How Bleeding is Stopped When a Person has an Inhibitor
People with inhibitors do not bleed more often than other people with hemophilia. However, in someone with an inhibitor, regular factor treatment cannot always stop the bleeding. Taking factor as usual might be enough to stop bleeding in someone with a low inhibitor response level. A person with a high response level, though, will need other ways of treating the bleed.
Treatment to control bleeding in someone with an inhibitor is different for each person. The treatment is based on the inhibitor level, whether the person is a high or low responder, and the type of bleed. The treatment also depends on the type of factor products available. Because it may take a number of different methods to control the bleeding, the medical team must watch the process closely.
One way to treat the bleed is to give the person large amounts of factor to overcome the inhibitor. This method may be used in a patient who is about to have surgery. It may also be used when the bleed is life-threatening. There is a problem with this treatment, however. After three to five days of treatment, the inhibitor level may rise even higher than before. The level may take weeks, even months, to go down. This can cause problems if the person needs treatment again before the level drops.
Another way to treat the bleed is to give the person with an inhibitor a special type of factor concentrate. Two types of factor concentrate have been approved in the United States for this purpose, Activated Prothrombin Complex Concentrate (aPCC) and Recombinant FVIIa ("factor seven-a").
Activated Prothrombin Complex Concentrate (aPCC) is sold under the brand name FEIBA. This is a "plasma-derived product", meaning that it is made from human blood. It is treated in several different ways to minimize the risk of it containing viruses. This product contains factors II, VII, and X in their "activated" forms. This means it can bypass factors VIII or IX in the clotting process and stop the bleeding.
Recombinant Factor VIIa is sold under the brand name NovoSeven RT. It is a recombinant factor concentrate that is not made from blood. The factor VIIa can bypass factors VIII and IX and activate factor X to form a clot. Factor VIIa must be given every two hours and is very expensive.
Both aPCC and Factor VIIa carry a risk of causing unwanted blood clots.