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Methenamine/Sodium Salicylate/Benzoic Acid

    Brands

    DEA Class; OTC

    Common Brand Names; Cystex

    • Antibiotics, Other

    Methenamine: Hydrolyzed in acidic urine to ammonia and formaldehyde, which are bactericidal agents; does not convert to formaldehyde in serum.

    Sodium salicylate: Analgesic

    Benzoic acid: Elicits weak antifungal and antibacterial properties; also helps acidify urine

    Use only after eradication of UTI by other appropriate antibiotic

    Methenamine: Indicated for prophylaxis/suppression for chronic recurring UTIs when long-term therapy is required

    Sodium salicylate: Analgesic

    Benzoic acid: Elicits weak antifungal and antibacterial properties; also helps acidify urine

    Methenamine

    • Hypersensitivity to methenamine or tartrazine (FD&C Yellow No. 5)
    • Renal or severe hepatic insufficiency
    • Concurrent sulfonamides or acetazolamide may form insoluble precipitate in urine

    Sodium Salicylate

    • Hypersensitivity to aspirin or NSAIDs
    • Bleeding gastrointestinal ulcers
    • Asthma, Nasal polyps associated with asthma
    • Hemolytic anemia from PK & G6PD deficiency
    • Hemophilia
    • Hemorrhagic diathesis
    • Hemorrhoids, Lactating women, Sarcoidosis, Thrombocytopenia, Ulcerative colitis

    Methenamine

    • Dysuria
    • Gastric upset
    • Nausea
    • Rash

    Sodium salicylate

    • Angioedema
    • Bronchospasm
    • CNS alteration
    • Dermatologic problems
    • GI pain/ulceration/bleeding
    • Hepatotoxicity
    • Hearing loss

    Methenamine

    • Large doses may cause bladder irritation, urinary frequency, albuminuria, and hematuria
    • Maintain acidic pH of urine, especially when treating urea-splitting organisms (eg, Proteus, Pseudomonas)
    • Monitor LFTs, especially with history of liver impairment
    • Safe use not established during pregnancy, especially 1st and 2nd trimester
    • May precipitate uric acid stones in patients with gout

    Sodium Salicylate

    • Anemia
    • GI malabsorption
    • History of peptic ulcers
    • Gout
    • Hepatic disease
    • Hypochlorhydria, Hypoprothrombinemia, Renal impairment, Renal calculi, Thyrotoxicosis, Vitamin K deficiency

    Pregnancy Category: C

    Lactation: methenamine is excreted in human milk; caution advised, risk to infant cannot be ruled out

    Adults

    Urinary Tract Infection Prophylaxis

    2 tablets PO q12hr

    Administer with meals and at bedtime

    Methenamine/sodium salicylate/benzoic acid

    tablet

    • 162mg/162.5mg/32mg