Fosfomycin

Fosfomycin 3 g Sachet (Granules for Oral Solution)

Fosfomycin (fosfomycin trometamol) is a single-dose antibiotic taken by mouth and supplied as granules for oral solution. In UK prescribing information, it is used for uncomplicated lower urinary tract infection (acute cystitis) in women caused by susceptible strains of Escherichia coli and Enterococcus faecalis. It is not indicated for pyelonephritis (kidney infection) or perinephric abscess, so clinicians and patients should check the relevant UK product information for the licensed indication and prescribing details.

Dosage and Directions

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

How to take: Pour the entire contents of the sachet into 3 to 4 ounces of water (1/2 cup) and stir until dissolved. Do not use hot water. Take it immediately after dissolving. Do not take it dry.

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

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 occur 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 UK healthcare professional.
• 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 medicines that increase gastrointestinal motility) may lower serum concentrations and urinary excretion of fosfomycin.
• Cimetidine does not affect fosfomycin pharmacokinetics when given at the same time.

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 events have been reported after marketing, 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 prescriber in the United Kingdom 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. In the event of overdose, treatment should be symptomatic and supportive. Seek urgent medical help if an overdose is suspected.

Storage

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