What is Hiprex (methenamine) used for?

From the Guidelines

Hiprex, also known as methenamine hippurate, is primarily used to prevent recurrent urinary tract infections (UTIs) in women without abnormalities of the urinary tract, as recommended by the European Association of Urology guidelines 1.

Key Points

• The typical adult dosage of Hiprex is 1 gram twice daily, usually taken morning and evening, as stated in the JAMA Network Open guidelines 1.
• Hiprex works by converting to formaldehyde in acidic urine, which kills bacteria by denaturing their proteins and DNA.
• For effectiveness, patients should maintain acidic urine (pH below 5.5), which can be achieved by consuming cranberry juice or vitamin C supplements and avoiding alkaline foods and antacids.
• Hiprex is not suitable for treating active infections with symptoms like fever or pain, as it only works preventatively.

Benefits and Side Effects

• Hiprex is particularly useful for people prone to recurrent UTIs, such as those with structural abnormalities of the urinary tract or who require intermittent catheterization.
• Side effects are generally mild and may include stomach upset, nausea, or rash, as reported in the JAMA Network Open guidelines 1.
• Patients should drink plenty of water while taking this medication to help flush the urinary system.

Evidence-Based Recommendation

• The use of methenamine hippurate to prevent UTIs is supported by a systematic review and a nonblinded RCT, which found that methenamine was noninferior to antibiotics for the prevention of UTIs 1.
• The European Association of Urology guidelines recommend the use of methenamine hippurate to reduce recurrent UTI episodes in women without abnormalities of the urinary tract 1.

From the FDA Drug Label

To reduce the development of drug-resistant bacteria and maintain the effectiveness of Methenamine Hippurate Tablets and other antibacterial drugs, Methenamine Hippurate Tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria Methenamine Hippurate Tablets are indicated for prophylactic or suppressive treatment of frequently recurring urinary tract infections when long-term therapy is considered necessary.

Methenamine (Hiprex) is used for the prophylactic or suppressive treatment of frequently recurring urinary tract infections when long-term therapy is considered necessary 2.

• The drug should only be used after eradication of the infection by other appropriate antimicrobial agents.
• It is intended to prevent or treat infections proven or strongly suspected to be caused by susceptible bacteria.

From the Research

Uses of Hiprex (Methenamine)

• Hiprex (methenamine) is used to prevent urinary tract infections (UTIs) in adult women with a history of recurrent UTIs 3, 4.
• It is also used to treat chronic urinary tract infections, particularly in patients with residual urine, which is considered a factor in the chronicity of the infection 5, 6.
• Methenamine hippurate has been shown to reduce the number of reinfections in patients with recurrent UTIs, although it may not be effective in treating established infections 5, 6.
• Additionally, methenamine hippurate may have a potential role in the treatment of calcium stone disease, as it can reduce the risk index for renal stone formation 7.

Comparison with Antibiotics

• Methenamine hippurate has been compared to antibiotic prophylaxis in preventing recurrent UTIs in women, with results showing that it is not inferior to antibiotics in preventing UTIs 4.
• The use of methenamine hippurate may also reduce the risk of antimicrobial resistance, as it is a non-antibiotic agent 4.
• However, further research is needed to fully evaluate the effectiveness of methenamine hippurate in preventing UTIs and as an alternative to antibiotic treatment 3, 4.

Key Findings

• Methenamine hippurate can reduce the incidence of symptomatic UTIs in women with recurrent UTIs 4.
• It may be less costly and more effective than antibiotics in terms of quality-adjusted life-years gained, although this finding is not consistent over the longer term 4.
• The use of methenamine hippurate may be associated with a lower risk of antimicrobial resistance compared to antibiotic prophylaxis 4.