Fluocinonide Ointment
»Fluocinonide Ointment contains not less than 90.0percent and not more than 110.0percent of the labeled amount of fluocinonide (C26H32F2O7).
Packaging and storage— Preserve in collapsible tubes or tight containers.
Identification— Weigh an amount of Ointment,equivalent to about 2.5mg of fluocinonide,into a glass-stoppered,50-mLcentrifuge tube containing 20mLof cyclohexane.Gently disperse to form a suspension.Add 5mLof water and 10mLof methanol.Shake vigorously,allow the phases to separate,and discard the upper phase.Add 20mLof water and 5mLof chloroform,shake vigorously,centrifuge,and transfer a portion of the chloroform layer to a small test tube containing about 200mg of anhydrous sodium sulfate.Mix,and allow to stand until the extract is clear.Using the clear chloroform extract as the Test preparation,proceed as directed in the Identificationtest under Fluocinonide Cream,beginning with “Apply 10µLof the Test solution.”
Minimum fill á755ñ: meets the requirements.
Assay—
Mobile phase— Prepare a filtered and degassed mixture of acetonitrile and water (1:1).Adjust the ratio as necessary to obtain suitable chromatographic performance.
Standard preparation— Dissolve an accurately weighed quantity of USP Fluocinonide RSin acetonitrile to obtain a solution having a known concentration of about 400µg per mL.Transfer 10.0mLof this solution to a 100-mLvolumetric flask.Dilute with methanol to volume,and mix.The final concentration of USP Fluocinonide RSis about 40µg per mL.
Assay preparation— Transfer an accurately weighed quantity of Ointment,containing about 1.35mg of fluocinonide,to a round-bottom,50-mLcentrifuge tube.Add 35.0mLof methanol.Emulsify,using an ultrasonic probe,and centrifuge to bring the insoluble matter to the bottom.The clear supernatant is the Assay preparation.
Chromatographic system (see Chromatography á621ñ)—Proceed as directed under Fluocinonide Cream,except that the flow rate for the Mobile phaseis about 1mLper minute.
Procedure— Separately inject equal volumes (about 20µL)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 fluocinonide (C26H32F2O7)in the portion of Ointment taken by the formula:
0.035C(rU/rS),
in which Cis the concentration,in µg per mL,of USP Fluocinonide RSin the Standard preparation,and rUand rSare the peak responses due to fluocinonide obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Clydewyn M.Anthony,Ph.D.,Scientist
Expert Committee:(PA1)Pharmaceutical Analysis 1
USP28–NF23Page 842
Phone Number:1-301-816-8139
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