Perspectives on the use of factor IX complex concentrates in the treatment of bleeding in persons with acquired factor VIII inhibition.

In contrast to the type of bleeding encountered in congenital hemophilia with inhibitors, the diathesis toward bleeding exhibited by patients with spontaneously acquired factor VIII (FVIII) inhibitors often is severe and life threatening. Large hematomas and retropharyngeal or central nervous system hemorrhage may appear suddenly. Thus, a high premium is placed on rapid therapeutic intervention. Several treatment options are at the physician's disposal. The role of factor IX (FIX) complex concentrates, both standard and purposely activated, is discussed. The FIX products are also known as prothrombin complex concentrates (PCCs). Prudent choice of any treatment modality requires weighing its benefits and shortcomings. Advantages of PCCs--particularly the activated products--include availability, ease of reconstitution and administration, and at least partial efficacy; control of bleeding episodes can be achieved with PCCs in many (but not all) instances. One salient disadvantage of therapy with FIX complex concentrates is that they are not subjected to such rigorous viral-attenuation processes as are most of the currently marketed FVIII products. Therefore, a small but definite risk of infection with hepatitis B or C (HBV, HCV) remains. An assay that detects antibodies against HCV has been licensed and is being used to screen blood donors. Nevertheless, up to the present time the U.S. Food and Drug Administration (FDA) has ruled that HCV screening of plasmapheresis donors should not be performed for plasma collections destined to be pooled for fractionation and that units of HCV-positive source plasma (e.g., that provided by American Red Cross donors) found to be HCV positive be sent for fractionation. The starting plasma from which FIX complex concentrates and human FVIII concentrates are made thus contains some HCV and may also contain some HBV. Because nonhemophiliacs with acquired antibodies against FVIII are unlikely to have had prior exposure to blood products and are unlikely to have been vaccinated against HBV, they are at risk of viral hepatitis and its sequelae when treated with FIX complex concentrates. Furthermore, therapy with FIX complex concentrates is not always effective in controlling bleeding in persons with FVIII inhibitors, its mechanism of action in bypassing the need for FVIII remains unclear, very large doses are required, and it has an attendant risk of several adverse effects when used in large, repeated doses. These include disseminated intravascular coagulation, thromboembolism, and acute myocardial infarction. Thus, FIX complex concentrates may play a useful role in the treatment of bleeding in nonhemophiliacs with acquired inhibitors against FVIII, but one must carefully consider their disadvantages profile.(ABSTRACT TRUNCATED AT 400 WORDS)