Sigurd Knaub

Pharmacokinetics of Beriplex P/N prothrombin complex concentrate in healthy volunteers

Prothrombin complex concentrates (PCCs) are widely administered for emergency oral anticoagulation reversal and for coagulation defects in liver disease. Pharmacokinetic data may help to optimize treatment. The objective of this study was to characterize the pharmacokinetics of a PCC (Beriplex P/N) containing coagulation factors II (FII), VII (FVII), IX (FIX) and X (FX) and anticoagulant proteins C and S. Fifteen healthy volunteers received a single rapid 50 IU/kg infusion of PCC and underwent frequent blood sampling until 144 hours (h) after infusion. Coagulation factors and anticoagulant protein pharmacokinetic parameters were estimated by non-linear regression. The mean infusion rate of PCC was 7.9 ml/min, equivalent to 196.4 IU/min. By the earliest post-infusion sampling point at 5 minutes (min), plasma FIX concentration increased by a median of 73%. Median increases in FII, FVII and FX at 5 min were 122%, 62% and 158%, respectively. Proteins C and S also increased rapidly. The median terminal half-life of FIX was 16.7 h, FII 59.7 h, FVII 4.2 h and FX 30.7 h. The median in-vivo recovery of FIX was 1.57 %/IU/kg and that of the other three coagulation factors > 2 %/IU/kg. Plasma concentration of thrombogenicity marker D-dimer did not increase, and there was no clinical evidence of thrombosis. Through up to 12 weeks follow-up there were no laboratory findings indicating PCC-related viral exposure. Rapid PCC infusion produced prompt sustained increases in coagulation factors and anticoagulant proteins with no clinical evidence of thrombosis or viral transmission.

Incidence of bleeding symptoms in 100 patients with inherited afibrinogenemia or hypofibrinogenemia

arin-induced thrombocytopenia. Curr Hematol Rep 2003; 2: 148–57. 4 Shibata S, Harpel PC, Gharavi A, Rand J, Filit H. Autoantibodies to heparin from patients with antiphospholipid antibody syndrome inhibit formation of antithrombin III-thrombin complexes. Blood 1994; 83: 2532–40. 5 Martinuzzo ME, Forastierio RR, Adamczuk Y, Pombo G, Carreras LO. Antiplatelet factor 4–heparin antibodies in patients with antiphospholipid antibodies. Thromb Res 1999; 95: 271–9. 6 Kovacs MJ. Successful treatment of heparin induced thrombocytopenia (HIT) with fondaparinux. Thromb Haemost 2005; 93: 999– 1000. 7 Parody R, Oliver A, Souto JC, Fontcuberta J. Fondaparinux (ARIXTRA) as an alternative anti-thrombotic prophylaxis when there is hypersensitivity to low molecular weight and unfractionated heparins. Haematologica 2003; 88: ECR32. 8 Spinler SA. New concepts in heparin-induced thrombocytopenia: diagnosis and management. J Thromb Thrombolysis 2006; 21: 17–21. 9 Savi P, Chong BH,Greinacher A,Gruel Y,Kelton JG,Warkentin TE, Eichler P, Meuleman D, Petitou M, Herault JP, Carioiu R, Herbert JM. Effect of fondaparinux on platelet activation in the presence of heparin-dependent antibodies: a blinded comparative multicenter study with unfractionated heparin. Blood 2005; 105: 139–44. 10 Girardi G, Redecha P, Salmon JE. Heparin prevents antiphospholipid antibody-induced fetal loss by inhibiting complement activation. Nat Med 2004; 10: 1222–6.

Rotational thromboelastography for monitoring of fibrinogen concentrate therapy in fibrinogen deficiency.

To characterize a functional assay for circulating fibrinogen based on rotational thrombelastography. Maximum clot firmness was determined by rotational thrombelastography in normal human plasma pool, fibrinogen-deficient plasma pool, normal whole blood, and individual plasma samples from 17 patients with fibrinogen deficiency. Plasma samples spiked with varying concentrations of exogenous fibrinogen were also measured. Results were compared with enzyme-linked immunosorbent assay and Clauss assay. The impact of sample freezing and filtration and use of cytochalasin D were also investigated. Over the tested range of 0–3 mg/ml added exogenous fibrinogen, the maximum clot firmness standard curve for determination of fibrinogen in plasma pools (n = 7) was linear (r2 = 0.97). Maximum clot firmness was highly linearly correlated both with Clauss assay (r2 = 0.93) and enzyme-linked immunosorbent assay (r2 = 0.95). In unspiked plasma samples from individual patients with fibrinogen deficiency, fibrinogen was undetectable by rotational thromboelastography. By all evaluated methods, the response to spiking with fibrinogen in such samples coincided closely in patients with afibrinogenemia and hypofibrinogenemia. In dysfibrinogenemia, smaller Clauss assay responses to spiking were observed, whereas the enzyme-linked immunosorbent assay response was variable. Maximum clot firmness was the only evaluated method of fibrinogen assessment to yield consistent results across all categories of fibrinogen deficiency. These in-vitro results suggest the potential clinical utility of rotational thromboelastography as a versatile method for monitoring the response to fibrinogen concentrate among patients with fibrinogen deficiency. Clinical investigations using rotational thromboelastography after in-vivo fibrinogen administration to patients with congenital fibrinogen deficiency are warranted.

The first recombinant human coagulation factor VIII of human origin: human cell line and manufacturing characteristics.

Since the early 1990s, recombinant human clotting factor VIII (rhFVIII) produced in hamster cells has been available for haemophilia A treatment. However, the post‐translational modifications of these proteins are not identical to those of native human FVIII, which may lead to immunogenic reactions and the development of inhibitors against rhFVIII. For the first time, rhFVIII produced in a human host cell line is available.

Novel, human cell line-derived recombinant factor VIII (human-cl rhFVIII; Nuwiq®) in adults with severe haemophilia A: efficacy and safety

Nuwiq® [human cell line‐derived recombinant factor VIII (human‐cl rhFVIII)] is a new generation rFVIII protein, without chemical modification or fusion to any other protein, produced in a human cell line.

Prophylaxis vs. on-demand treatment with Nuwiq(®) (Human-cl rhFVIII) in adults with severe haemophilia A.

Haemophilia A is treated with FVIII, either prophylactically or on demand. Prophylaxis is the gold standard in children and evidence is accumulating in adults.

PK-guided personalized prophylaxis with Nuwiq(®) (human-cl rhFVIII) in adults with severe haemophilia A.

Nuwiq® (human‐cl rhFVIII) is a 4th generation recombinant human FVIII, without chemical modification or protein fusion, produced in a human cell‐line.

A retrospective study of Octaplex in the treatment of bleeding in patients with haemophilia A complicated by inhibitors.

The nonactivated prothrombin complex concentrate (PCC) Octaplex (Octapharma PPGmbH, Vienna, Austria) has been used successfully for the treatment of congenital and acquired coagulation factor deficiencies and associated bleeding. The aims of this study were to assess retrospectively whether Octaplex is an effective treatment option for haemophilia A patients with high-titre inhibitors of factor VIII (FVIII) and to investigate the impact of Octaplex on thrombin generation in vitro and ex vivo. Retrospective data were collected from 15 haemophilia A patients with FVIII inhibitors who had been treated with Octaplex. Mild bleeds were treated for a median of 1 day with a median dose of 77 IU/kg and moderate bleeds for 3 days with 57 IU/kg. The physicians overall satisfaction with Octaplex, taking into account efficacy, safety and cost in comparison with other treatment options, was assessed for each bleed. The overall rating was good, very good or excellent for 29 of 41 (71%) bleeds. No adverse drug reactions were reported. In in-vitro studies of thrombin generation with normal plasma samples, experimental inhibition of FVIII activity prolonged the lag phase, diminished the peak thrombin concentration and decreased the area under the concentration–time curve, as expected. Marked improvement in thrombin generation parameters was achieved by adding 0.5–3 IU factor IX/ml PCC into the samples. The same held true when using plasma samples from haemophilia A patients with FVIII inhibitors. These results demonstrate that Octaplex overcomes inhibition of FVIII in in-vitro and ex-vivo assays of thrombin generation, and that Octaplex is an effective treatment option for haemophilia A patients with FVIII inhibitors.

Use of objective efficacy criteria for evaluation of von Willebrand factor/factor VIII concentrates.

von Willebrand disease (VWD) is the most common inherited coagulation disorder and is typically treated by restoring the deficient von Willebrand factor (VWF) with exogenous VWF or by stimulating release of endogenous VWF with desmopressin. Assessment of treatment efficacy is complex because there are no standardized criteria or consistent methodology in their application. The traditionally used four-point Likert scale, with criteria that are not clearly defined or easily quantifiable, relies on a subjective rating of efficacy, and is thus open to observer bias. This article presents a novel approach to assessing efficacy of VWF replacement therapy. A new objective scoring system for assessment of the treatment efficacy of bleeding episodes (objective set of criteria for evaluation of treatment efficacy in VWD) was developed to assess a new-generation human plasma-derived VWF/coagulation factor VIII concentrate (Wilate). This manuscript analyzes the results obtained using a traditional subjective scoring system for hemostatic efficacy and compares them with results obtained when a specifically developed set of stringent objective and well defined success/failure criteria are applied in a clinical trial setting. This new assessment tool provided improved objectification of the subjective judgments obtained from the recipients of the replacement therapy. A validated tool like this could ultimately be applied to clinical comparability studies for the multiplicity of new generation replacement products, as healthcare providers, regulatory agencies, and manufacturers must now consider the additional benefits conveyed by treatment modalities, such as treatment duration, alternative dosing regimens, and treatment frequency. The objective criteria appear to be more robust and present a more conservative assessment of treatment efficacy while avoiding observer and recipient bias and inconsistencies. This new approach may be a more suitable alternative for hemostatic assessment of coagulation products in VWD patients than the currently used subjective methods.

Efficacy and safety of a new human fibrinogen concentrate in patients with congenital fibrinogen deficiency: An interim analysis of a Phase III trial

Fibrinogen concentrate is the preferred choice for fibrinogen replacement in congenital fibrinogen deficiency. This study investigated hemostatic efficacy of a new plasma‐derived, double virus‐inactivated (using two dedicated virus inactivation/elimination steps) human fibrinogen concentrate for on‐demand treatment of bleeding episodes (BEs) and surgical prophylaxis.