Identification—
Dilute a volume of Oral Solution, equivalent to about 20 mg of hydroxyzine hydrochloride, with 50 mL of methanol, and mix. Apply 100 µL of this solution and 100 µL of a solution in the same medium containing about 350 µg of
USP Hydroxyzine Hydrochloride RS per mL to a suitable thin-layer chromatographic plate (see
Chromatography 
621
), coated with a 0.25-mm layer of chromatographic silica gel and dried in air for 30 minutes followed by drying in vacuum at 140
for 30 minutes. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of toluene, alcohol, and ammonium hydroxide (150:95:1) 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, and allow the solvent to evaporate. Locate the spots by lightly spraying with
potassium iodoplatinate TS: the
RF value of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.
Assay—
Standard preparation—
Dissolve a suitable quantity of
USP Hydroxyzine Hydrochloride RS, accurately weighed, in water to obtain a solution having a known concentration of about 100 µg per mL.
Assay preparation—
Transfer an accurately measured volume of Oral Solution, equivalent to about 20 mg of hydroxyzine hydrochloride, to a 200-mL volumetric flask, dilute with water to volume, mix, and pass a portion through a polytef membrane filter having a 5-µm or finer porosity.
Procedure—
Proceed as directed for
Procedure in the
Assay under
Hydroxyzine Hydrochloride Tablets. Calculate the quantity, in mg, of hydroxyzine hydrochloride (C
21H
27ClN
2O
2·2HCl) in each mL of the Oral Solution taken by the formula:
0.2(C/V)(rU / rS),
in which
C is the concentration, in µg per mL, of
USP Hydroxyzine Hydrochloride RS in the
Standard preparation; V is the volume, in mL, of Oral Solution taken; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
Hydroxyzine Hydrochloride Syrup