Is it acceptable to give Macrobid (nitrofurantoin) to a patient with impaired renal function, specifically an estimated Glomerular Filtration Rate (eGFR) of 38.4?

From the FDA Drug Label

This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Anuria, oliguria, or significant impairment of renal function (creatinine clearance under 60 mL per minute or clinically significant elevated serum creatinine) are contraindications

• The patient's eGFR is 38.4, which indicates significant impairment of renal function.
• According to the drug label, anuria, oliguria, or significant impairment of renal function are contraindications for the use of Macrobid (nitrofurantoin).
• Therefore, it is not acceptable to give Macrobid to a patient with an eGFR of 38.4 due to the increased risk of toxic reactions 1.

From the Research

No, Macrobid (nitrofurantoin) is not recommended for patients with an eGFR of 38.4 mL/min/1.73m². Nitrofurantoin is contraindicated in patients with creatinine clearance less than 60 mL/min or eGFR below 60 mL/min/1.73m² 2. In patients with impaired renal function, the medication does not achieve adequate urinary concentrations to be effective against urinary tract infections. Additionally, when renal function is decreased, nitrofurantoin and its metabolites can accumulate in the bloodstream, increasing the risk of serious adverse effects including peripheral neuropathy and pulmonary reactions.

Key Considerations

• The patient's eGFR of 38.4 mL/min/1.73m² indicates impaired renal function, which may affect the efficacy and safety of nitrofurantoin.
• Alternative antibiotics such as trimethoprim-sulfamethoxazole, ciprofloxacin, or cephalexin should be considered based on infection susceptibility 3.
• The prescriber should select an antibiotic that is both effective against the causative organism and has appropriate clearance in patients with reduced renal function.

Relevant Evidence

• A study published in 2022 found that nitrofurantoin was prescribed most frequently for outpatient treatment of UTI/cystitis, but its use may be limited in patients with impaired renal function 3.
• Another study published in 1975 found that nitrofurantoin did not reach minimal inhibitory urinary drug concentration below a unilateral creatinine clearance of 20 ml per minute 2.
• A more recent study published in 2018 found that E. coli had a high sensitivity to nitrofurantoin, but this may not be relevant in patients with impaired renal function 4.

Clinical Implications

• Patients with impaired renal function require careful selection of antibiotics to ensure effective treatment and minimize adverse effects.
• The use of nitrofurantoin in patients with an eGFR of 38.4 mL/min/1.73m² is not recommended due to the risk of adverse effects and reduced efficacy.
• Alternative antibiotics should be considered, and the prescriber should consult relevant guidelines and evidence-based recommendations to ensure optimal treatment outcomes.