» Prednisolone Cream contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of C21H28O5, in a suitable cream base.
Packaging and storage Preserve in collapsible tubes or in tight containers.
Identification Evaporate in a test tube to dryness about 5 mL of the dilute solution obtained in the Assay. Add 2 to 3 mL of warm perchloric acid, mix, and warm on a steam bath for about 2 minutes: a blood-red color develops. Add 5 mL of water: the color is not discharged.
Minimum fill 755: meets the requirements.
Sulfuric acid reagent Prepare a solution of sulfuric acid, dehydrated alcohol, and water solution (4:3:3).
Modified phenylhydrazine-sulfuric acid TS Dissolve 65 mg of phenylhydrazine hydrochloride in 100 mL of Sulfuric acid reagent.
Standard preparation Dissolve in dehydrated alcohol a suitable quantity, accurately weighed, of USP Prednisolone RS, and dilute quantitatively and stepwise with dehydrated alcohol to obtain a solution having a known concentration of about 0.1 mg per mL.
Assay preparation To an accurately weighed portion of Cream, equivalent to about 20 mg of prednisolone, add 25 mL of dehydrated alcohol. Warm on a steam bath to disperse the assay specimen, then chill to congeal it. Filter through paper, previously washed with dehydrated alcohol, into a 200-mL volumetric flask. Repeat twice more, starting with add 25 mL of dehydrated alcohol. Dilute with dehydrated alcohol to volume. (Retain about 5 mL of this dilution for the Identification test.)
Procedure Pipet 2 mL of Assay preparation into each of two 50-mL conical flasks (identify as Assay preparation and Assay preparation blank). Pipet 2 mL of Standard preparation into each of two 50-mL conical flasks (identify as Standard preparation and Standard preparation blank). Pipet 2 mL of dehydrated alcohol into a 50-mL conical flask (identify as Reagent blank). Add 20.0 mL of Sulfuric acid reagent to the Assay preparation blank and to the Standard preparation blank. Add 20.0 mL of Modified phenylhydrazine-sulfuric acid to the Assay preparation, to the Standard preparation, and to the Reagent blank, respectively. Maintain the flasks in a water bath at 60 for about 45 minutes, then chill in a water-ice bath. Filter each through a fine-porosity, sintered-glass funnel, and identify the filtrate flasks correspondingly. Concomitantly determine the absorbances of the solutions at the wavelength of maximum absorbance at about 410 nm, with a suitable spectrophotometer, against dehydrated alcohol. Calculate the quantity, in mg, of C21H28O5 in the portion of Cream taken by the formula:
200C[(AU AUB AR) / (AS ASB AR)]in which C is the concentration, in mg per mL, of USP Prednisolone RS in the Standard preparation, AU and AS are the absorbances of the solutions from the Assay preparation and the Standard preparation, respectively, AUB and ASB are the absorbances of the solutions from the Assay preparation blank and the Standard preparation blank, respectively, and AR is the absorbance of the Reagent blank.
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USP32NF27 Page 3369