Drug Detail:Methenamine (Methenamine [ meh-theh-na-meen ])
Drug Class: Urinary anti-infectives
Usual Adult Dose for Cystitis
Hippurate: 1 g orally twice a day (morning and night)
Mandelate: 1 g orally 4 times a day (after each meal and at bedtime)
Uses:
- Hippurate: For prophylactic or suppressive treatment of frequently recurring urinary tract infections (UTIs) when long-term therapy deemed necessary
- Mandelate: For the suppression or elimination of bacteriuria associated with pyelonephritis, cystitis, and other chronic UTIs; for infected residual urine due to some neurologic diseases
Usual Adult Dose for Cystitis Prophylaxis
Hippurate: 1 g orally twice a day (morning and night)
Mandelate: 1 g orally 4 times a day (after each meal and at bedtime)
Uses:
- Hippurate: For prophylactic or suppressive treatment of frequently recurring urinary tract infections (UTIs) when long-term therapy deemed necessary
- Mandelate: For the suppression or elimination of bacteriuria associated with pyelonephritis, cystitis, and other chronic UTIs; for infected residual urine due to some neurologic diseases
Usual Adult Dose for Pyelonephritis
Hippurate: 1 g orally twice a day (morning and night)
Mandelate: 1 g orally 4 times a day (after each meal and at bedtime)
Uses:
- Hippurate: For prophylactic or suppressive treatment of frequently recurring urinary tract infections (UTIs) when long-term therapy deemed necessary
- Mandelate: For the suppression or elimination of bacteriuria associated with pyelonephritis, cystitis, and other chronic UTIs; for infected residual urine due to some neurologic diseases
Usual Adult Dose for Urinary Tract Infection
Hippurate: 1 g orally twice a day (morning and night)
Mandelate: 1 g orally 4 times a day (after each meal and at bedtime)
Uses:
- Hippurate: For prophylactic or suppressive treatment of frequently recurring urinary tract infections (UTIs) when long-term therapy deemed necessary
- Mandelate: For the suppression or elimination of bacteriuria associated with pyelonephritis, cystitis, and other chronic UTIs; for infected residual urine due to some neurologic diseases
Usual Pediatric Dose for Cystitis
Hippurate:
6 to 12 years: 0.5 to 1 g orally twice a day (morning and night)
13 years or older: 1 g orally twice a day (morning and night)
Mandelate:
6 to 12 years: 0.5 g orally 4 times a day (after each meal and at bedtime)
13 years or older: 1 g orally 4 times a day (after each meal and at bedtime)
Uses:
- Hippurate: For prophylactic or suppressive treatment of frequently recurring UTIs when long-term therapy deemed necessary
- Mandelate: For the suppression or elimination of bacteriuria associated with pyelonephritis, cystitis, and other chronic UTIs; for infected residual urine due to some neurologic diseases
Usual Pediatric Dose for Cystitis Prophylaxis
Hippurate:
6 to 12 years: 0.5 to 1 g orally twice a day (morning and night)
13 years or older: 1 g orally twice a day (morning and night)
Mandelate:
6 to 12 years: 0.5 g orally 4 times a day (after each meal and at bedtime)
13 years or older: 1 g orally 4 times a day (after each meal and at bedtime)
Uses:
- Hippurate: For prophylactic or suppressive treatment of frequently recurring UTIs when long-term therapy deemed necessary
- Mandelate: For the suppression or elimination of bacteriuria associated with pyelonephritis, cystitis, and other chronic UTIs; for infected residual urine due to some neurologic diseases
Usual Pediatric Dose for Pyelonephritis
Hippurate:
6 to 12 years: 0.5 to 1 g orally twice a day (morning and night)
13 years or older: 1 g orally twice a day (morning and night)
Mandelate:
6 to 12 years: 0.5 g orally 4 times a day (after each meal and at bedtime)
13 years or older: 1 g orally 4 times a day (after each meal and at bedtime)
Uses:
- Hippurate: For prophylactic or suppressive treatment of frequently recurring UTIs when long-term therapy deemed necessary
- Mandelate: For the suppression or elimination of bacteriuria associated with pyelonephritis, cystitis, and other chronic UTIs; for infected residual urine due to some neurologic diseases
Usual Pediatric Dose for Urinary Tract Infection
Hippurate:
6 to 12 years: 0.5 to 1 g orally twice a day (morning and night)
13 years or older: 1 g orally twice a day (morning and night)
Mandelate:
6 to 12 years: 0.5 g orally 4 times a day (after each meal and at bedtime)
13 years or older: 1 g orally 4 times a day (after each meal and at bedtime)
Uses:
- Hippurate: For prophylactic or suppressive treatment of frequently recurring UTIs when long-term therapy deemed necessary
- Mandelate: For the suppression or elimination of bacteriuria associated with pyelonephritis, cystitis, and other chronic UTIs; for infected residual urine due to some neurologic diseases
Renal Dose Adjustments
Renal dysfunction: Contraindicated
Liver Dose Adjustments
Severe liver dysfunction: Contraindicated
Precautions
Safety and efficacy have not been established in patients younger than 6 years.
Consult WARNINGS section for additional precautions.
Dialysis
Renal dysfunction: Contraindicated
Other Comments
Administration advice:
- Hippurate: Only use after infection eradicated by other appropriate antibacterial drugs
- Restrict alkalinizing foods and drugs; antibacterial activity of this drug is greater in acid urine (maximum efficacy occurs up to pH 5.5).
- Start supplemental acidification of the urine if needed based on urinary pH and clinical response.
Storage requirements:
- Store at 25C (77F); excursions permitted to 15C to 30C (59F to 86F).
- Mandelate: Store in tight, light-resistant bottle
General:
- Mandelate: When used as recommended, this drug is especially suitable for long-term therapy due to its safety and because no resistance to formaldehyde develops; pathogens resistant to other antibacterial agents may respond to this drug.
- Mandelate prophylactic use rationale: As urine is a good culture medium for many urinary pathogens, inoculation by a few organisms (relapse or reinfection) may cause bacteriuria in susceptible patients. The rationale for managing recurring UTI (bacteriuria) is to change urine from growth-supporting to growth-inhibiting medium; data available showing long-term use of this drug can prevent bacteriuria recurrence in patients with chronic pyelonephritis.
- Mandelate therapeutic use rationale: This drug helps sterilize urine; if underlying pathologic conditions prevent sterilization by any means, it can help suppress bacteriuria. This drug should not be used alone for acute parenchymal infections causing systemic symptoms (e.g., chills, fever); thorough diagnostic investigation as a part of overall UTI management recommended with use of this drug.
Monitoring:
- Genitourinary: Urinary pH; urine cultures
- Hepatic: Liver function studies (periodically during therapy)
Patient advice:
- To ensure an acidic pH, restrict or avoid milk products and antacids containing sodium carbonate or bicarbonate.
- Avoid missing doses and complete the entire course of therapy.
