fondaparinux

(fon-da-par-i-nux) fondaparinux,

Arixtra

(trade name)

Classification

Therapeutic: anticoagulants
Pharmacologic: active factor x inhibitors
Pregnancy Category: B

Indications

Prevention and treatment of deep vein thrombosis and pulmonary embolism.Systemic anticoagulation for other diagnoses.

Action

Binds selectively to antithrombin III (AT III). This binding potentiates the neutralization (inactivation) of active factor X (Xa).

Therapeutic effects

Interruption of the coagulation cascade resulting in inhibition of thrombus formation. Prevention of thrombus formation decreases the risk of pulmonary emboli.

Pharmacokinetics

Absorption: 100% absorbed following subcutaneous administration.Distribution: Distributes mainly throughout the intravascular space.Metabolism and Excretion: Eliminated mainly unchanged in urine.Half-life: 17–21 hr.

Time/action profile (anticoagulant effect)

ROUTE	ONSET	PEAK	DURATION
Subcut	rapid	3 hr	24 hr

Contraindications/Precautions

Contraindicated in: Hypersensitivity;Severe renal impairment (CCr <30 mL/min; ↑ risk of bleeding);Body weight <50 kg (for prophylaxis) (markedly ↑ risk of bleeding);Active major bleeding;Bacterial endocarditis;Thrombocytopenia due to fondaparinux antibodies.Use Cautiously in: Mild-to-moderate renal impairment (CCr 30–50 mL/min);Untreated hypertension;Recent history of ulcer disease;Body weight <50 kg (for treatment of DVT or PE) (may ↑ risk of bleeding); Geriatric: Patients >65 yr (↑ risk of bleeding);Malignancy;History of heparin-induced thrombocytopenia; Obstetric / Lactation / Pediatric: Safety not established; use during pregnancy only if clearly needed.Exercise Extreme Caution in: History of congenital or acquired bleeding disorder;Severe uncontrolled hypertension;Hemorrhagic stroke;Recent CNS or ophthalmologic surgery;Active GI bleeding/ulceration;Retinopathy (hypertensive or diabetic);Spinal/epidural anesthesia or spinal puncture (↑ risk of spinal/epidural hematoma that may lead to long-term or permanent paralysis).

Adverse Reactions/Side Effects

Central nervous system

confusion
dizziness
headache
insomnia

Cardiovascular

edema
hypotension

Gastrointestinal

constipation
diarrhea
dyspepsia
↑ liver enzymes
nausea
vomiting

Genitourinary

urinary retention

Dermatologic

bullous eruption
hematoma
purpura
rash

Hematologic

bleeding (most frequent)
thrombocytopenia

Fluid and Electrolyte

hypokalemia

Miscellaneous

hypersensitivity reactions including angioedema (life-threatening)
fever
↑ wound drainage

Interactions

Drug-Drug interaction

Risk of bleeding may be ↑ by concurrent use of warfarin or drugs that affect platelet function, including aspirin, NSAIDs, dipyridamole, some cephalosporins, valproates, clopidogrel, ticlopidine, abciximab, eptifibatide, tirofiban, and dextran.↑ risk of bleeding with arnica, chamomile, clove, dong quai, feverfew, garlic, ginger, gingko, Panax ginseng, and others.

Route/Dosage

Treatment of DVT/PE

Subcutaneous (Adults) <50 kg—5 mg once daily for at least 5 days until therapeutic anticoagulation with warfarin is achieved (INR >2 for 2 consecutive days); warfarin may be started within 72 hr of fondaparinux (has been used for up to 26 days); 50–100 kg—7.5 mg once daily for at least 5 days until therapeutic anticoagulation with warfarin is achieved (INR >2 for 2 consecutive days); >100 kg—10 mg once daily for at least 5 days until therapeutic anticoagulation with warfarin is achieved (INR >2 for 2 consecutive days); warfarin may be started within 72 hr of fondaparinux.

Prevention of DVT/PE

Subcutaneous (Adults) 2.5 mg once daily, starting 6–8 hr after surgery, continuing for 5–9 days (up to 11 days) following abdominal surgery or knee/hip replacement or continuing for 24 days following hip fracture surgery (up to 32 days).

Availability (generic available)

Solution for subcut injection: 2.5 mg/0.5 mL in prefilled syringes, 5 mg/0.4 mL in prefilled syringes, 7.5 mg/0.6 mL in prefilled syringes, 10 mg/0.8 mL in prefilled syringes

Nursing implications

Nursing assessment

Assess for signs of bleeding and hemorrhage (bleeding gums; nosebleed; unusual bruising; black, tarry stools; hematuria; fall in hematocrit; sudden drop in BP; guaiac positive stools); bleeding from surgical site. Notify health care professional if these occur.
Assess for evidence of additional or increased thrombosis. Symptoms will depend on area of involvement. Monitor neurological status frequently for signs of impairment, especially in patients with indwelling epidural catheters for administration of analgesia or with concomitant use of drugs affecting hemostasis (NSAIDs, platelet inhibitors, other anticoagulants). Risk is increased by traumatic or repeated epidural or spinal puncture. May require urgent treatment.
Lab Test Considerations: Monitor platelet count closely; may cause thrombocytopenia. If platelet count is <100,000/mm³, discontinue fondaparinux.
- Fondaparinux is not accurately measured by prothrombin time (PT), activated thromboplastin time (aPTT), or international standards of heparin or low-molecular-weight heparins. If unexpected changes in coagulation parameters or major bleeding occurs, discontinue fondaparinux.
- Monitor CBC, serum creatinine levels, and stool occult blood tests routinely during therapy.
- May cause asymptomatic ↑ in AST and ALT. Elevations are fully reversible and not associated with ↑ in bilirubin.
- May cause ↑ aPTT temporally associated with bleeding with or without concomitant administration of other anticoagulants and thrombocytopenia with thrombosis similar to heparin-induced thrombocytopenia, with or without exposure to heparin or low-molecular-weight heparins.

Potential Nursing Diagnoses

Ineffective tissue perfusion (Indications)
Risk for injury (Side Effects)

Implementation

Fondaparinux cannot be used interchangeably with heparin, low-molecular-weight heparins, or heparinoids as they differ in manufacturing process, anti-Xa and anti-IIa activity, units, and dose. Each of these medications has its own instructions for use.
- Initial dose should be administered 6-8 hr after surgery. Administration before 6 hr after surgery has been associated with risk of major bleeding.
Subcutaneous: Administer subcut only into fatty tissue, alternating sites between right and left anterolateral or posterolateral abdominal wall. Inject entire length of needle at a 45° or 90° angle into a skin fold held between thumb and forefinger; hold skin fold throughout injection. Do not aspirate or massage. Rotate sites frequently. Do not administer IM because of danger of hematoma formation. Solution should be clear; do not inject solution containing particulate matter. Do not mix with other injections.
- Fondaparinux is provided in a single-dose prefilled syringe with an automatic needle protection system. Do not expel air bubble from prefilled syringe before injection to prevent loss of drug.

Patient/Family Teaching

Advise patient to report any symptoms of unusual bleeding or bruising, dizziness, itching, rash, fever, swelling, or difficulty breathing to health care professional immediately.
Instruct patient not to take aspirin or NSAIDs without consulting health care professional during therapy.

Evaluation/Desired Outcomes

Prevention and treatment of deep vein thrombosis and pulmonary embolism.

Arixtra

A selective factor-Xa-inhibiting synthetic heparin anticoagulant, which is a pentasaccharide that covers the active site of heparin specific for antithrombin III.
Indications
Prophylaxis of deep vein thrombosis (DVT) and PEs in hospitalised patients, including those with hip fractures and injuries, or patients undergoing total hip or total knee replacement surgery; it may be used to manage heparin-induced thrombocytopaenia (HIT).
Adverse effects
Bleeding, thrombocytopaenia, local reactions, increased aminotransferases.

fondaparinux

One of a new class of antithrombotic drugs used to prevent deep vein THROMBOSIS during major surgery. The drug is an inhibitor of activated Factor X which is a key enzyme in the coagulation cascade. It has been found effective in the management of pulmonary embolism and has been shown to reduce the risks of acute coronary ischaemia. A brand name is Arixtra.