Fondaparinux (Arixtra)

Synthetic antithrombotic agent with specific anti-factor Xa activity.

Factor X- inhibitor.

Is not an unfractionated heparin or low molecular weight heparin as the latter are proteoglycans isolated from animal tissues.

It is comprised of 5 sugar moieties that mediate the anticoagulant activity of unfractionated heparin and low molecular weight heparin.

Synthetic pentasaccharide that is a ultra low molecular weight selective factor Xa inhibitor.

Its pentasaccharide sequence resembles anti-thrombin binding site of heparins.

Similar to heparin in that its anti-coagulation function is exerted via the inhibitory activity of the serine protease inhibitor anti-thrombin.

Given once daily as a subcutaneous injection and has a plasma half-life of 17 hours.

Contraindicated in patients a creatinine clearance of less than 30 mL/Mmin.

No need for monitoring.

Dose of 7.5 mg has the same efficacy and safety as low molecular weight heparin in the management of symptomatic deep vein thrombosis.

More effective than enoxaparin or unfractionated heparin in preventing venous thrombosis after orthopedic surgery.

Similar effectiveness to unfractionated heparin or low molecular weight heparin in treating patients with deep vein thrombosis or pulmonary embolism.

With acute coronary artery syndromes and in patients undergoing percutaneous coronary artery intervention is as effective as enoxaparin and safer than unfractionated heparin.

In the OASIS-5 (Organization for the Assessment if Strategies for Ischemic Syndromes) trial fondaparinux had improved efficacy in preventing ischemic events in patients with non ST elevation myocardial infarction compared to enoxaparin, with a large reduction in bleeding and a significant reduction in mortality, myocardial infarction and strokes at 3-6 months.

Doses of 5 mg and 10 mg are appropriate for patients with less than 50 kg and more than 100 kg body weights, respectively.

2.5 mg subcutaneously daily for prophylaxis.

Is at least as effective as intravenous unfractionated heparin and as safe when used as the initial treatment for patients with hemodynamically stable pulmonary embolism.

Can cross placental and blood brain barriers and membranes making its use in pregnancy, the elderly and in patients on dialysis questionable.

Prolonged usage can result in drug accumulation with bleeding complications.

Does not cross react with heparin induced antibodies and platelet count monitoring may not be necessary.

Not associated with heparin associated thrombocytopenia.

Has low skin allergenic potential, almost 20 times less compared to heparin.

In routine care of patients with non-STEMI is associated with lower odds than low molecular heparin of major bleeding events and death both in hospital in and up to 180 days afterwards (Szummer K et al).

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