Packaging and storage
Preserve in tight,light-resistant containers.Store below 40

,preferably between 15

and 30

,unless otherwise specified by the manufacturer.
Identification
A:
Infrared Absorption á197Kñ
Test specimen
Transfer a volume of Oral Solution,equivalent to about 24mg of loperamide hydrochloride,to a separator containing about 100mLof water and 1mLof sodium hydroxide solution (1in 2),and gently swirl the contents.Add 50mLof methylene chloride,shake gently by hand,releasing pressure often,and then shake by mechanical means for 20minutes.Allow the layers to separate.Transfer the lower methylene chloride layer to a separator containing 100mLof water.Shake gently by hand,releasing pressure often,and then shake by mechanical means for 10minutes.Allow the layers to separate.Transfer the lower methylene chloride layer to a 250-mLbeaker,and evaporate on a steam bath with the aid of a current of air to dryness.Add 10mLof methanol and 500mg of potassium bromide to the beaker,and mix.Evaporate on a steam bath with the aid of a current of air to dryness,and use the residue.
B:
The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay.
Assay
Buffer solution
Transfer 3.0g of monobasic potassium phosphate to a 1-Lvolumetric flask,dissolve in and dilute with water to volume,and mix.
Mobile phase
Prepare a mixture of
Buffer solutionand acetonitrile (63:37),and adjust with 0.9Mphosphoric acid to a pHof 3.0.Mix,filter,and degas.Make adjustments if necessary (see
System Suitabilityunder
Chromatography á621ñ).
Standard preparation
Dissolve an accurately weighed quantity of
USP Loperamide Hydrochloride RSin methanol,and dilute quantitatively,and stepwise if necessary,with
Mobile phaseto obtain a solution having a known concentration of about 10µg per mL.
Assay preparation
Transfer an accurately measured volume of Oral Solution,equivalent to about 1.0mg of loperamide hydrochloride,to a 100-mLvolumetric flask.Dilute with Mobile phaseto volume,mix,and filter.
Chromatographic system(see Chromatography á621ñ)
The liquid chromatograph is equipped with a 214-nm detector and a 4.0-mm ×8.0-cm column that contains 5-µm packing L7.The flow rate is about 1.5mLper minute.Chromatograph the
Standard preparation,and record the peak areas as directed for
Procedure:the tailing factor 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 10µL)of the
Standard preparation and the
Assay preparationinto the chromatograph,record the chromatograms,and measure the areas for the major peaks.Calculate the quantity,in mg,of loperamide hydrochloride (C
29H
33ClN
2O
2·HCl)in each mLof Oral Solution taken by the formula:
100(C/V)(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Loperamide Hydrochloride RSin the
Standard preparation;Vis the volume of Oral Solution taken to prepare the
Assay preparation;and
rUand
rSare the peak areas obtained from the
Assay preparationand the
Standard preparation,respectively.