What is UREX?

1 Answer
May 31, 2014

UREX is the trademark name of an oral antibiotic that is used to prevent returning urinary tract infections.


The chemical name for UREX is methenamine hippurate. It is a salt of the basic methenamine and hippuric acid. Its structure is


The methenamine is the cage-like structure with four nitrogen atoms. It is made from ammonia and formaldehyde.

The hippuric acid (Greek hippos, horse, ouron, urine) is the structure on the right.

The hippuric acid helps to make the urine acidic. When the urine is acidic, methenamine hydrolyzes to formaldehyde and ammonia. The formaldehyde kills the bacteria.