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Factor VIII

 
Dental Dictionary: factor VIII

n
antihemophilic factor [AHF], antihemophilic globulin, antihemophilic globulin A, antihemophilic factor A, plasma thromboplastin factor [PTF], plasmokinin, platelet cofactor I, prothrombokinase, thrombocatalysin, thrombocytolysin, thrombokatilysin, thrombo-plastic plasma component [TPC], thromboplastinogen

A factor essential for the formation of blood thromboplastin. A deficiency results in classic hemophilia (hemophilia A); the clotting time is prolonged, and thromboplastin and prothrombin conversion is diminished.

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Drug Info: Antihemophilic Factor, AHF, Factor VIII
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Brand names: Advate®Alphanate®Bioclate®Helixate® FSHemofil® MHumate-P®Hyate C®Koate®-DVIKogenate®Kogenate® FSMonarc-M ™Monarc-M™ Monarc-M®Monoclate-P®Recombinate™ReFacto®



Antihemophilic Factor, AHF, Factor VIII injection

What is antihemophilic factor injection?

Antihemophilic factor (AHF, Factor VIII) is a natural protein, normally present in the blood that helps blood to clot. A deficiency or lack of this protein is responsible for the inherited disease, hemophilia A. Antihemophilic factor helps to prevent or control bleeding in patients who lack factor VIII, treats joint bleeds, or prevents bleeding complications during surgery. Some antihemophilic factor products may be used to treat von Willebrand's disease. A number of antihemophilic factor products are available and can come from human or animal sources or are man-made.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
• acquired immunodeficiency syndrome (AIDS) or if you are HIV-positive
• an unusual or allergic reaction to human or animal (cow, hamster, mouse, or pig) proteins
• pregnant or trying to get pregnant
• breast-feeding

How should I use this medicine?

Antihemophilic factor is for injection into a vein. It is usually given by a health-care professional in a hospital or clinic setting. If you are given antihemophilic factor for home use, you will be instructed in the proper injection technique. Follow the directions exactly. Always wash your hands before use. Only use a disposable syringe once. Let the powder and solution warm to room temperature before use. Follow mixing directions carefully to avoid foaming. Swirl but do not shake the solution. Throw away any unused portion.

What if I miss a dose?

Try not to miss doses. Ask your prescriber or health care professional for instructions if you miss a dose.

What drug(s) may interact with antihemophilic factor?

No drug-drug interactions have been reported for antihemophilic factor.

Tell your prescriber or health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your health care professional before stopping or starting any of your medicines.

What should I watch for while taking antihemophilic factor?

Some antihemophilic factor products are derived from human plasma, and there is a small risk that these products may contain certain types of virus or bacteria. All products are processed to kill most viruses and bacteria. If you have questions concerning the risk of viral infections, discuss them with your prescriber or health care professional. If you are a newly diagnosed hemophiliac, you should have a hepatitis A and B vaccination.

If you are a hemophilia patient, carry an identification card with you at all times. The card should have your name, the name and dose of your medication(s), the name and phone number of your prescriber or health care professional, and a contact person in case of emergency.

If you are going to have surgery or a dental procedure, tell your prescriber or health care professional that you use a antihemophilic factor product.

Patients should consider enrolling in voluntary programs with their prescribers to be notified of any product recalls.

What side effects may I notice from receiving antihemophilic factor?

Side effects that you should report to your prescriber or health care professional as soon as possible:
• allergic reactions including difficulty breathing, hives, rash, tightness in throat, swelling of tongue, or wheezing
• chest pain, fast or irregular heartbeat (palpitations)
• fever or chills
• dizziness, fainting
• increased tiredness
• shortness of breath or swelling in a leg
• signs of viral infection including fever, drowsiness, chills, runny nose followed in about 2 weeks by a rash and joint pain
• yellowing of skin or eyes, stomach pain

Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):
• blurred vision
• flushing
• headache
• nausea, vomiting
• numbness or tingling in hands or feet

Where can I keep my medicine?

Keep out of the reach of children.

For most products, store in a refrigerator between 2 and 8 degrees C (36 and 46 degrees F). For unreconstituted Helixate® FS or Kogenate® FS, storage at room temperature (up to 25 degrees C or 77 degrees F) for up to 3 months is allowed. Once stored at room temperature, Helixate® FS or Kogenate® FS should not be returned to the refrigerator for storage. For any Antihemophilic Factor, factor VIII product, read and make sure to follow individual manufacturer's storage guidelines each time you get a supply; older forms of Helixate® FS, Kogenate® FS, and other brands should not be stored at room temperature. Do not freeze. Throw away after expiration date. Once the solution has been prepared, use it within 1—3 hours.

Last updated: 8/27/2003 9:09:00 AM

Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.

Science Q&A: What is factor VIII?
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Factor VIII is one of the enzymes involved in the clotting of blood. Hemophiliacs lack this enzyme and are at high risk of bleeding to death unless they receive supplemental doses of factor VIII. The lack of factor VIII is due to a defective gene, which shows a sex-linked inherited pattern (it affects about one in 10 thousand males). Females can carry the gene. Hemorrhage into joints and muscles usually makes up the majority of bleeding episodes.

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Wikipedia: Factor VIII
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edit
Coagulation factor VIII, procoagulant component (hemophilia A)
PBB Protein F8 image.jpg
PDB rendering based on 1d7p.
Available structures
1d7p, 1iqd, 3cdz
Identifiers
Symbols F8; AHF; DXS1253E; F8 protein; F8B; F8C; FVIII; HEMA
External IDs OMIM306700 MGI88383 HomoloGene49153
RNA expression pattern
PBB GE F8 205756 s at tn.png
More reference expression data
Orthologs
Species Human Mouse
Entrez 2157 14069
Ensembl ENSG00000185010 ENSMUSG00000031196
UniProt P00451 Q684Q7
RefSeq NM_000132 (mRNA) NM_007977 (mRNA)
NP_000123 (protein) NP_032003 (protein)
Location Chr X:
153.72 - 153.9 Mb
Chr X:
71.43 - 71.64 Mb
PubMed search [1] [2]

Factor VIII (FVIII) is an essential blood clotting factor also known as anti-hemophilic factor (AHF). In humans, Factor VIII is encoded by the F8 gene.[1][2] Defects in this gene results in hemophilia A, a well known recessive X-linked coagulation disorder.[3]

Factor VIII participates in blood coagulation; it is a cofactor for factor IXa which, in the presence of Ca+2 and phospholipids forms a complex that converts factor X to the activated form Xa. The Factor VIII gene produces two alternatively spliced transcripts. Transcript variant 1 encodes a large glycoprotein, isoform a, which circulates in plasma and associates with von Willebrand factor in a noncovalent complex. This protein undergoes multiple cleavage events. Transcript variant 2 encodes a putative small protein, isoform b, which consists primarily of the phospholipid binding domain of factor VIIIc. This binding domain is essential for coagulant activity.[4]

Contents

Genetics

The gene for Factor VIII is located on the X chromosome (Xq28). The gene for factor VIII presents an interesting primary structure, as another gene is embedded in one of its introns.[5]

Physiology

FVIII is a glycoprotein procofactor. It has been found to be synthesized and released into the bloodstream by the vascular, glomerular, and tubular endothelium, and the sinusoidal cells of the liver[6], though there is still considerable ambiguity as to what the primary site of release in humans is. In the circulating blood, it is mainly bound to von Willebrand factor to form a stable complex. Upon activation by thrombin, (Factor IIa), it dissociates from the complex to interact with Factor IXa in the coagulation cascade. It is a cofactor to Factor IXa in the activation of Factor X, which, in turn, with its cofactor Factor Va, activates more thrombin. Thrombin cleaves fibrinogen into fibrin which polymerizes and crosslinks (using Factor XIII) into a blood clot.

No longer protected by vWF, activated FVIII is proteolytically inactivated in the process (most prominently by activated Protein C and Factor IXa) and quickly cleared from the blood stream.

Factor VIII is not affected by liver disease. In fact, levels usually are elevated in such instances.[7]

Therapeutic use

FVIII concentrated from donated blood plasma (Aafact), or alternatively recombinant FVIII can be given to hemophiliacs to restore hemostasis.

The transfer of a plasma byproduct into the blood stream of a patient with hemophilia often led to the transmission of diseases such as hepatitis B and C and HIV before purification methods were improved. Antibody formation to Factor VIII can also be a major concern for patients receiving therapy against bleeding; the incidence of these inhibitors is dependent of various factors, including the Factor VIII product itself.[8]

In the 1980s, some pharmaceutical companies such as Bayer sparked controversy by continuing to sell contaminated factor VIII after new heat-treated versions were available.[9] In the early 1990s, pharmaceutical companies began to produce recombinant synthesized factor products, which now prevent nearly all forms of disease transmission during replacement therapy.

See also

References

  1. ^ Toole JJ, Knopf JL, Wozney JM, Sultzman LA, Buecker JL, Pittman DD, Kaufman RJ, Brown E, Shoemaker C, Orr EC (1984). "Molecular cloning of a cDNA encoding human antihaemophilic factor". Nature 312 (5992): 342–7. PMID 6438528. 
  2. ^ Truett MA, Blacher R, Burke RL, Caput D, Chu C, Dina D, Hartog K, Kuo CH, Masiarz FR, Merryweather JP (October 1985). "Characterization of the polypeptide composition of human factor VIII:C and the nucleotide sequence and expression of the human kidney cDNA". DNA 4 (5): 333–49. PMID 3935400. 
  3. ^ Antonarakis SE (July 1995). "Molecular genetics of coagulation factor VIII gene and hemophilia A". Thromb. Haemost. 74 (1): 322–8. PMID 8578479. 
  4. ^ "Entrez Gene: F8 coagulation factor VIII, procoagulant component (hemophilia A)". http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=2157. 
  5. ^ Levinson B, Kenwrick S, Lakich D, Hammonds G, Gitschier J (1990). "A transcribed gene in an intron of the human factor VIII gene". Genomics 7 (1): 1–11. doi:10.1016/0888-7543(90)90512-S. PMID 2110545. 
  6. ^ Kumar, Abbas, Fausto (2005). Robbins and Cotran Pathologic Basis of Disease. Pennsylvania: Elsevier. pp. 655. ISBN 1-889325-04-X. 
  7. ^ R. Rubin, L. Leopold (1998). Hematologic Pathophysiology. Madison, Conn: Fence Creek Publishing. ISBN 1-889325-04-X. 
  8. ^ Lozier J (2004). "Overview of Factor VIII Inhibitors". CMEonHemophilia.com. http://www.cmeonhemophilia.com/pub/overview.of.factor.viii.inhibitors.php. Retrieved 2009-01-07. 
  9. ^ Bogdanich W, Koli E (2003-05-22). "2 Paths of Bayer Drug in 80's: Riskier One Steered Overseas". The New York Times. http://query.nytimes.com/gst/fullpage.html?res=9A00E4DA1F3EF931A15756C0A9659C8B63&sec=&spon=&pagewanted=1=2157. Retrieved 2009-01-07. 

Further reading

External links


 
 

 

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Dental Dictionary. Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved.  Read more
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