Fonidel2.5 mg/0.5 ml

Fonidel is a synthetic anticoagulant with established, guideline-supported uses in the prevention and treatment of thromboembolic disorders.

FDA-approved / established indications

• Prophylaxis of venous thromboembolism (VTE) in patients undergoing hip fracture surgery, hip replacement surgery, knee replacement surgery, or abdominal surgery who are at risk of thromboembolic complications.
• Prophylaxis of VTE in medically ill patients at risk for thromboembolic complications due to severely restricted mobility during acute illness.
• Treatment of acute deep vein thrombosis (DVT), given together with warfarin.
• Treatment of acute pulmonary embolism (PE), given together with warfarin, when initial treatment is started in the hospital.

Guideline-supported / commonly used off-label indications

• Acute coronary syndrome (unstable angina/NSTEMI and STEMI), as an anticoagulant per cardiology society guidelines.
• As an alternative parenteral anticoagulant in patients with a history of heparin-induced thrombocytopenia (HIT) who require anticoagulation, based on expert/guideline recommendations rather than formal labeling.

In all indications requiring combination therapy (e.g. DVT/PE treatment with warfarin), Fonidel is continued until a therapeutic INR is achieved.

Each pre-filled syringe contains Fondaparinux Sodium as the active ingredient, available in strengths such as 2.5 mg/0.5 mL, 5 mg/0.4 mL, 7.5 mg/0.6 mL, and 10 mg/0.8 mL for subcutaneous injection, formulated in water for injection with sodium chloride for tonicity.

Fonidel is a synthetic pentasaccharide anticoagulant chemically distinct from heparin and low-molecular-weight heparins. It is administered by subcutaneous injection and is used to prevent and treat venous thromboembolic events and in the management of acute coronary syndromes.

Unlike heparins, Fonidel is a fully synthetic molecule, which eliminates the risk of contamination associated with animal-derived anticoagulants and produces a more predictable, selective anticoagulant effect.

Fonidel belongs to the class of anticoagulants, specifically the selective factor Xa inhibitors (synthetic pentasaccharides).

Fondaparinux Sodium is a synthetic and specific inhibitor of activated Factor Xa. Its antithrombotic activity is the result of antithrombin III (ATIII)-mediated selective inhibition of Factor Xa. By selectively binding to ATIII, Fondaparinux Sodium potentiates (about 300-fold) the innate neutralization of Factor Xa by ATIII, which interrupts the coagulation cascade and inhibits thrombin formation and thrombus development.

Fondaparinux Sodium does not inactivate thrombin (activated Factor II) and has no known effect on platelet function. It is absorbed rapidly and completely after subcutaneous injection (bioavailability 100%), reaches peak plasma concentration in about 2 hours, has a half-life of approximately 17-21 hours in patients with normal renal function (allowing once-daily dosing), and is eliminated primarily unchanged via the kidneys.

Concomitant use of Fonidel with other drugs that increase the risk of bleeding requires caution and closer monitoring:

• Other anticoagulants (heparin, low-molecular-weight heparins, warfarin, direct oral anticoagulants) - additive anticoagulant effect and increased bleeding risk; avoid unless specifically indicated (e.g. bridging to warfarin).
• Antiplatelet agents (aspirin, clopidogrel, other NSAIDs) - increased risk of bleeding due to combined effects on hemostasis.
• Thrombolytics - significantly increased bleeding risk when used together.

Drugs that affect platelet function or coagulation should be discontinued prior to Fonidel administration when possible, or used only with careful clinical monitoring.

The most common adverse effect of Fonidel is bleeding. Other reported side effects include:

• Bleeding at the injection site, hematoma, or bruising.
• Anemia.
• Nausea and gastrointestinal upset.
• Elevated liver transaminases (usually mild and reversible).
• Rash, pruritus.
• Fever.
• Thrombocytopenia (uncommon but clinically important; requires platelet count monitoring).

Serious but rare effects include major hemorrhage and spinal/epidural hematoma when neuraxial anesthesia is used concurrently (see Precautions).

Pregnancy: Data on the use of Fonidel in pregnancy are limited. It should be used during pregnancy only if clearly needed and if the potential benefit justifies the potential risk to the fetus; use only under close physician supervision.

Lactation: It is not known whether Fonidel is excreted in human milk in clinically significant amounts. Caution should be exercised, and a physician should be consulted before use during breastfeeding.

Bleeding risk: Fonidel increases the risk of bleeding, and there is no specific reversal agent available (protamine does not neutralize its effect). Use with caution in patients with increased risk of hemorrhage, including those with bleeding disorders, active peptic ulcer disease, recent surgery, or concurrent use of drugs that affect hemostasis.

Spinal/epidural hematoma: Patients receiving Fonidel who undergo neuraxial anesthesia (spinal/epidural) or spinal puncture are at risk of developing an epidural or spinal hematoma, which can result in long-term or permanent paralysis. This risk is increased by the use of indwelling epidural catheters, concomitant use of other drugs affecting hemostasis, and traumatic or repeated punctures. Patients should be monitored frequently for signs of neurological impairment.

Renal impairment: Fonidel is eliminated primarily by the kidneys and accumulates in renal impairment, increasing bleeding risk; it is contraindicated in severe renal impairment and should be used with caution and reduced dosing in moderate renal impairment.

Thrombocytopenia: Monitor platelet counts; discontinue if severe thrombocytopenia with a positive antibody test occurs.

Not interchangeable on a unit-for-unit basis with heparin or low-molecular-weight heparins.

Overdosage with Fonidel may lead to bleeding complications. There is no known antidote or specific reversal agent. In case of suspected overdose or serious bleeding, discontinue the drug immediately and seek emergency medical attention or contact a poison control center right away. Management is supportive (e.g. surgical hemostasis, blood replacement, fresh frozen plasma); recombinant factor VIIa may be considered by treating physicians in life-threatening bleeding, but this should only be decided by qualified medical personnel.

Store at room temperature (below 30°C), protected from light, in the original package until time of use. Do not freeze. Keep out of reach of children.

Renal impairment: Fonidel is contraindicated in severe renal impairment (creatinine clearance below 30 mL/min); use with caution and consider dose reduction in moderate renal impairment (creatinine clearance 30-50 mL/min). See Precautions and Dosage sections.

Hepatic impairment: No dose adjustment is generally required in mild to moderate hepatic impairment; data are limited, so use with caution.

Elderly: No dose adjustment based on age alone is required, but elderly patients often have reduced renal function, so renal status should be assessed before and during treatment.

Low body weight: Contraindicated for prophylactic dosing in patients weighing less than 50 kg due to increased bleeding risk.

Pediatric patients: Safety and efficacy have not been established in children; use is not recommended.

Duration depends on indication: 5-9 days for post-surgical VTE prophylaxis (up to 24 days total in hip fracture surgery with extended prophylaxis), up to 14 days for prophylaxis in medically ill patients, and at least 5-7 days (until a therapeutic INR on warfarin is achieved) for treatment of acute DVT or PE with Fonidel.

Anticoagulant; selective Factor Xa inhibitor; synthetic pentasaccharide.

Category B

Safety and efficacy of Fonidel in pediatric patients have not been established. It is not recommended for use in children outside of specialist supervision and limited reported experience in refractory cases.