Betamethasone Cream

» Betamethasone Cream contains not less than 90.0 percent and not more than 115.0 percent of the labeled amount of C22H29FO5 in a suitable cream base.

Packaging and storage— Preserve in collapsible tubes or in tight containers.

—

USP Betamethasone RS

Thin-layer chromatographic identification test

201

—

Test solution: 1 mg per mL, prepared by concentrating 10 mL of the Assay preparation on a steam bath to 1 mL.

Standard solution— Prepare a solution of USP Betamethasone RS in dehydrated alcohol having a concentration of 1 mg per mL.

Developing solvent system: a mixture of chloroform and diethylamine (2:1).

Spray reagent: a mixture of sulfuric acid, methanol, and nitric acid (10:10:1).

Procedure— Proceed as directed in the chapter, except to spray the plate with the Spray reagent, and heat at 105

for 10 minutes.

Microbial enumeration tests

and Tests for specified microorganisms

— It meets the requirements of the tests for absence of Staphylococcus aureus and Pseudomonas aeruginosa.

Minimum fill

755

: meets the requirements.

Assay—

Mobile phase, Internal standard solution, Standard preparation, and Chromatographic system— Prepare as directed in the Assay under Betamethasone.

Assay preparation— Transfer an accurately weighed quantity of Cream, equivalent to about 2 mg of betamethasone, into a capped 50-mL centrifuge tube. Add 10.0 mL of Internal standard solution and 10.0 mL of alcohol. Mix by rotation for about 20 minutes. Centrifuge at 2500 rpm for about 10 minutes. Transfer a portion of the supernatant to a suitable vial.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C22H29FO5 in the portion of Cream taken by the formula:

20C(RU / RS)

in which C is the concentration, in mg per mL, of USP Betamethasone RS in the Standard preparation; and RU and RS are the peak height ratios of the betamethasone peak and the internal standard peak obtained from the Assay preparation and the Standard preparation, respectively.

Auxiliary Information— Please check for your question in the FAQs before contacting USP.

Topic/Question	Contact	Expert Committee
Monograph	Domenick Vicchio, Ph.D. Senior Scientific Liaison 1-301-998-6828	(SM42010) Monographs - Small Molecules 4
Reference Standards	RS Technical Services 1-301-816-8129 rstech@usp.org
61	Radhakrishna S Tirumalai, Ph.D. Principal Scientific Liaison 1-301-816-8339	(GCM2010) General Chapters - Microbiology
62	Radhakrishna S Tirumalai, Ph.D. Principal Scientific Liaison 1-301-816-8339	(GCM2010) General Chapters - Microbiology

USP35–NF30 Page 2336

Pharmacopeial Forum: Volume No. 28(6) Page 1773