Miconazole Nitrate Vaginal Suppositories
» Miconazole Nitrate Vaginal Suppositories contain 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 tight containers, at controlled room temperature.
USP Reference standards 11
Identification Place a portion of the stock solution, prepared as directed in the Assay, containing about 25 mg of miconazole nitrate, in a 50-mL beaker, and evaporate on a steam bath with the aid of a current of filtered air to dryness. Dry the residue at 105 for 10 minutes: the IR absorption spectrum of a potassium bromide dispersion of it so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Miconazole Nitrate RS.
Internal standard solution Dissolve a suitable quantity of cholestane in a mixture of chloroform and methanol (1:1) to obtain a solution having a concentration of about 1 mg per mL.
Standard preparation Dissolve an accurately weighed quantity of USP Miconazole Nitrate RS in methanol to obtain a solution having a known concentration of about 500 µg per mL. Transfer 10.0 mL of this solution to a test tube, and evaporate on a steam bath to dryness with the aid of a current of filtered air. Dissolve the residue in 2.0 mL of Internal standard solution to obtain a solution having a concentration of about 2500 µg per mL.
Assay preparation Transfer 1 Suppository to a stoppered, 50-mL centrifuge tube. Add 30 mL of pentane, and shake by mechanical means for 20 minutes to dissolve the suppository base and to disperse the miconazole nitrate. Centrifuge to obtain a clear supernatant. Aspirate, and discard the clear liquid. Wash the residue with three 20-mL portions of pentane, shaking, centrifuging, and aspirating in the same manner. Discard the pentane washings. Evaporate the residual pentane from the residue with the aid of a current of filtered air. Using small portions of methanol, transfer the residue to a 100-mL volumetric flask. Dissolve in and dilute with methanol to volume, and mix. Transfer an accurately measured volume of this stock solution, equivalent to about 5 mg of miconazole nitrate, to a suitable container, and evaporate to dryness on a steam bath with the aid of a current of filtered air. Dissolve the residue in 2.0 mL of Internal standard solution.
Chromatographic system (see Chromatography 621) The gas chromatograph is equipped with a flame-ionization detector and a 2-mm × 1.2-m column packed with 3% phase G32 on support S1A. The carrier gas is helium, flowing at a rate of about 50 mL per minute. The injection port, detector, and column temperatures are maintained at about 250, 300, and 250, respectively. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative retention times for cholestane and miconazole nitrate are about 0.44 and 1.0, respectively; the resolution, R, between cholestane and miconazole nitrate is not less than 2.0; and the relative standard deviation for replicate injections is not more than 3.0%.
Procedure Separately inject equal volumes (about 1 µL) of the Assay preparation and the Standard preparation into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the quantity, in mg, of miconazole nitrate (C18H14Cl4N2O·HNO3) in the portion of Suppository taken by the formula:
(0.2C/V)(RU / RS)in which C is the concentration, in µg per mL, of the USP Miconazole Nitrate RS in the Standard preparation; V is the volume, in mL, of stock solution used to prepare the Assay preparation; and RU and RS are the ratios of the peak responses of miconazole nitrate to that of cholestane obtained from the Assay preparation and Standard preparation, respectively.
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USP35NF30 Page 3919Pharmacopeial Forum: Volume No. 31(5) Page 1389