A: Tablets meet the requirements under Identification—Organic Nitrogenous Bases á181ñ.

B: Thin-Layer Chromatographic Identification Test á201ñ—

Medium: 0.01Nhydrochloric acid;900mL.

Apparatus 1: 100rpm.

Time: 45minutes.

Mobile phase— Prepare a suitable degassed and filtered mixture of water and methanol (55:45)that contains 0.69g of monobasic sodium phosphate in each 100mLand is adjusted with phosphoric acid,if necessary,to a pHof 4.0.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 230-nm detector,a 4.6-mm ×25-cm precolumn positioned between the pump and the injection valve that contains packing L27,and a 4.6-mm ×25-cm analytical column that contains packing L9.The flow rate is about 2mLper minute.Chromatograph replicate injections of the Standard solution,and record the peak responses as directed for Procedure:the relative standard deviation is not more than 2.0%.

Procedure— Inject about 100µLof a filtered portion of the solution under test,suitably diluted with Mobile phase,if necessary,into the chromatograph,record the chromatogram,and measure the response for the major peak.Determine the amount of C25H27ClN2·2HCl dissolved from the peak response obtained in comparison with the peak response obtained from a Standard solution having a known concentration of USP Meclizine Hydrochloride RSin a mixture of Mediumand Mobile phase(1:1),similarly chromatographed.An amount of alcohol not to exceed 1%of the total volume of the Standard solution may be used to dissolve USP Meclizine Hydrochloride RSprior to dilution.

Tolerances— Not less than 75%(Q)of the labeled amount of C25H27ClN2·2HCl is dissolved in 45minutes.

Procedure for content uniformity— Place 1Tablet in a 100-mLvolumetric flask,add 50mLof dilute hydrochloric acid (1in 100),shake by mechanical means for 30minutes,add the dilute acid to volume,and filter,discarding the first 20mLof the filtrate.Dilute quantitatively and stepwise with the same acid to obtain a solution having a concentration of about 15µg of meclizine hydrochloride per mL.Similarly,prepare a Standard solution of USP Meclizine Hydrochloride RSin dilute hydrochloric acid (1in 100)having a known concentration of about 15µg per mL.Concomitantly determine the absorbances of the solution from the Tablet and the Standard solution in 1-cm cells at the wavelength of maximum absorbance at about 232nm,with a suitable spectrophotometer,using dilute hydrochloric acid (1in 100)as the blank.Calculate the quantity,in mg,of meclizine hydrochloride (C25H27ClN2·2HCl)in the Tablet taken by the formula: in which Tis the quantity,in mg,of meclizine hydrochloride in the Tablet;Dis the concentration,in µg per mL,of meclizine hydrochloride in the solution from the Tablet,on the basis of the labeled quantity per Tablet and the extent of dilution;Cis the concentration,in µg per mL,of USP Meclizine Hydrochloride RSin the Standard solution;and AUand ASare the absorbances of the solution from the Tablet and the Standard solution,respectively.

Mobile phase— Prepare a filtered and degassed mixture of methanol and water (65:35)that contains 0.69g of monobasic sodium phosphate in each 100mL,and adjust with phosphoric acid,if necessary,to a pHof 4.0.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Solvent mixture— Prepare a mixture of 0.1Nhydrochloric acid and Mobile phase(1:1).

Standard preparation— Dissolve an accurately weighed quantity of USP Meclizine Hydrochloride RSin Solvent mixtureto obtain a solution having a known concentration of about 0.25mg per mL.

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 25mg of meclizine hydrochloride,to a 100-mLvolumetric flask.Add about 60mLof Solvent mixture,sonicate for about 10minutes,and shake by mechanical means for about 30minutes.Dilute with Solvent mixtureto volume,mix,and filter a portion of this solution,discarding the first 5mLof the filtrate.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 230-nm detector,a 4.6-mm ×25-cm precolumn (positioned between the pump and the injection valve)that contains packing L27,and a 4.6-mm ×25-cm analytical column that contains packing L9.The flow rate is about 1.6mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the tailing factor for the analyte peak is not more than 2.0;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 25µL)of the Standard preparationand the Test preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of meclizine hydrochloride (C25H27ClN2·2HCl)in the portion of Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Meclizine Hydrochloride RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.