Methenamine hippurate tablet
Spl unclassified section
To reduce the development of drug-resistant bacteria and maintain the effectiveness ofmethenamine hippurate tablets, USPand other antibacterial drugs, methenamine hippurate tablets, USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.
Methenamine hippurate tablets, USP are available as 1 g oval shaped, scored and peach colored tablets. Chemically, methenamine hippurate is Hexamethylenetetramine monohippurate. The molecular formula of methenamine hippurate is C 15H 21N 5O 3and molecular weight is 319.36. Its structural formula is:
Eachmethenamine hippurate tablet, USP intended for oral administration contains 1 g of methenamine hippurate. In addition, it also contains the following inactive ingredients: colloidal silicon dioxide, magnesium stearate, povidone K29/32, saccharin sodium and FD&C Yellow #6 Aluminum Lake as a color additive.
Meets USP Dissolution Test 2.
Microbiology:Methenaminehippurate tablets,USP has antibacterial activity because the methenamine component is hydrolyzed 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 aerogenesis generally resistant. The urine must be kept sufficiently acid for urea-splitting organisms such as Proteusand Pseudomonasto be inhibited.
Human Pharmacology: Within 1/2 hour after ingestion of a single 1-gram dose of methenamine hippurate, USP, antibacterial activity is demonstrable in the urine. Urine has continuous antibacterial activity whenmethenamine hippurate tablets,USP is administered 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 tablets, USP are indicated for prophylactic or suppressive treatment of frequently recurring urinary tract infections when long-term 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 tablets, USP and other antibacterial drugs, methenamine hippurate tablets, USP 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.
Methenaminehippurate tablets, USP are contraindicated in patients with renal insufficiency, severe hepatic insufficiency, or severe dehydration. Methenamine preparations should not be given to patients taking sulfonamides because some sulfonamides 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.
Prescribingmethenamine hippurate tablets,USP 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 maintain an acid pH of the urine, especially when treating infections due to urea-splitting organisms such as Proteusand strains of Pseudomonas.
2. In a few instances in one study, the serum transaminase levels were slightly elevated during treatment but returned to normal whilethe patients were still takingmethenamine hippurate tablets,USP. Because of this report, it is recommended that liver function studiesbe 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 tablets, USP 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.
Methenaminehippurate tablets,USP taken during pregnancy can interfere with laboratory tests of urine estriol (resulting inunmeasurably low values) when acid hydrolysis is used in the laboratory procedure. This interference is due to the presence intheurine of methenamine and/or formaldehyde. Enzymatic hydrolysis, in place of acid hydrolysis, will circumvent this problem.
Clinical studies ofmethenamine hippurate tablets, USPdid not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal or cardiac function, and of concomitant disease or other drug therapy.
Methenaminehippurate tablets, USPare contraindicated in patients with renal insufficiency and severe hepatic insufficiency (see CONTRAINDICATIONS ).
Information for patients
Patients should be counseled that antibacterial drugs including methenamine hippurate tablets, USP should only be used to treat bacterial infections. They do not treat viral infections (e.g., the common cold). Whenmethenamine hippurate tablets,USP are prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed. Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable bymethenamine hippurate tablets, USP or other antibacterial drugs in the future.
Minor adverse reactions have been reported in less than 3.5% of patients treated. These reactions have included nausea, upset stomach, dysuria, and rash.
To report SUSPECTED ADVERSE REACTIONS, contact Impax Laboratories, Inc. at 1-800-934-6729 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
Dosage and administration
1 tablet (1 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 g) twice daily (morning and night) for pediatric patients 6 to 12 years of age. Since the antibacterial activity of methenamine hippurate tablets, USP is greater in acid urine, restriction of alkalinizing foods and medications is desirable. If necessary, as indicated by urinary pH and clinical response, supplemental acidification of the urine should be instituted. The efficacy of therapy should be monitored by repeated urine cultures.
Methenaminehippurate tabletsUSP, 1 g are supplied as peach, oval shaped compressed tablets debossed cor on the left and 139 on the right side of bisect on one side and other side is plain.
Methenamine hippurate tablets USP, 1 g are supplied:
Bottles of 100 (NDC 0115-1754-01)
Store at 20 to 25C (68 to 77F) [See USP Controlled Room Temperature].
Dispense in well-closed, light-resistant container with child-resistant closure.
Storage and handling section
Hayward, CA 94544
Ingredients and appearance - Product information
Methenamine hippurate tablet- Methenamine hippurate
|Product Type||HUMAN PRESCRIPTION DRUG LABEL||Item Code (Source)||NDC: 0115-1754|
|Route of Administration||Oral|
|Methenamine hippurate ( UNII: M329791L57)( Methenamine - UNII: J50OIX95QV )||1 gin 1|
|Silicon dioxide||( UNII: ETJ7Z6XBU4)|
|Magnesium stearate||( UNII: 70097M6I30)|
|Povidone||( UNII: FZ989GH94E)|
|Saccharin sodium||( UNII: SB8ZUX40TY)|
|Fd&c yellow no. 6||( UNII: H77VEI93A8)|
|Color||ORANGE (peach)||Imprint Code||cor;139|
|#||Item Code||Package Description||Marketing Start Date|
|1||NDC: 0115-1754-01||100 in 1 BOTTLE, PLASTIC||2003/07/01|
|Marketing Category||Application Number or Monograph Citation||Territorial Authority||Marketing Start Date|