Packaging and storage
Preserve in well-closed containers.
Add the following:
When more than one Dissolution
test is given, the labeling states the Dissolution
test used only if Test 1
is not used.USP29
A portion of finely powdered Tablets responds to the Identification
test under Methenamine Hippurate
Change to read:
water; 900 mL.
Dissolve an accurately weighed quantity of USP Methenamine Hippurate RS
in water to obtain a solution having a known concentration of about 22 µg per mL.
Determine the amount of C6H12N4·C9H9NO3 dissolved by employing UV absorption, using a suitable spectrophotometer, at the wavelength of maximum absorbance at about 227 nm on filtered portions of the solution under test, suitably diluted with water, if necessary, in comparison with the Standard solution.
Not less than 80% (Q) of the labeled amount of C6H12N4·C9H9NO3 is dissolved in 30 minutes.
If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 2
water; 900 mL.
Standard solution and Procedure
Proceed as directed for Test 1.
Not less than 80% (Q)
of the labeled amount of C6
is dissolved in 60 minutes.USP29
Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 700 mg of methenamine hippurate, to a 250-mL conical flask. Add 50 mL of alcohol, then add thymolphthalein TS, and titrate with 0.1 N sodium hydroxide VS. Perform a blank determination on a mixture of 50 mL of alcohol and 20 mL of water, and make any necessary correction. Each mL of 0.1 N sodium hydroxide is equivalent to 31.94 mg of methenamine hippurate (C6H12N4·C9H9NO3).
: Behnam Davani, Ph.D., MBA, Senior Scientist
Expert Committee : (MDAA05) Monograph Development-Antivirals and Antimicrobials
USP29NF24 Page 1376
: Volume No. 31(1) Page 63
Phone Number : 1-301-816-8394