Fondaparinux

ARIXTRA

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Pronunciation: fon-da-PAR-in-ux (a-RIX-tra)

Fondaparinux ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Fondaparinux ballicule

What it isSynthetic pentasaccharide activating antithrombin against factor Xa; VTE prophylaxis and treatment.

Why this oneNegligible HIT cross-reactivity makes it a practical anticoagulant when heparin-induced thrombocytopenia is suspected.

What limits itNo reliable reversal agent exists; renal accumulation increases bleeding, and neuraxial procedures risk spinal hematoma.

Fondaparinux molecular structure (skeletal formula) — Molecular structure: Fondaparinux

FDA-approved for

VTE prophylaxis/treatment (2001)

FDA label

Read the full label on DailyMed ↗

BOXED WARNING Epidural or spinal hematomas (which may cause long-term or permanent paralysis) may occur with neuraxial anesthesia or spinal puncture in anticoagulated patients.

FDA dosing	Population	Start	Target	Max
DVT prophylaxis (hip fracture, hip/knee replacement, abdominal surgery)	Adult	2.5 mg SC QD	2.5 mg SC QD	2.5 mg SC QD
DVT/PE treatment, body weight <50 kg	Adult	5 mg SC QD	5 mg SC QD	5 mg SC QD
DVT/PE treatment, body weight 50-100 kg	Adult	7.5 mg SC QD	7.5 mg SC QD	7.5 mg SC QD
DVT/PE treatment, body weight >100 kg	Adult	10 mg SC QD	10 mg SC QD	10 mg SC QD

Renal Contraindicated if CrCl <30 mL/min; use with caution CrCl 30-50 mL/min

Hepatic No adjustment needed (mild to moderate impairment)

Instructions

Subcutaneous use only; do not mix with other injections or infusions
Prophylaxis initial dose no earlier than 6-8 hours after surgery
Prophylaxis duration 5-9 days (up to 24 additional days for hip fracture)
Treatment continue ≥5 days until INR 2-3 achieved with warfarin

Available strengths

inj 5 mg/0.4 mL
inj 2.5 mg/0.5 mL
inj 7.5 mg/0.6 mL
inj 10 mg/0.8 mL

Contraindications

Severe renal impairment (CrCl <30 mL/min)
Active major bleeding
Bacterial endocarditis
Thrombocytopenia with a positive anti-platelet antibody test in the presence of fondaparinux
Body weight <50 kg (VTE prophylaxis only)

Cautions

Spinal/epidural hematoma
Hemorrhage
Increased bleeding risk in renal impairment and low body weight <50 kg
Thrombocytopenia
Not for use as heparin/LMWH substitute for HIT

Adverse reactions

Bleeding complications
Mild local injection-site irritation
Anemia
Thrombocytopenia

Pregnancy Published data have not reported a clear association with adverse developmental outcomes; low placental transfer observed.

Lactation Undefined

Cost

Fondaparinux (ARIXTRA)

What pharmacies pay · NADAC 9/30/26

Strength		#/mo	generic $/unit	CostPlus
5 mg/0.4 mL	inj	per unit	$55.31/mL	not offered
2.5 mg/0.5 mL	inj	per unit	$22.16/mL	not offered
7.5 mg/0.6 mL	inj	per unit	$42.81/mL	not offered
10 mg/0.8 mL	inj	per unit	$44.82/mL	not offered

Generic entry2011

⚠ BOXED WARNING

Spinal or epidural hematoma with neuraxial anesthesia

Classes and tags

Clinical profile

Therapeutic safety burden3 / 4

Overdose danger3 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk1 / 4

Legacy pregnancy categoryB

Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.

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