What is the recommended dosage of Fosfomycin for uncomplicated urinary tract infections?

Fosfomycin Dosage for Uncomplicated Urinary Tract Infections

The recommended dosage of fosfomycin for uncomplicated urinary tract infections is a single 3-gram oral dose. 1, 2

Standard Dosing Regimen

• Fosfomycin tromethamine is administered as a single 3-gram oral sachet for women 18 years and older with uncomplicated urinary tract infections (acute cystitis) 2
• The single-dose regimen provides therapeutic urinary concentrations for 24-48 hours, which is sufficient for treating uncomplicated UTIs 1
• The medication should not be taken in dry form but must be mixed with water before ingestion 2
• Fosfomycin may be taken with or without food 2

Clinical Efficacy

• The single 3-gram dose of fosfomycin has demonstrated high clinical recovery rates (88.9%) and bacteriological eradication rates (94.9%) in uncomplicated UTIs 3
• Both the European Association of Urology and American Urological Association recommend fosfomycin as a first-line treatment option for uncomplicated cystitis in women 1
• Clinical efficacy is comparable to other first-line agents like nitrofurantoin, with the advantage of single-dose administration 1, 4

Special Considerations

• Fosfomycin is specifically indicated for uncomplicated cystitis in women and should not be used for pyelonephritis, complicated UTIs, or routinely in men due to limited efficacy data 1
• For vancomycin-resistant Enterococcus (VRE) causing uncomplicated UTIs, the same single 3-gram oral dose is recommended 5
• The single-dose regimen offers advantages in terms of convenience and patient compliance compared to multi-day regimens 4

Alternative Dosing for Specific Situations

• For complicated lower UTIs (off-label use), some studies support using 3 grams of oral fosfomycin administered once every 48 or 72 hours for a total of 3 doses 6
• This extended regimen may be considered for patients who have previously failed treatment with another agent or are infected with multidrug-resistant pathogens 6
• Pharmacokinetic studies suggest that two 3-gram doses administered 72 hours apart can maintain effective urinary concentrations for approximately 7 days 7

Common Side Effects

• Gastrointestinal side effects (diarrhea, nausea, and vomiting) are the most commonly reported adverse events, occurring in approximately 4.3% of patients 1, 3
• Side effects are generally mild and transient 8

Follow-up Recommendations

• Routine post-treatment urinalysis or urine cultures are not indicated for asymptomatic patients 1
• If symptoms do not resolve by the end of treatment or recur within 2 weeks, urine culture and antimicrobial susceptibility testing should be performed 1