Randomized double-blind study of prophylactic methenamine hippurate treatment of patients with indwelling catheters.

Catheterized patients with heavy bacteriuria and short catheter life received a short-course of antimicrobial therapy and then were allocated at random to double-blind treatment for 5 months with methenamine hippurate (MH), 1 g three times daily, or placebo 1 g 3 times daily. MH treatment reduced the number of catheter blockages and instances of spontaneous removal of the catheter, and doubled catheter life (p less than 0.001). It is suggested that the doubled catheter life was due to the reduced bacteriuria and lowering of urinary pH.