Is one sachet really the entire treatment?

Yes, for the approved use. The label describes a single dose taken dissolved in water, and the medicine stays in the urine long enough for that to be the course.

Why does the label say in women?

Because that is the population in which the approved use was established. It does not mean the infection cannot occur otherwise; it means this label does not cover it, and a man with urinary symptoms needs a different assessment.

How soon should symptoms improve?

The label does not promise a timeline, and neither will we. Symptoms that continue after treatment are a reason to be seen rather than to take a second sachet.

Fosfomycin

A single sachet dissolved in water, approved for uncomplicated cystitis in women and for nothing else in the label.

Class: Phosphonic acid antibacterial
Sold as: Sold as: Monurol, Monuril; Prescription only

From the approved label

Fosfomycin tromethamine

Approved uses: 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 Escherichia coli and Enterococcus faecalis.
If persistence or reappearance of bacteriuria occurs after treatment with fosfomycin tromethamine granules for oral solution, other therapeutic agents should be selected (see PRECAUTIONS and CLINICAL STUDIES sections).
Fosfomycin tromethamine granules for oral solution is not indicated for the treatment of pyelonephritis or perinephric abscess.
Forms and strengths: Fosfomycin Tromethamine Granules for Oral Solution is supplied as a white to off-white powder in a single-dose sachet containing the equivalent of 3 grams of fosfomycin.
How it is taken: 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 section).
Must not be used when: Fosfomycin tromethamine granules for oral solution is contraindicated in patients with known hypersensitivity to the drug.
Interactions: Metoclopramide When co-administered with fosfomycin tromethamine, metoclopramide, a drug which increases gastrointestinal motility, lowers the serum concentration and urinary excretion of fosfomycin.
Other drugs that increase gastrointestinal motility may produce similar effects.
Cimetidine Cimetidine does not affect the pharmacokinetics of fosfomycin when co-administered with fosfomycin tromethamine.
Warnings and precautions: Clostridium difficile associated 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. difficile produces toxins A and B which contribute to the development of CDAD.
Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy.
Common side effects: 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: Drug-Related Adverse Events (%) in Fosfomycin and Comparator Populations Adverse Events Fosfomycin N=1,233 Nitrofurantoin N=374 Trimethoprim/sulfamethoxazole N=428 Ciprofoxacin N=455 Diarrhea 9.0 6.4 2.3 Vaginitis 5.5 5.3 4.7 Nausea...
Pregnancy: Teratogenic Effects When administered intramuscularly as the sodium salt at a dose of 1 gram to pregnant women, fosfomycin crosses the placental barrier. Fosfomycin tromethamine crosses the placental barrier of rats; it does not produce teratogenic effects in pregnant rats at dosages as high as 1,000 mg/kg/day (approximately 9 and 1.4 times the human dose based on body weight and mg/m 2, respectively).

Label holder:: Amneal Pharmaceuticals NY LLC
Label version:: 2 April 2024

This section reports the approved product information. The wording is condensed from the regulator's own summary, and the full document is linked under Sources.

Written by us

How it works

Fosfomycin blocks an early step in building the bacterial cell wall, and it is excreted into the urine where it stays at useful levels long enough for one dose to be the whole course. That is the reason the label describes a single sachet rather than a schedule.

Original and generic

Sold as Monurol and Monuril depending on the country, and available as a generic sachet. The formulation matters more than the brand here, because the dose is designed around a single administration.

What it costs

One sachet, so the price is the price of one dose. It is usually dearer per treatment than a course of nitrofurantoin and cheaper than most consultations.

How to get it legally

Prescription only across Europe. The label is narrow in a way worth repeating: uncomplicated cystitis, in women. Symptoms in a man, or symptoms with fever or flank pain, fall outside it, and a service that dispenses on a questionnaire without asking those questions is not following the document it dispenses against.

Questions

Is one sachet really the entire treatment?: Yes, for the approved use. The label describes a single dose taken dissolved in water, and the medicine stays in the urine long enough for that to be the course.
Why does the label say in women?: Because that is the population in which the approved use was established. It does not mean the infection cannot occur otherwise; it means this label does not cover it, and a man with urinary symptoms needs a different assessment.
How soon should symptoms improve?: The label does not promise a timeline, and neither will we. Symptoms that continue after treatment are a reason to be seen rather than to take a second sachet.

Sources

Fosfomycin Tromethamine: prescribing informationDailyMed, US National Library of Medicine. Label version 2 April 2024
Drugs@FDA: ANDA216600US Food and Drug Administration