Methenamine Dosage

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.