Methenamine Mandelate

Description

DESCRIPTION Methenamine mandelate, a urinary antibacterial agent, is the chemical combination of mandelic acid with methenamine. Methenamine mandelate is available for oral use as film-coated tablets. Methenamine mandelate tablets contain 500 mg and 1000 mg (1 g) methenamine mandelate and the following inactive ingredients: croscarmellose sodium, FD&C blue #2 aluminum lake, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polyvinyl alcohol, silicon dioxide, talc and titanium dioxide.

What Is Methenamine Mandelate Used For?

INDICATIONS AND USAGE Methenamine mandelate is indicated for the suppression or elimination of bacteriuria associated with pyelonephritis, cystitis, and other chronic urinary tract infections; also those neurologic diseases leading to an infected residual urine. When used as recommended, methenamine mandelate is particularly suitable for long-term therapy because of its safety and because resistance to the nonspecific bactericidal action of formaldehyde does not develop. Pathogens resistant to other antibacterial agents may respond to methenamine mandelate because of the nonspecific effect of formaldehyde formed in an acid urine. Prophylactic Use Rationale: Urine is a good culture medium for many urinary pathogens. Inoculation by a few organisms (relapse or reinfection) may lead to bacteriuria in susceptible individuals. Thus, the rationale of management in recurring urinary tract infection (bacteriuria) is to change the urine from a growth-supporting to a growth-inhibiting medium. There is a growing body of evidence that long-term administration of methenamine mandelate can prevent the recurrence of bacteriuria in patients with chronic pyelonephritis. Therapeutic Use Rationale : Methenamine mandelate helps to sterilize the urine, and in some situations in which underlying pathologic conditions prevent sterilization by any means, it can help to suppress the bacteriuria. Methenamine mandelate should not be used alone for acute infections with parenchymal involvement causing systemic symptoms such as chills and fever. A thorough diagnostic investigation as a part of the overall management of the urinary tract infection should accompany the use of methenamine mandelate.

Dosage and Administration

DOSAGE AND ADMINISTRATION The average adult dose is 4 g a day given as one 1000 mg tablet or two 500 mg tablets after each meal and at bedtime. Children 6 to 12 years of age should receive half the adult dose; one 500 mg tablet, 4 times a day.

Side Effects (Adverse Reactions)

ADVERSE REACTIONS Gastrointestinal disturbances (nausea, stomach upset), generalized skin rash, dysuria, painful or difficult urination may occur occasionally with the use of methenamine preparations. Microscopic and rarely, gross hematuria have been described.

Drug Interactions

Drug Interactions Formaldehyde and sulfamethizole form an insoluble precipitate in acid urine; therefore, methenamine mandelate should not be administered concurrently with sulfamethizole or other sulfonamides. Concurrent use of salicylates may lead to increased serum salicylate levels since excretion of salicylates is reduced in acidified urine.

Contraindications

CONTRAINDICATIONS Methenamine mandelate tablets are contraindicated in patients with renal insufficiency, severe hepatic disease, severe dehydration, and in patients who have exhibited hypersensitivity to any components of this product.

Pregnancy and Breastfeeding

Pregnancy Teratogenic Effects. Pregnancy Category C. Animal reproduction studies have not been conducted with methenamine mandelate. It is also not known whether methenamine mandelate can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Since methenamine is known to cross the placental barrier, methenamine mandelate should be given to a pregnant woman only if the potential benefit outweighs the risk.

Nursing Mothers Methenamine is excreted in breast milk. Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

How Supplied

HOW SUPPLIED Methenamine Mandelate Tablets, USP 500 mg are blue, unscored, oval, film-coated, debossed with "CE 34" on one side and plain on the other side. Supplied in bottles of 60 (NDC 62135-200-60) Supplied in bottles of 100 (NDC 62135-200-01) Supplied in bottles of 120 (NDC 62135-200-12) Methenamine Mandelate Tablets, USP 1000 mg (1 g) are blue, unscored, oval, film-coated, debossed with "CE 35" on one side and plain on the other side. Supplied in bottles of 60 (NDC 62135-201-60) Supplied in bottles of 100 (NDC 62135-201-01) Supplied in bottles of 120 (NDC 62135-201-12) Preserve in well-closed containers Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature]. Manufactured for: Chartwell RX LLC. Congers, NY 10920 Made in USA L70516 Rev. 09/2021