Hemophilia A medical therapy
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Medical Therapy
There is no definitive treatment for hemophilia A, the mainstay of therapy is supportive and preventative care. Most haemophilia patients require regular supplementation with intravenous recombinant factor VIII, also known as replacement therapy. This is highly individually determined. Apart from "routine" supplementation, extra factor concentrate is given around surgical procedures and after trauma, as well as emergently during any bleeding episode. Recombinant factor VIII concentrates do not contain any plasma or albumin, and therefore do not carry the risk of transmitting bloodborne viruses.
Other therapeutic options include cryoprecipitate, fresh frozen plazma (FFP), desmopressin (DDAVP), and anti-fibrinoltytic agents.
- Cryoprecipitate contains moderately high concentrations of factor VIII and may be given for joint and muscle bleeds. However, as it is derived from blood it carries risk of viral contamination
- FFP (fresh frozen plasma) contains clotting factors VIII and IX at significantly less concentrations than cryoprecipitate. As such, it is not routinely recommended as first-line therapy for hemophiliacs with bleeding episodes, given that the high amount of volume required to correct the coagulation deficit may result in circulatory volume overload.
- DDAVP, or desmopressin, is a synthetic hormone which stimulates the release of factor VIII. It may be given to patients with mild, or sometimes moderate, hemophilia to treat minor bleeding
- Anti-fibrinolytic medications, most commonly epsilon aminocarproic acid), may be given orally or intravenously to prevent clots from being dissolved. It is often given orally prior to dental work to reduce risk of bleeding.
- Patients with hemophilia may also require transfusion of packed red blood cells if excessive bleeding results in anemia.
In children, an easily accessible intravenous port (e.g. Port-a-Cath) may have to be inserted to minimise frequent traumatic intravenous cannulation. These devices have made prophylaxis in hemophilia much easier for families because the problems of "finding a vein" for infusion two to three times a week are eliminated. However, there are risks involved with their use, the most worrisome being that of infection. Studies differ but some show an infection rate as high as 50 percent. These infections can usually be treated with intravenous antibiotics but sometimes the device must be removed. Also, there are other studies that show a risk of clots forming at the tip of the catheter. Still, many families have chosen to use the device in spite of the risk because of the benefits. Like any other procedure, one must weigh the risks and benefits.
A particular therapeutic conundrum is the development of "inhibitor" antibodies against factor VIII due to frequent infusions. These probably develop as the body recognises the factor VIII as foreign, as the body does not have its own "copy". 20-30% of patients with severe hemophilia A develop inhibitors, and in these patients, factor VIII infusions are ineffective. If a patient develops an inhibitor to factor VIII, physicians may either attempt to infuse larger doses of recombinant clotting factor, or try different clotting factor sources. These antibodies may self-resolve with time. No definitive therapy exists otherwise for patients who develop inhibitors to factor VIII. Recently activated factor VII (NovoSeven®) has become available as a treatment for haemorrhage in patients with haemophilia and factor inhibitors.