Haiprex (Methenamine Hippurate)

Haiprex is an oral medication whose active ingredient is methenamine hippurate, supplied as a tablet formulation marketed in the European Union. It belongs to the urinary antiseptic class and is used primarily for the prevention of recurrent urinary tract infections. The drug works by releasing formaldehyde in acidic urine, providing antibacterial activity against common urinary pathogens. Haiprex is available without a specified strength in its standard oral dosage form.

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.