From the Guidelines
Monurol (fosfomycin) is a suitable treatment option for UTIs in elderly patients with poor renal clearance, with a recommended dose of a single 3-gram sachet dissolved in water, taken as a one-time dose, as supported by the IDSA/ESCMID guideline 1.
Key Considerations
- Fosfomycin is primarily eliminated unchanged in the urine and achieves high urinary concentrations even in patients with decreased kidney function, making it an effective option for elderly patients with poor renal function.
- The standard dosing regimen is generally appropriate for elderly patients with impaired renal function, but patients with severe renal impairment (creatinine clearance <10 mL/min) may require closer monitoring due to the potential for prolonged drug elimination and increased risk of side effects.
- Common side effects of fosfomycin include diarrhea, nausea, headache, and dizziness, and patients should be advised to take the medication on an empty stomach (2-3 hours after a meal) and to completely dissolve the powder in water before drinking.
Treatment Benefits
- Fosfomycin works by inhibiting bacterial cell wall synthesis and is effective against many common UTI pathogens, including E. coli.
- The single-dose regimen of fosfomycin improves compliance, particularly in the elderly population, and has minimal drug interactions.
- According to the IDSA/ESCMID guideline, fosfomycin is a recommended treatment option for uncomplicated cystitis, with a single dose being a suitable treatment duration 1.
From the FDA Drug Label
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. Renal Insufficiency: In 5 anuric patients undergoing hemodialysis, the t1/2 of 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 t1/2 of 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.
The dose of Monurol (fosfomycin) does not need to be adjusted in the elderly. However, in patients with renal insufficiency, the excretion of fosfomycin is significantly decreased, and the half-life is increased.
- Key points:
- No dosage adjustment is necessary in the elderly.
- Renal impairment significantly decreases the excretion of fosfomycin.
- The half-life of fosfomycin increases with decreasing renal function. 2
From the Research
Monurol Dose for UTI in the Elderly with Poor Renal Clearance
- The effectiveness of Monurol (fosfomycin tromethamine) in treating urinary tract infections (UTIs) in the elderly with poor renal clearance is supported by several studies 3, 4.
- A study published in 2017 found that fosfomycin tromethamine was successful in treating cystitis in solid organ transplant recipients with renal dysfunction, with no significant difference in treatment success between those with creatinine clearance <40 mL/min and those with creatinine clearance ≥40 mL/min 3.
- Another study published in 2013 reviewed the use of fosfomycin trometamol as a single-dose oral treatment for patients with acute lower urinary tract infections and pregnant women with asymptomatic bacteriuria, and found that it had similar clinical and bacteriological efficacy to other antibiotics 4.
- However, it is essential to note that the studies did not specifically focus on the elderly population with poor renal clearance, and more research is needed to confirm the efficacy of Monurol in this population.
- Other antibiotics, such as nitrofurantoin, have also been studied for the treatment of uncomplicated UTIs, and have been found to be effective, but with a higher risk of side effects 5.
- The choice of antibiotic should be based on the patient's individual risk profile, prior antibiotic treatment, and the spectrum of pathogens and antibiotic susceptibility, as well as the ecological adverse effects of antimicrobial therapy and the side effects for the patient under treatment 6.