Azathioprine Sodium for Injection
»Azathioprine Sodium for Injection is a sterile solid prepared by the freeze-drying of an aqueous solution of Azathioprine and Sodium Hydroxide.It contains not less than 93.0percent and not more than 107.0percent of the labeled amount of azathioprine (C9H7N7O2S).
Packaging and storage— Preserve in Containers for Sterile Solidsas described under Injections á1ñ,at controlled room temperature.
Completeness of solution á641ñ— The contents of 1container are soluble in 10mLof water,to give a clear,bright yellow solution,essentially free from foreign matter.
Identification— The principal spot in the chromatogram of the specimen under examination obtained in the test for Limit of mercaptopurineshows the same RFvalue as that obtained with the solution of USP Azathioprine RS.
Bacterial endotoxins á85ñ— It contains not more than 1.0USP Endotoxin Unit per mg of azathioprine.
pHá791ñ: between 9.8and 11.0,the contents of 1container being dissolved in 10mLof water.
Water,Method Iá921ñ: not more than 7.0%,the Test Preparationbeing prepared as directed for a hygroscopic specimen.
Limit of mercaptopurine— Prepare solutions in dimethylformamide containing,respectively,10mg of Azathioprine Sodium for Injection per mL,10mg of USP Azathioprine RSper mL,and 100µg of USP Mercaptopurine RSper mL.Apply 15µLof the USP Mercaptopurine RSsolution and 5-µLportions of the other two solutions at points about 2cm from the bottom edge of a thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 250-µm layer of microcrystalline cellulose.Allow the spots to dry,and develop the chromatogram in a suitable chamber,using butyl alcohol,previously saturated with 5Nammonium hydroxide,as the solvent,until the solvent front has moved about 15cm from the point of application.Remove the plate,air-dry,and locate the spots by viewing under short-and long-wavelength UVlight:any spot in the chromatogram from azathioprine,other than the principal spot,is not more intense than the spot in the chromatogram obtained with USP Mercaptopurine RS(3.0%).
Other requirements— It meets the requirements under Injections á1ñand Uniformity of Dosage Units á905ñ.
Assay—
Standard preparation— Transfer 25mg of USP Azathioprine RS,accurately weighed,to a 50-mLvolumetric flask,dissolve in 2.5mLof 0.1Nsodium hydroxide,dilute with water to volume,and mix.Pipet 10.0mLof this solution into a 50-mLvolumetric flask,dilute with 0.1Nsulfuric acid to volume,and mix.
Assay preparation— Transfer the contents of 1vial of Azathioprine Sodium for Injection with the aid of water to a 100-mLvolumetric flask,dilute with water to volume,and mix.Pipet 10mLof this solution into another 100-mLvolumetric flask,dilute with 0.1Nsulfuric acid to volume,and mix.
Procedure— Transfer 20mLeach of the Standard preparationand the Assay preparation,separately,to polarographic cells,and deaerate for 10minutes with nitrogen that previously has been saturated with 0.1Nsulfuric acid.Blanket the solution with saturated nitrogen,insert the dropping mercury electrode of a suitable polarograph,and record the polarogram from -0.60volt to -1.00volt,using a saturated calomel electrode as the reference electrode.Determine the height of the diffusion current as the difference between the residual current and diffusion current plateau.Calculate the quantity,in mg,of azathioprine (C9H7N7O2S)in the volume of solution from the vial used for the Assay preparationtaken by the formula:
0.1C(id)U/(id)S,
in which Cis the concentration,in µg per mL,of USP Azathioprine RSin the Standard preparation;and (id)Uand (id)Sare the diffusion currents of the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist
Expert Committee:(PA6)Pharmaceutical Analysis 6
USP28–NF23Page 207
Phone Number:1-301-816-8389