A: Tablets meet the requirements under Identification—Organic Nitrogenous Bases 181.

B: Thin-Layer Chromatographic Identification Test 201—

Medium: 0.01 N hydrochloric acid; 900 mL.

Apparatus 1: 100 rpm.

Time: 45 minutes.

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

Chromatographic system (see Chromatography 621)— 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 2 mL per 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 100 µL of 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 RS in a mixture of Medium and 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 RS prior to dilution.

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

Procedure for content uniformity— Place 1 Tablet in a 100-mL volumetric flask, add 50 mL of dilute hydrochloric acid (1 in 100), shake by mechanical means for 30 minutes, add the dilute acid to volume, and filter, discarding the first 20 mL of the filtrate. Dilute quantitatively and stepwise with the same acid to obtain a solution having a concentration of about 15 µg of meclizine hydrochloride per mL. Similarly, prepare a Standard solution of USP Meclizine Hydrochloride RS in dilute hydrochloric acid (1 in 100) having a known concentration of about 15 µg 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 232 nm, with a suitable spectrophotometer, using dilute hydrochloric acid (1 in 100) as the blank. Calculate the quantity, in mg, of meclizine hydrochloride (C25H27ClN2·2HCl) in the Tablet taken by the formula: in which T is the quantity, in mg, of meclizine hydrochloride in the Tablet; D is 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; C is the concentration, in µg per mL, of USP Meclizine Hydrochloride RS in the Standard solution; and AU and AS are the absorbances of the solution from the Tablet and the Standard solution, respectively.

(Official January 1, 2007)

Mobile phase— Prepare a filtered and degassed mixture of methanol and water (65:35) that contains 0.69 g of monobasic sodium phosphate in each 100 mL, and adjust with phosphoric acid, if necessary, to a pH of 4.0. Make adjustments if necessary (see System Suitability under Chromatography 621).

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

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

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

Chromatographic system (see Chromatography 621)— 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 1.6 mL per 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 25 µL) of the Standard preparation and the Test preparation into 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 C is the concentration, in mg per mL, of USP Meclizine Hydrochloride RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.