Identification—
Transfer an amount of finely ground Tablets,equivalent to 100mg of Astemizole,to a 100-mLvolumetric flask,add methanol to volume,mix,and filter.Prepare a Standard solution of
USP Astemizole RSin methanol having a concentration of 1mg per mL.Separately apply 10µLof each solution to a thin-layer chromatographic plate (see
Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Develop the chromatogram in a solvent system consisting of a mixture of toluene,dioxane,methanol,and ammonium hydroxide (60:30:10:1)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,air-dry,and examine under short-wavelength UVlight:the
RFvalue of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.
Dissolution á711ñ—
Medium:
simulated gastric fluid TS(without the enzyme);800mL.
Apparatus 2:
100rpm.
Time:
45minutes.
Procedure—
Determine the amount of astemizole (C
28H
31FN
4O)dissolved from UVabsorbances at the wavelength of maximum absorbance at about 285nm of filtered portions of the solution under test,suitably diluted with
Medium,in comparison with a Standard solution having a known concentration of
USP Astemizole RSin the same
Medium.
Tolerances—
Not less than 80%(Q)of the labeled amount of astemizole (C28H31FN4O)is dissolved in 45minutes.
Chromatographic purity—
Mobile phase,Standard preparation,and Chromatographic system—
Proceed as directed in the
Assayunder
Astemizole.
Test solution—
Use theAssay preparation.
Procedure—
Inject a volume (about 10µL)of the
Test solutioninto the chromatograph,record the chromatogram,and measure the peak responses.Calculate the percentage of each impurity in the portion of Tablets taken by the formula:
100(ri/rs),
in which
riis the peak response for each impurity;and
rsis the sum of the responses of all of the peaks:not more than 0.25%of any individual impurity is found;and the sum of all impurities is not more than 1.0%.
Assay—
Mobile phase,Standard preparation,and Chromatographic system—
Proceed as directed in the
Assayunder
Astemizole.
Assay preparation—
Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed quantity of the powder,equivalent to about 50mg of astemizole,to a 50-mLvolumetric flask.Add 25mLof Mobile phase,mix for 30minutes,dilute with Mobile phaseto volume,and centrifuge.Use the supernatant as the Assay preparation.
Procedure—
Separately inject equal volumes (about 10µL)of the
Standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of astemizole (C
28H
31FN
4O)in the portion of Tablets taken by the formula:
50C(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Astemizole RSin the
Standard preparation;and
rUand
rSare the peak responses obtained from the
Assay preparationand the
Standard preparation,respectively.