Classes
DEA Class; OTC
Common Brand Names; Cystex
- Antibiotics, Other
Description
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
Indications
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
Contraindications
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
Adverse Effects
Methenamine
- Dysuria
- Gastric upset
- Nausea
- Rash
Sodium salicylate
- Angioedema
- Bronchospasm
- CNS alteration
- Dermatologic problems
- GI pain/ulceration/bleeding
- Hepatotoxicity
- Hearing loss
Warnings
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 and Lactation
Pregnancy Category: C
Lactation: methenamine is excreted in human milk; caution advised, risk to infant cannot be ruled out
Maximum Dosage
Urinary Tract Infection Prophylaxis
2 tablets PO q12hr
Administer with meals and at bedtime
How supplied
Methenamine/sodium salicylate/benzoic acid
tablet
- 162mg/162.5mg/32mg
