Impaired kidney function may not justify avoidance of nitrofurantoin

Research suggests that impaired kidney function does not justify avoidance of nitrofurantoin, used to treat urinary tract infections (pictured) — Impaired kidney function does not justify avoidance of nitrofurantoin, used to treat urinary tract infections (pictured)

Nitrofurantoin is commonly used to treat urinary tract infections (UTI) but is not recommended in patients with an estimated kidney glomerular filtration rate below 60ml/min/1.73m². This advice is controversial, however, and new research suggests it may be unfounded.

Investigators led by Amit Garg from Western University, Ontario, performed a population-based study of nearly 200,000 women who had been prescribed one of four antibiotics for a UTI. The analysis in CMAJ
^[1] (online, 27 April 2015) showed the risk of treatment failure in women given nitrofurantoin did not differ between those with relatively high GFRs and those with relatively low GFRs.

However, treatment failure was more likely with nitrofurantoin than with any of the other three antibiotics (ciprofloxacin, norfloxacin or trimethoprim–sulfamethoxazole), irrespective of kidney function.