Betamethasone Valerate Ointment
» Betamethasone Valerate Ointment contains an amount of betamethasone valerate (C27H37FO6) equivalent to not less than 90.0 percent and not more than 110.0 percent of the labeled amount of betamethasone (C22H29FO5), in a suitable ointment base.
Packaging and storage Preserve in collapsible tubes or in tight containers, and avoid exposure to excessive heat.
USP Reference standards 11
Identification It responds to the Identification test under Betamethasone Valerate Cream.
Microbial enumeration tests 61 and Tests for specified microorganisms 62 It meets the requirements of the tests for absence of Staphylococcus aureus and Pseudomonas aeruginosa.
Minimum fill 755: meets the requirements.
Mobile phase and Chromatographic systemProceed as directed in the Assay under Betamethasone Valerate.
Internal standard solution Transfer about 20 mg of beclomethasone dipropionate to a 50-mL volumetric flask, add a 1 in 1000 solution of glacial acetic acid in alcohol to volume, and mix.
Standard preparation Transfer about 30 mg of USP Betamethasone Valerate RS, accurately weighed, to a 50-mL volumetric flask, add a 1 in 1000 solution of glacial acetic acid in alcohol to volume, and mix. Transfer 5.0 mL of this solution to a suitable stoppered vial, add 10.0 mL of Internal standard solution, and mix to obtain a solution having a known concentration of about 0.2 mg of USP Betamethasone Valerate RS per mL.
Assay preparation Transfer an accurately weighed portion of Ointment, equivalent to about 2.5 mg of betamethasone, to a 50-mL centrifuge tube. Add 10.0 mL of the Internal standard solution and 5.0 mL of a 1 in 1000 solution of glacial acetic acid in alcohol. Insert the stopper into the tube, and place in a water bath held at 70 until the specimen melts. Remove from the bath, and shake vigorously until the specimen resolidifies. Repeat the heating and shaking two more times. Place the tube in an ice-methanol bath for 20 minutes, then centrifuge to separate the phases. Decant the clear supernatant into a suitable stoppered flask, and allow to warm to room temperature.
Procedure Proceed as directed for Procedure in the Assay under Betamethasone Valerate. Calculate the quantity, in mg, of C22H29FO5 in the portion of Ointment taken by the formula:
(392.46 / 476.59)(15C)(RU / RS)in which 392.46 and 476.59 are the molecular weights of betamethasone and betamethasone valerate, respectively; C is the concentration, in mg per mL, of USP Betamethasone Valerate RS in the Standard preparation; and RU and RS are the peak response ratios obtained from the Assay preparation and the Standard preparation, respectively.
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USP35NF30 Page 2348