Methenamine Hippurate
(meth en' a meen hip' ure ate).
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C6H12N4·C9H9NO3 319.36

Glycine, N-benzoyl, compd. with 1,3,5,7-tetraazatricyclo[,7]decane (1:1).

Hexamethylenetetramine monohippurate [5714-73-8].
» Methenamine Hippurate, dried in vacuum at 60 for 1 hour, contains not less than 95.5 percent and not more than 102.0 percent of C6H12N4·C9H9NO3, and contains not less than 54.0 percent and not more than 58.0 percent of hippuric acid (C9H9NO3).
Packaging and storage— Preserve in well-closed containers.
USP Reference standards 11
USP Methenamine Hippurate RS Click to View Structure
Loss on drying 731 Dry it in vacuum at 60 for 1 hour: it loses not more than 1.0% of its weight.
Residue on ignition 281: not more than 0.1%.
Sulfate— Dissolve 200 mg in 10 mL of water, and add 5 drops of 3 N hydrochloric acid and 5 drops of barium chloride TS: no turbidity appears within 1 minute.
Hippuric acid content— Transfer about 1 g, accurately weighed, to a 250-mL conical flask, and add 50 mL of water. When solution is complete, add phenolphthalein TS, and titrate with 0.1 N sodium hydroxide VS. Each mL of 0.1 N sodium hydroxide is equivalent to 17.92 of C9H9NO3.
Assay— Dissolve about 700 mg of Methenamine Hippurate, accurately weighed, in 50 mL of glacial acetic acid, and titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 31.94 mg of C6H12N4·C9H9NO3.
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Monograph Leonel M. Santos, Ph.D.
Senior Scientific Liaison
(SM12010) Monographs - Small Molecules 1
Reference Standards RS Technical Services
USP35–NF30 Page 3848