Reviewed on 11/15/2021

Brand Name: Arixtra

Generic Name: Fondaparinux

Drug Class: Anticoagulants, Hematologic; Factor Xa Inhibitors

What Is Fondaparinux and How Does It Work?

Fondaparinux is a prescription medication used to treat Deep Vein Thrombosis/Acute Pulmonary Embolism.

  • Fondaparinux is available under the following different brand names: Arixtra

What Are Dosages of Fondaparinux?

Dosages of Fondaparinux:

Adult dosage

Prefilled syringe

  • 2.5mg/0.5mL
  • 5mg/0.4mL
  • 7.5mg/0.6mL
  • 10mg/0.8mL

Deep Vein Thrombosis/Acute Pulmonary Embolism


  • Patients weighing less than 50 kg: 5mg SC once daily
  • Patients 50-100 kg: 7.5 mg SC once daily
  • Patients weighing more than 100 kg: 10 mg SC once daily
  • Administer for 5-9 days; up to 26 days administered in a clinical trial


  • Patients weighing more than 50 kg: 2.5 mg SC once daily for 5-9 days or up to 10 days following abdominal surgery; for hip replacement, 11 days recommended and a minimum 10-14 days recommended for patients undergoing total hip or knee arthroplasty, or hip fracture surgery; administered for up to 35 days in some instances

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”.

What Are Side Effects Associated with Using Fondaparinux?

Common side effects of Fondaparinux include:

Serious side effects of Fondaparinux include:

Rare side effects of Fondaparinux include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.


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What other drugs interact with Fondaparinux?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them.  Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first

  • Fondaparinux has severe interactions with the following drugs:
  • Fondaparinux has serious interactions with at least 62 other drugs. 
  • Fondaparinux has moderate interactions with at least 122 other drugs.
  • Fondaparinux has minor interactions with at least 17 other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drugs interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use.  Keep a list of all your medications with you, and share this information with your doctor and pharmacist.  Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

What are warnings and precautions for Fondaparinux?


Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Fondaparinux?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Fondaparinux?”


  • Use with caution in the elderly (prolonged half-life in patients older than 75 years of age), peptic ulcer disease, bleeding disorder, recent stroke, recent surgery (brain, spinal cord, or eye), concurrent use of platelet inhibitors or anticoagulants, moderate renal impairment (CrCl 30-50 mL/min); may cause prolonged anticoagulation in patients with CrCl 30 to 50 mL/min
  • Discontinue if platelets less than 100,000/μL
  • Not for IM administration
  • Therapy increases the risk of hemorrhage in patients at risk for bleeding, including conditions such as congenital or acquired bleeding disorders, active ulcerative and angiodysplastic gastrointestinal disease, hemorrhagic stroke, uncontrolled arterial hypertension, diabetic retinopathy, or shortly after brain, spinal, or ophthalmological surgery; cases of elevated aPTT temporally associated with bleeding events have been reported following administration of the drug (with or without concomitant administration of other anticoagulants); do not administer agents that enhance the risk of hemorrhage unless essential for management of the underlying condition, such as vitamin K antagonists for the treatment of VTE; if co-administration is essential, closely monitor patients for signs and symptoms of bleeding
  • Do not use interchangeably with heparin or LMWHs
  • Thrombocytopenia with thrombosis reported with use; discontinue therapy if the platelet count falls below 100,000/mm³
  • Risk of spinal or epidural hematomas if a spinal puncture occurs (see Black Box Warnings)
  • Do not administer initial dose earlier than 6-8 hours after surgery; administration earlier than 6 hours after surgery increases the risk of major bleeding
  • Increased risk of bleeding in patients less than 50 kg; dosage reduction recommended
  • Not for administration as prophylactic for patients undergoing hip fracture, hip replacement, or knee replacement surgery and abdominal surgery

Pregnancy and Lactation

  • Available data from published literature and postmarketing reports have not reported a clear association with adverse developmental outcomes; fondaparinux sodium plasma concentrations obtained from four women treated during pregnancy and their newborn infants demonstrated low placental transfer of fondaparinux sodium; there are risks to mothers associated with untreated venous thromboembolism in pregnancy and risk of hemorrhage in the mother and fetus associated with the use of anticoagulants
  • Pregnancy confers an increased risk for thromboembolism that is higher for women with the underlying thromboembolic disease and certain high-risk pregnancy conditions; published data describe that women with a previous history of venous thrombosis are at high risk for recurrence during pregnancy
  • Fetal/neonatal adverse reactions
    • The drug has been demonstrated to cross the placenta in humans; use of anticoagulants may increase risk of bleeding in the fetus and neonate; monitor neonates for bleeding
  • Labor or delivery
    • All patients receiving anticoagulants, including pregnant women, are at risk for bleeding; use during labor or delivery in women who are receiving neuraxial anesthesia may result in epidural or spinal hematomas; pregnant women receiving therapy should be carefully monitored for evidence of bleeding or unexpected changes in coagulation parameters; consideration for use of a shorter-acting anticoagulant should be specifically addressed as delivery approaches
  • There are no data on presence in human milk or effects on milk production; limited clinical data during lactation preclude a clear determination of the risk of therapy to an infant during lactation; therefore, developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for therapy and any potential adverse effects on the breastfed infant from therapy or underlying maternal condition

Medscape. Fondaparinux.

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