fondaparinux sodium
Pharmacologic class: Selective factor Xa inhibitor
Therapeutic class: Anticoagulant, antithrombotic
Pregnancy risk category B
Action
Selectively inhibits factor Xa, disrupting blood coagulation and inhibiting thrombin formation and thrombus development
Availability
Injection: 2.5 mg/0.5 ml in single-dose syringe
Indications and dosages
➣ Prevention of deep-vein thrombosis after hip fracture surgery or hip or knee replacement surgery
Adults: 2.5 mg subcutaneously 6 to 8 hours after surgery, once hemostasis occurs; usual duration is 5 to 9 days (up to 11 days) given daily. After hip fracture surgery, extended prophylactic course of up to 24 additional days is recommended; some patients have tolerated a total course of 32 days.
➣ Deep-vein thrombosis and pulmonary emboli
Adults: 5 mg subcutaneously once daily for patients weighing less than 50 kg (110 lb), 7.5 mg subcutaneously for patients weighing 50 to 100 kg (110 to 220 lb) or 10 mg subcutaneously for patients weighing more than 100 kg (220 lb) for 5 days and until therapeutic oral anticoagulant effect occurs (as shown by International Normalized Ratio of 2 to 3). Usual duration of therapy is 5 to 9 days, but may continue for up to 26 days.
Dosage adjustment
• Renal impairment
Contraindications
• Hypersensitivity to drug
• Bacterial endocarditis
• Severe renal disease
• Active major bleeding
• Patients weighing less than 50 kg (110 lb) who have undergone hip fracture, hip replacement, or knee replacement surgery
Precautions
Use cautiously in:
• diabetic retinopathy, hepatic disease, blood dyscrasias, heparin-induced thrombocytopenia, severe hypertension, alcoholism
• patients older than age 75
• pregnant or breastfeeding patients
• children (safety and efficacy not established).
Administration
☞ Withhold for at least 6 to 8 hours after surgery, to minimize risk of major bleeding.
☞ Give by subcutaneous injection only. Don't give I.M.
• Rotate injection sites among fatty tissue areas on left and right anterolateral and posterolateral abdominal walls.
• Don't expel air bubble from syringe; doing so may reduce amount of drug delivered.
• Listen for slight click when plunger is fully released. After drug has been injected, needle retracts and white safety indicator is visible.
• Don't mix with other injections or infusions.
• Know that when drug is used to treat deep-vein thrombosis and pulmonary emboli, concomitant warfarin treatment should begin as soon as possible (usually within 72 hours).
Adverse reactions
CNS: depression, dizziness, asthenia, headache, abnormal thinking, confusion, insomnia, neuropathy
CV: hypotension
GI: nausea, vomiting, diarrhea, constipation, abdominal pain, dyspepsia, dry mouth, anorexia
GU: urinary retention, urinary tract infection
Hematologic: anemia, hematoma, purpura, minor bleeding, major bleeding, thrombocytopenia, retroperitoneal hemorrhage, postoperative hemorrhage
Metabolic: hypokalemia
Skin: bullous eruption
Other: increased wound drainage, injection site bleeding, pain, edema, fever
Interactions
Drug-drug. Anticoagulants: increased risk of bleeding
Drug-herbs. Anise, astragalus, bilberry, black currant, bladder wrack, bogbean, boldo, borage, buchu, capsaicin, cat's claw, celery, chaparral, cinchona, clove oil, dandelion, dong quai, fenugreek, feverfew, garlic, ginger, ginkgo, papaya, red clover, rhubarb, safflower oil, skullcap, tan-shen: additive anticoagulant effect
St. John's wort: reduced anticoagulant effect
Patient monitoring
• Monitor CBC, platelet count, creatinine level, and renal function tests. Assess stools for occult blood.
• Monitor vital signs, temperature, and fluid intake and output.
☞ Stay alert for bleeding tendency, especially postoperative hemorrhage.
• Check for increased wound drainage after surgery.
☞ In patient undergoing concomitant neuraxial anesthesia or spinal puncture, watch for neurologic impairment (indicating possible spinal or epidural hematoma).
☞ Discontinue drug if severe renal impairment occurs.
Patient teaching
☞ Instruct patient to immediately report bleeding.
• Caution patient to avoid activities that can cause injury. Tell him to use soft toothbrush and electric razor to avoid gum and skin injury.
• Tell patient that he'll undergo regular blood testing during therapy.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and herbs mentioned above.