METHENAMINE HIPPURATE TABLETS, USP

To reduce the development of drug-resistant bacteria and maintain the effectiveness of methenamine hippurate tablets USP and other anti bacterial drugs, methenamine hippurate should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.

Each yellow capsule-shaped tablet contains 1 g methenamine hippurate which is the Hippuric Acid Salt of Methena mine (hexamethylene tetramine). The tablet also contains inactive ingredients. FD&C Yellow No. 5 (tartrazine, see PRECAUTIONS), Magnesium Stearate, Povidone, and Saccharin Sodium.

Microbiology: methenamine hippurate tablets USP has antibacterial activity because the methenamine component is hydolyzed to formaldehyde in acid urine. Hippuric acid, the other component, has some antibacterial activity and also acts to keep the urine acid. The drug is generally active against E. coli, enterococci and staphylococci. Enterobacter aerogenes is generally resistant. The urine must be kept sufficiently acid for urea-splitting organisms such as Proteus and Pseudomonas to be inhibited.

Human Pharmacology:
Within 1/2 hour after ingestion of a single 1-gram dose of methenamine hippurate, anti bacterial activity is demonstrable in the urine. Urine has continuous anti bacterial activity when methenamine hippurate is ad min istered at the recommended dosage schedule of 1 gram twice daily.Over 90% of methenamine moiety is excreted in the urine within 24 hours after administration of a single 1-gram dose. Similarly, the hippurate moiety is rapidly absorbed and excreted, and it reaches the urine by both tubular secretion and glomerular filtration. This action may be important in older patients or in those with some degree of renal impairment.

Methenamine hippurate is indicated for prophylactic or suppressive treatment of frequently recurring urinary tract infections when longterm therapy is considered necessary. This drug should only be used after eradication of the infection by other appropriate antimicrobial agents.

To reduce the development of drug-resistant bacteria and maintain the effectiveness of methenamine hippurate and other antibacterial drugs, methenamine hippurate should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

Methenamine hippurate tablets USP is contraindicated in patients with renal insufficiency, severe hepatic insufficiency, or severe dehydration. Methenamine preparations should not be given to patients taking sulfonamides because some sulfona mides may form an insoluble precipitate with formaldehyde in the urine.

Large doses of methenamine (8 grams daily for 3 to 4 weeks) have caused bladder irritation, painful and frequent micturition, albuminuria, and gross hematuria.

Prescribing methenamine hippurate in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.

1. Care should be taken to maintainan acid pH of the urine, especially when treating infections due to urea-splitting organisms such as Proteus and strains of Pseudomonas.
2. In a few instances in one study, the serum transaminase levels were slightly elevated during treatment but returned to normal while the patients were still taking methenamine hippurate. Because of this report, it is recommended that liver function studies be performed periodically on patients taking the drug, especially those with liver dysfunction.
3. Use in Pregnancy: In early pregnancy the safe use of methenamine hippurate is not established. In the last trimester, safety is suggested,but not definitely proved. No adverse effects on the fetus were seen in studies in pregnant rats and rabbits.Methenamine hippurate taken during pregnancy can interfere with laboratory tests of urine estriol (resulting in unmeasurably low values) when acid hydrolysis is used in the laboratory procedure. This interference is due to the presence in the urine of methenamine and/or formaldehyde. Enzymatic hydrolysis, in place of acid hydrolysis, will circumvent this problem.
4. This product contains FD&C Yellow No. 5 (tartra zine), which may cause allergictype reactions (including bronchial asthma) in certain susceptible individuals. Although the overall incidence of FD&C Yellow No. 5 (tartra zine) sensitivity in the general population is low, it is frequently seen in patients who also have aspirin hypersensitivity.

REPORTING ADVERSE REACTION STATEMENT AND PHONE NUMBERS CALL YOUR DOCTOR FOR MEDICAL ADVICE ABOUT SIDE EFFECTS. YOU MAY REPORT SIDE EFFECTS TO THE FDA AT 1-800-FDA- 1088 OR LEADING PHARMA,LLC AT 844-740-7500

Minor adverse reactions have been reported in less than 3.5% of patients treated. These reactions have included nausea, upset stomach, dysuria, and rash.

1 tablet (1.0 g) twice daily (morning and night) for adults and pediatric patients over 12 years of age. 1/2 to 1 tablet (0.5 to 1.0 g) twice daily (morning and night) for pediatric patients 6 to 12 years of age. Since the antibacterial activity of methenamine hippurate is greater in acid urine, restriction of alkalinizing foods and medications is desirable. If necessary, as indicated by urinary pH and clinical response, supplemental acid ifica tion of the urine should be instituted. The efficacy of therapy should be monitored by repeated urine cultures.

1-gram scored, capsuleshaped yellow tablets debossed W 1037 in bottles of 100 (NDC 69315-210-01) Store at 25°C (77°F); excursions permitted to 15-30°C (59-86°F) [see USP Controlled Room Temperature].

Prescribing information as of January 2016

Distributed by:

Leading Pharma, LLC
Fairfield, NJ 07004

Manufactured by:
Patheon Pharmaceuticals, Inc.
Cincinnati, OH 45237

70032118


Rev. 01/16 .