Determining If Methenamine Is Appropriate for Use as a Urinary Antiseptic Agent

 

Requirements:

(1) An acidified urine to <= pH 5-6 (with ascorbic acid 1-2 grams po q4h).

(2) Fluid restriction to concentrate the urine (target urinary specific gravity >= 1.015).

(3) A high enough dose to produce sufficient formaldehyde.

 

Contraindications:

(1) Inability to sterilize the urine first.

(2) Hyperuricemia and/or gout. (risk of uric acid nephrolithiasis in acid urine with hyperuricuria)

(3) Hepatic insufficiency (due to generation of ammonia during metabolism to formaldehyde)

(4) Presence of an indwelling or condom-type urinary catheter (urine is drained off as it is formed).

(5) Concurrent therapy with a sulfonamide (precipitate on exposure to formaldehyde).

(6) Renal failure with creatinine clearance < 50 mL/min (for methenamine salts; pure methenamine can be used).

 

Do not use for treating:

(1) pyelonephritis