(hye drox' i zeen pam' oh ate).
Ethanol, 2-[2-[4-[(4-chlorophenyl)phenylmethyl]-1-piperazinyl]ethoxy]-, (±)-, compd. with 4,4¢-methylenebis[3-hydroxy-2- naphthalenecarboxylic acid] (1:1).
(±)-2-[2-[4-(p-Chloro--phenylbenzyl)-1-piperazinyl]ethoxy]ethanol 4,4¢-methylenebis[3-hydroxy-2-naphthoate] (1:1) [10246-75-0].
» Hydroxyzine Pamoate contains not less than 97.0 percent and not more than 102.0 percent of C21H27 ClN2O2·C23H16O6, calculated on the anhydrous basis.
Packaging and storage Preserve in tight containers.
USP Reference standards 11
USP Pamoic Acid RS
B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.
Water, Method I 921: not more than 5.0%.
Residue on ignition 281: not more than 0.2%.
Heavy metals, Method II 231: 20 ppm.
Mobile phase Dissolve 8.65 g of sodium 1-octanesulfonate in about 1000 mL of water in a 2000-mL volumetric flask, add 4.0 mL of phosphoric acid, dilute with water to volume, mix, and pass through a 0.5-µm or finer porosity membrane filter. Prepare a suitable mixture of this solution and acetonitrile (45:55), making any adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation Dissolve an accurately weighed quantity of USP Hydroxyzine Hydrochloride RS in dimethylformamide to obtain a solution having a known concentration of about 1 mg per mL. Transfer 2.0 mL of the resulting solution to a 100-mL volumetric flask, dilute with Mobile phase to volume, mix, and pass through a 0.5-µm or finer porosity membrane filter.
Assay preparation Transfer about 90 mg of Hydroxyzine Pamoate, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with dimethylformamide to volume, and mix. Transfer 2.0 mL of the resulting solution to a 100-mL volumetric flask, dilute with Mobile phase to volume, mix, and pass through a 0.5-µm or finer porosity membrane filter, discarding the first 5 mL of the filtrate.
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a 230-nm detector and a 3.9-mm × 30-cm column that contains packing L1. The flow rate is about 1.5 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the column efficiency, calculated from the analyte peak, is not less than 2000 theoretical plates, and the relative standard deviation for replicate injections is not more than 2%. Chromatograph the Assay preparation, and record the peak responses as directed for Procedure: the resolution, R, between hydroxyzine and pamoic acid is not less than 1.5.
Procedure Separately inject equal volumes (about 50 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. The relative retention times are about 0.5 for hydroxyzine and 1.0 for pamoic acid. Calculate the percentage of C21H27ClN2O2·C23H16O6 in the portion of Hydroxyzine Pamoate taken by the formula:
100(763.27 / 447.83)(CS / CU)(rU / rS)in which 763.27 and 447.83 are the molecular weights of hydroxyzine pamoate and hydroxyzine hydrochloride, respectively; CS is the concentration, in mg per mL, of USP Hydroxyzine Hydrochloride RS in the Standard preparation; CU is the concentration, in mg per mL, of Hydroxazine Pamoate in the Assay preparation; and rU and rS are the hydroxyzine peak responses obtained from the Assay preparation and the Standard preparation, respectively.
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USP35NF30 Page 3461Pharmacopeial Forum: Volume No. 34(2) Page 271