Aminosalicylate Sodium
C7H6NNaO3·2H2O 211.15

Benzoic acid,4-amino-2-hydroxy-,monosodium salt,dihydrate.
Monosodium 4-aminosalicylate dihydrate [6018-19-5].

Anhydrous 175.12 [133-10-8].
»Aminosalicylate Sodium contains not less than 98.0percent and not more than 101.0percent of C7H6NNaO3,calculated on the anhydrous basis.
[Caution—Prepare solutions of Aminosalicylate Sodium within 24hours of administration.Under no circumstances use a solution if its color is darker than that of a freshly prepared solution. ]
Packaging and storage— Preserve in tight,light-resistant containers,protected from excessive heat.
Clarity and color of solution— One g dissolves in 10mLof water to give a clear solution that has not more than a faint yellow color.One g dissolves in a freshly prepared mixture of 5mLof nitric acid and 45mLof water to give a clear solution that has not more than a slight color.
Identification—
A: Dissolve 250mg in 3mLof 1Nsodium hydroxide,transfer to a 500-mLvolumetric flask,dilute with water to volume,and mix.Transfer a 5-mLaliquot to a 250-mLvolumetric flask containing 12.5mLof pH7phosphate buffer (see under Buffer Solutionsin the section Reagents,Indicators,and Solutions),dilute with water to volume,and mix.This solution,when compared in a suitable spectrophotometer against a blank of the same buffer in the same concentration,exhibits absorbance maxima at 265±2nm and 299±2nm,and the ratio A265/A299is between 1.50and 1.56.
B: Place about 1g in a small,round-bottom flask,and add 10mLof acetic anhydride.Heat the flask on a steam bath for 30minutes,add 40mLof water,mix,filter,cool,and allow to stand until the diacetyl derivative has crystallized.Collect the precipitate on a filter,wash with water,and dry at 105for 1hour:the diacetyl derivative so obtained melts between 191and 197.
C: Dissolve 50mg in 5mLof water,add 1mLof 3Nhydrochloric acid,and filter if necessary.To the filtrate add 1drop of ferric chloride TS:a violet color is produced.
D: Asolution of it responds to the tests for Sodium á191ñ.
pHá791ñ: between 6.5and 8.5,in a solution (1in 50).
Water,Method Iá921ñ: between 16.0%and 18.0%.
Chloride á221ñ— Dissolve 0.50g in a mixture of 5mLof nitric acid and 15mLof water:the solution shows no more chloride than corresponds to 0.30mLof 0.020Nhydrochloric acid (0.042%).
Limit of m-aminophenol—
Mobile phase— Prepare as directed in the Assayunder Aminosalicylic Acid.
Internal standard solution,Standard preparation,and Chromatographic system— Prepare as directed in the test for Limit of m-aminophenolunder Aminosalicylic Acid.
Test preparation— Use the Assay preparation,prepared as directed in the Assay.
Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Test preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.The relative retention times are about 0.66for sulfanilamide and 1.0for m-aminophenol.Calculate the percentage of m-aminophenol,in relation to the quantity of aminosalicylate sodium in the portion of Aminosalicylate Sodium taken by the formula:
10(C/W)(RU/RS),
in which Cis the concentration,in µg per mL,of USPm-Aminophenol RSin the Standard preparation;Wis the quantity of aminosalicylate sodium,in mg,in the portion of Aminosalicylate Sodium taken,as determined in the Assay;and RUand RSare the ratios of the response of the m-aminophenol peak to the response of the sulfanilamide peak obtained from the Test preparationand the Standard preparation,respectively:not more than 0.25%of m-aminophenol is found.
Hydrogen sulfide,sulfur dioxide,and amyl alcohol— Dissolve about 500mg in 5mLof 1Nsodium hydroxide,add 6mLof 3Nhydrochloric acid,and stir vigorously:no odor of hydrogen sulfide or sulfur dioxide is perceptible,and not more than a faint odor of amyl alcohols is perceptible.Apiece of moistened lead acetate test paper held over the mixture does not become discolored.
Organic volatile impurities,Method Iá467ñ: meets the requirements.
Assay—
Mobile phase,Internal standard solution,Standard preparation,and Chromatographic system— Prepare as directed in the Assayunder Aminosalicylic Acid.
Assay preparation— Transfer about 69mg of Aminosalicylate Sodium,accurately weighed,to a 100-mLlow-actinic volumetric flask,add 50mLof Mobile phase,and swirl to dissolve.Add 10.0mLof Internal standard solution,dilute with Mobile phaseto volume,and mix.
Procedure— Proceed as directed for Procedurein the Assayunder Aminosalicylic Acid.Calculate the quantity of C7H6NNaO3,in mg,in the Aminosalicylate Sodium taken by the formula:
(175.12/153.14)(100C)(RU/RS),
in which 175.12and 153.14are the molecular weights of anhydrous aminosalicylate sodium and aminosalicylic acid,respectively;Cis the concentration,in mg per mL,of USP Aminosalicylic Acid RSin the Standard preparation;and RUand RSare the ratios of the response of the aminosalicylic acid peak to the response of the acetaminophen peak obtained from the Assay preparationand the Standard preparation;respectively.
Auxiliary Information— Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 131
Phone Number:1-301-816-8394