Test solution— Transfer an accurately measured volume of Oral Suspension,equivalent to about 160mg of megestrol acetate,to a separatory funnel,add 50mLof water and 40mLof chloroform,and shake.Allow the phases to separate,and discard the aqueous layer.

Standard solution— Prepare a solution containing about 4.0mg of USP Megestrol Acetate RSper mLof chloroform.

Developing solvent system: a mixture of chloroform and ethyl acetate (4:1).

Medium: 0.5%sodium lauryl sulfate in water;900mL.

Apparatus 2: 50rpm.

Time: 20minutes.

Procedure— [NOTE—Use a separate syringe for each vessel.]Withdraw more than 10mLof the Oral Suspension using a 10-mLsyringe with a long cannula.Remove air bubbles from the syringe.Adjust the volume to the 10-mLmark on the syringe,and remove the needle.Wipe the tip of the syringe,and accurately weigh (gross weight).Operate the apparatus,and rapidly dispense the Oral Suspension to the side of the vessel at about half way from the bottom.Similarly dispense the Oral Suspension into other vessels.Accurately weigh each syringe after dispensing the sample (tare weight).Record sample weights.After completion of the dissolution,pass an aliquot through a filter having a 0.45-µm porosity,and dilute 2.0mLof the filtrate to 50.0mLwith Dissolution Mediumto obtain a solution having a concentration of about 18µg per mL.Determine the amount of C24H32O4dissolved by employing UVabsorption at the wavelength of maximum absorbance at about 292nm on filtered portions of the solution under test,in comparison with a Standard solution having a known concentration of USP Megestrol Acetate RSin the same Medium.

Tolerances: Not less than 75%(Q)of the labeled amount of C24H32O4is dissolved in 20minutes.

Mobile phase— Prepare a filtered and degassed mixture of acetonitrile and water (11:9).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Megestrol Acetate RSin Mobile phase,and dilute quantitatively,and stepwise if necessary,with Mobile phaseto obtain a solution having a known concentration of about 80µg per mL.

Assay preparation— Transfer an accurately measured volume of Oral Suspension,equivalent to about 160mg of megestrol acetate,to a 100-mLvolumetric flask,and dissolve in and dilute with Mobile phaseto volume.Transfer 5.0mLof the solution so obtained to a 100-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.

Chromatographic system (seeChromatography á621ñ)— The liquid chromatograph is equipped with a 280-nm detector and a 3.9-mm ×30-cm column that contains packing L1.The flow rate is about 1.5mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency is not less than 2500theoretical plates;the tailing factor is not more than 1.4;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 25µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of megestrol acetate (C24H32O4)in the portion of Oral Suspension taken by the formula: in which Cis the concentration,in µg per mL,of USP Megestrol Acetate RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.