| 1. |
- Agersø, H, et al.
(författare)
-
Recombinant human factor VIIa (rFVIIa) cleared principally by antithrombin following IV administration in haemophilia patients.
- 2011
-
Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 9:2, s. 333-338
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: The objective of the present study was to evaluate the pharmacokinetics and the clearance pathways of rFVIIa after intravenous administration to haemophilia patients. Methods: Ten severe haemophilia patients were included in the study; all patients were intravenously administered a clinical relevant dose of 90 μg/kg (1.8 nmol/kg) rFVIIa. Blood samples were collected consecutively to describe the pharmacokinetics of rFVIIa. All samples were analysed using three different assays: a clot assay to measure the activity (FVIIa:C), an enzyme immunoassay (EIA) to measure the antigen levels (FVII:Ag), and a EIA (FVIIa-AT) to measure the FVIIa antithrombin III (AT) complex. Pharmacokinetic parameters were evaluated both by use of standard non-compartmental methods and by use of mixed effects methods. A population pharmacokinetic model was used to simultaneously model all three datasets. The total body clearance of rFVIIa:C was estimated to be 38 mL/h/kg. The rFVII:AT complex formation was responsible for 65% of the total rFVIIa:C clearance. The initial and the terminal half-life of rFVIIa:C was estimated to be 0.6 and 2.6 hours, respectively. The formation of rFVII-AT complex were able to explain the difference observed between the rFVIIa:C and the rFVII:Ag concentration. The non-compartmental analysis resulted in almost identical parameters.
|
|
| 2. |
- Brophy, D F, et al.
(författare)
-
Monitoring rFVIIa 90 μg kg(-1) dosing in haemophiliacs: comparing laboratory response using various whole blood assays over 6 h.
- 2011
-
Ingår i: Haemophilia. - : Wiley. - 1351-8216. ; 17:5, s. 949-957
-
Tidskriftsartikel (refereegranskat)abstract
- Summary. Recombinant FVIIa is a haemostatic agent administered to patients with severe FVIII or FIX deficiency with inhibitors. Although rFVIIa is effective at stopping bleeding, a reliable assay to monitor its effect is lacking. To characterize the pharmacokinetics and global coagulation effects of rFVIIa for 6 h following a IV dose of 90 μg kg(-1) . Ten non-bleeding subjects with severe FVIII or FIX deficiency were infused with a single-dose of rFVIIa 90 μg kg(-1) body weight and blood was collected before and at 0.5, 1, 2, 4 and 6 h postdose. Global haemostasis was characterized throughout the study utilizing whole blood analyses (Hemodyne HAS, TEG, ROTEM). The clearance and half-life of factor FVII:C was estimated as 39.0 ± 8.8 mL h(-1) kg(-1) and 2.1 ± 0.2 h respectively. There was good inter-assay agreement with respect to clot initiation parameters (R, CT and FOT) and these parameters all fell to a mean of approximately 9 min following rFVIIa dosing. The platelet contractile force (PCF) and clot elastic modulus (CEM) were positively correlated to FVII:C (P < 0.0001), and these parameters were dynamic throughout the 6-h period. The MA and MCF did not correlate to FVII:C nor did they significantly change during the study. Prothrombin F1 + 2 significantly increased following rFVIIa dosing (P < 0.001), but remained steady throughout the study. There was no change in D-dimer concentrations over time. The FOT, R and CT characterized clot initiation following rFVIIa dosing. The PCF and CEM were correlated to FVII:C and characterized the dynamics of platelet function and clot strength over the rFVIIa dosing interval. The clinical significance of these findings needs additional study.
|
|
| 3. |
|
|
| 4. |
- Larsen, Malte Selch, et al.
(författare)
-
Prediction of human pharmacokinetics of activated recombinant factor VII and B-domain truncated factor VIII from animal population pharmacokinetic models of haemophilia
- 2018
-
Ingår i: European Journal of Pharmaceutical Sciences. - : ELSEVIER SCIENCE BV. - 0928-0987 .- 1879-0720. ; 115, s. 196-203
-
Tidskriftsartikel (refereegranskat)abstract
- Various experimental animal models are used in haemophilia research, however, little is known about how well the different species predict pharmacokinetic (PK) profiles in haemophilia patients. The aim of the current study was to describe the plasma concentration-time profile of recombinant activated factor VII (rFVIIa) and recombinant factor VIII (rFVIII) in several experimental animal models using population PK modelling, and apply a simulation-based approach to evaluate how well the developed animal population PK models predict human PK. PK models were developed for rFVIIa and rFVIII in mice, rats, monkeys, and dogs using nonlinear mixed-effects modelling, accounting for inter-individual variability, nonlinear kinetics and covariate effects. Three scaling principles were applied to predict human PK: proportional scaling to body weight from single species, scaling with fixed theory-based allometric exponents from single species, and allometric interspecies scaling with estimated allometric coefficients and exponents. The plasma concentration-time profile of rFVIIa and rFVIII in mice, rats, monkeys and dogs were accurately described by the developed species-specific PK models, accounting for nonlinear kinetics and gender-specific difference in clearance for rFVIII. The predictive performance of the animal population PK models of rFVIIa and rFVIII revealed significant species-variation. The developed PK models of rFVIIa and rFVIII in monkeys and dogs along with allometric interspecies scaling revealed high predictive performance for human PK, and may promote rational decision-making in future first-in-human trials for rFVIIa and rFVIII variants.
|
|
