Fosfomycin

Fosfomycin 3 g Sachet (Granules for Oral Solution)

Fosfomycin (fosfomycin trometamol) is a single-dose oral antibiotic supplied as granules for oral solution. In Australian prescribing information, it is indicated for the treatment of acute uncomplicated lower urinary tract infection (acute cystitis) in women caused by susceptible strains of Escherichia coli and Enterococcus faecalis. It is not indicated for the treatment of pyelonephritis (kidney infection) or perinephric abscess.

Dosage and directions

Adults (women 18 years and over): one sachet (3 g) taken as a single dose. It can be taken with or without food.

How to take: Empty the entire contents of the sachet into 1/2 cup of water and stir to dissolve. Do not use hot water. Take it straight away after dissolving. Do not take it dry.

Your symptoms should improve within about 2 to 3 days. If they do not, contact your healthcare provider.

Precautions

• Do not use more than one single dose to treat one episode of acute cystitis. Repeated daily doses did not improve outcomes and increased side effects.
• Antibiotic-associated diarrhoea: diarrhoea can happen with antibiotics. Get medical advice straight away if you develop watery or bloody stools, with or without stomach cramps and fever, even up to 2 months after taking the dose.
• Pregnancy: use during pregnancy only if clearly needed. Breastfeeding: it is not known whether fosfomycin tromethamine passes into human milk; discuss feeding options with your Australian healthcare provider.
• Paediatrics: safety and effectiveness in children 12 years and under have not been established.

Contraindications

Do not use in patients with known hypersensitivity to fosfomycin.

Drug interactions

• Metoclopramide (and other drugs that increase gastrointestinal motility) may lower serum concentrations and urinary excretion of fosfomycin.
• Cimetidine does not affect fosfomycin pharmacokinetics when given together with it.

Possible side effects

In clinical studies, the most common drug-related side effects (>1%) were diarrhoea, vaginitis, nausea, headache, dizziness, asthenia, and dyspepsia. Other events reported in clinical trials included rhinitis, back pain, dysmenorrhoea, pharyngitis, abdominal pain, rash, and temporary changes in lab results.

Rare serious adverse events have been reported in post-marketing experience (mostly outside the United States), including angioedema, aplastic anaemia, asthma exacerbation, cholestatic jaundice, hepatic necrosis, and toxic megacolon; during post-marketing surveillance, anaphylaxis and hearing loss have also occurred.

Missed dose

This product is taken as a single dose. If you forget to take it, take it as soon as you remember on the same day. Do not take an extra sachet to make up for a missed dose; contact your Australian prescriber for advice.

Overdose

Events observed in patients who have taken too much fosfomycin include vestibular loss, impaired hearing, metallic taste, and a general decline in taste perception. If an overdose happens, treatment should be symptomatic and supportive. Seek urgent medical help in Australia if an overdose is suspected.

Storage

Store at 25°C (77°F); excursions permitted to 15-30°C (59-86°F). Keep out of reach of children.