Fosfogen3 gm/sachet

Fosfogen is indicated for the following use:

• Uncomplicated urinary tract infection (acute cystitis) in women: Fosfogen is FDA-approved as a single-dose oral treatment for acute cystitis caused by susceptible strains of Escherichia coli and Enterococcus faecalis in female patients 12 years of age and older. This is an established, guideline-supported indication.

Not indicated for: Fosfogen is not indicated for the treatment of pyelonephritis, perinephric abscess, or complicated urinary tract infections, as adequate drug levels for these conditions have not been established. It is also not approved for use in men, as efficacy in this population has not been demonstrated.

Use of Fosfogen outside of these established indications (e.g., for other Gram-negative or Gram-positive infections) is considered off-label and is not routinely recommended without specific susceptibility data and specialist guidance.

Each sachet contains Fosfomycin Trometamol equivalent to 3 g of fosfomycin, along with pharmaceutically acceptable flavoring and sweetening agents (such as orange flavor, saccharin sodium, and sucrose or mandarin flavor, depending on the manufacturer's formulation) to form a granular powder for oral solution.

Fosfogen is a broad-spectrum, phosphonic acid-derivative antibacterial agent supplied as a white to off-white granular powder intended to be dissolved in water and taken orally as a single dose. It is chemically the tromethamine salt of fosfomycin, which improves the aqueous solubility and oral bioavailability of the parent compound.

Fosfogen was developed specifically for the single-dose outpatient treatment of uncomplicated lower urinary tract infections and achieves high, sustained concentrations in urine, which underlies its once-only dosing regimen.

Fosfogen belongs to the phosphonic acid derivative antibiotics, a distinct structural class of antibacterial agents unrelated to beta-lactams, aminoglycosides, quinolones, or other common antibiotic classes.

Fosfomycin Trometamol exerts its bactericidal effect through a mechanism distinct from other antibiotic classes.

Mechanism of Action

Fosfomycin Trometamol inhibits bacterial cell wall synthesis at an early step. It irreversibly inactivates the enzyme enolpyruvyl transferase (MurA), which normally catalyzes the condensation of uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) with phosphoenolpyruvate. By blocking this reaction, Fosfomycin Trometamol prevents formation of the peptidoglycan precursor required for bacterial cell wall assembly, leading to cell lysis and bacterial death.

Pharmacokinetics

After oral administration, Fosfomycin Trometamol is absorbed and rapidly converted to active fosfomycin. It is not significantly protein-bound and is eliminated almost entirely unchanged by the kidneys via glomerular filtration, achieving high concentrations in the urine that remain above the minimum inhibitory concentration for susceptible uropathogens for 24–48 hours after a single dose. The plasma elimination half-life is approximately 4 hours in patients with normal renal function.

Fosfogen powder must be dissolved completely in a glass of cool (not hot) water before drinking; it must never be taken as a dry powder or mixed with hot liquids, which can reduce its effectiveness. The dissolved solution should be consumed right away. It may be taken with or without food.

Fosfogen has a limited number of well-established, clinically significant drug interactions:

• Metoclopramide (and other agents that increase gastrointestinal motility): Concomitant use can reduce serum and urinary concentrations of fosfomycin by accelerating gastric emptying and reducing absorption, potentially decreasing efficacy. Concurrent use of metoclopramide with Fosfogen should generally be avoided.
• Cimetidine: May similarly reduce peak concentrations of fosfomycin; clinical significance appears limited but caution is reasonable.

No clinically significant interactions have been established with warfarin or other commonly co-administered medications, but patients should inform their physician of all medicines they are taking before starting Fosfogen.

Most adverse effects associated with Fosfogen are mild and self-limited following the single-dose regimen.

Common

• Diarrhea
• Nausea
• Headache
• Vaginitis
• Dizziness
• Abdominal pain or dyspepsia

Less Common / Rare

• Rash or pruritus
• Asthenia (weakness)
• Rare reports of severe diarrhea associated with Clostridioides difficile (antibiotic-associated colitis), which can range from mild to life-threatening and may occur up to several weeks after treatment
• Rare hypersensitivity reactions, including angioedema

Pregnancy: Available data have not shown clear evidence of harm to the fetus with Fosfogen; however, as with most medicines, Fosfogen should be used during pregnancy only if clearly needed and if the potential benefit justifies the potential risk to the fetus. A physician should be consulted before use in pregnancy.

Lactation: Fosfomycin is excreted in low amounts in human breast milk. Fosfogen should be used with caution during breastfeeding, and a physician should be consulted to weigh the benefits of treatment against any potential risk to the nursing infant.

• Fosfogen is intended only for the treatment of uncomplicated cystitis in women; it should not be used for pyelonephritis, complicated UTI, or in men, since efficacy for these situations has not been established.
• Use with caution in patients with severe renal impairment (creatinine clearance less than approximately 10 mL/min), as reduced renal function can lower urinary concentrations of the drug and decrease clinical efficacy.
• If symptoms of urinary tract infection persist or worsen after 2–3 days, or recur shortly after treatment, patients should contact their physician, as this may indicate a more complicated infection requiring a different treatment approach.
• As with other antibiotics, prolonged or repeated use may result in overgrowth of non-susceptible organisms, including Clostridioides difficile; if severe or persistent diarrhea occurs, medical advice should be sought promptly.
• Take Fosfogen exactly as prescribed by your physician; do not stop, extend, skip doses, or share this medicine with others without medical advice.

There is limited clinical experience with overdose of Fosfogen. Theoretically, overdose could be expected to produce exaggerated gastrointestinal effects such as nausea, vomiting, and diarrhea. There is no specific antidote.

In case of a suspected overdose, seek immediate medical attention or contact a poison control center. General supportive measures should be provided, and adequate hydration should be maintained to promote renal elimination of the drug. Do not attempt to manage a suspected overdose at home without medical guidance.

Store at room temperature (below 30°C), away from light and moisture. Keep out of reach of children. Do not store the solution after it has been dissolved in water; prepare and use immediately.

Renal impairment: Fosfogen should be used with caution in patients with significant renal impairment, as reduced glomerular filtration lowers urinary drug concentrations and may reduce efficacy; it is generally not recommended for patients with creatinine clearance less than approximately 10 mL/min.

Hepatic impairment: No specific dose adjustment is established as required, since Fosfogen is eliminated primarily by the kidneys, but caution and physician guidance are advised.

Elderly: Age-related decline in renal function should be considered; renal function should be assessed before use in elderly patients.

Pediatric patients: See Pediatric Uses below.

Fosfogen is uniquely formulated for single-dose treatment. One 3 g sachet, taken as a single oral dose, constitutes the complete course of therapy for an uncomplicated urinary tract infection; no additional doses are required or recommended for the same episode unless a physician determines otherwise.

Fosfogen granules must be dissolved in approximately 90–120 mL (3–4 ounces) of cool water immediately before use. Stir well until fully dissolved (a slightly cloudy solution is normal), and drink the entire solution right away. Do not use hot water, and do not prepare the solution in advance for later use, as stability after dissolution is limited.

Phosphonic acid derivative antibiotic; antibacterial agent (Urinary anti-infective)

Fosfomycin Trometamol acts by irreversibly inhibiting the bacterial enzyme enolpyruvyl transferase (MurA), which catalyzes an essential early step in bacterial cell wall (peptidoglycan) biosynthesis. By blocking the addition of phosphoenolpyruvate to UDP-N-acetylglucosamine, Fosfomycin Trometamol prevents the formation of the peptidoglycan building blocks required for bacterial cell wall integrity, resulting in a bactericidal effect against susceptible organisms such as Escherichia coli and Enterococcus faecalis.

B

The safety and efficacy of Fosfogen have been established for female patients 12 years of age and older for the treatment of uncomplicated urinary tract infection (acute cystitis). Safety and efficacy in children younger than 12 years of age have not been established, and Fosfogen is not recommended for use in this younger age group. Use in male pediatric patients has also not been established.