Fosfomycin  (PDF Version)


Antibiotic Class:

Phosphonic acid derivative


Antimicrobial Spectrum:

Gram-positive: Staphylococcus spp., Enterococcus spp.

Gram-negative: E. coli, Enterobacter spp., Citrobacter spp., Klebsiella spp., Proteus spp., Providencia spp. P. aeruginosa


Mechanism of Action:

Irreversibly attaches to pyruvyl transferase, an important enzyme in the early step of bacterial cell wall synthesis



No data



Cmax: 26.28.1mcg/ml; Half-life: 3.60.44 (hr); Tmax: 2.50.8 (hr); Table 2


Adverse Effects:

GI: diarrhea, nausea, abdominal pain

Other: vaginitis, headache, dizziness



PO: Powder for reconstitution


UTI in children < 5 years old: 2g once

UTI in Adults: 3g once


Disease state based dosing:

Renal failure: Dosing adjustments not necessary

Hepatic failure: Dosing adjustments not necessary



Precautions:  Food delays absorption administer on an empty stomach


Drug Interactions:

Cisapride: decreased urinary concentrations of fosfomycin

Metoclopromide: decreased urinary concentrations of fosfomycin



Category B: No evidence of risk in humans but studies inadequate.


Monitoring Requirements:

Therapeutic:  Culture and sensitivities, signs and symptoms of infection

Toxic:  None


Brand names/Manufacturer: