Alumina and Magnesia Oral Suspension
»Alumina and Magnesia Oral Suspension is a mixture containing aluminum hydroxide [Al(OH)3]and Magnesium Hydroxide [Mg(OH)2].It contains the equivalent of not less than 90.0percent and not more than 110.0percent of the labeled amounts of aluminum hydroxide [Al(OH)3]and magnesium hydroxide [Mg(OH)2].It may contain a flavoring agent,and may contain suitable antimicrobial agents.
Packaging and storage— Preserve in tight containers,and avoid freezing.
Labeling— Oral Suspension may be labeled to state the aluminum hydroxide content in terms of the equivalent amount of dried aluminum hydroxide gel,on the basis that each mg of dried gel is equivalent to 0.765mg of Al(OH)3.
Identification—
A: To a solution of 5g in 10mLof 3Nhydrochloric acid add 5drops of methyl red TS,heat to boiling,add 6Nammonium hydroxide until the color of the solution changes to deep yellow,then continue boiling for 2minutes,and filter:the filtrate responds to the tests for Magnesium á191ñ.
B: Wash the precipitate obtained in Identificationtest Awith hot ammonium chloride solution (1in 50),and dissolve the precipitate in hydrochloric acid:the solution responds to the tests for Aluminum á191ñ.
Microbial limits á61ñ— Its total aerobic microbial count does not exceed 100cfu per mL,and it meets the requirements of the test for absence of Escherichia coli.
Acid-neutralizing capacity á301ñ— The acid consumed by the minimum single dose recommended in the labeling is not less than 5mEq,and not less than the number of mEq calculated by the formula:
0.55(0.0385A)+0.8(0.0343M),
in which 0.0385and 0.0343are the theoretical acid-neutralizing capacities,in mEq,of Al(OH)3and Mg(OH)2,respectively,and AandMare the quantities,in mg,of Al(OH)3and Mg(OH)2in the specimen tested,based on the labeled quantities.
pHá791ñ: between 7.3and 8.5.
Chloride á221ñ— Dissolve 5.0g in the minimum volume of nitric acid required to achieve complete solution,add 1mLof acid in excess,then add water to make 100mL,and filter:a 10-mLportion of the filtrate shows no more chloride than corresponds to 1.0mLof 0.020Nhydrochloric acid (0.14%).
Sulfate á221ñ— Dissolve 5.0g in 5mLof 3Nhydrochloric acid,with gentle heating.Cool,add water to make 250mL,mix,and filter:a 20-mLportion of the filtrate shows no more sulfate than corresponds to 0.40mLof 0.020Nsulfuric acid (0.1%).
Other requirements— It meets the requirements of the tests for Arsenicand Heavy metalsunder Aluminum Hydroxide Gel.
Assay for aluminum hydroxide—
Edetate disodium titrant— Prepare and standardize as directed in the Assayunder Ammonium Alum.
Assay preparation— Transfer an accurately measured quantity of Oral Suspension,previously well shaken in its original container,equivalent to about 1200mg of aluminum hydroxide,to a suitable beaker.Add 20mLof water,stir,and slowly add 10mLof hydrochloric acid.Heat gently,if necessary,to aid solution,cool,and filter into a 200-mLvolumetric flask.Wash the filter with water into the flask,add water to volume,and mix.
Procedure— Pipet 10mLof Assay preparationinto a 250-mLbeaker,add 20mLof water,then add,in the order named and with continuous stirring,25.0mLof Edetate disodium titrantand 20mLof acetic acid–ammonium acetate buffer TS,and heat near the boiling point for 5minutes.Cool,add 50mLof alcohol and 2mLof dithizone TS,and mix.Titrate with 0.05Mzinc sulfate VSuntil the color changes from green-violet to rose-pink.Perform a blank determination,substituting 10mLof water for the Assay preparation,and make any necessary correction.Each mLof 0.05MEdetate disodium titrantconsumed is equivalent to 3.900mg of Al(OH)3.
Assay for magnesium hydroxide—
Assay preparation— Prepare as directed in the Assay for aluminum hydroxide.
Procedure— Pipet a volume of Assay preparation,equivalent to about 40mg of magnesium hydroxide,into a 400-mLbeaker,add 200mLof water and 20mLof triethanolamine,and stir.Add 10mLof ammonia-ammonium chloride buffer TSand 3drops of an eriochrome black indicator solution prepared by dissolving 200mg of eriochrome black Tin a mixture of 15mLof triethanolamine and 5mLof dehydrated alcohol,and mix.Cool the solution to between 3and 4by immersion of the beaker in an ice bath,then remove,and titrate with 0.05Medetate disodium VSto a blue endpoint.Perform a blank determination,substituting 10mLof water for the Assay preparation,and make any necessary correction.Each mLof 0.05Medetate disodium consumed is equivalent to 2.916mg of Mg(OH)2.
Auxiliary Information— Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(PA4)Pharmaceutical Analysis 4
USP28–NF23Page 77
Pharmacopeial Forum:Volume No.27(3)Page 2515
Phone Number:1-301-816-8251