Trihexyphenidyl Hydrochloride
(trye hex'' ee fen' i dil hye'' droe klor' ide).
» Trihexyphenidyl Hydrochloride contains not less than 98.0 percent and not more than 102.0 percent of C20H31NO·HCl, calculated on the dried basis.
Packaging and storage
Preserve in tight containers.
Identification
B:
It responds to the tests for Chloride
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C:
The retention time exhibited by trihexyphenidyl hydrochloride in the chromatogram of the Assay preparation corresponds to that of the Standard preparation, as obtained in the Assay.
Loss on drying
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Residue on ignition
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Delete the following:
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Chloride content
Dissolve about 1.2 g, accurately weighed, in a mixture consisting of 50 mL of methanol, 5 mL of glacial acetic acid, and 5 mL of water. Add 3 drops of eosin Y TS, and mix. Stir, preferably with a magnetic stirrer, and titrate with 0.1 N silver nitrate VS until the straw-orange suspension that forms during the titration changes sharply to red. Each mL of 0.1 N silver nitrate is equivalent to 3.545 mg of Cl. Not less than 10.3% and not more than 10.7% of Cl, calculated on the dried basis, is found.
Chromatographic purity
Standard preparations
Dissolve USP Trihexyphenidyl Hydrochloride RS in a mixture of chloroform and isopropylamine (98:2), and mix to obtain a solution having a known concentration of 2.5 mg per mL. Dilute quantitatively with a mixture of chloroform and isopropylamine (98:2) to obtain Standard preparation A, containing 500 µg of the Reference Standard per mL, and Standard preparation B, containing 250 µg of the Reference Standard per mL.
Test preparation
Dissolve an accurately weighed quantity of Trihexyphenidyl Hydrochloride in a mixture of chloroform and isopropylamine (98:2) to obtain a solution containing 50 mg per mL.
Spray reagent
Dissolve 0.8 g of bismuth subnitrate in a mixture of 40 mL of water and 10 mL of glacial acetic acid (Solution A). Dissolve 8 g of potassium iodide in 20 mL of water (Solution B). On the day of use, mix equal volumes of Solution A and Solution B.
Procedure
Apply separately 10 µL of the Test preparation and 10 µL of each Standard preparation to a suitable thin-layer chromatographic plate (see Chromatography
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Assay
Mobile phase
Prepare a mixture of acetonitrile, water, and triethylamine (920:80:0.2), adjust with phosphoric acid to a pH of 4.0, mix, filter, and degas. Make adjustments if necessary (see System Suitability under Chromatography
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Standard preparation
Dissolve an accurately weighed quantity of USP Trihexyphenidyl Hydrochloride RS in acetonitrile, and dilute quantitatively, and stepwise if necessary, with acetonitrile to obtain a solution having a known concentration of about 0.2 mg per mL.
Assay preparation
Transfer about 20 mg of Trihexyphenidyl Hydrochloride, accurately weighed, to a 100-mL volumetric flask, dissolve in acetonitrile, dilute with acetonitrile to volume, and mix.
Chromatographic system
(see Chromatography
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Procedure
Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C20H31NO·HCl in the portion of Trihexyphenidyl Hydrochloride taken by the formula:
100C(rU / rS)
in which C is the concentration, in mg per mL, of USP Trihexyphenidyl Hydrochloride RS in the Standard preparation, and rU and rS are the trihexyphenidyl peak responses obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information
Please check for your question in the FAQs before contacting USP.
USP38NF33 Page 5686
Pharmacopeial Forum: Volume No. 40(4)
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