Antihemophilic factor VIII and von Willebrand factor are naturally occurring proteins found in human blood. Factor VIII is a protein that facilitates clotting, and relies on binding to the von Willebrand factor to prolong its life. Factor VIII unbound has a half-life of 1-2 hours, but when it binds to von Willebrand factor (vWf) it has a half-life of 7-8 hours. Von Willebrand factor is also a protein found in the blood, which along with supporting factor VIII is instrumental in maintaining homeostasis.
Patients with blood disorders such as von Willebrand disease or hemophilia A are deficient in factor VIII, and as a result, can suffer chronic internal and external bleeding; this can lead to complications and excessive blood loss. To treat this deficiency, patients receive intravenous injections of von Willebrand factor and factor VIII to make up the body's natural deficiency.
Antihemophilic factor injections are sold under a variety of brand names, including Alphanate (Grifols USA, LLC), Helixate (CSL Behring), and Kogenate (Bayer). Generic forms of the medication are available.
Antihemophilic factor injections can cause serious side effects. Patients should contact their doctor immediately if they begin to experience any of the following serious side effects after they begin antihemophilic factor injections:
Antihemophilic factor injections can be hard on the body and may take time to adapt to. Some side effects may simply be caused by the body trying to adjust to accommodate the injections and not necessarily symptoms of new or worsening conditions brought on by the injections. The following side effects are less dangerous, but patients should report all of the following side effects to their doctor if they experience them after beginning their antihemophilic factor injections:
This is not necessarily a complete list of side effects. Side effects other than those listed here may occur. Patients can report new side effects to the FDA at 1 800 FDA 1088 or www.fda.gov/medwatch.
Factor VIII and von Willebrand factor injections can come in a variety of strengths, depending on the condition being treated and the severity of the condition. Patients should follow their doctor's instructions as to how strong the injections should be.
Patients should receive their first injection from their doctor or other trained professional and receive training from their doctor on how to perform the injections themselves. Patients should not perform the injections themselves unless they fully understand how the medication works and how to properly perform the injection.
The medication is stored as a powder and has to be reconstituted by being mixed with a liquid before it can be injected. Patients should make sure that the solution they intend to inject has warmed to room temperature before they inject it.
Patients should consult their doctor if they miss or cannot perform the injection of a dose.
Factor VIII and von Willebrand factor may interact with a broad range of drugs and/or supplements. Patients should make sure to disclose all drugs, medications, and supplements they are taking to their doctor before considering receiving antihemophilic factor injections.
Antihemophilic factor is known to interact with any drug that affects bleeding or blood clotting. Patients should avoid taking any drug that affects bleeding or blood clotting while they are receiving antihemophilic factor injections. By doing so, patients will put themselves at greater risk of new or worsening side effects, and may diminish the effectiveness of both the antihemophilic factor injection and the other drug. Patients should disclose any and all drugs that may affect bleeding or blood clotting to their doctor before beginning to receive antihemophilic factor injections.
Patients should use only fresh, sterile needles to perform the injections. Under no circumstances should a patient ever reuse an old needle, especially not a needle already used by someone other than the patient.
Patients who need to undergo surgery during the time their antihemophilic factor injections are active may need to stop receiving their injections for a period of time. Antihemophilic factor can complicate surgical proceedings.
Patients with bleeding disorders or who are receiving injections of von Willebrand factor and factor VIII should carry an ID card or another form of identification on them at all times, as their condition and their injections may be relevant to any medical emergency the patient may find themselves in.
In some cases, the factor VIII and von Willebrand factor that patients inject comes from human plasma. While plasma donors are thoroughly screened, and the donated plasma is rigorously tested and treated, it is possible for some diseases to remain in the plasma, and those diseases can be transmitted to the patient using it. Some viruses, such as parvovirus B19 and hepatitis A, are especially difficult to identify/remove from factor VIII.
The symptoms of parvovirus B19 can include fever and chills, followed after two weeks by rashes and some joint pain. Patients should contact their doctors immediately if they begin to experience these symptoms after injecting factor VIII and vWf. Parvovirus B19 is especially dangerous to pregnant women and to patients with compromised immune systems.
The symptoms of hepatitis A can include tiredness, nausea, fever, stomach pain, and even jaundice. Patients should contact their doctor immediately if they begin to experience these symptoms after injecting factor VIII and vWf.
Patients with a history of blood clots, including deep vein thrombosis and pulmonary embolisms should consult with their doctor before beginning to receive antihemophilic factor injections. Antihemophilic factor injections will aggravate these conditions.
Even in patients without a history of blood clots, antihemophilic factor will raise a patient's chances of developing a rogue blood clot. Patients should contact their doctor immediately if they experience symptoms which may include severe headaches, numbness, chest pain, shortness of breath, or speech and vision problems. These symptoms may be signs that the patient has developed a blood clot.
Patients with a history of strokes should consult with their doctor before receiving injections of the antihemophilic factor. Antihemophilic factor injections may increase the patient's risk of stroke.
Factor VIII and von Willebrand factor injections can produce serious allergic reactions. Patients should contact their doctor if they begin to experience signs of allergic reaction after injecting antihemophilic factor, including hives, swelling of the face, rash, or difficulty breathing.
Antihemophilic factor is considered a class C drug for pregnancy, meaning that risk to the fetus cannot be ruled out. It is also not known whether or not antihemophilic factor can be transmitted through breast milk, or if it can be damaging to a breastfeeding baby. Patients who are pregnant or breastfeeding should not receive injections of the antihemophilic factor without first consulting their doctor on risks to the fetus/baby.
In some cases, patients' bodies developed antibodies to cope with the sudden influx of factor VIII and von Willebrand factor. Patients who experience a drop in the effectiveness of antihemophilic factor injections should contact their doctor immediately.
It is possible to overdose on factor VIII and von Willebrand factor. If patients fear they may have injected too much of the antihemophilic factor they should seek emergency medical treatment.
Insufficient clinical trials have been performed to rule out the risk of complication or contraindication in geriatric (65+) patients. Patients who are 65 or older who are considering receiving injections of the antihemophilic factor should consult with their doctor before beginning the injections.
Across multiple clinical studies, no evidence has been found of pediatric-specific complications or contraindications.
The powdered mixture of factor VIII and von Willebrand factor can be safely stored in a refrigerator. Once reconstituted, the solution of liquid and powdered antihemophilic factor can be safely stored at room temperature for up to 3 hours, The reconstituted solution should never be refrigerated or be allowed heat up past 30 degrees Celsius (86 degrees Fahrenheit).
The antihemophilic factor can be safely stored in a refrigerator for as long as 6 months, or until the printed expiration date. Patients should dispose of the medication by whichever date comes first.
If the antihemophilic factor powder is ever allowed to warm back up to room temperature after being refrigerated it should not be placed back in the refrigerator. Patients should contact their doctor for instructions in the event this is allowed to happen.
Factor VIII and von Willebrand factor injections can be a life-changing treatment for patients suffering from blood disorders. Because the injection is little more than proteins that the body naturally produces there are relatively few side effects to the injections, and they are usually easy for the body to take. The real danger to the patient comes in the injection process, which the patient must fully understand and respect before they endeavor to perform it themselves. The patient should make sure to properly reconstitute the medicine, warm it to the proper temperature and inject in a timely manner. Additionally, they should make sure that they follow their doctor's instructions perfectly when performing the injections.
If patients are able to successfully and routinely perform the injections themselves, then the antihemophilic factor offers little but upside for the patient, who most likely would otherwise be living with rogue and uncontrollable episode of bleeding.