The old and new: PCCs, VIIa, and long-lasting clotting factors for hemophilia and other bleeding disorders.

What is the correct use of established clotting factors, prothrombin complex concentrates (PCCs), and activated factor VII in bleeding complications of trauma, surgery, and old and new oral anticoagulants? How will new clotting factors, specifically the long-acting factors, change the hemostatic management of coagulation deficiency disorders? From bench to bedside, comparative coagulation studies and clinical trials of modified clotting factors are providing insights to help guide hemostatic management of congenital and acquired bleeding disorders. Comparative thrombin-generation studies and preclinical and clinical trials suggest that PCCs and fresh-frozen plasma are effective in reversing the anticoagulant effects of warfarin, yet there are few data to guide reversal of the new oral anticoagulants dabigatran and rivaroxaban. Although coagulation studies support the use of PCCs to reverse new oral anticoagulants, correlation with clinical response is variable and clinical trials in bleeding patients are needed. For congenital bleeding disorders, exciting new technologies are emerging from the bench. Data from clinical trials of molecularly modified coagulation factors with extended half-lives suggest the possibility of fewer infusions, reduced bleeds, and better quality of life in persons with hemophilia. Preclinical studies of other novel prohemostatic approaches for hemophilia and other congenital coagulation disorders include RNA interference silencing of antithrombin, monoclonal anti-tissue factor pathway inhibitor (anti-antibody, anti-tissue factor pathway inhibitor) aptamer, bispecific anti-IXa/X antibody, and fucoidans. Understanding the comparative coagulation studies of established prohemostatic agents, the pharmacokinetics of new long-acting clotting factors, and their correlation with bleeding outcomes will provide opportunities to optimize the hemostatic management of both congenital and acquired hemostatic disorders.

Pharmacokinetic allometric scaling of coagulation factors and tissue-type plasminogen activators.

The objective of this study was to evaluate the predictive performance of pharmacokinetic interspecies scaling of coagulation factors and tissue-type plasminogen activators to predict clearance, volume of distribution at steady-state and half-life in humans from animal data. The human pharmacokinetic parameters were predicted using one, two or at least three animal species. The results of the study indicated that the pharmacokinetic parameters of coagulation factors and tissue-type plasminogen activators can be predicted with reasonable accuracy in humans when three or more animal species are available. Two-species scaling can also be performed, but the accuracy of predicted parameters is less than three-species scaling.

Differential response to bypassing agents complicates treatment in patients with haemophilia and inhibitors.

The bypassing agents factor eight inhibitor bypassing activity (FEIBA) anti-inhibitor coagulant complex and recombinant activated factor VII (rFVIIa) have been established as safe and effective therapies for treating bleeding episodes in haemophilia patients with inhibitors. However, the efficacy of each bypassing agent can vary, and neither agent is universally effective. The reasons for such variability have yet to be confirmed, but may involve patient-specific factors and the mechanisms of action (MOAs) and pharmacokinetic profiles of these two agents. This issue underscores the necessity of both products in the comprehensive care of patients with haemophilia and inhibitors. The objective of this review is to discuss the evidence of a differential haemostatic response to bypassing agents and the potential roles of MOA and patient-specific factors in contributing to the differences in response.