Methenamine hippurate may be effective for preventing UTI in patients without renal tract abnormalities, particularly when used for short-term prophylaxis. It does not appear to work in patients with neuropathic bladder or in patients who have renal tract abnormalities. The rate of adverse events was low, but poorly described.
There is a need for further large well-conducted RCTs to clarify this question, particularly for longer term use for people without neuropathic bladder.
Secondary prevention of recurrent urinary tract infections. Comparison of the effect of placebo, methenamine hippurate, nitrofurantoin and trimethoprim alone.
290 patients with recurrent urinary tract infection were treated with either placebo, methenamine hippurate, nitrofurantoin or trimethoprim. 38.9% of the patients had chronic pyelonephritis and 23.8% azotemia. During the follow-up period of 1 year 63.2% recurred in the placebo group, 34.2% in the methenamine hippurate group, 25.0% in the nitrofurantoin group and 10.4% in the trimethoprim group. 62.5% of the recurrences in the trimethoprim group were associated with trimethoprim-resistant strains. However, such strains appeared only in 6.5% of the patients treated with trimethoprim, compared with 16.2% in the placebo, 8.3% in the nitrofurantoin and 11.0% in the methenamine hippurate groups. Side-effects were mild and occurred most frequently in the nitrofurantoin group (13.9%).