Interfos Adulti (Fosfomycin Trometamol)

Fosfomycin Trometamol is used to treat bacterial infections of the urinary tract.

• Uncomplicated urinary tract infections: eliminates the causative bacteria and resolves urinary symptoms.
• Acute uncomplicated cystitis: provides a single oral dose that clears infection in most patients.
• Susceptible uropathogen infections: offers high urinary concentrations that achieve bactericidal activity.

• Fosfomycin Trometamol exerts its antibacterial effect by irreversibly inhibiting the enzyme MurA (enolpyruvyl transferase), a key catalyst in the early stage of peptidoglycan synthesis. By blocking the formation of N‑acetylmuramic acid, the drug prevents construction of the bacterial cell wall, leading to cell lysis and death of susceptible Gram‑positive and Gram‑negative organisms. This mechanism is independent of common resistance pathways and results in rapid bactericidal activity.

Fosfomycin Trometamol may cause adverse reactions, ranging from mild to severe.

Common Side Effects

• Nausea: mild stomach upset that may resolve without treatment.
• Diarrhea: loose stools occurring during or after therapy.
• Headache: transient head discomfort.
• Abdominal pain: cramping or discomfort in the stomach area.
• Flatulence: increased intestinal gas.
• Taste disturbance: altered taste perception.

Serious or Rare Side Effects

• Allergic reactions: rash, itching, swelling, or anaphylaxis.
• Severe skin reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Clostridioides difficile infection: severe colitis following antibiotic use.
• Hepatic dysfunction: elevated liver enzymes or jaundice.
• Renal impairment: worsening kidney function in susceptible patients.
• Anaphylaxis: life‑threatening systemic allergic response.

When prescribing Fosfomycin Trometamol, clinicians should consider several precautionary measures to ensure safe use.

• Renal function assessment: evaluate creatinine clearance before initiating therapy.
• Pregnancy safety: use only if potential benefit justifies the risk, as data are limited.
• Breastfeeding: assess risk versus benefit, as excretion in milk is possible.
• Known hypersensitivity: avoid in patients with previous allergic reactions to fosfomycin.
• Concomitant nephrotoxic drugs: monitor renal function if used together.
• Drug interactions: review patient medication list for potential interactions.
• Store at below 25°C: keep in the original packaging, protect from moisture and heat.

Fosfomycin Trometamol can interact with other medicines, affecting its absorption or activity.

Major Interactions (Avoid)

• Antacids containing magnesium or aluminum: reduce fosfomycin absorption; separate dosing by at least 2 hours.
• Metoclopramide or other pro‑kinetic agents: delay gastric emptying and lower drug exposure.
• Co‑administration with other nephrotoxic agents: may increase risk of renal toxicity.

Moderate Interactions (Monitor Closely)

• Warfarin: fosfomycin may potentiate anticoagulant effect; monitor INR.
• Oral contraceptives: possible reduction in efficacy; advise additional contraceptive measures.
• Diuretics: may alter renal excretion of fosfomycin; monitor fluid and electrolyte balance.