From the Guidelines
Nitrofurantoin generally becomes less effective in patients with reduced kidney function, rather than at a specific age, and its effectiveness is not directly related to the patient's age, but rather to their kidney function. While advanced age itself doesn't directly make nitrofurantoin ineffective, kidney function naturally declines with aging, which is why the medication is often avoided in elderly patients, typically those over 65 years old 1. The drug requires adequate renal function to concentrate in the urine where it exerts its antibacterial effect against urinary tract infections. When kidney function is impaired, nitrofurantoin doesn't reach therapeutic concentrations in the urine, resulting in treatment failure. Additionally, reduced clearance of the drug can lead to increased systemic exposure and higher risk of adverse effects, particularly pulmonary toxicity. For this reason, healthcare providers should assess kidney function before prescribing nitrofurantoin, especially in older adults, and consider alternative antibiotics when creatinine clearance is below the recommended threshold.
Some key points to consider when prescribing nitrofurantoin include:
- The patient's kidney function, as measured by creatinine clearance, should be adequate to ensure the drug reaches therapeutic concentrations in the urine 1.
- The presence of risk factors for antimicrobial resistance, such as recent antibiotic use or travel to areas with high resistance rates, should be taken into account when selecting empirical treatment regimens 1.
- Local resistance rates should be considered when choosing an antibiotic, and agents with antipseudomonal activity should only be used in patients with risk factors for nosocomial pathogens 1.
- Nitrofurantoin is a reasonable drug of choice for patients with uncomplicated cystitis, based on its efficacy and ability to spare use of more systemically active agents for treating other infections 1.
Overall, the effectiveness of nitrofurantoin is dependent on the patient's kidney function, rather than their age, and healthcare providers should carefully assess kidney function and consider alternative antibiotics when necessary to ensure the best possible outcomes for patients with urinary tract infections.
From the Research
Nitrofurantoin Effectiveness in Treating UTIs
- The effectiveness of nitrofurantoin in treating urinary tract infections (UTIs) is not directly related to the patient's age, but rather to their renal function 2, 3, 4.
- Studies have shown that nitrofurantoin can be effective in patients with reduced kidney function, but the evidence is limited and more research is needed to determine the optimal dosage and treatment regimen for these patients 3, 4.
Renal Function and Nitrofurantoin Use
- The contraindication of nitrofurantoin in patients with a creatinine clearance (CrCl) below 60 mL/min is not supported by strong evidence, and some studies suggest that it can be used safely and effectively in patients with a CrCl as low as 30 mL/min 3, 5.
- A study found that nitrofurantoin exposure was not affected by age and eGFR, suggesting that it can be used in older adults with renal impairment 4.
Clinical Relevance of Nitrofurantoin
- Nitrofurantoin has been shown to be effective in treating uncomplicated UTIs, especially in patients with Escherichia coli and other pathogens 6.
- The clinical significance of nitrofurantoin has been raised due to its good efficacy and tolerability, as well as the increasing resistance rates of uropathogenic Escherichia coli to other antibiotics 6.