Drug General Information (ID: DDIJPC7VFQ)
Drug Name			Sulfamethoxazole		Drug Info		Methenamine		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antiinfective Agents				Urinary Antispasmodics
Structure

Mechanism of Sulfamethoxazole-Methenamine Interaction (Severity Level: Major)
Increased risk of other adverse reactions (Unspecific) Click to Show/Hide Mechanism Graph
Drug Name		Sulfamethoxazole				Methenamine
Mechanism		Sulfonamides				Increase the risk of urine crystal precipitation in combination with sulfonamides
Key Mechanism Factor 1
		Factor Name		Adverse reactions
		Factor Description		An adverse reaction is an unexpected negative reaction to a medication or treatment that happens even when it's used correctly.
Mechanism Description		Increased risk of adverse reactions by the combination of Sulfamethoxazole and Methenamine

Recommended Action
Management		Methenamine preparations should not be given to patients taking sulfonamides due to the risk of crystalluria. An alkalinizing agent should not be added because this may render methenamine less effective.

References
1	Product Information. Hiprex (methenamine). Hoechst Marion-Roussel Inc, Kansas City, MO.
2	Product Information. Urised (methenamine). Polymedica Pharmaceuticals USA Inc, Woburn, MA.