Procedure for content uniformity— Transfer 1finely powdered Tablet to a 50-mLvolumetric flask,add 25mLof chloroform,and shake by mechanical means for 15minutes.Dilute with chloroform to volume,mix,and filter,discarding the first 20mLof the filtrate.Dilute a portion of the subsequent filtrate quantitatively and stepwise,if necessary,with chloroform to obtain a solution containing approximately 20µg of paramethasone acetate per mL.Transfer 10.0mLeach of this solution and of a solution of USP Paramethasone Acetate RSin the same medium having a known concentration of about 20µg per mLto separate 25-mLvolumetric flasks,and transfer 10mLof chloroform to a third flask to provide the blank.To each flask add 3.0mLof a 1in 4000solution of blue tetrazolium in alcohol and 5.0mLof a 1in 20solution of tetramethylammonium hydroxide TSin alcohol,mixing after each addition.Fifteen minutes,accurately timed,after the addition of the last reagent,add 1mLof glacial acetic acid to each flask,dilute with chloroform to volume,and mix.Concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 525nm,with a suitable spectrophotometer,against the blank.Calculate the quantity,in mg,of C24H31FO6in the Tablet taken by the formula: in which Tis the labeled quantity,in mg,of paramethasone acetate in the Tablet,Cis the concentration,in µg per mL,of USP Paramethasone Acetate RSin the Standard solution,Dis the concentration,in µg per mL,of the solution from the Tablet,based upon the labeled quantity per Tablet and the extent of dilution,and AUand ASare the absorbances of the solution from the Tablet and the Standard solution,respectively.

Standard preparation— Transfer about 6mg of USP Paramethasone Acetate RS,accurately weighed,to a separator containing 15mLof water,and proceed as directed under Assay preparation,beginning with “add 3drops of hydrochloric acid.”

Assay preparation— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 6mg of paramethasone acetate,to a separator containing 15mLof water,add 3drops of hydrochloric acid,and heat on a steam bath for 5minutes,mixing frequently.Cool the separator to room temperature,add 4drops of sodium hydroxide solution (1in 2),and immediately extract with four 25-mLportions of chloroform.Filter the extracts through anhydrous sodium sulfate,collecting the extracts in a beaker.[Caution—Do not allow the filter paper to extend above the top of the funnel.]Rinse the filter with several small portions of chloroform,add the rinsings to the beaker,and evaporate the chloroform on a steam bath with the aid of a current of air until about 3mLremains.Transfer the residual liquid,with the aid of several small portions of chloroform,to a glass-stoppered,10-mLconical flask,and evaporate on a steam bath with the aid of a current of air to dryness.Add 2.0mLof chloroform to the flask,insert the stopper,and mix to dissolve the residue.

Procedure— Concomitantly determine the absorbances of the solutions in 1-mm cells at the wavelength of maximum absorbance at 6.04µm,with a suitable IRspectrophotometer,using chloroform as the blank.Calculate the quantity,in mg,of C24H31FO6in the portion of Tablets taken by the formula: in which Wis the weight,in mg,of USP Paramethasone Acetate RSused in preparing the Standard preparation,and AUand ASare the absorbances of the Assay preparationand the Standard preparation,respectively.