Selective Factor Xa Inhibitor (Synthetic Pentasaccharide) Pregnancy: B

Fondaparinux Sodium

Brand names: Arixtra

Adult dose

Dose: 2.5 mg subcutaneously once daily (prophylaxis); 5–10 mg once daily (treatment, weight-based)

Route: subcutaneous injection

Frequency: once daily

Max: 10 mg/day

Weight-based VTE treatment: <50 kg: 5 mg; 50–100 kg: 7.5 mg; >100 kg: 10 mg; no dose adjustment for HIT — does not cross-react with heparin antibodies

Paediatric dose

Route:

Not licensed under 17 years

Dose adjustments

Renal

Avoid if eGFR <20 ml/min; caution if eGFR 20–50 ml/min

Hepatic

No dose adjustment required

Clinical pearls

Does NOT cause HIT — can be used in suspected HIT when anticoagulation is still needed
No antidote — recombinant factor VIIa used in severe haemorrhage
OASIS-5 trial: non-inferior to enoxaparin for ACS with 50% less major bleeding

Contraindications

eGFR <20 ml/min
Active significant bleeding
Bacterial endocarditis

Side effects

Bleeding
Anaemia
Thrombocytopaenia (rare)
Oedema
Injection site reactions

Interactions

Drugs affecting haemostasis (NSAIDs, antiplatelets)
Thrombolytics

Monitoring

Renal function
FBC (platelets)
Signs of bleeding

Reference: BNFc; BNF 86; NICE guidelines; OASIS-5 trial. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways