Sodium Nitroprusside
Na2[Fe(CN)5NO]·2H2O 297.95

Ferrate(2-),pentakis(cyano-C)nitrosyl-,disodium,dihydrate,(OC-6-22)-.
Disodium pentacyanonitrosylferrate(2-)dihydrate [13755-38-9].

Sodium nitroferricyanide dihydrate.
Anhydrous 261.92 [14402-89-2].
»Sodium Nitroprusside contains not less than 99.0percent of Na2[Fe(CN)5NO]·2H2O.
Packaging and storage— Preserve in tight,light-resistant containers.Store at 25,excursions permitted between 15and 30.
Labeling— Where it is intended for use in preparing injectable dosage forms,the label states that it is sterile or must be subjected to further processing during the preparation of injectable dosage forms.
Identification—
A:Ultraviolet Absorption á197Uñ— [NOTE—Use low-actinic glassware.]
Solution: 1in 135.
Medium: water.
Wavelength range: 350nm to 700mm.
B: Dissolve 5mg in 2mLof water,and add 2drops of acetone and 0.5mLof 2Nsodium hydroxide:an orange color is produced.Add 2mLof acetic acid:the color changes to purple.
C: Asolution (1in 4)responds to the flame test for Sodium á191ñ.
Water,Method Iá921ñ: between 9.0%and 15.0%.
Insoluble substances— Dissolve 10.0g in 50mLof water,heat the solution on a steam bath for 30minutes,filter,wash the residue with water,and dry at 105to constant weight:the weight of the residue is not greater than 1mg (0.01%).
Chloride—
Standard chloride solution— Dissolve 42.4mg of potassium chloride in water to make 100.0mLof solution.Each mLof this solution contains 0.2mg of chloride.
Procedure— Transfer 1.0g of Sodium Nitroprusside to a 250-mLconical flask,transfer 1.0mLof Standard chloride solutionto a similar flask,and add to each flask 85mLof water.To the flask containing the substance under test,add 15mLof cupric sulfate solution (83in 1000),mix,and allow any undissolved particles to settle.Carefully add cupric sulfate solution (83in 1000)to the flask containing the diluted Standard chloride solution,with mixing,so that its color matches that of the test solution in the first flask.Filter the contents of each flask,and discard the first 25mLof the filtrate.To 10mLof the subsequent filtrate from each flask add 2mLof nitric acid,and mix.Add 1mLof 1Nsilver nitrate to each,and again mix:the test solution so treated becomes no more turbid than the treated Standard chloride solution(0.02%).
Limit of ferricyanide— Dissolve 500mg in 20mLof ammonium acetate TS,previously adjusted with 1Nacetic acid to a pHof 4.62.Divide this solution into halves,and transfer each half to a separate 50-mLvolumetric flask,identified as Aand B,respectively.To flask Badd 1.0mLof a freshly prepared solution of potassium ferricyanide containing 78µg per mL.To both flasks add 5mLof ferrous ammonium sulfate solution (1in 1000),dilute with water to volume,and mix.Allow the flasks to stand for 1hour,and concomitantly determine the absorbance of the solutions at the wavelength of maximum absorbance at about 720nm,using as a blank a solution prepared by dissolving 250mg of the specimen in 10mLof the pH4.62ammonium acetate TSand diluting with water to 50mL.The absorbance of the solution in flask Ais not greater than the absorbance of the solution in flask Bminus the absorbance of the solution in flask A(0.02%of ferricyanide).
Limit of ferrocyanide— Dissolve 2.0g in 40mLof water,divide the solution into halves,and transfer each half to a separate 50-mLvolumetric flask,identified as Aand B,respectively.To flask Badd 2mLof a freshly prepared solution of potassium ferrocyanide containing 200µg per mL.To both flasks add 0.2mLof ferric chloride TS,dilute with water to volume,and mix.Allow to stand for 20minutes,accurately timed,and concomitantly measure the absorbance of the solutions at the wavelength of maximum absorbance at about 695nm,using as a blank a solution prepared by dissolving 1.0g of the specimen in water to make 50mL:the absorbance of the solution in flask Ais not greater than the absorbance of the solution in flask Bminus the absorbance of the solution in flask A(0.02%of ferrocyanide).
Sulfate—
Standard sulfate solution— Dissolve 15mg of anhydrous sodium sulfate in water to make 100.0mLof solution.Each mLof this solution contains 0.1mg of sulfate.
Procedure— Dissolve 5.0g of Sodium Nitroprusside in water to make 250.0mLof solution,and filter the solution into a flat-bottom,250-mLgraduated flask.Transfer 5.0mLof Standard sulfate solutionto a similar flask,and dilute to the same volume as the test solution.To each flask add 10drops of glacial acetic acid and 5mLof 1Nbarium chloride,and allow to stand for 10minutes.Place both flasks over a fluorescent light source,and observe:the turbidity in the treated test solution is not more intense than that of the treated Standard sulfate solution(0.01%).
Other requirements— Where the label states that Sodium Nitroprusside is sterile,it meets the requirements for Sterility Tests á71ñand for Bacterial endotoxinsunder Sodium Nitroprusside for Injection.Where the label states that Sodium Nitroprussidemust be subjected to further processing during the preparation of injectable dosage forms,it meets the requirements for Bacterial endotoxinsunder Sodium Nitroprusside for Injection.
Assay— Dissolve about 500mg of Sodium Nitroprusside,accurately weighed,in 130mLof chloride-free water.Titrate with 0.1Nsilver nitrate VS,determining the endpoint potentiometrically,using a silver-silver chloride electrode system.Each mLof 0.1Nsilver nitrate is equivalent to 14.90mg of Na2[Fe(CN)5NO]·2H2O.
Auxiliary Information— Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate
Expert Committee:(PA5)Pharmaceutical Analysis 5
USP28–NF23Page 1789
Pharmacopeial Forum:Volume No.29(5)Page 1578
Phone Number:1-301-816-8305