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Brand Name
Fosfomycin Tromethamine
View Brand InformationFDA approval date: October 06, 2020
Form: Granule, Powder
What is Fosfomycin Tromethamine?
Fosfomycin tromethamine granules for oral solution is indicated only for the treatment of uncomplicated urinary tract infections in women due to susceptible strains of Escherichia coli and Enterococcus faecalis. Fosfomycin tromethamine granules for oral solution is not indicated for the treatment of pyelonephritis or perinephric abscess. If persistence or reappearance of bacteriuria occurs after treatment with fosfomycin tromethamine granules for oral solution, other therapeutic agents should be selected.
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Brand Information
Fosfomycin Tromethamine (Fosfomycin Tromethamine)
1DESCRIPTION
Fosfomycin Tromethamine Granules for Oral Solution contains fosfomycin tromethamine, a synthetic, broad spectrum, bactericidal antibiotic for oral administration. It is available as a single-dose sachet which contains white granules consisting of 5.631 grams of fosfomycin tromethamine (equivalent to 3 grams of fosfomycin), and the following inactive ingredients: orange flavor, saccharin and sucrose. The contents of the sachet must be dissolved in water. Fosfomycin tromethamine, a phosphonic acid derivative, is available as (
2CLINICAL PHARMACOLOGY
Absorption:Fosfomycin tromethamine is rapidly absorbed following oral administration and converted to the free acid, fosfomycin. Absolute oral bioavailability under fasting conditions is 37%. After a single 3-gram dose of fosfomycin tromethamine, the mean (± 1 SD) maximum serum concentration (C max) achieved was 26.1 (± 9.1) mcg/mL within 2 hours. The oral bioavailability of fosfomycin is reduced to 30% under fed conditions. Following a single 3-gram oral dose of fosfomycin tromethamine with a high-fat meal, the mean C maxachieved was 17.6 (± 4.4) mcg/mL within 4 hours.
Cimetidine does not affect the pharmacokinetics of fosfomycin when coadministered with fosfomycin tromethamine. Metoclopramide lowers the serum concentrations and urinary excretion of fosfomycin when coadministered with fosfomycin tromethamine. (See
Fosfomycin is distributed to the kidneys, bladder wall, prostate, and seminal vesicles. Following a 50 mg/kg dose of fosfomycin to patients undergoing urological surgery for bladder carcinoma, the mean concentration of fosfomycin in the bladder, taken at a distance from the neoplastic site, was 18.0 mcg per gram of tissue at 3 hours after dosing. Fosfomycin has been shown to cross the placental barrier in animals and man.
Excretion:Fosfomycin is excreted unchanged in both urine and feces. Following oral administration of fosfomycin tromethamine, the mean total body clearance (CL TB) and mean renal clearance (CL R) of fosfomycin were 16.9 (± 3.5) L/hr and 6.3 (± 1.7) L/hr, respectively. Approximately 38% of a 3-gram dose of fosfomycin tromethamine is recovered from urine, and 18% is recovered from feces. Following intravenous administration, the mean CL TBand mean CL Rof fosfomycin were 6.1 (±1.0) L/hr and 5.5 (± 1.2) L/hr, respectively.
A mean urine fosfomycin concentration of 706 (± 466) mcg/mL was attained within 2 to 4 hours after a single oral 3-gm dose of fosfomycin tromethamine under fasting conditions. The mean urinary concentration of fosfomycin was 10 mcg/mL in samples collected 72 to 84 hours following a single oral dose of fosfomycin tromethamine.
Following a 3-gram dose of fosfomycin tromethamine granules administered with a high fat meal, a mean urine fosfomycin concentration of 537 (± 252) mcg/mL was attained within 6 to 8 hours. Although the rate of urinary excretion of fosfomycin was reduced under fed conditions, the cumulative amount of fosfomycin excreted in the urine was the same, 1118 (± 201) mg (fed) vs. 1140 mg (± 238) (fasting). Further, urinary concentrations equal to or greater than 100 mcg/mL were maintained for the same duration, 26 hours, indicating that fosfomycin tromethamine granules for oral solution can be taken without regard to food.
Special Populations:
Geriatric:Based on limited data regarding 24-hour urinary drug concentrations, no differences in urinary excretion of fosfomycin have been observed in elderly subjects. No dosage adjustment is necessary in the elderly.
Gender:There are no gender differences in the pharmacokinetics of fosfomycin.
Renal Insufficiency:In 5 anuric patients undergoing hemodialysis, the t 1/2of fosfomycin during hemodialysis was 40 hours. In patients with varying degrees of renal impairment (creatinine clearances varying from 54 mL/min to 7 mL/min), the t 1/2of fosfomycin increased from 11 hours to 50 hours. The percent of fosfomycin recovered in urine decreased from 32% to 11% indicating that renal impairment significantly decreases the excretion of fosfomycin.
Following oral administration of fosfomycin tromethamine, the mean half-life for elimination (t
Microbiology
Fosfomycin (the active component of fosfomycin tromethamine) has
There is generally no cross-resistance between fosfomycin and other classes of antibacterial agents such as beta-lactams and aminoglycosides.
Fosfomycin has been shown to be active against most strains of the following microorganisms, both
Aerobic gram-positive microorganisms
Enterococcus faecalis
Aerobic gram-negative microorganisms
Escherichia coli
The following in vitrodata are available, but their clinical significance is unknown.
The following in vitrodata are available, but their clinical significance is unknown.
Fosfomycin exhibits in vitro minimum inhibitory concentrations (MIC’s) of 64 mcg/mL or less against most (≥ 90%) strains of the following microorganisms; however, the safety and effectiveness of fosfomycin in treating clinical infections due to these microorganisms has not been established in adequate and well-controlled clinical trials:
Aerobic gram-positive microorganisms
Enterococcus faecium Aerobic gram-negative microorganisms
Citrobacter diversus SUSCEPTIBILITY TESTING
For specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by FDA for this drug, please see: https://www.fda.gov/STIC.
Enterococcus faecium Aerobic gram-negative microorganisms
Citrobacter diversus SUSCEPTIBILITY TESTING
For specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by FDA for this drug, please see: https://www.fda.gov/STIC.
3INDICATIONS & USAGE
Fosfomycin tromethamine granules for oral solution is indicated only for the treatment of uncomplicated urinary tract infections (acute cystitis) in women due to susceptible strains of
If persistence or reappearance of bacteriuria occurs after treatment with fosfomycin tromethamine granules for oral solution, other therapeutic agents should be selected. (See
4CONTRAINDICATIONS
Fosfomycin tromethamine is contraindicated in patients with known hypersensitivity to the drug.
5WARNINGS
Clostridium difficileassociated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including fosfomycin tromethamine, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile.
C. difficileproduces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficilecause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must 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 antibiotic use not directed against
6ADVERSE REACTIONS
Clinical Trials:
In clinical studies, drug related adverse events which were reported in greater than 1% of the fosfomycin-treated study population are listed below:
In clinical trials, the most frequently reported adverse events occurring in greater than 1% of the study population regardless of drug relationship were: diarrhea 10.4%, headache 10.3%, vaginitis 7.6%, nausea 5.2%, rhinitis 4.5%, back pain 3.0%, dysmenorrheal 2.6%, pharyngitis 2.5%, dizziness 2.3%, abdominal pain 2.2%, pain 2.2%, dyspepsia 1.8%, asthenia 1.7%, and rash 1.4%.
The following adverse events occurred in clinical trials at a rate of less than 1%, regardless of drug relationship: abnormal stools, anorexia, constipation, dry mouth, dysuria, ear disorder, fever, flatulence, flu syndrome, hematuria, infection, insomnia, lymphadenopathy, menstrual disorder, migraine, myalgia, nervousness, paresthesia, pruritus, SGPT increased, skin disorder, somnolence, and vomiting.
One patient developed unilateral optic neuritis, an event considered possibly related to fosfomycin tromethamine therapy.
Post-marketing Experience:
Serious adverse events from the marketing experience with fosfomycin tromethamine outside of the United States have been rarely reported and include: angioedema, aplastic anemia, asthma (exacerbation), cholestatic jaundice, hepatic necrosis, and toxic megacolon.
Although causality has not been established, during post marketing surveillance, the following events have occurred in patients prescribed fosfomycin tromethamine: anaphylaxis and hearing loss.
Laboratory Changes:
Significant laboratory changes reported in U.S. clinical trials of fosfomycin tromethamine without regard to drug relationship include: increased eosinophil count, increased or decreased WBC count, increased bilirubin, increased SGPT, increased SGOT, increased alkaline phosphatase, decreased hematocrit, decreased hemoglobin, increased and decreased platelet count. The changes were generally transient and were not clinically significant.
7OVERDOSAGE
In acute toxicology studies, oral administration of high doses of fosfomycin tromethamine up to 5 g/kg were well-tolerated in mice and rats, produced transient and minor incidences of watery stools in rabbits, and produced diarrhea with anorexia in dogs occurring 2 to 3 days after single dose administration. These doses represent 50 to 125 times the human therapeutic dose.
The following events have been observed in patients who have taken fosfomycin tromethamine in overdose: vestibular loss, impaired hearing, metallic taste, and general decline in taste perception. In the event of overdosage, treatment should be symptomatic and supportive.
8DOSAGE & ADMINISTRATION
The recommended dosage for women 18 years of age and older for uncomplicated urinary tract infection (acute cystitis) is one sachet of fosfomycin tromethamine granules for oral solution. Fosfomycin tromethamine granules for oral solution may be taken with or without food.
Fosfomycin tromethamine granules for oral solution should not be taken in its dry form. Always mix fosfomycin tromethamine granules for oral solution with water before ingesting. (See
PREPARATION
Fosfomycin tromethamine granules for oral solution should be taken orally. Pour the entire contents of a single-dose sachet of fosfomycin tromethamine granules for oral solution into 3 to 4 ounces of water (1/2 cup) and stir to dissolve. Do not use hot water. Fosfomycin tromethamine granules for oral solution should be taken immediately after dissolving in water.
9HOW SUPPLIED
Fosfomycin Granules for Oral Solution is a white, orange-flavored granular powder for oral administration. Each single-dose sachet contains granules equivalent to 3 grams of fosfomycin.
The product is available as follows:
Store at 20°C to 25°C (68°F to 77°F); excursions permitted between 15°C and 30°C (59°F and 86°F) [see USP Controlled Room Temperature].
Keep this and all drugs out of the reach of children.
For Institutional Use Only
10CLINICAL STUDIES
In controlled, double-blind studies of acute cystitis performed in the United States, a single-dose of fosfomycin tromethamine was compared to three other oral antibiotics (See table below). The study population consisted of patients with symptoms and signs of acute cystitis of less than 4 days duration, no manifestations of upper tract infection (e.g., flank pain, chills, fever), no history of recurrent urinary tract infections (20% of patients in the clinical studies had a prior episode of acute cystitis within the preceding year), no known structural abnormalities, no clinical or laboratory evidence of hepatic dysfunction, and no known or suspected CNS disorders, such as epilepsy, or other factors which would predispose to seizures. In these studies, the following clinical success (resolution of symptoms) and microbiologic eradication rates were obtained.
11REFERENCES
- National Committee for Clinical Laboratory Standards, Methods for Dilution. Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically – Third Edition; Approved Standard NCCLS Document M7-A3, Vol. 13, No. 25 NCCLS, Villanova, PA, December, 1993.
- National Committee for Clinical Laboratory Standards, Performance Standard for Antimicrobial Disk Susceptibility Tests – Fifth Edition; Approved Standard NCCLS Document M2-A5, Vol. 13, No. 24 NCCLS, Villanova, PA, December, 1993.
Distributed by:
Kesin Pharma
Oldsmar, FL 34677
PI-024-V01
Rev. 09/2025
12PACKAGE LABEL.PRINCIPAL DISPLAY PANEL
NDC 81033-
Fosfomycin Tromethamine
Granules for Oral Solution
Rx Only
single-dose sachet
single-dose sachet
