Infectofos (Fosfomycin Sodium)

Infectofos (fosfomycin sodium) is used for the treatment of infections caused by susceptible bacteria, especially within the urinary, intra‑abdominal and skin‑soft tissue categories.

• Complicated urinary tract infection: effective against Gram‑negative uropathogens, reducing bacterial load.
• Complicated intra‑abdominal infection: provides broad‑spectrum coverage for mixed aerobic and anaerobic organisms.
• Severe skin and soft‑tissue infection: helps eradicate resistant Staphylococcus and Streptococcus species.
• Bacteremia/sepsis: used as part of combination therapy for systemic infections when rapid bacterial eradication is needed.

• Fosfomycin sodium inhibits bacterial cell wall synthesis by irreversibly binding to the MurA enzyme (phosphoenolpyruvate‑dependent enolpyruvyl transferase), preventing the formation of N‑acetylmuramic acid, a key precursor of peptidoglycan. This blockade disrupts cell wall construction, leading to bacterial lysis and death, and it is effective against a wide range of Gram‑positive and Gram‑negative organisms.

Adverse reactions may occur with any medication. The following lists have been reported for intravenous fosfomycin.

Common Side Effects

• Nausea: mild to moderate feeling of sickness.
• Diarrhea: loose stools that may be self‑limiting.
• Headache: transient cranial discomfort.
• Infusion site reactions: erythema, pain or phlebitis at the injection site.

Serious or Rare Side Effects

• Hypersensitivity reactions: including anaphylaxis, rash or angioedema.
• Clostridioides difficile infection: severe colitis following disruption of gut flora.
• Renal impairment: acute kidney injury, especially with concomitant nephrotoxic drugs.
• Severe skin reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Electrolyte disturbances: hypernatremia or hypokalemia in susceptible patients.

Prior to initiating therapy, clinicians should consider several safety aspects.

• Renal function: assess baseline creatinine and adjust dosing in severe impairment.
• Hypersensitivity: discontinue immediately if an allergic reaction occurs.
• Pregnancy: use only when the potential benefit justifies the potential risk to the fetus.
• Concomitant nephrotoxic agents: monitor renal parameters closely when combined with aminoglycosides or loop diuretics.
• Storage at 2-8°C: keep refrigerated, protect from light, do not freeze or shake the solution.

Fosfomycin may interact with other medicines; some require avoidance while others need monitoring.

Major Interactions (Avoid)

• Aminoglycosides: increased risk of nephrotoxicity when co‑administered.
• Loop diuretics: may potentiate ototoxic effects.
• Anticoagulants (e.g., heparin): heightened bleeding risk.

Moderate Interactions (Monitor Closely)

• Probenecid: can reduce fosfomycin clearance, raising plasma levels.
• Warfarin: monitor INR as fosfomycin may alter anticoagulant effect.
• Oral contraceptives: potential reduction in hormonal efficacy, advise additional contraceptive measures.