Can fosfomycin be given orally?

Fosfomycin Oral Administration

Yes, fosfomycin can be given orally as fosfomycin tromethamine, which is administered as a single 3-gram dose for uncomplicated urinary tract infections in women. 1

Oral Formulation and Administration

• Fosfomycin tromethamine is available as granules for oral solution that must be dissolved in water before consumption 1
• The preparation involves pouring the entire contents of a single-dose sachet into 3-4 ounces (1/2 cup) of cold water and stirring to dissolve 1
• It can be taken with or without food, although food may reduce bioavailability from 37% to 30% 1

Pharmacokinetics of Oral Fosfomycin

• After a single 3-gram oral dose, peak serum concentrations (Cmax) of 26.1 μg/mL are achieved within 2 hours under fasting conditions 1
• High urinary concentrations (>700 μg/mL) are achieved within 2-4 hours after administration 1
• Therapeutic urinary concentrations are maintained for 24-48 hours following a single dose 2, 3
• Mean elimination half-life is approximately 5.7 hours 1, 3

Clinical Indications for Oral Fosfomycin

• Primarily indicated for uncomplicated urinary tract infections (acute cystitis) in women 1, 2
• The European Association of Urology recommends oral fosfomycin as a first-line treatment option for uncomplicated cystitis in women 2
• Not recommended for pyelonephritis or complicated UTIs due to insufficient data regarding efficacy 4

Efficacy of Oral Fosfomycin

• Clinical cure rates of 75-90% have been reported for uncomplicated UTIs 3, 5
• While bacterial efficacy may be somewhat lower than other first-line agents, clinical efficacy is comparable 4, 2
• Particularly useful against multidrug-resistant pathogens including ESBL-producing organisms, VRE, and MRSA 4, 6

Important Clinical Considerations

• Oral fosfomycin should not be used for pyelonephritis - fluoroquinolones and cephalosporins are preferred for oral treatment of pyelonephritis 4
• For complicated UTIs requiring fosfomycin, intravenous formulation (not available in all countries) may be more appropriate 4
• Resistance can develop during treatment, particularly in isolates with higher MICs or heteroresistance 7
• The convenience of single-dose administration improves patient compliance 2, 5

Common Adverse Effects

• Generally well-tolerated with primarily gastrointestinal side effects 3, 5
• Diarrhea, nausea, and vomiting are the most commonly reported adverse events 4

Oral fosfomycin provides a convenient single-dose option for uncomplicated UTIs with good clinical efficacy and minimal side effects. However, it should not be used for more serious infections like pyelonephritis where other antibiotics are preferred.