fosfomycin: clinical use

Prescribing considerations

• Reserve intravenous fosfomycin for listed infections when commonly recommended initial antibacterials are inappropriate.
• Base selection on infection site, severity, microbiology and local susceptibility information.
• Use within combination antibacterial therapy whenever possible to reduce selection of resistance.
• Assess renal function, sodium burden and risk of fluid overload before treatment.

Contraindications and cautions

• Hypersensitivity to fosfomycin or the product's excipients.
• Use particular caution with renal impairment, heart failure, hypertension, cirrhosis, nephrotic syndrome, pulmonary oedema, hypoalbuminaemia or sodium restriction.

Monitoring

• Renal function
• Serum sodium and potassium
• Fluid status and signs of sodium overload
• White-cell count during intravenous treatment
• Clinical and microbiological response, including emergence of resistance
• INR where relevant in patients receiving oral anticoagulants

Clinical pharmacology

Fosfomycin is a bactericidal phosphonic-acid derivative that inhibits the first intracellular stage of peptidoglycan synthesis. Protein binding is negligible, it is not hepatically metabolised, and elimination is predominantly renal; impaired renal function prolongs elimination.

Formulation and product differences

• The selected product is a sodium-containing powder that requires reconstitution and dilution for intravenous infusion.
• Glucose solutions or water for injections may be used during preparation as specified in the product information; sodium chloride-containing solvents must not be used.
• The intravenous formulation's licensing and administration instructions must not be assumed to apply to oral fosfomycin products.

Solution for infusion

Route: Intravenous

Strengths: 40 mg/mL