Bypassing Agents

Hemophilia is a blood disorder in which patients do not make enough of the clotting factors that control bleeding. Following accident or injury, people with hemophilia may be unable to stop bleeding. In severe cases, patients may bleed spontaneously at joints.

While there is no cure for hemophilia, there are treatments to manage the disease. However, in some cases, patients develop resistance to treatments — usually by developing antibodies against the clotting factors that are used to treat the disease.

What are bypassing agents?

Bypassing agents are treatments that “bypass” the need for clotting factor treatment. They also can be used to treat acquired hemophilia, a rare type of hemophilia in which the body erroneously develops antibodies against its own clotting factors.

Examples of bypassing agents

FEIBA is a treatment that can be used to treat hemophilia A and hemophilia B in patients with inhibitors. FEIBA contains several clotting factors that help convert prothrombin into thrombin — a protein that is essential in forming stable blood clots.

NovoSeven RT resembles human clotting factor VIIa, which promotes the production of fibrin, another protein required for clot formation. NovoSeven RT is different enough from human factor VIIa that patients’ antibodies are less likely to recognize it.

Obizur is a recombinant factor VIII derived from pigs that can be used to treat patients with acquired hemophilia A. Their antibodies do not usually attack Obizur as it is slightly different from the human clotting factor VIII.


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