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.
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.
Authors: Stefan C Carlsson; Christer Mattsson; Ulf G Eriksson; Troy C Sarich; Karin Wåhlander; Asa Eliasson; Björn W Karlson; Sunita B Sheth; Peter Held Journal: Thromb Res Date: 2005 Impact factor: 3.944
Authors: Joachim Stangier; Bengt I Eriksson; Ola E Dahl; Lennart Ahnfelt; Gerhard Nehmiz; Hildegard Stähle; Karin Rathgen; Robbyna Svärd Journal: J Clin Pharmacol Date: 2005-05 Impact factor: 3.126
Authors: B I Eriksson; O E Dahl; H R Büller; R Hettiarachchi; N Rosencher; M-L Bravo; L Ahnfelt; F Piovella; J Stangier; P Kälebo; P Reilly Journal: J Thromb Haemost Date: 2005-01 Impact factor: 5.824
Authors: B I Eriksson; O E Dahl; L Ahnfelt; P Kälebo; J Stangier; G Nehmiz; K Hermansson; V Kohlbrenner Journal: J Thromb Haemost Date: 2004-09 Impact factor: 5.824
Authors: Ulf G Eriksson; Jaap W Mandema; Mats O Karlsson; Lars Frison; Per Olsson Gisleskog; Ulrika Wählby; Bengt Hamrén; David Gustafsson; Bengt I Eriksson Journal: Clin Pharmacokinet Date: 2003 Impact factor: 6.447