Nitrofurantoin can be prescribed in place of fluoroquinolones when trimethoprim-sulfamethoxazole cannot be used, researchers conclude.
Five-day courses of nitrofurantoin are equivalent clinically and microbiologically to a three-day course of trimethoprim-sulfamethoxazole (TMP/SMX) for treating acute uncomplicated cystitis in women, researchers say.
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The finding, which was published in Archives of Internal Medicine (2007;167:2207-2212), could enable clinicians to prevent further emergence of microbial resistance to fluoroquinolones, which frequently are used as an alternative to TMP/SMX when the latter cannot be used because of resistance or allergy.
Evidence-based guidelines from the Infectious Diseases Society of America concluded that a three-day course of trimethoprim-sulfamethoxazole is the preferred regimen for acute uncomplicated cystitis because of its high efficacy and minimal adverse effects, the researchers noted. Resistant to TMP/SMX, however, is now present in more than 20% of women with acute cystitis in many locales, making the use of an alternative drug necessary.
Nitrofurantoin has been used for more than 50 years for uncomplicated cystitis, the investigators observed. Although it remains active against most uropathogens, its popularity is hindered by a recommended seven-day dosing regimen and concerns about efficacy and tolerance, they noted. Few studies have evaluated the efficacy and tolerance of the drug, especially in a regimen shorter than seven days.
Kalpana Gupta, MD, MPH, and her colleagues at the University of Washington in Seattle randomly assigned 338 women (aged 18-45 years) with acute uncomplicated cystitis to receive either nitrofurantoin 100 mg twice daily for five days or one double-strength trimethoprim-sulfamethoxazole tablet twice daily for three days.
Clinical cure was achieved in 79% of the trimethoprim-sulfamethoxazole group and 84% of the nitrofurantoin recipients. Clinical and microbiological cure rates at the first follow-up visit were equivalent. The researchers concluded that a five-day course of nitrofurantoin “should be considered an effective fluoroquinolone-sparing alternative for the treatment of acute cystitis in women.”
Dr. Gupta, who is now at Boston University and the VA Hospital in Boston, noted that increasing rates of fluoroquinolone resistance are being reported worldwide, including in some regions of the United States. To prevent further emergence of fluoroquinolone resistance, they noted, many experts recommend limiting the use of these agents to more serious infections, with fluoroquinolone-sparing drugs being preferred as second-line therapy for UTI when trimethoprim-sulfamethoxazole cannot be used.
Although the study was not specifically designed to evaluate a three-day regimen of nitrofurantoin, it demonstrated that most women (98%) had microbiological cure after three days of therapy.
