Haiprex (Methenamine Hippurate)

Haiprex is indicated for the prophylactic management of urinary tract infections in patients with a history of recurrent episodes.

• Prevention of recurrent uncomplicated urinary tract infections in women.
• Adjunctive use in patients with neurogenic bladder who are prone to infections.
• Long‑term prophylaxis for individuals with structural urinary tract abnormalities.
• Supportive therapy during periods of increased infection risk, such as after catheter removal.

The safety profile of Haiprex reflects its mechanism of releasing formaldehyde in the urinary tract; side effects are generally mild but some reactions may require medical attention.

Common

• Nausea or mild gastrointestinal upset.
• Dyspepsia or heartburn.
• Mild urinary irritation or frequency.
• Headache.
• Dizziness.
• Metallic or unpleasant taste.

Serious

• Allergic reactions such as rash or pruritus.
• Severe skin eruption or Stevens‑Johnson‑like symptoms.
• Hematuria or significant changes in urine color.
• Hepatic dysfunction indicated by elevated liver enzymes.
• Persistent vomiting or severe nausea.
• Anaphylaxis or other life‑threatening hypersensitivity.

When considering Haiprex, clinicians should evaluate patient-specific factors and potential risks associated with its use.

• Ensure urine pH is acidic; the drug is less effective in alkaline urine.
• Use caution in patients with renal impairment or reduced urinary output.
• Avoid use in individuals with known hypersensitivity to methenamine or hippuric acid.
• Monitor for signs of hepatic or renal dysfunction during prolonged therapy.
• Discuss potential pregnancy and lactation considerations with the prescriber.
• Review concomitant use of other urinary antiseptics to prevent overlapping toxicity.

Haiprex may interact with other medications that alter urine pH or compete for renal excretion.

Avoid

• Alkalinizing agents such as potassium citrate or sodium bicarbonate that raise urine pH.
• Strong diuretics that significantly increase urinary flow and may reduce drug concentration.
• Medications known to cause severe hepatic injury when combined.

Use with caution

• Antacids containing magnesium or aluminum that could affect absorption.
• Other urinary antiseptics or antibiotics, to avoid additive toxicity.
• Drugs metabolized by the same renal transport pathways.
• Supplements that modify urinary pH, such as vitamin C in high doses.