Pharmacotherapeutic group: urinary antibacterial agent, ATC code: J01XX05
Mechanism of action
Methenamine Tablets contain Methenamine Hippurate, a salt of methenamine and hippuric acid, which is absorbed and excreted rapidly. In acidic environment, methenamine is hydrolyzed to formaldehyde, which, together with hippuric acid mediates the antibacterial effect in urine. Bacteriological studies have shown that the urine has antibacterial effect already 30 minutes after intake of the drug.
Pharmacodynamic effects
Methenamine Tablets is active against microorganisms, which usually causes urinary tract infection, e.g. Eschericha coli and Aerobacter aerogenes. The substance has decreased effect on urea-degrading bacteria, e.g. Pseudomonas and some strains of Proteus. Urea-degrading bacteria hydrolyze the urea to ammonium hydroxide which is basic and increase urinary pH. This results in reduced hydrolysis of methenamine to formaldehyde.