What it's for (Indications)
- Fosfomycin trometamol is specifically indicated for the treatment of uncomplicated urinary tract infections (uUTIs) in females aged 18 years and older, caused by susceptible strains of *Escherichia coli* and *Enterococcus faecalis*.
- This includes acute cystitis where the infection is confined to the bladder and is not associated with structural or neurological abnormalities of the urinary tract, or other comorbidities that would complicate the infection.
- Its utility lies in its single-dose regimen and broad spectrum of activity against common uropathogens, making it a valuable option for uncomplicated cases.
- Prior to treatment, appropriate culture and susceptibility testing should be performed to determine the susceptibility of the causative microorganisms to fosfomycin, although therapy may be initiated before results are available.
- The judicious use of antibiotics is crucial to minimize the development of drug-resistant bacteria.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | The recommended dosage for fosfomycin trometamol for the treatment of uncomplicated urinary tract infections in females 18 years of age and older is a single oral dose of 3 grams. The contents of one sachet should be dissolved in 90 to 120 mL (approximately 3 to 4 ounces) of cold water (not hot water) and stirred to ensure complete dissolution. The entire solution should be consumed immediately after preparation. It is crucial to administer the full dose to achieve optimal therapeutic concentrations and prevent potential treatment failure or development of resistance. This single-dose regimen simplifies patient adherence and is effective due to its favorable pharmacokinetic profile, including high and sustained concentrations in the urine. The drug may be taken with or without food. |
Safety & Warnings
Common Side Effects
- Commonly reported adverse reactions associated with fosfomycin trometamol are primarily gastrointestinal and include diarrhea, nausea, dyspepsia, and abdominal pain.
- Other frequently observed side effects can involve the central nervous system, such as headache and dizziness, and dermatological reactions like rash.
- Less common but potentially serious adverse effects include hypersensitivity reactions, ranging from mild skin manifestations to severe systemic responses such as anaphylaxis and angioedema.
- Pseudomembranous colitis and *Clostridioides difficile*-associated diarrhea (CDAD) have also been reported with fosfomycin, similar to other antibacterial agents, and can range in severity from mild diarrhea to fatal colitis.
- Patients should be advised to seek immediate medical attention if they experience severe or persistent diarrhea, allergic reactions, or other concerning symptoms.
Serious Warnings
- Black Box Warning: Fosfomycin trometamol does not carry an official FDA Black Box Warning. However, serious warnings and precautions must be considered by healthcare professionals and patients. **Serious Warnings:** 1. ***Clostridioides difficile*-Associated Diarrhea (CDAD):** Treatment with nearly all antibacterial agents, including fosfomycin, has been associated with *Clostridioides difficile*-associated diarrhea (CDAD), which may range in severity from mild diarrhea to fatal colitis. *C. difficile* produces toxins A and B which contribute to the development of CDAD. CDAD should be considered in all patients who present with diarrhea following antibiotic use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents. If CDAD is suspected or confirmed, ongoing antibacterial treatment not directed against *C. difficile* may need to be discontinued, and appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of *C. difficile*, and surgical evaluation should be instituted as clinically indicated. 2. **Hypersensitivity Reactions:** Serious and occasionally fatal hypersensitivity reactions, including anaphylaxis and angioedema, have been reported in patients receiving fosfomycin. If a severe hypersensitivity reaction occurs, fosfomycin should be discontinued immediately, and appropriate medical therapy should be instituted. Patients should be advised to seek immediate medical attention if they experience symptoms of an allergic reaction such as rash, itching, swelling of the face, tongue, or throat, severe dizziness, or trouble breathing. 3. **Limitations of Use:** Fosfomycin is indicated only for uncomplicated urinary tract infections. Its safety and effectiveness in treating pyelonephritis or complicated urinary tract infections, or infections caused by organisms other than *E. coli* and *E. faecalis*, have not been established. Misuse or overuse of antibiotics can lead to the development of drug-resistant bacteria.
- Fosfomycin trometamol therapy requires careful consideration of several warnings.
- The potential for severe hypersensitivity reactions, including anaphylaxis and angioedema, exists, and immediate medical intervention is necessary if such reactions occur.
- Treatment with antibacterial agents, including fosfomycin, alters the normal flora of the colon and may permit overgrowth of *Clostridioides difficile*.
- This can lead to *Clostridioides difficile*-associated diarrhea (CDAD), which can range in severity from mild diarrhea to fatal colitis.
- CDAD should be considered in all patients who present with diarrhea following antibiotic use.
- If CDAD is suspected or confirmed, ongoing antibacterial treatment not directed against *C.
- difficile* may need to be discontinued.
- Renal impairment may prolong the elimination half-life of fosfomycin; caution and appropriate monitoring are advised in patients with compromised renal function.
- Superinfections with non-susceptible organisms may occur with antibiotic use, necessitating clinical reassessment.
How it Works (Mechanism of Action)
Fosfomycin trometamol exerts its bactericidal action by interfering with an early stage of bacterial cell wall synthesis. Specifically, it inhibits the enzyme UDP-N-acetylglucosamine-3-enolpyruvyltransferase (also known as MurA). This enzyme catalyzes the first committed step in peptidoglycan biosynthesis by forming UDP-N-acetylglucosamine-3-enolpyruvyl ether, an essential precursor for the formation of N-acetylmuramic acid. By irreversibly binding to and inactivating MurA, fosfomycin prevents the synthesis of this critical peptidoglycan component, leading to a defective bacterial cell wall and ultimately bacterial cell death. This unique mechanism of action contributes to its effectiveness against a range of gram-positive and gram-negative bacteria commonly implicated in urinary tract infections, and it typically shows little cross-resistance with other classes of antibiotics.
Commercial Brands (Alternatives)
No other brands found for this formula.