| 1. |
- Eriksson, Bengt I., 1946, et al.
(författare)
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An open-label study of the pharmacokinetics and pharmacodynamics of dabigatran etexilate 150 mg once daily in Caucasian patients with moderate renal impairment undergoing primary unilateral elective total knee or hip replacement surgery
- 2016
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Ingår i: Thrombosis Research. - : Elsevier BV. - 0049-3848. ; 144, s. 158-164
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Tidskriftsartikel (refereegranskat)abstract
- Background: In adults with moderate renal impairment (creatinine clearance [CrCl] 30-50 mL/min) undergoing total hip or knee replacement (THR/TKR), the recommended dose of dabigatran etexilate is 150 mg once daily (qd). We investigated the steady state pharmacokinetics, pharmacodynamics and safety in these patients. Methods: Single-arm, open-label phase 4 study (NCT01184989) in Caucasian patients receiving dabigatran etexilate 75 mg 1-4 h after surgery and 150 mg qd on days 2-10 (TKR) or days 2-35 (THR). Plasma total dabigatran concentrations (day 6 +/- 1) were determined by high-performance liquid chromatography tandem mass spectrometry and indirectly using the commercially available diluted thrombin time (dTT) assay (Hemoclot (R) Thrombin Inhibitors). Results: Of 112 patients (mean CrCl 42.5mL/min, age 79.1 years, 69.6% female), 100 completed the study. Geometric mean trough and peak dabigatran concentrations were 47.5 ng/mL (10th-90th percentile 19.7-120) and 166 ng/mL (49.1-364), respectively. There were four major bleeding events and no venous thromboembolic events. Dabigatran concentrations determined from dTT (and falling within the assay range of 50-500 ng/mL) underestimated actual values by 7.6% (90% confidence interval 5.3, 9.9), which is within the acceptance limits of +/- 15%. Conclusions: These findings in Caucasians with moderate renal impairment undergoing THR or TKR support the use of the 150 mg qd dose of dabigatran etexilate. With adequate set-up, calibration and quality control the dTT assay might be appropriate for situations, such as serious bleeding or a need for urgent surgery, where determination of dabigatran levels would be helpful. (C) 2016 Published by Elsevier Ltd.
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| 2. |
- Eriksson, Bengt I., 1946, et al.
(författare)
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A new oral direct thrombin inhibitor, dabigatran etexilate, compared with enoxaparin for prevention of thromboembolic events following total hip or knee replacement: the BISTRO II randomized trial
- 2005
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Ingår i: J Thromb Haemost. - 1538-7933. ; 3:1, s. 103-11
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Dabigatran etexilate is an oral direct thrombin inhibitor undergoing evaluation for the prevention of venous thromboembolism (VTE) following orthopedic surgery. METHODS: In a multicenter, parallel-group, double-blind study, 1973 patients undergoing total hip or knee replacement were randomized to 6-10 days of oral dabigatran etexilate (50, 150 mg twice daily, 300 mg once daily, 225 mg twice daily), starting 1-4 h after surgery, or subcutaneous enoxaparin (40 mg once daily) starting 12 h prior to surgery. The primary efficacy outcome was the incidence of VTE (detected by bilateral venography or symptomatic events) during treatment. RESULTS: Of the 1949 treated patients, 1464 (75%) patients were evaluable for the efficacy analysis. VTE occurred in 28.5%, 17.4%, 16.6%, 13.1% and 24% of patients assigned to dabigatran etexilate 50, 150 mg twice daily, 300 mg once daily, 225 mg twice daily and enoxaparin, respectively. A significant dose-dependent decrease in VTE occurred with increasing doses of dabigatran etexilate (P < 0.0001). Compared with enoxaparin, VTE was significantly lower in patients receiving 150 mg twice daily [odds ratio (OR) 0.65, P = 0.04], 300 mg once daily (OR 0.61, P = 0.02) and 225 mg twice daily (OR 0.47, P = 0.0007). Compared with enoxaparin, major bleeding was significantly lower with 50 mg twice daily (0.3% vs. 2.0%, P = 0.047) but elevated with higher doses, nearly reaching statistical significance with the 300 mg once-daily dose (4.7%, P = 0.051). CONCLUSIONS: Oral administration of dabigatran etexilate, commenced early in the postoperative period, was effective and safe across a range of doses. Further optimization of the efficacy/safety balance will be addressed in future studies.
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| 3. |
- Eriksson, Bengt I., 1946, et al.
(författare)
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Dose escalating safety study of a new oral direct thrombin inhibitor, dabigatran etexilate, in patients undergoing total hip replacement: BISTRO I
- 2004
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Ingår i: J Thromb Haemost. - 1538-7933. ; 2:9, s. 1573-80
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Dabigatran etexilate (BIBR 1048) is an oral direct thrombin inhibitor undergoing evaluation for the prevention of venous thromboembolism (VTE) following total hip replacement. Following oral administration, dabigatran etexilate is rapidly converted to its active form dabigatran (BIBR 953 ZW). OBJECTIVES: To determine the safe therapeutic range of dabigatran etexilate following total hip replacement. METHODS: In a multicenter, open-label, dose-escalating study, 314 patients received oral doses of dabigatran etexilate (12.5, 25, 50, 100, 150, 200 and 300 mg twice daily or 150 and 300 mg once daily) administered 4-8 h after surgery, for 6-10 days. Dose escalation was based on clinical and pharmacokinetic data. The primary safety outcome was major bleeding. The primary efficacy outcome included venographic deep vein thrombosis (DVT), symptomatic DVT and pulmonary embolism, during the treatment period. RESULTS: No major bleeding event was observed in any group, but two patients at the highest dose (300 mg twice daily) suffered bleeding from multiple sites associated with reduced renal clearance and prolonged pharmacodynamic (PD) parameters. A dose-response was demonstrated for minor bleeding events. Of the 289 treated patients, 225 patients had evaluable venograms. The overall incidence of DVT was 12.4% (28/225 patients). There was no consistent relationship between the dose and incidence of DVT, the highest incidence in any group being 20.8% (5/24 patients). The lowest dose (12.5 mg twice daily) showed a high rate of proximal DVT [12.5% (3/24)] and no increase in PD parameters. Peak and trough plasma concentrations, area under the dabigatran plasma concentration-time curve and PD parameters also increased in proportion with the dose. Higher dabigatran plasma concentrations were associated with lower DVT rates. Approximately 20% of the patients had low plasma concentrations after the first dose suggesting further optimization of the preliminary tablet formulation is required. CONCLUSIONS: Dabigatran etexilate demonstrates an acceptable safety profile, with a therapeutic window above 12.5 mg and below 300 mg twice daily. The low number of VTE events within each treatment group indicates a satisfactory antithrombotic potential, although the study was not powered for an efficacy analysis. Additional studies are ongoing to optimize oral absorption and the efficacy/safety balance.
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| 4. |
- Liesenfeld, K. H., et al.
(författare)
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Effects of the direct thrombin inhibitor dabigatran on ex vivo coagulation time in orthopaedic surgery patients: a population model analysis
- 2006
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Ingår i: Br J Clin Pharmacol. - 0306-5251. ; 62:5, s. 527-37
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To describe the pharmacokinetic-pharmacodynamic (PK-PD) characteristics of the direct thrombin inhibitor dabigatran in hip replacement patients by assessing coagulation parameters activated partial thromboplastin time (aPTT) and ecarin clotting time (ECT), interindividual variability and factors affecting PD responses. METHODS: BISTRO I patients received oral dabigatran etexilate postsurgery for 6-10 days. Dabigatran plasma concentrations and aPTT/ECT were measured on the day of surgery, on subsequent days and at steady state. PK-PD characteristics of the dabigatran-aPTT/ECT relationships were evaluated using NONMEM V. RESULTS: The dabigatran concentration-aPTT relationship was described combining a linear and an E(max) model. Mean baseline aPTT was 33.4 s and E(max) (maximum increase in aPTT contributed by the E(max) model) was 26.9 s. The dabigatran concentration needed to attain 50% of maximum effect (EC(50)) was 94.7 ng ml(-1) and the mean slope of the linear concentration-response relationship (SLOP) was 0.0509 s ng(-1) ml(-1). Baseline aPTT and E(max) were highest following surgery and declined with time. The dabigatran concentration-ECT relationship fitted a linear model. Mean baseline ECT was 28 s and decreased with time; 50% of the maximum effect was observed after 2.9 days. SLOP decreased from 0.38 to 0.27 s ng(-1) ml(-1) with a half-life of 1.1 day, indicating greater PD effects on the day of surgery. Interindividual and residual variability was low. Covariates could not explain variability of this model. CONCLUSIONS: aPTT and ECT prolongation were directly correlated with dabigatran concentrations. Blood coagulation prolongation was most pronounced following surgery. Data suggest that ECT provides a more precise description of the anticoagulant effect than aPTT.
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| 5. |
- Stangier, J, et al.
(författare)
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Identification and immunocytochemical localization of proctolin in pericardial organs of the shore crab, Carcinus maenas.
- 1986
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Ingår i: Peptides. - : Elsevier. - 0196-9781 .- 1873-5169. ; 7:1, s. 67-72
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Tidskriftsartikel (refereegranskat)abstract
- The occurrence of proctolin (Arg-Tyr-Leu-Pro-Thr) in crab neurohemal pericardial organs (POs) has been demonstrated by isolation of the pentapeptide by HPLC and manual microsequencing according to the DABITC-PITC double coupling technique. From one pair of POs approximately 5.4 pmol were obtained (= 45 pmol/mg protein). Immunocytochemically, an extensive system of positive structures was found in both whole mount preparations and semithin sections, consisting of numerous varicose fibres of varying diameter and many knoblike neurosecretory terminals abutting upon the epineurium of the PO trunks. The relatively high concentration in the POs as well as the pattern of proctolin-positive fibres and terminals clearly suggest a neurohormonal role of the pentapeptide in decapod crustaceans.
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| 6. |
- Stangier, J., et al.
(författare)
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Pharmacokinetic profile of the oral direct thrombin inhibitor dabigatran etexilate in healthy volunteers and patients undergoing total hip replacement
- 2005
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Ingår i: J Clin Pharmacol. - 0091-2700. ; 45:5, s. 555-63
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Tidskriftsartikel (refereegranskat)abstract
- Dabigatran etexilate is an oral low-molecular-weight direct thrombin inhibitor. Following oral administration, dabigatran etexilate is rapidly converted to its active form, dabigatran. The authors investigated the absorption, distribution, and elimination of a single 150-mg dose capsule formulation of dabigatran etexilate in healthy volunteers and patients undergoing total hip replacement. In an open-label, 3-way crossover study, dabigatran etexilate was administered to 18 male volunteers in the fasted state, after administration of food and with coadministration of the proton pump inhibitor, pantoprazole. In a subsequent multicenter, open-label study, 59 patients received a single dose of dabigatran etexilate, administered 1 to 3 hours following total hip replacement. In healthy volunteers, food had no effect on the extent of absorption of dabigatran etexilate, although there was reduced interindividual variability for dabigatran maximum plasma concentration and AUC(0-infinity). A decrease in the mean dabigatran AUC(0-infinity) (904 to 705 ng*h/mL) occurred with coadministration of pantoprazole. In patients undergoing total hip replacement, immediate onset of absorption was seen with the maximum plasma concentration of dabigatran occurring after 6 hours. The AUC(0-24) of dabigatran was 88% of the steady-state AUC using a preliminary tablet formulation and 106% of that seen in the healthy volunteer study. Compared with healthy volunteers, the postoperative profile was flattened with delayed peak concentrations. In summary, administration of the dabigatran etexilate capsule with food has no effect on the extent of dabigatran absorption, with a moderate decrease when coadministered with pantoprazole. Adequate plasma concentrations of dabigatran were seen with early postoperative administration of the dabigatran etexilate capsule. These pharmacokinetic characteristics confirm the suitability of this oral solid dosage form for use in future clinical trials.
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