Effect of short-term high-dose treatment with methenamine hippurate on urinary infection in geriatric patients with an indwelling catheter. IV. Clinical evaluation.

An evaluation has been made of the clinical and laboratory effects of short-term (34 days), high-dose (2g x 3 daily) treatment with methenamine hippurate (MH) of 14 geriatric patients with an indwelling catheter and clinical features of urinary tract infection. During MH treatment the number of catheter changes was halved, each catheter remaining in situ for an average of 12.0 days as compared to 6.2 days in the pre-treatment control period and 5.2 days in the post-treatment control period; the difference is significant (p = 0.008; Friedman two-way analysis of variance). Urine pH was reduced (pH 7.0--6.5--7.0; p = 0.01) and the standard bicarbonate in blood was slightly elevated (24.1--25.7--25.0 mmol/l; p= 0.008) during the MH treatment period, when compared to pre- and post-treatment control periods. It is suggested that MH treatment reduced the complications associated with indwelling catheters due to reduction in urine pH, bacteriuria, and pyuria. Blockage of catheters is thought to be due to intraluminal salt precipitations with trapping of clumps, and is primarily not correlated with urine viscosity.