Included as part of the PRECAUTIONS section.

Hemorrhage

Use ARIXTRA (fondaparinux sodium) with extreme caution in conditions with increased risk of hemorrhage, 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. Isolated cases of elevated aPTT temporally associated with bleeding events have been reported following administration of ARIXTRA (fondaparinux sodium) (with or without concomitant administration of other anticoagulants) [See ADVERSE REACTIONS].

Do not administer agents that enhance the risk of hemorrhage with ARIXTRA (fondaparinux sodium) unless essential for the 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 administer the initial dose of ARIXTRA (fondaparinux sodium) earlier than 6 to 8 hours after surgery. Administration earlier than 6 hours after surgery increases risk of major bleeding [see DOSAGE AND ADMINISTRATION and ADVERSE REACTIONS].

Renal Impairment and Bleeding Risk

ARIXTRA (fondaparinux sodium) increases the risk of bleeding in patients with impaired renal function due to reduced clearance [see CLINICAL PHARMACOLOGY ].

The incidence of major bleeding by renal function status reported in clinical trials of patients receiving ARIXTRA (fondaparinux sodium) for VTE surgical prophylaxis is provided in Table 1. In these patient populations, the following is recommended:

• Do not use ARIXTRA (fondaparinux sodium) for VTE prophylaxis and treatment in patients with CrCl < 30 mL/min [see CONTRAINDICATIONS].
• Use ARIXTRA (fondaparinux sodium) with caution in patients with CrCl 30 to 50 mL/min.

Table 1: Incidence of Major Bleeding in Patients Treated With ARIXTRA (fondaparinux sodium) by Renal Function Status for Surgical Prophylaxis and Treatment of Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE)

Assess renal function periodically in patients receiving ARIXTRA (fondaparinux sodium) . Discontinue the drug immediately in patients who develop severe renal impairment while on therapy. After discontinuation of ARIXTRA (fondaparinux sodium) , its anticoagulant effects may persist for 2 to 4 days in patients with normal renal function (i.e., at least 3 to 5 half-lives). The anticoagulant effects of ARIXTRA (fondaparinux sodium) may persist even longer in patients with renal impairment [see CLINICAL PHARMACOLOGY].

Body Weight < 50 Kg and Bleeding Risk

ARIXTRA (fondaparinux sodium) increases the risk for bleeding in patients who weigh less than 50 kg, compared to patients with higher weights.

In patients who weigh less than 50 kg:

• Do not administer ARIXTRA (fondaparinux sodium) as prophylactic therapy for patients undergoing hip fracture, hip replacement, or knee replacement surgery and abdominal surgery [see CONTRAINDICATIONS].
• Use ARIXTRA (fondaparinux sodium) with caution in the treatment of PE and DVT.

During the randomized clinical trials of VTE prophylaxis in the peri-operative period following hip fracture, hip replacement, or knee replacement surgery and abdominal surgery, major bleeding occurred at a higher rate among patients with a body weight < 50 kg compared to those with a body weight > 50 kg (5.4% versus 2.1% in patients undergoing hip fracture, hip replacement, or knee replacement surgery; 5.3% versus 3.3% in patients undergoing abdominal surgery).

Thrombocytopenia

Thrombocytopenia can occur with the administration of ARIXTRA (fondaparinux sodium) . Thrombocytopenia of any degree should be monitored closely. Discontinue ARIXTRA (fondaparinux sodium) if the platelet count falls below 100,000/mm³. Moderate thrombocytopenia (platelet counts between 100,000/mm³ and 50,000/mm³) occurred at a rate of 3.0% in patients given ARIXTRA (fondaparinux sodium) 2.5 mg in the peri-operative hip fracture, hip replacement, or knee replacement surgery and abdominal surgery clinical trials. Severe thrombocytopenia (platelet counts less than 50,000/mm³) occurred at a rate of 0.2% in patients given ARIXTRA (fondaparinux sodium) 2.5 mg in these clinical trials. During extended prophylaxis, no cases of moderate or severe thrombocytopenia were reported.

Moderate thrombocytopenia occurred at a rate of 0.5% in patients given the ARIXTRA (fondaparinux sodium) treatment regimen in the DVT and PE treatment clinical trials. Severe thrombocytopenia occurred at a rate of 0.04% in patients given the ARIXTRA (fondaparinux sodium) treatment regimen in the DVT and PE treatment clinical trials.

Isolated occurrences of thrombocytopenia with thrombosis that manifested similar to heparin-induced thrombocytopenia have been reported with the use of ARIXTRA in postmarketing experience. [See ADVERSE REACTIONS.]

Neuraxial Anesthesia and Post-operative Indwelling Epidural Catheter Use

Spinal or epidural hematomas, which may result in long-term or permanent paralysis, can occur with the use of anticoagulants and neuraxial (spinal/epidural) anesthesia or spinal puncture. The risk of these events may be higher with post-operative use of indwelling epidural catheters or concomitant use of other drugs affecting hemostasis such as NSAIDs [see BOXED WARNING]. In the postmarketing experience, epidural or spinal hematoma has been reported in association with the use of ARIXTRA (fondaparinux sodium) by subcutaneous (SC) injection. Monitor patients undergoing these procedures for signs and symptoms of neurologic impairment. Consider the potential risks and benefits before neuraxial intervention in patients anticoagulated or who may be anticoagulated for thromboprophylaxis.

Monitoring: Laboratory Tests

Routine coagulation tests such as Prothrombin Time (PT) and Activated Partial Thromboplastin Time (aPTT) are relatively insensitive measures of the activity of ARIXTRA (fondaparinux sodium) and international standards of heparin or LMWH are not calibrators to measure anti-Factor Xa activity of ARIXTRA (fondaparinux sodium) . If unexpected changes in coagulation parameters or major bleeding occur during therapy with ARIXTRA (fondaparinux sodium) , discontinue ARIXTRA (fondaparinux sodium) . In postmarketing experience, isolated occurrences of aPTT elevations have been reported following administration of ARIXTRA [see ADVERSE REACTIONS].

Periodic routine complete blood counts (including platelet count), serum creatinine level, and stool occult blood tests are recommended during the course of treatment with ARIXTRA.

The anti-Factor Xa activity of fondaparinux sodium can be measured by anti-Xa assay using the appropriate calibrator (fondaparinux). The activity of fondaparinux sodium is expressed in milligrams ( mg ) of the fondaparinux and cannot be compared with activities of heparin or low molecular weight heparins. [See CLINICAL PHARMACOLOGY]

Latex

The packaging (needle guard) of the prefilled syringe of ARIXTRA (fondaparinux sodium) contains dry natural latex rubber that may cause allergic reactions in latex sensitive individuals.

Patient Counseling Information

See FDA-Approved Patient Labeling

Patient Advice

If the patients have had neuraxial anesthesia or spinal puncture, and particularly, if they are taking concomitant NSAIDS, platelet inhibitors, or other anticoagulants, they should be informed to watch for signs and symptoms of spinal or epidural hematomas, such as tingling, numbness (especially in the lower limbs) and muscular weakness. If any of these symptoms occur, the patients should contact his or her physician immediately.

The use of aspirin and other NSAIDS may enhance the risk of hemorrhage. Their use should be discontinued prior to ARIXTRA (fondaparinux sodium) therapy whenever possible; if co-administration is essential, the patient's clinical and laboratory status should be closely monitored. [See DRUG INTERACTIONS.]

If patients must self-administer ARIXTRA (fondaparinux sodium) (e.g., if ARIXTRA (fondaparinux sodium) is used at home), they should be advised of the following:

• ARIXTRA (fondaparinux sodium) should be given by subcutaneous injection. Patients must be instructed in the proper technique for administration.
• As with all anticoagulants, the most important risk with ARIXTRA (fondaparinux sodium) administration is bleeding. Patients should be counseled on signs and symptoms of possible bleeding.
• It may take them longer than usual to stop bleeding.
• They may bruise and/or bleed more easily when they are treated with ARIXTRA (fondaparinux sodium) .
• They should report any unusual bleeding, bruising, or signs of thrombocytopenia (such as a rash of dark red spots under the skin) to their physician [see WARNINGS AND PRECAUTIONS].
• To tell their physicians and dentists of all medications they are taking, including those obtained without a prescription, such as aspirin or other NSAIDs. [See DRUG INTERACTIONS].

Keep out of the reach of children.

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment of Fertility

No long-term studies in animals have been performed to evaluate the carcinogenic potential of fondaparinux sodium.

Fondaparinux sodium was not genotoxic in the Ames test, the mouse lymphoma cell (L5178Y/TK^+/-) forward mutation test, the human lymphocyte chromosome aberration test, the rat hepatocyte unscheduled DNA synthesis (UDS) test, or the rat micronucleus test.

At subcutaneous doses up to 10 mg /kg/day (about 32 times the recommended human dose based on body surface area), fondaparinux sodium was found to have no effect on fertility and reproductive performance of male and female rats.

Use In Specific Populations

Pregnancy

Pregnancy Category B. Reproduction studies have been performed in pregnant rats at subcutaneous doses up to 10 mg /kg/day (about 32 times the recommended human dose based on body surface area) and pregnant rabbits at subcutaneous doses up to 10 mg /kg/day (about 65 times the recommended human dose based on body surface area) and have revealed no evidence of impaired fertility or harm to the fetus due to fondaparinux sodium. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, ARIXTRA (fondaparinux sodium) should be used during pregnancy only if clearly needed.

Nursing Mothers

Fondaparinux sodium was found to be excreted in the milk of lactating rats. However, it is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when ARIXTRA (fondaparinux sodium) is administered to a nursing mother.

Pediatric Use

Safety and effectiveness of ARIXTRA (fondaparinux sodium) in pediatric patients have not been established. Because risk for bleeding during treatment with ARIXTRA (fondaparinux sodium) is increased in adults who weigh < 50 kg, bleeding may be a particular safety concern for use of ARIXTRA (fondaparinux sodium) in the pediatric population [see WARNINGS AND PRECAUTIONS].

Geriatric Use

In clinical trials the efficacy of ARIXTRA (fondaparinux sodium) in the elderly (65 years or older) was similar to that seen in patients younger than 65 years; however, serious adverse events increased with age. Exercise caution when using ARIXTRA (fondaparinux sodium) in elderly patients, paying particular attention to dosing directions and concomitant medications (especially anti-platelet medication). [See WARNINGS AND PRECAUTIONS.]

Fondaparinux sodium is substantially excreted by the kidney, and the risk of adverse reactions to ARIXTRA (fondaparinux sodium) may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, assess renal function prior to ARIXTRA administration. [See CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS, and CLINICAL PHARMACOLOGY.]

In the peri-operative hip fracture, hip replacement, or knee replacement surgery clinical trials with patients receiving ARIXTRA (fondaparinux sodium) 2.5 mg , serious adverse events increased with age for patients receiving ARIXTRA (fondaparinux sodium) . The incidence of major bleeding in clinical trials of ARIXTRA (fondaparinux sodium) by age is provided in Table 6.

Table 6: Incidence of Major Bleeding in Patients Treated With ARIXTRA (fondaparinux sodium) by Age

Renal Impairment

Patients with impaired renal function are at increased risk of bleeding due to reduced clearance of ARIXTRA [see CONTRAINDICATIONS and WARNINGS AND PRECAUTIONS]. Assess renal function periodically in patients receiving ARIXTRA (fondaparinux sodium) . Discontinue ARIXTRA (fondaparinux sodium) immediately in patients who develop severe renal impairment while on therapy. After discontinuation of ARIXTRA (fondaparinux sodium) , its anticoagulant effects may persist for 2 to 4 days in patients with normal renal function (i.e., at least 3 to 5 half-lives). The anticoagulant effects of ARIXTRA (fondaparinux sodium) may persist even longer in patients with renal impairment [see CLINICAL PHARMACOLOGY].

Hepatic Impairment

Following a single, subcutaneous dose of 7.5 mg of ARIXTRA (fondaparinux sodium) in patients with moderate hepatic impairment (Child-Pugh Category B) compared to subjects with normal liver function, changes from baseline in aPTT, PT/INR, and antithrombin III were similar in the two groups. However, a higher incidence of hemorrhage was observed in subjects with moderate hepatic impairment than in normal subjects, especially mild hematomas at the blood sampling or injection site. The pharmacokinetics of fondaparinux have not been studied in patients with severe hepatic impairment. [See DOSAGE AND ADMINISTRATION and CLINICAL PHARMACOLOGY.]

Last reviewed on RxList: 4/15/2010
This monograph has been modified to include the generic and brand name in many instances.