Direct factor Xa inhibitors ('xabans') are a class of anticoagulant

Anticoagulant

An anticoagulant is a substance that prevents coagulation of blood. A group of pharmaceuticals called anticoagulants can be used in vivo as a medication for thrombotic disorders. Some anticoagulants are used in medical equipment, such as test tubes, blood transfusion bags, and renal dialysis...

 drugs which act directly upon Factor X

Factor X

Factor X, also known by the eponym Stuart-Prower factor or as prothrombinase, is an enzyme of the coagulation cascade. It is a serine endopeptidase .-Physiology:...

 in the coagulation cascade, without using antithrombin

Antithrombin

Antithrombin is a small protein molecule that inactivates several enzymes of the coagulation system. Antithrombin is a glycoprotein produced by the liver and consists of 432 amino acids. It contains three disulfide bonds and a total of four possible glycosylation sites...

 as a mediator.

Clinical uses

Direct factor Xa inhibitors are being used clinically. Clinical trials published in journals such as the New England Journal of Medicine

New England Journal of Medicine

The New England Journal of Medicine is an English-language peer-reviewed medical journal published by the Massachusetts Medical Society. It describes itself as the oldest continuously published medical journal in the world.-History:...

and The Lancet

The Lancet

The Lancet is a weekly peer-reviewed general medical journal. It is one of the world's best known, oldest, and most respected general medical journals...

have shown promise for these compounds as substitutes for the currently administered vitamin K

Vitamin K

Vitamin K is a group of structurally similar, fat soluble vitamins that are needed for the posttranslational modification of certain proteins required for blood coagulation and in metabolic pathways in bone and other tissue. They are 2-methyl-1,4-naphthoquinone derivatives...

 antagonists or low molecular weight heparin

Low molecular weight heparin

In medicine, low-molecular-weight heparin is a class of medication used as an anticoagulant in diseases that feature thrombosis, as well as for prophylaxis in situations that lead to a high risk of thrombosis....

. Advantages of orally administered direct Xa inhibitors lie in the fact that they have a predictable effect, do not require frequent monitoring or re-dosing, are given through the mouth and not by injection and have few (known) drug interactions. Disadvantages include the currently limited prospective experience and the theoretical interactions with statin

Statin

Statins are a class of drugs used to lower cholesterol levels by inhibiting the enzyme HMG-CoA reductase, which plays a central role in the production of cholesterol in the liver. Increased cholesterol levels have been associated with cardiovascular diseases, and statins are therefore used in the...

 medication, as they are metabolized at least in part by the same cytochrome

Cytochrome

Cytochromes are, in general, membrane-bound hemoproteins that contain heme groups and carry out electron transport.They are found either as monomeric proteins or as subunits of bigger enzymatic complexes that catalyze redox reactions....

 enzyme, CYP3A4

CYP3A4

Cytochrome P450 3A4 , a member of the cytochrome P450 mixed-function oxidase system, is one of the most important enzymes involved in the metabolism of xenobiotics in the body. CYP3A4 is involved in the oxidation of the largest range of substrates of all the CYPs. As a result, CYP3A4 is present in...

.

Examples

A naturally occurring inhibitor of factor Xa was first reported in 1987. Tuszynski et al. discovered antistasin, which was isolated from the extracts of Mexican leach, Haementeria officinalis. Soon after this, another naturally occurring inhibitor, tick anticoagulant peptide (TAP) was isolated from the extract of tick Ornithodoros

Ornithodoros

Ornithodoros is a genus in the soft-bodied tick family, Argasidae. The Linnean name derives from ornithos and doros , meaning "bird" and "gift," respectively...

 moubata.

Examples include:

• Apixaban
  Apixaban
  Apixaban is a compound being investigated as an anticoagulant. It is a direct factor Xa inhibitor. It is presently undergoing phase III trials in the prevention of venous thromboembolism, together with a number of related competing compounds, such as rivaroxaban...
  
  
• Edoxaban
  Edoxaban
  Edoxaban is an anticoagulant drug which acts as a direct factor Xa inhibitor. It is being developed by Daiichi Sankyo...
  
  
• Otamixaban
  Otamixaban
  Otamixaban is a direct factor Xa inhibitor, currently being developed by the French pharmaceutical company Sanofi-Aventis as a treatment for acute coronary syndrome....
  
  
• Rivaroxaban
  Rivaroxaban
  Rivaroxaban is an oral anticoagulant invented and manufactured by Bayer; in a number of countries it is marketed as Xarelto. In the United States, it is marketed by Janssen Pharmaceutica. It is the first available orally active direct factor Xa inhibitor. Rivaroxaban is well absorbed from the gut...
  
  
• YM466

External links

• Direct Factor Xa Inhibitors as Anticoagulants | PharmaXChange.info – A review and presentation on the available factor Xa inhibitors which can be used as anticoagulants.
• Oral Xa inhibitors – Literature review of the evidence regarding oral Xa inhibitors