From the Guidelines
Fosfomycin for a urinary tract infection (UTI) should be given as a single 3-gram oral dose, not divided into two doses, as recommended by the American College of Physicians 1. The standard regimen is one 3-gram sachet dissolved in water and taken immediately. If a second dose is being considered, it would usually be given 2-3 days after the first dose, though this is not the standard recommendation for uncomplicated UTIs. Fosfomycin works by inhibiting bacterial cell wall synthesis and achieves high urinary concentrations that persist for 24-48 hours after a single dose, which is why one dose is usually sufficient for uncomplicated UTIs. Some key points to consider when prescribing fosfomycin include:
- The medication should be taken on an empty stomach (2-3 hours after a meal or 2 hours before eating) with a full glass of water for optimal absorption.
- Patients should be advised that fosfomycin may cause gastrointestinal side effects like diarrhea, nausea, or headache.
- If symptoms of UTI persist after 2-3 days, patients should contact their healthcare provider as this may indicate the need for a different antibiotic. According to the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases, fosfomycin is an effective treatment for uncomplicated UTIs, with a clinical cure rate of 90% and a bacterial cure rate of 78% 1. However, the most recent and highest quality study recommends a single dose of fosfomycin for uncomplicated cystitis 1. Therefore, the recommended dosing regimen for fosfomycin in uncomplicated UTIs is a single 3-gram oral dose, and this should be taken as directed to ensure optimal efficacy and minimize side effects.
From the Research
Fosfomycin Dosage for UTI
- The recommended dosage of fosfomycin for the treatment of uncomplicated lower urinary tract infections (UTIs) is a single oral dose of 3g 2.
- However, for complicated UTIs, a regimen of 3 grams of oral fosfomycin administered once every 48 or 72 hours for a total of 3 doses may be used 3.
- There is no specific guidance on administering 3g of oral fosfomycin in 2 doses for UTI treatment in the provided studies.
Treatment Duration and Frequency
- A single oral dose of fosfomycin trometamol 3g is effective for the treatment of uncomplicated lower UTIs 2.
- For complicated UTIs, fosfomycin may be administered every 48 or 72 hours for a total of 3 doses 3.
- The frequency and duration of fosfomycin treatment may vary depending on the severity and complexity of the UTI, as well as the patient's response to treatment.
Efficacy and Safety
- Fosfomycin has been shown to be effective in treating UTIs, with similar clinical and bacteriological efficacy to other antibiotics such as ciprofloxacin, norfloxacin, and nitrofurantoin 2.
- Fosfomycin is generally well tolerated, with gastrointestinal adverse events being the most commonly reported 2.
- The incidence of adverse events was found to be more in fosfomycin relative to the nitrofurantoin group 4.