sulfamethoxazole and Hiprex Interactions

Interactions between sulfamethoxazole and Hiprex (methenamine)

methenamine and sulfamethoxazole (Moderate Drug-Drug)

GENERALLY AVOID: Methenamine produces an acidic urine, which may predispose patients to sulfonamide-induced crystalluria.

MANAGEMENT: The interaction is not expected with more water-soluble sulfonamides such as sulfisoxazole. An alkalinizing agent should not be added because this may render methenamine less effective.