IMPORTANT SAFETY INFORMATION

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Hiprex^® (methenamine hippurate tablets USP)

WHAT IS HIPREX USED FOR?

Hiprex^® (methenamine hippurate tablets USP) are used to prevent or control recurring urinary tract infections caused by certain bacteria. Hiprex is not used to treat an active infection; Hiprex should only be used after the infection has been treated with other antibiotics.

WHEN SHOULD I NOT TAKE THE DRUG?

You should not take Hiprex if you are allergic to methenamine hippurate, formaldehyde, or any of the other ingredients in the drug, or if you are taking a sulfonamide drug.

You should not take Hiprex unless your doctor has confirmed that your infection is caused by bacteria that is susceptible to Hiprex. Hiprex is effective only against bacterial infections in the urinary tract. It will not work for other types of bacterial infections or for viral infections (such as the common cold or flu). Unnecessary use of Hiprex can lead to its decreased effectiveness and the development of antibiotic-resistant bacteria.

You should not take Hiprex if you have kidney failure, severe liver insufficiency, or you are severely dehydrated.

WHAT WARNINGS SHOULD I KNOW ABOUT HIPREX?

Large doses of Hiprex (8 pills/day for 3-4 weeks) can cause bladder irritation, painful and frequent urination, cause protein to leak into the urine, and cause blood in the urine.

You should also be aware that taking Hiprex before a bacterial infection has been confirmed increases the risk of developing drug resistant bacteria.

When taking Hiprex:

• You should take every precaution to maintain an acid pH of your urine
• If you have liver dysfunction, you should periodically have liver function tests
• Safe use in early pregnancy has not been established. In the last trimester of your pregnancy, safety has been suggested, but has not been proven
• Hiprex contains FD&C Yellow No. 5 (tartazine) dye, which can cause bronchial asthma

Hiprex should only be used to treat bacterial infections. Hiprex will not treat a viral infection (such as the common cold)

WHAT SHOULD I TELL MY HEALTHCARE PROVIDER?

• If you are allergic to methenamine or any of the ingredients in Hiprex, including Yellow Dye No. 5
• If you are pregnant, plan to become pregnant or are nursing
• If you have kidney failure, liver failure, or are severely dehydrated
• If you are taking a sulfonamide (sulfa) drug
• If you have been diagnosed with a bacterial infection

WHAT OTHER MEDICATIONS MIGHT INTERACT WITH HIPREX?

• Sulfa drugs

WHAT ARE THE SIDE EFFECTS OF HIPREX?

A very serious allergic reaction to this drug is rare. Seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, or trouble breathing.

Most side effects have been mild and reported in < 3.5% of people taking Hiprex.

These minor side effects have included:

• Nausea
• Upset stomach
• Difficulty urinating
• Rash

Large doses of Hiprex (8 pills daily for 3-4 weeks) have caused bladder irritation, painful and frequent urination, excess protein in the urine and blood in the urine. If you experience any of these side effects, contact your doctor immediately.

WHAT IF I OVERDOSE?

There is no specific treatment for suspected overdose.

Seek emergency help. Supportive measures should be taken.

Call the Poison Control Hotline (1-800-222-1222).

To report SUSPECTED ADVERSE REACTIONS, contact Validus Pharmaceuticals, LLC at — VALIDUS (1-866-982-5438) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch