Magnesium Citrate for Oral Solution
»Magnesium Citrate for Oral Solution,when constituted as directed in the labeling,yields a solution that contains not less than 90.0percent and not more than 110.0percent of the labeled amount of magnesium citrate (C12H10Mg3O14).
Packaging and storage— Preserve in tight containers.
Labeling— The label contains directions for constitution of the powder and states the equivalent amount of magnesium citrate (C12H10Mg3O14)in a given volume of the Oral Solution obtained after constitution.
Microbial limits á61ñ— It meets the requirements of the test for absence of Escherichia coliand Salmonellaspecies.
Uniformity of dosage units á905ñ: meets the requirements.
Content of anhydrous citric acid—
Cation-exchange column ,Test solution,and Procedure—Proceed as directed in the test for Content of anhydrous citric acidunder Magnesium Carbonate and Citric Acid for Oral Solution.The content of anhydrous citric acid is between 76.6%and 93.7%of the labeled amount of magnesium citrate.
NOTE—Perform the following tests on the Oral Solution obtained after constitution as directed in the labeling.Accurately measure the volume of the constituted Oral Solution.
Other requirements— It responds to the Identificationtests and meets the requirements for Chloride,Sulfate,and Tartaric acidunder Magnesium Citrate Oral Solution.
Assay— Transfer an accurately measured volume of constituted Oral Solution,equivalent to about 18.7g of magnesium citrate (C12H10Mg3O14),to a 1000-mLvolumetric flask.Add 200mLof 1Nhydrochloric acid,swirl,and allow to stand for about 10minutes.Dilute with water to volume,and mix.Stir by mechanical means for about 30minutes.Transfer 10.0mLof this solution to a 250-mLbeaker.Add 10mLof ammonia–ammonium chloride buffer TS,5mLof triethanolamine,0.3mLof eriochrome black TS,and titrate with 0.05Medetate disodium VSuntil the last hint of violet disappears (blue endpoint).Each mLof 0.05Medetate disodium is equivalent to 7.520mg of magnesium citrate (C12H10Mg3O14).
Auxiliary Information— Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(PA4)Pharmaceutical Analysis 4
USP28–NF23Page 1170
Phone Number:1-301-816-8251