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Miconazole Nitrate Topical Powder
» Miconazole Nitrate Topical Powder contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of miconazole nitrate (C18H14Cl4N2O·HNO3).
Packaging and storage
Preserve in well-closed containers.
Identification
Transfer a portion of Topical Powder, equivalent to about 100 mg of miconazole nitrate to a 50-mL beaker, disperse in 40 mL of methanol, and mix for a minimum of 5 minutes. Allow to settle for 5 to 10 minutes, and filter into a 100-mL beaker. Evaporate on a steam bath to dryness. Dry the residue at 105
Microbial enumeration tests
Minimum fill
Assay
Internal standard solution
Dissolve cholestane in chloroform to obtain a solution having a concentration of about 0.5 mg per mL.
Standard preparation
Dissolve an accurately weighed quantity of USP Miconazole Nitrate RS in a mixture of chloroform and methanol (1:1) to obtain a solution having a known concentration of about 0.8 mg per mL. Transfer 5.0 mL of this solution to a test tube, add 2.0 mL of Internal standard solution, and evaporate at a temperature not higher than 40
Assay preparation
Transfer an accurately weighed portion of Topical Powder, equivalent to about 20 mg of miconazole nitrate, to a stoppered 50-mL centrifuge tube. Add 25.0 mL of methanol, and shake by mechanical means for 30 minutes to dissolve the miconazole nitrate. Centrifuge to obtain a clear supernatant. Transfer 5.0 mL of this solution to a test tube, add 2.0 mL of Internal standard solution, and evaporate at a temperature not higher than 40
Chromatographic system
(see Chromatography
Procedure
Separately inject equal volumes (about 5 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. The relative retention times for cholestane and miconazole nitrate are about 0.5 and 1.0, respectively. Calculate the quantity, in mg, of miconazole nitrate (C18H14Cl4N2O·HNO3) in the portion of Topical Powder taken by the formula:
10C(RU / RS)
in which C is the concentration, in mg per mL, of USP Miconazole Nitrate RS in the Standard preparation, and RU and RS are the peak response ratios of the miconazole nitrate peak to the cholestane peak obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information
Please check for your question in the FAQs before contacting USP.
USP35NF30 Page 3918
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