml/min) who participated in these two trials. The primary efficacy endpoint in both studies and the post hoc analysis was total VTE and all cause mortality; the key pre-specified secondary efficacy endpoint was major VTE and VTE-related mortality. Bleeding events (the primary safety endpoint) were blindly adjudicated and categorised as major bleeding events (MBE), which includes surgical site bleedings. A total of 1825 patients were treated with 220 mg dabigatran etexilate, 1866 with 150 mg dabigatran etexilate and 1848 with 40 mg enoxaparin. Of these, 337 patients had moderate renal impairment. 68% of these patients could be evaluated for the primary efficacy endpoint, 72% for the secondary efficacy endpoint, and all patients were included in the safety and bleeding analyses. The incidence of total VTE and all cause mortality was 17.7% (14/79), 23.5% (16/68) and 27.8% (25/90) in the 220 mg dabigatran etexilate, 150 mg dabigatran etexilate and enoxaparin groups, respectively. When the secondary efficacy endpoint was analysed a similar trend was seen, with a descriptive statistical significance for a lower event rate in the 220 mg group: 1.2% (1/83; p=0.04 vs enoxaparin using Fisher’s exact test), 4.3% (3/70) with 150 mg dabigatran etexilate; and 9.0% (8/89) in the enoxaparin group. MBE occurred in 6/113 patients (5.3%) in the 220 mg dabigatran etexilate-treated group, in none of the patients in the 150 mg dabigatran etexilate-treated group (0/96; p=0.04 vs enoxaparin using Fisher’s exact test), and in 6/128 patients (4.7%) receiving enoxaparin. Of note, 3/6 MBE in the 220 mg group started before oral dabigatran etexilate treatment was initiated. In conclusion, oral 150 mg dabigatran etexilate showed similar efficacy compared with subcutaneous enoxaparin in patients with moderate renal impairment undergoing hip or knee replacement surgery, with an apparently lower rate of major bleeding. As bleeding is a major concern, especially in this population, the 150 mg once daily dose of dabigatran etexilate is currently recommended by EMEA for this group.

Dabigatran etexilate (Pradaxa^®) is an oral direct thrombin inhibitor that was recently approved in Europe and Canada for the prevention of venous thromboembolism (VTE) in patients undergoing elective total knee replacement or total hip replacement surgery. Two pivotal clinical trials, RE-MODEL (Eriksson BI et al. J Thromb Haemost2007; 5: 2178–2185) and RENOVATE (Eriksson BI et al. Lancet2007; 370: 949–956), studied the efficacy and safety of 220 mg and 150 mg dabigatran etexilate once daily compared with 40 mg subcutaneous enoxaparin. A post hoc pooled analysis was performed in elderly patients (> 75 years) since renal function gradually declines with age. The primary efficacy endpoint was total VTE and all cause mortality and the secondary efficacy endpoint was major VTE and VTE-related mortality. The primary safety endpoint was major bleeding events (MBE), including those occurring at the surgical site. All bleeding events were blindly adjudicated. Of the patients treated with 220 mg dabigatran etexilate (n=1825), 150 mg dabigatran etexilate (n=1866) and enoxaparin (n=1848), 883 patients (16%) were over 75 years. 73% of these elderly patients were evaluable for the primary efficacy endpoint and 75% were evaluable for the secondary efficacy endpoint. All patients > 75 years were evaluable for safety outcomes, including bleeding. The incidence of total VTE and all cause mortality was 20.8% (44/212), 22.6% (49/217), and 27.2% (58/213), respectively, in the three groups. A similar trend was observed for major VTE and VTE-related mortality: 220 mg dabigatran etexilate, 1.9% (4/216, p=0.045 vs enoxaparin using Fisher’s exact test); 150 mg dabigatran etexilate, 4.5% (10/221); enoxaparin, 6.0% (13/218). MBE occurred in 11 of the 295 elderly patients receiving 220 mg dabigatran etexilate (3.7%), 4 of the 282 elderly patients receiving 150 mg dabigatran etexilate (1.4%) and in 9 of the 306 elderly patients taking enoxaparin (2.9%). Notably, 6/11 MBE in the dabigatran 220 mg group and 2/4 MBE in the 150 mg group started before the first dose of treatment. We conclude that in elderly patients (> 75 years) undergoing hip or knee replacement surgery, oral 150 mg dabigatran etexilate exhibited a numerically favourable bleeding profile with no difference in efficacy compared with 40 mg enoxaparin. Because safety, particularly bleeding, is of paramount importance in the elderly, the 150 mg once daily dose of dabigatran etexilate is currently recommended by EMEA for this group.

Introduction: Venous thromboembolism (VTE) is a common, potentially fatal complication of major orthopaedic surgery. Although pharmacological thromboprophylaxis is recommended following total hip replacement (THR) for a minimum of 10 days, and up to 35 days, its extended use is not universally accepted – an effective, safe and convenient, oral anticoagulant would improve implementation of these recommendations. This trial compared short-term thromboprophylaxis using enoxaparin with extended thromboprophylaxis using rivaroxaban – a once-daily, oral, direct Factor Xa inhibitor – after THR, in the largest, prospective, randomized clinical trial conducted to date for the evaluation of the risk/benefit of extended prophylaxis.

Method: In this global, double-blind trial, 2509 patients undergoing THR were randomized to receive either subcutaneous enoxaparin 40 mg once daily (od), started the evening before surgery and continued for 10–14 days, followed by placebo until day 35±4 (short-term prophylaxis), or oral rivaroxaban 10 mg od, started 6–8 hours after surgery and continuing for 35±4 days (extended prophylaxis). Mandatory, bilateral venography was conducted on day 36±4. The primary efficacy endpoint was the composite of any deep vein thrombosis (DVT), non-fatal pulmonary embolism (PE), and all-cause mortality. The main secondary efficacy endpoint was major VTE (the composite of proximal DVT, non-fatal PE, and VTE-related death). Safety endpoints included the incidence of major and non-major bleeding.

Results: The incidence of the primary efficacy endpoint was significantly reduced with extended thromboprophylaxis with rivaroxaban compared with short-term enoxaparin (2.0% and 9.3%, respectively; p< 0.001; relative risk reduction [RRR] 79%), as was major VTE (0.6% versus 5.1%; p< 0.001; RRR 88%). The incidence of major bleeding was the same in both groups (0.1%). Non-major bleeding was reported in 6.5% of patients who received extended thromboprophylaxis with rivaroxaban and in 5.5% of those treated with short-term enoxaparin.

Conclusion: Extended duration thromboprophylaxis with rivaroxaban is both significantly more effective and adds no disadvantage, in terms of bleeding, when compared with short-term prophylaxis. These data suggest that extended thromboprophylaxis provides substantial benefits to patients undergoing THR and rivaroxaban provides a safe and effective option for this strategy.

Rivaroxaban is an oral, direct Factor Xa inhibitor in clinical development for the prevention of VTE after major orthopaedic surgery. Data from three phase II trials of twice-daily (bid) rivaroxaban in patients undergoing elective, total hip or knee replacement were pooled to determine whether age, gender or weight affected the efficacy or safety of rivaroxaban, and thus whether dose adjustment would be necessary. Patients received 5–9 days of oral rivaroxaban (2.5–30 mg bid, post-operatively), or s.c. enoxaparin. A logistic regression model using total daily dose of rivaroxaban as a covariate, and adjusted for differences between dose groups with respect to study, age and gender, was used to estimate rates of the primary efficacy endpoint (DVT, PE or all-cause mortality; n=1380 intention-to-treat patients) and clinically relevant bleeding (major and non-major clinically relevant bleeding; safety population, n=1854). Rivaroxaban at total daily doses of 5–20 mg had similar efficacy and safety to enoxaparin. Overall, logistic regression showed a positive dose–response relationship with rivaroxaban for clinically relevant bleeding (p< 0.001), and a flat relationship for the primary efficacy endpoint (p=0.115). The risk of VTE increased with age – the efficacy endpoint was estimated to occur in 17.3–9.4%, 18.7–17.3% and 26.6–20.2% of patients aged < 60 yrs, 60–70 yrs and > 70 yrs receiving rivaroxaban (total daily dose 5–60 mg), respectively, in separate regression models. Age was also prognostic for clinically relevant bleeding with rates of 1.4–12.0% (< 60 yrs), 2.7–15.4% (60–70 yrs) and 5.7–15.4% (> 70 yrs). The rates are for a population distributed equally across the studies and genders. Incidences of the efficacy endpoint were higher in females (25.8–20.5%) than males (16.6–10.7%), while clinically relevant bleeding occurred more frequently in males (5.4–16.3%) than in females (1.7–11.6%), after adjustment for age. Weight was not prognostic for the efficacy endpoint or clinically relevant bleeding (p=0.87 and p=0.48, respectively, after adjustment for age, gender and study), nor did it modify the dose–response relationships with rivaroxaban. Incidences of the efficacy endpoint for a population of equal study and gender distribution and of mean patient age were 23.4–15.7% and 19.1–14.6% in patients weighing < 65 kg and ≥90 kg, respectively, with corresponding bleeding rates of 3.3–16.5% and 3.2–17.5%. This analysis indicates that age, gender or weight did not affect the dose–response relationships (or lack thereof) between rivaroxaban and the primary efficacy endpoint or clinically relevant bleeding. As expected, age was prognostic for VTE and bleeding. These findings suggest that rivaroxaban may not require dose adjustment for age, gender or weight in orthopaedic patients.

BACKGROUND: Oral DVT prophylaxis not requiring monitoring is an advantage in orthopaedic patients. Dabigatran etexilate is an oral direct thrombin inhibitor undergoing evaluation for the prevention of venous thromboembolic events (VTE) following orthopaedic surgery.

METHODS: In a phase III, multicenter, non-inferiority, double-blind study, patients undergoing total knee replacement were randomized to 3 treatments. The patients received 8±2 days of oral dabigatran etexilate, 150 or 220 mg once daily starting with a half dose (i.e.75 or 110 mg) 1–4 hours after surgery, or subcutaneous enoxaparin 40 mg once daily starting 12 hours prior to surgery. The primary efficacy outcome was the composite of total VTE and all causes of mortality during the treatment period. All efficacy and safety outcome events were adjudicated by blinded independent committees.

RESULTS: Efficacy could be evaluated for 1541 (75%) treated and operated patients. Total VTE and death occurred in 40.5%, 36.4% and 37.7% of patients assigned to dabigatran etexilate 150 or 220mg once daily or enoxaparin, respectively. Proximal DVT and/ or PE occurred in 3.8%, 2.6% and 3.5% of patients receiving dabigatran 150 or 220mg or enoxaparin, respectively. Three deaths occurred during the treatment period, one in each of the treatment groups. Safety was evaluated for all 2076 patients receiving study treatment. The rate of major bleeding was 1.3%, 1.5% and 1.3% of patients receiving dabigatran 150 or 220mg or enoxaparin. Elevated LFTs (ALT > 3xULN) occurred in 3.7%, 2.8% and 4.0% of the patients treated with 150 and 220 mg dabigatran or enoxaparin during the study. A temporary rise in LFTs was observed during the follow-up period in 0.5% of the patients who had received dabigatran and in 0.4% of the patients who had received enoxaparin.

CONCLUSIONS: Non-inferiority for the primary efficacy endpoint was met for both doses of dabigatran etexilate compared to enoxaparin. There was no difference in bleeding rates between the treatment groups. Oral administration of dabigatran etexilate once daily, given early in the postoperative period, was effective and safe for the prevention of total VTE in patients undergoing total knee replacement surgery.

Routine prophylaxis is recommended to prevent venous thromboembolism (VTE) – manifesting as deep vein thrombosis (DVT) and/or pulmonary embolism (PE) – in patients undergoing major orthopaedic surgery. Rivaroxaban (BAY 59-7939) is a novel, oral, direct Factor Xa inhibitor in development for the prevention and treatment of VTE. The efficacy and safety of 5–9 days’ prophylaxis with rivaroxaban were investigated in three randomized, double-blind, phase IIb trials in patients undergoing elective, total hip or knee replacement (THR or TKR), relative to subcutaneous enoxaparin.

Two trials (one in patients undergoing THR, N=722; and one in patients undergoing TKR, N=621) investigated twice-daily (bid) rivaroxaban (at total daily doses of 5–60 mg); the third (in patients undergoing THR, N=873) investigated once-daily (od) rivaroxaban (at doses of 5, 10, 20, 30 or 40 mg od).

Rivaroxaban – at all doses tested – had similar efficacy to enoxaparin in the bid trials. This promising finding was strengthened by the od trial, in which the observed incidences of the primary efficacy endpoint (DVT, non-fatal PE or all-cause mortality) were lower in patients receiving rivaroxaban 5, 10, 20, 30 and 40 mg od (14.9%, 10.6%, 8.5%, 13.5% and 6.4%, respectively) than enoxaparin (25.2%). Although there was no significant dose–response relationship between rivaroxaban and the primary efficacy endpoint in these trials, there was with major VTE (proximal DVT, PE or VTE-related death; p=0.0072) in the od trial (incidences were 8.5%, 2.7%, 0.9%, 1.9% and 1.1% with rivaroxaban 5, 10, 20, 30 and 40 mg od, respectively, vs 2.8% with enoxaparin).

Significant dose–response relationships between rivaroxaban and major bleeding were observed in all three trials. In the bid trials, major bleeding rates with rivaroxaban were similar to those with enoxaparin at total daily doses of 5–20 mg. In the od trial, major bleeding occurred in 2.3%, 0.7%, 4.3%, 4.9% and 5.1% of patients receiving rivaroxaban 5, 10, 20, 30 and 40 mg od, respectively, and in 1.9% of those receiving enoxaparin.

Rivaroxaban was generally well tolerated in the bid and od trials, and the incidence of nausea and vomiting with early post-operative oral rivaroxaban administration was low for all doses tested.

The bid trials suggest that oral rivaroxaban at total daily doses of 5–20 mg may be a safe and effective alternative to enoxaparin for the prevention of VTE after major orthopaedic surgery. The od trial suggests that the more-convenient od regimen is feasible and that 10 mg od, a dose within the range identified by the bid trials, should be investigated further. As a result, oral rivaroxaban 10 mg od is currently being investigated in four phase III trials for the prevention of VTE after major orthopaedic surgery (the RECORD trials).

Purpose: Thromboembolic events, such as deep vein thrombosis (DVT) and pulmonary embolism (PE), are a serious risk after major orthopaedic surgery. BAY 59-7939 is a novel, oral, direct Factor Xa inhibitor in clinical development for the prevention and treatment of thromboembolic disorders. The efficacy and safety of BAY 59-7939 for thromboprophylaxis have been determined relative to enoxaparin in two clinical trials, one after elective total hip replacement surgery, and one after elective total knee replacement surgery. This pre-specified analysis combines data from two multicenter, multinational, double-blind, dose-ranging studies; the hip surgery trial was performed in Europe, and the knee surgery trial in North America.

Methods: Patients (N=1343) were randomized to oral BAY 59-7939 at 2.5, 5, 10, 20, or 30 mg twice daily (bid), or subcutaneous enoxaparin (40 mg once daily starting 12 hours before hip surgery, or 30 mg bid starting 12 hours after knee surgery), continuing until mandatory bilateral venography was performed 5–9 days after surgery. The primary efficacy endpoint was a composite of DVT, PE, and all-cause mortality. The primary safety endpoint was major, post-operative bleeding.

Results: The primary efficacy endpoint occurred in 21.6%, 22.9%, 16.1%, 24.4%, and 19.3% of patients receiving BAY 59-7939 2.5, 5, 10, 20, and 30 mg bid, respectively, and 27.8% receiving enoxaparin (n=914). No significant dose–response relationship for efficacy was observed with BAY 59-7939 (P=0.39); this was potentially due to the efficacy achieved with the lower BAY 59-7939 doses. A significant dose–response relationship was observed for major, post-operative bleeding with BAY 59-7939 (P< 0.001), which occurred in 0.9%, 1.3%, 2.1%, 3.9%, and 7.0% of patients receiving BAY 59-7939 2.5, 5, 10, 20, and 30 mg bid, respectively, and 1.7% of patients receiving enoxaparin (n=1317).

Conclusions: This analysis showed that BAY 59-7939 has a wide therapeutic window for the prevention of VTE following major orthopaedic surgery, and, at doses of 2.5–10 mg bid, has similar efficacy and safety to the enoxaparin regimens.

Funding : Commerical funding

Funding Parties : This study was sponsored by Bayer HealthCare AG

Aims: To investigate the efficacy and safety of a new dosage regimen of the oral direct thrombin inhibitor ximelagatran, and its subcutaneous (sc) form melagatran, started in close proximity to surgery. Methods: In a randomised, double-blind, parallel-group study, duration 8–11 days, patients undergoing total hip or knee replacement (THR, n= 1856; TKR, n= 908) received either sc melagatran 2 mg immediately before surgery followed by sc 3 mg in the evening after surgery, and then by oral ximelagatran 24 mg bid as a fixed dose (the ximelagatran group), or sc enoxaparin 40 mg od, started the evening before surgery. Bilateral venography was performed on the final day of treatment. Results: The rate of proximal deep vein thrombosis plus pulmonary embolism was 2.3% in the ximelagatran group vs. 6.3% in the enoxaparin group (p< 0.000002; RRR 63.2%). The total rates of venous thromboembolism (VTE) were 20.3% vs. 26.6%, respectively (p< 0.0003; RRR 23.6%). Cases with symptomatic VTE were rare: 8 in the ximelagatran group and 12 in the enoxaparin group. Bleeding events were more common in the ximelagatran group compared with the enoxaparin group (3.3% vs. 1.2%) as were the transfusion rates (66.8% vs. 61.7%). Importantly, there were no differences in fatal bleeding, critical organ bleeding or bleeding requiring re-operation. Conclusion: Pre-operatively initiated sc melagatran followed by oral ximelagatran was superior in efficacy to enoxaparin in preventing VTE in patients undergoing THR or TKR.

Ximelagatran is an oral direct thrombin inhibitor intended for the prophylaxis and treatment of thrombo-embolic complications. Purpose: The efficacy and safety of ximelagatran, and its subcutaneous (sc) form melagatran, were evaluated in patients undergoing total hip or knee replacement (THR, TKR). Study 1 was a randomised, double-blind, controlled, dose–response study in which patients received 2-6 doses of sc melagatran (1, 1.5, 2.25, or 3 mg bid) followed by oral ximelagatran (8, 12, 18, or 24 mg bid), or sc dalteparin (5000 IU od). Melagatran treatment was initiated immediately before surgery. Study 2 was a randomized, double-blind, controlled study in which patients received 1–5 doses of sc melagatran (3 mg bid) initiated 4–12 h after surgery followed by oral ximelagatran (24 mg bid), or sc enoxaparin (40 mg od). In both studies, low-molecular-weight heparin (LMWH) was started the evening before surgery, and all treatment regimens were continued for 8–11 days. Bilateral venography was performed on the final day of treatment.

Results: In Study 1, 1876 patients underwent THR (n=1270) or TKR (n=606). A significant dose-dependent reduction in venous thromboembolism (VTE) was seen with melagatran + ximelagatran for both THR (P< 0.0001) and TKR (P=0.0014). The rate of VTE was significantly lower with the highest dose of melagatran + ximelagatran (15.1%) when compared with dalteparin (28.2%) (P< 0.0001). In Study 2, 2788 patients underwent THR (n=1923) or TKR (n=865). The VTE rate was 31% in the melagatran + ximelagatran group and 27% in the enoxaparin group (P=0.053). Total bleeding volume was not significantly different between treatment groups. Conclusion: Fixed-dose sc melagatran followed by oral ximelagatran are efficacious and well tolerated for the prophylaxis of VTE following THR or TKR.