Change to read:

A: To 10mLof Oral Suspension add 15mLof acetone,and warm to 50,with stirring,to coagulate the excipients.Filter,evaporate the acetone with the aid of a warm air blast nearly to dryness,add 10mLof acetic acid,heat to boiling,and filter while hot.Cool the filtrate to room temperature.Filter the precipitated nitrofurantoin,and dry at 105for 1hour:the IRabsorption spectrum of a mineral oil dispersion of the precipitate so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Nitrofurantoin RS.

B: It responds to Identificationtest Bunder Nitrofurantoin.

FOR ORAL SUSPENSION PACKAGED IN SINGLE-UNIT CONTAINERS: meets the requirements.

FOR ORAL SUSPENSION PACKAGED IN MULTIPLE-UNIT CONTAINERS: meets the requirements.

Change to read:

pH7.0Phosphate bufferand Mobile phase— Prepare as directed in the Assayunder Nitrofurantoin.

Internal standard solution— Dissolve about 13mg of acetanilide in Mobile phase,dilute with Mobile phaseto 200mL,and mix.

Standard NF250preparation— Prepare a solution of USP Nitrofurantoin Related Compound A RSUSP28in Mobile phaseto contain 125µg per mL.[NOTE—USP Nitrofurantoin Related Compound A RSis N-(aminocarbonyl)-N-[([5-nitro-2-furanyl]methylene)amino]glycine.]USP28Dilute 2.0mLof this solution with Mobile phaseto 100.0mL,and mix.

Standard nitrofurantoin preparation— Transfer about 25mg of USP Nitrofurantoin RS,accurately weighed,to a 100-mLvolumetric flask with the aid of about 50mLof dimethylformamide.Add 20mLof water,cool to room temperature,and dilute with dimethylformamide to volume to obtain a Standard solution.Transfer a 4.0-mLaliquot of this Standard solutionto a glass-stoppered flask,add 15.0mLof Internal standard solution,and mix.

Assay preparation— Transfer an accurately measured volume of freshly mixed Oral Suspension,equivalent to about 25mg of nitrofurantoin,to a 100-mLvolumetric flask,add 20mLof water to the flask,and mix.Add about 50mLof dimethylformamide,and shake the flask for about 20minutes.Cool to room temperature,and dilute with dimethylformamide to volume.Centrifuge a portion of the solution,and transfer a 4.0-mLaliquot of the supernatant liquid to a glass-stoppered flask.Add 15.0mLof Internal standard,and mix.Filter a portion of the solution through a 5-µm pore size polytef filter,discarding the first few mLof the filtrate.

Test preparation— Transfer an accurately measured volume of the freshly mixed Oral Suspension,equivalent to 5mg of nitrofurantoin,to a 100-mLvolumetric flask.Dilute with Mobile phaseto volume,and mix.Centrifuge a portion of this solution.Pass a portion of the supernatant through a 5-µm pore size polytef filter,discarding the first few mLof the filtrate.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with both a 254-nm detector and a 375-nm detector and a 3.9-mm ×30-cm column that contains packing L1.For the Assay,chromatograph the Standard nitrofurantoin preparation,adjusting the operating parameters so that the retention time of the nitrofurantoin peak is about 8minutes and its peak height is about half full-scale:the relative standard deviation of the ratio of the peak responses in replicate injections is not more than 2.0%,and the resolution,R,of the acetanilide and nitrofurantoin peaks is not less than 3.5.The flow rate is about 1.2mLper minute.For the NF250test,adjust the operating parameters so that the NF250peak has a retention time of between 3and 6minutes and its height is about 0.1full-scale.The flow rate is about 1.2mLper minute.

Procedure for limit of N-(aminocarbonyl)-N-[([5-nitro-2-furanyl]methylene)amino]glycine— Inject separately equal volumes (30µLto 60µL)of Standard NF250preparationand the Test preparationinto the chromatograph,and record the peak responses with the 375-nm detector:the height of any peak appearing in the chromatogram of the Test preparationat a retention time corresponding to that of the main peak in the Standard NF250preparationis not greater than the height of the latter (5.0%).

Procedure for assay— Inject equal volumes (about 15µL)of Standard nitrofurantoin preparationand the Assay preparationseparately into the chromatograph,and record the peak responses with the 254-nm detector.Calculate the quantity,in mg,of C8H6N4O5in each mLof the Oral Suspension taken by the formula: in which Cis the concentration,in µg per mL,of USP Nitrofurantoin RSin the Standard solution;Vis the volume,in mL,of Oral Suspension taken;and RUand RSare the ratios of the peak responses of the nitrofurantoin to the internal standard obtained from the Assay preparationand the Standard nitrofurantoin preparation,respectively.