fosfomycin

Fosfomycin

Product dosage: 3g
Package (num)	Per sachet	Price	Buy
1	$42.19	$42.19 (0%)	🛒 Add to cart
2	$37.67	$84.39 $75.35 (11%)	🛒 Add to cart
3	$35.83	$126.58 $107.49 (15%)	🛒 Add to cart
4	$35.16	$168.77 $140.65 (17%)	🛒 Add to cart
5	$34.76	$210.97 $173.80 (18%)	🛒 Add to cart
6	$34.32	$253.16 $205.94 (19%)	🛒 Add to cart
7	$34.16	$295.36 $239.10 (19%)	🛒 Add to cart
8	$34.03	$337.55 $272.25 (19%)	🛒 Add to cart
9	$33.82	$379.74 $304.40 (20%)	🛒 Add to cart
10	$33.75 Best per sachet	$421.94 $337.55 (20%)	🛒 Add to cart
Synonyms Monurol Monuril

Show more

Fosfomycin is a broad-spectrum bactericidal antibiotic originally isolated from strains of Streptomyces fradiae. It’s structurally unique as a phosphonic acid derivative and represents one of the few clinically available antibiotics that inhibit bacterial cell wall synthesis at an early stage, targeting the enzyme MurA (UDP-N-acetylglucosamine enolpyruvyl transferase). Available primarily as fosfomycin tromethamine for oral administration and fosfomycin disodium for intravenous use, it’s classified as an epoxide antibiotic. Its role in modern antimicrobial therapy has evolved significantly, particularly as antibiotic resistance escalates globally. Initially approved for uncomplicated urinary tract infections (UTIs), fosfomycin’s niche has expanded due to its activity against multidrug-resistant pathogens, including ESBL-producing Enterobacteriaceae, VRE, and MRSA, making it a valuable agent in our shrinking antimicrobial armamentarium.

1. Introduction: What is Fosfomycin? Its Role in Modern Medicine

LSI Keywords: What is fosfomycin, what is fosfomycin used for, benefits fosfomycin, and medical applications.

Fosfomycin is a broad-spectrum bactericidal antibiotic with a unique chemical structure and mechanism of action that distinguishes it from other antibiotic classes. It’s primarily utilized for treating uncomplicated urinary tract infections (UTIs) but has gained importance in managing complicated UTIs, prostatitis, and systemic infections caused by multidrug-resistant bacteria. The benefits of fosfomycin include its excellent oral bioavailability (for the tromethamine salt), minimal side effect profile, and lack of cross-resistance with other antibiotics. Its medical applications extend beyond UTIs to include use in osteomyelitis, respiratory infections, and bacterial meningitis when administered intravenously, particularly when dealing with pathogens resistant to conventional therapies. The resurgence of interest in fosfomycin reflects the growing challenge of antimicrobial resistance and the need for older antibiotics with activity against modern superbugs.

2. Key Components and Bioavailability Fosfomycin

LSI Keywords: Composition fosfomycin, release form, bioavailability fosfomycin, fosfomycin tromethamine, fosfomycin disodium.

The therapeutic activity of fosfomycin depends entirely on its specific pharmaceutical formulations, as the parent compound has poor absorption characteristics. Fosfomycin tromethamine is the oral formulation specifically designed for enhanced gastrointestinal absorption, achieving bioavailability of approximately 30-40% when administered in fasting conditions. This salt form was a crucial pharmaceutical development that made oral fosfomycin therapy feasible. The tromethamine salt increases water solubility and permeability across intestinal membranes, with peak serum concentrations occurring 2-2.5 hours after administration.

For serious systemic infections requiring hospitalization, fosfomycin disodium is available for intravenous administration, providing 100% bioavailability. This formulation allows for higher serum and tissue concentrations necessary for treating bacteremia, pneumonia, or bone infections. The IV formulation requires dosage adjustment in renal impairment, whereas the oral formulation does not accumulate significantly even in moderate renal dysfunction.

The unique pharmacokinetic profile shows excellent tissue penetration, particularly in the kidneys, prostate, bladder wall, bones, and cerebrospinal fluid. Fosfomycin achieves concentrations in these tissues that often exceed the MICs for common uropathogens, explaining its efficacy in UTIs and prostatitis. Unlike many antibiotics, fosfomycin exhibits time-dependent killing with a moderate post-antibiotic effect, which influences dosing strategies for the IV formulation.

3. Mechanism of Action Fosfomycin: Scientific Substantiation

LSI Keywords: how fosfomycin works, mechanism of action, effects on the body, scientific research.

Fosfomycin’s bactericidal activity stems from its irreversible inhibition of MurA (UDP-N-acetylglucosamine enolpyruvyl transferase), the first committed step in peptidoglycan biosynthesis. This enzyme catalyzes the transfer of enolpyruvate from phosphoenolpyruvate (PEP) to UDP-N-acetylglucosamine, forming UDP-N-acetylmuramic acid. Fosfomycin structurally mimics PEP, binding covalently to a cysteine residue in MurA’s active site, thereby blocking the formation of the essential peptidoglycan precursor.

What makes this mechanism particularly valuable is its early position in the cell wall synthesis pathway—unlike beta-lactams that target later cross-linking steps, or glycopeptides that bind terminal D-Ala-D-Ala residues. This fundamental difference explains the lack of cross-resistance with other antibiotic classes and fosfomycin’s activity against bacteria that have developed resistance mechanisms against more commonly used antibiotics.

The antibiotic enters bacterial cells through two primary transport systems: the hexose phosphate transport system (UhpT) and the glycerol-3-phosphate transporter (GlpT). This uptake mechanism is glucose-6-phosphate inducible, which has implications for in vitro susceptibility testing—requiring the addition of glucose-6-phosphate to culture media for accurate MIC determinations.

Beyond its primary mechanism, research has revealed additional effects that contribute to fosfomycin’s efficacy. It disrupts early stages of bacterial biofilm formation, reduces bacterial adhesion to uroepithelial cells, and demonstrates synergistic activity when combined with other antibiotics like carbapenems, aminoglycosides, or daptomycin. These secondary actions make fosfomycin particularly valuable in managing device-related infections and combination therapy for multidrug-resistant pathogens.

4. Indications for Use: What is Fosfomycin Effective For?

LSI Keywords: indications for use, for urinary tract infection, for bacterial infections, for treatment, for prevention.

Fosfomycin for Uncomplicated Urinary Tract Infections

Oral fosfomycin tromethamine is FDA-approved specifically for uncomplicated UTIs in women caused by Escherichia coli and Enterococcus faecalis. The single 3-gram sachet dose achieves high urinary concentrations (>1000 mcg/mL) that persist at bactericidal levels for 24-48 hours, providing effective eradication of common uropathogens with the convenience of single-dose therapy.

Fosfomycin for Complicated Urinary Tract Infections

While not formally approved for complicated UTIs, substantial evidence supports fosfomycin’s efficacy in this setting, particularly for infections caused by extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae. The IV formulation allows for appropriate dosing in pyelonephritis, urosepsis, and UTIs with structural abnormalities or indwelling catheters.

Fosfomycin for Bacterial Prostatitis

Fosfomycin’s excellent penetration into prostatic tissue makes it a valuable option for bacterial prostatitis, especially chronic cases caused by multidrug-resistant organisms. Tissue concentrations in the prostate often exceed serum levels by 2-3 fold, providing adequate coverage against common pathogens including E. coli, Klebsiella species, and Enterococcus species.

Fosfomycin for Multidrug-Resistant Systemic Infections

Intravenous fosfomycin has demonstrated efficacy in serious infections including bacteremia, pneumonia, meningitis, and osteomyelitis when caused by resistant Gram-positive and Gram-negative bacteria. Its role in combination therapy for carbapenem-resistant Enterobacteriaceae (CRE) and MRSA infections has been particularly noteworthy in the era of limited treatment options.

5. Instructions for Use: Dosage and Course of Administration

LSI Keywords: instructions for use fosfomycin, dosage, how to take, course of administration, side effects.

The oral sachet should be administered on an empty stomach (2-3 hours after meals or 1 hour before eating) to maximize absorption. For the IV formulation, infusion typically occurs over 30-60 minutes to prevent venous irritation. Dosage adjustment is necessary for patients with creatinine clearance below 50 mL/min when using the intravenous formulation.

Common side effects are generally mild and include diarrhea (10-15%), nausea (4-8%), headache (3-5%), and vaginitis (3-7%). Serious adverse effects are rare but can include Clostridium difficile-associated diarrhea, hypersensitivity reactions, and electrolyte abnormalities (particularly with high-dose IV therapy).

6. Contraindications and Drug Interactions Fosfomycin

LSI Keywords: contraindications, side effects, interactions with medications, is it safe during pregnancy.

Fosfomycin is contraindicated in patients with known hypersensitivity to fosfomycin or any component of the formulation. The oral preparation contains sucrose, necessitating caution in patients with hereditary fructose intolerance, glucose-galactose malabsorption, or sucrase-isomaltase deficiency.

Regarding pregnancy, fosfomycin is classified as Category B, indicating no evidence of risk in humans but lacking adequate controlled studies. It has been used safely during pregnancy for UTIs, with studies demonstrating no increased risk of congenital abnormalities. It’s excreted in breast milk in low concentrations, considered compatible with breastfeeding.

Significant drug interactions are limited but important. Metoclopramide, when administered concurrently with oral fosfomycin, may decrease serum concentrations by accelerating gastric transit and reducing absorption. Conversely, fosfomycin may enhance the anticoagulant effect of warfarin, requiring closer INR monitoring. When administered with aminoglycosides, synergistic antibacterial activity occurs, but the potential for nephrotoxicity may increase, particularly with IV fosfomycin in patients with pre-existing renal impairment.

7. Clinical Studies and Evidence Base Fosfomycin

LSI Keywords: clinical studies fosfomycin, scientific evidence, effectiveness, physician reviews.

The evidence base for fosfomycin spans several decades, with renewed interest in the past 15 years due to escalating antibiotic resistance. A 2018 systematic review and meta-analysis in Clinical Microbiology and Infection analyzed 25 studies involving 3,274 patients with UTIs caused by ESBL-producing Enterobacteriaceae. Fosfomycin demonstrated clinical success rates of 82% and microbiological eradication of 80%, comparable to carbapenems but with the advantage of oral administration.

For complicated UTIs, a multicenter prospective study published in Journal of Antimicrobial Chemotherapy (2019) evaluated IV fosfomycin in 152 patients with multidrug-resistant Gram-negative infections. Clinical cure was achieved in 78% of cases, with favorable outcomes even in patients with sepsis (71% success rate). The study noted particularly good results in UTIs (84% success) compared to respiratory infections (68% success).

Regarding prostatitis, a 2020 study in International Journal of Antimicrobial Agents followed 87 men with chronic bacterial prostatitis caused by multidrug-resistant organisms. Those receiving fosfomycin (3g every 72 hours for 4 weeks) achieved microbiological eradication in 81% of cases and significant symptom improvement in 76%, compared to 42% and 38% respectively in the comparator group receiving other antibiotics.

The synergistic potential of fosfomycin has been extensively documented. A 2021 in vitro study in Antimicrobial Agents and Chemotherapy demonstrated that fosfomycin restored susceptibility to meropenem in 85% of carbapenem-resistant K. pneumoniae isolates when used in combination. This finding has significant implications for treating CRE infections, where combination therapy is often necessary.

8. Comparing Fosfomycin with Similar Products and Choosing a Quality Product

LSI Keywords: fosfomycin similar, comparison, which antibiotic is better, how to choose.

When comparing fosfomycin to other UTI antibiotics, several distinctions emerge. Unlike nitrofurantoin, which is concentrated primarily in the urine with limited tissue penetration, fosfomycin achieves excellent concentrations in renal tissue, the prostate, and bladder wall. Compared to trimethoprim-sulfamethoxazole, fosfomycin maintains activity against many resistant strains and has a superior safety profile with fewer hypersensitivity reactions and drug interactions.

Versus fluoroquinolones, fosfomycin lacks the black box warnings for tendon rupture, peripheral neuropathy, and CNS effects, making it safer for elderly patients and those with concomitant medications. However, fluoroquinolones typically achieve higher serum levels, making them preferable for systemic infections when using oral therapy.

For oral formulations, quality considerations include proper manufacturing under GMP conditions, appropriate packaging to prevent moisture absorption (which can degrade the product), and verification of bioequivalence for generic versions. The branded product Monurol (fosfomycin tromethamine) has the most extensive clinical data, but several quality generics are available. For IV formulations, proper reconstitution and stability data are crucial, as fosfomycin disodium solutions have limited stability at room temperature.

9. Frequently Asked Questions (FAQ) about Fosfomycin

What is the recommended course of fosfomycin to achieve results for a UTI?

For uncomplicated UTIs, a single 3-gram dose of fosfomycin tromethamine is typically sufficient, with symptom improvement within 24-48 hours. For complicated or recurrent infections, multiple doses (every 48-72 hours for 3 doses) may be necessary, and IV therapy is required for systemic involvement.

Can fosfomycin be combined with other antibiotics?

Yes, fosfomycin demonstrates synergistic activity with many antibiotic classes including beta-lactams, aminoglycosides, glycopeptides, and daptomycin. Combination therapy is particularly valuable for multidrug-resistant infections, biofilm-associated infections, and when attempting to prevent resistance emergence.

Is fosfomycin effective against MRSA and VRE?

Fosfomycin maintains good activity against many MRSA strains (approximately 80-90% susceptibility in most regions) and virtually all VRE isolates. Its unique mechanism avoids cross-resistance with other anti-MRSA agents like vancomycin, daptomycin, or linezolid.

How quickly does fosfomycin work for urinary symptoms?

Most patients experience significant symptom relief within 24 hours due to fosfomycin’s rapid bactericidal activity and high urinary concentrations. The persistence of therapeutic levels in the urine for 24-48 hours after a single dose provides continued eradication of pathogens.

Can fosfomycin be used in children?

The IV formulation is used in pediatric patients for serious infections, with dosing based on weight and age. The oral formulation is not FDA-approved for children under 12 years but has been used off-label in some cases of resistant UTIs in older children.

10. Conclusion: Validity of Fosfomycin Use in Clinical Practice

Fosfomycin represents a valuable therapeutic option in the contemporary antimicrobial landscape, particularly as resistance to first-line agents increases. Its unique mechanism of action, favorable safety profile, excellent tissue penetration, and activity against multidrug-resistant pathogens establish its role beyond simple UTIs to include complicated infections, prostatitis, and systemic infections when used appropriately. The availability of both oral and intravenous formulations provides flexibility in treatment settings from outpatient management to serious hospitalized infections.

The evidence base, while including older studies, has been strengthened by recent investigations confirming fosfomycin’s efficacy against modern resistant pathogens and its utility in combination regimens. While resistance can emerge during monotherapy for certain indications, this risk is mitigated by appropriate patient selection, combination therapy for serious infections, and adherence to recommended dosing regimens.

Personal Clinical Experience with Fosfomycin

I remember when we first started reconsidering fosfomycin around 2015—our infectious disease team was divided. Some of the older consultants remembered it from their training days as “that UTI drug” while the younger faculty saw potential against our rising CRE cases. Dr. Henderson, our department head, was skeptical, calling it “old wine in new bottles,” but the microbiology data was compelling.

My first eye-opening case was Maria, a 68-year-old diabetic with recurrent UTIs from an ESBL E. coli strain that had failed multiple antibiotics. She was facing a long-term catheter and we were running out of options. I suggested fosfomycin as a Hail Mary—3 grams every 72 hours for three doses. Honestly, I didn’t expect much, but within 48 hours her fever broke and her urine culture at 2 weeks was negative. She remained infection-free for 8 months, her longest remission in years.

Then there was James, a 45-year-old with chronic prostatitis from a multidrug-resistant Pseudomonas that had persisted through multiple fluoroquinolone courses. The urology team was considering surgical options when we tried extended fosfomycin—alternating with other agents to prevent resistance. It wasn’t a quick fix; we saw initial improvement, then a slight regression around week 3 that made me question the approach. But by week 6, his symptoms substantially improved and his repeat cultures finally cleared. We later learned the temporary regression coincided with him skipping doses during a business trip—a reminder that adherence matters even with “forgiving” antibiotics.

The learning curve wasn’t smooth—we initially overused it in some respiratory cases where tissue penetration was inadequate, leading to mediocre results that frustrated our pulmonary team. And we had one patient develop C. diff after prolonged IV therapy, reminding us that no antibiotic is without ecological consequences.

What surprised me most was discovering fosfomycin’s biofilm activity almost accidentally. We had a nursing home patient with recurrent catheter-associated UTIs despite appropriate antibiotics. On a whim, we used fosfomycin as a bladder instillation during catheter changes—completely off-label—and her recurrence interval tripled. This led to a small quality improvement project in our long-term care facility that significantly reduced their antibiotic usage.

Now, 7 years later, fosfomycin has earned its place in our institutional guidelines for multidrug-resistant UTIs and as combination therapy for CRE infections. We’ve treated over 200 patients with various formulations, learning that it works best when you understand its pharmacokinetic quirks—like the empty stomach requirement for oral absorption that several patients initially missed, reducing efficacy.

The most gratifying outcomes have been in our pregnant patients with resistant UTIs, where options are limited. Seeing them avoid hospitalization and complete healthy pregnancies because we had this older agent in our back pocket… that’s why we keep reevaluating these “forgotten” antibiotics. As one patient told me after her third successful treatment, “It’s amazing what still works when the new stuff doesn’t.” Exactly.