Fondaparinux

Indications

Fondaparinux is used for: Venous thromboembolic events, acute DVT, pulmonary embolism (PE), unstable angina, non-ST segment elevation MI

Adult Dose

Deep Vein Thrombosis/Acute Pulmonary Embolism Treatment <50 kg: 5 mg SC once daily 50-100 kg: 7.5 mg SC once daily >100 kg: 10 mg SC once daily Administer for 5-9 days; up to 26 days administered in clinical trials Prophylaxis >50 kg: 2.5 mg SC once daily for 5-9 days or up to 10 days following abdomonal 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

Child Dose

Safety and efficacy not established

Renal Dose

Renal impairment: CrCl (ml/min) Dosage Recommendation <20 Contraindicated. 20-50 1.5 mg once daily.

Administration

Administration Administer initial dose 6-8 hours after surgery, once hemostasis has been established SC administration is deep, alternating right and left anterior and posterior abdominal walls

Contra Indications

Hypersensitivity. Active clinically significant bleeding, acute bacterial endocarditis.

Precautions

Patient w/ increased risk of haemorrhage (e.g. congenital or acquired bleeding disorders, history or active GI ulceration, intracranial haemorrhage, recent brain, spinal or ophth surgery); body wt <50 kg. Increased risk of spinal or epidural haematomas in patient undergoing neuraxial (spinal/epidural) anaesth or spinal puncture esp w/ post-op use of indwelling epidural catheters and concurrent use of medications affecting haemostasis. Moderate renal and severe hepatic impairment. Pregnancy and lactation. Monitoring Parameters Monitor CBC, platelet count, serum creatinine and stool occult blood regularly. Lactation: Unknown whether drug is excreted in milk; use with caution

Pregnancy-Lactation

Pregnancy Available data from published literature and postmarketing reports have not reported 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 mother associated with untreated venous thromboembolism in pregnancy and a risk of hemorrhage in the mother and fetus associated with use of anticoagulants Pregnancy confers an increased risk for thromboembolism that is higher for women with 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 Drug has been demonstrated to cross 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 Lactation There are no data on presence in human milk, or effects on milk production; limited clinical data during lactation preclude a clear determination of risk of therapy to an infant during lactation; therefore, developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy and any potential adverse effects on breastfed infant from therapy or from underlying maternal condition

Interactions

Increased risk of bleeding w/ (e.g. desirudin, fibrinolytic drugs, glycoprotein IIb/IIIa-receptor antagonists, heparin, heparinoids or LMWH).

Adverse Effects

Side effects of Fondaparinux : >10% Anemia (1-20%), Fever (4-14%), Nausea (3-11%) 1-10% Rash (7.5%), Dizziness (4%), Confusion (3%), Constipation (5-9%), Diarrhea (2-3%), Edema (9%), Headache (2-5%), Hypokalemia (1-4%), Hypotension (4%), Insomnia (4-5%), Purpura (4%), Thrombocytopenia (3%), Urinary retention (3%), Urinary tract infection (2-4%), Vomiting (1-6%)

Mechanism of Action

Fondaparinux, a synthetic pentasaccharide, acts as a selective inhibitor of activated factor X. It works by binding selectively to ATIII, and potentiates the neutralisation of Factor Xa. This will interrupt the blood coagulation cascade and inhibit both thrombin formation and thrombus development. At the recommended dosage, fondaparinux does not affect fibrinolytic activity or platelet function. It cannot lyse established thrombi and does not affect clotting function tests (e.g. aPPT, INR).