Pregna-1,4-diene-3,20-dione, 21-(acetyloxy)-6-fluoro-11,17-dihydroxy-16-methyl-, (6,11,16)-.
6-Fluoro-11,17,21-trihydroxy-16-methylpregna-1,4-diene-3,20-dione 21-acetate [1597-82-6].
» Paramethasone Acetate contains not less than 95.0 percent and not more than 101.0 percent of C24H31FO6, calculated on the dried basis.
Packaging and storage Preserve in tight containers.
B: Ultraviolet Absorption 197U
Solution: 20 µg per mL.
Absorptivities at 242 nm, calculated on the dried basis, do not differ by more than 4.0%.
C: Prepare a solution of Paramethasone Acetate in a mixture of chloroform and methanol (1:1) containing 2 mg per mL. Apply 10 µL each of this solution and a chloroform-methanol (1:1) solution of USP Paramethasone Acetate RS containing 2 mg per mL to a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of methylene chloride, nitromethane, and glacial acetic acid (60:40:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, and allow to dry in air for 15 minutes. Return the plate to the developing chamber, and develop again, in the same solvent system, until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate. Locate the spots on the plate by examination under short-wavelength UV light: the RF value of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.
Specific rotation 781S: between +67 and +77.
Test solution: 10 mg per mL, in chloroform.
X-ray diffraction 941 The X-ray diffraction pattern of Paramethasone Acetate conforms to either one or a mixture of the patterns described by the data in the accompanying table.
Loss on drying 731 Dry it in vacuum at 105 for 4 hours: it loses not more than 1.0% of its weight.
Standard preparation Prepare as directed under Single-Steroid Assay 511, using USP Paramethasone Acetate RS to prepare a solution containing approximately 10 mg per mL.
Assay preparation Weigh accurately about 50 mg of Paramethasone Acetate, previously dried, dissolve it in a sufficient quantity of a mixture of equal volumes of alcohol and chloroform to make 5.0 mL, and mix.
Procedure Proceed as directed for Procedure under Single-steroid Assay 511, applying 10 µL each of the Assay preparation and the Standard preparation to the chromatographic plate, and using a solvent system consisting of methylene chloride, nitromethane, and glacial acetic acid (60:40:1), through the fourth sentence of the second paragraph under Procedure. Then centrifuge the tubes for 5 minutes, and determine the absorbances of the supernatants in 1-cm cells at the wavelength of maximum absorbance at about 242 nm, against the blank. Calculate the quantity, in mg, of C24H31FO6 in the portion of Paramethasone Acetate taken by the formula:
5C(AU / AS)in which C is the concentration, in mg per mL, of USP Paramethasone Acetate RS in the Standard preparation, and AU and AS are the absorbances of the solutions from the Assay preparation and the Standard preparation, respectively.
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USP32NF27 Page 3208