Nitrofurantoin for the treatment of uncomplicated urinary tract infection in female patients: the impact of dosing regimen, age, and renal function on drug exposure

PURPOSE: The aim of this study is to determine nitrofurantoin exposure in female patients with different age and renal function with complaints of an uncomplicated UTI. Also the nitrofurantoin exposure in relation to the dosage regimen will be studied. METHODS: Eight general practitioners (GP) participated in the study and included 38 patients with symptoms of an uncomplicated UTI, treated either with a dose of 50 mg q6h or 100 mg q12h, upon the discretion of the GP. Nitrofurantoin exposure was quantified in the patient’s 24-h urine samples by UHPLC-UV and the area under the curve was calculated. RESULTS: The 38 patients provided a range of 2–17 urine samples. The urine nitrofurantoin exposure was 1028 mg h/L for the patients receiving 50 mg q6h and 1036 mg h/L for those treated with 100 mg q12h (p = 0.97) and was not affected by age and eGFR (p = 0.64 and p = 0.34, respectively). CONCLUSION: The data obtained do not support the discouragement of nitrofurantoin use in the elderly and in patients with impaired renal function. Since only a small number of patients were included, a larger study with more patients is warranted to evaluate nitrofurantoin exposure and adverse effects.