Packaging and storage—
Preserve in tight containers.
Identification—
To a quantity of finely powdered Tablets, equivalent to about 10 mg of biperiden hydrochloride, add 5 mL of water, mix, and sonicate to disperse the powder. Add 5 mL of methanol into the flask, mix, and sonicate for 15 minutes. Filter the solution into a separator, add 2 mL of 1 N sodium hydroxide and 10 mL of chloroform, and shake for 3 minutes. Filter the chloroform layer into a stoppered flask, and use the chloroform filtrate as the test solution. In a similar manner, using about 10 mg of
USP Biperiden Hydrochloride RS in place of the powdered Tablets, prepare the Standard solution. Condition a suitable thin-layer chromatographic plate (see
Chromatography 
621
) coated with a 0.25-mm layer of chromatographic silica gel mixture, by heating the plate at 105
for 1 hour. Allow the plate to cool, and separately apply 20 µL each of the test solution and the Standard solution to the plate. Allow the applications to dry, and develop the chromatogram in a solvent system consisting of a mixture of methanol and ammonium hydroxide (100:1.5) 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 on the plate by exposing the plate for 10 minutes to iodine vapors in a pre-equilibrated closed chamber, on the bottom of which there are iodine crystals: the
RF value of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.
Dissolution 711—
Medium:
0.01 N hydrochloric acid; 500 mL.
Apparatus 2:
50 rpm.
Time:
45 minutes.
Determine the amount of C21H29NO·HCl dissolved by employing the following method.
Phosphate buffer–bromocresol purple solution—
Prepare as directed in the Assay.
Standard preparation—
Dissolve an accurately weighed quantity of
USP Biperiden Hydrochloride RS in methanol, and quantitatively dilute with methanol to obtain a solution having a known concentration of about 0.8 mg per mL. Pipet 5 mL of this solution into a 500-mL volumetric flask, add 0.01 N hydrochloric acid to volume, and mix. Pipet 25 mL of this solution into a suitable beaker, and adjust with 0.01 N sodium hydroxide to a pH of 5.3. Transfer this solution to a 100-mL volumetric flask with the aid of water, dilute with water to volume, and mix to obtain a
Standard preparation having a known concentration of about 2 µg per mL.
Test preparation—
Filter 75 mL of the solution under test, pipet 50 mL of the clear filtrate into a suitable beaker, and adjust with 0.01 N sodium hydroxide to a pH of 5.3. Transfer this solution to a 100-mL volumetric flask with the aid of water, dilute with water to volume, and mix.
Procedure—
Pipet 20 mL each of the Standard preparation, the Test preparation, and water to provide the blank, into individual separators, each containing 10.0 mL of Phosphate buffer–bromocresol purple solution. Extract the solution in each separator with 40.0 mL of chloroform for 10 minutes. After the layers have separated, pass each chloroform extract through filter paper into separate, glass-stoppered containers, discarding the first 10 mL of each filtrate. Determine the amount of C21H29NO·HCl dissolved from absorbances at the wavelength of maximum absorbance at about 408 nm (10-cm cells) of the extract from the Test preparation in comparison with that of the extract from the Standard preparation, using the blank to set the instrument.
Tolerances—
Not less than 75% (Q) of the labeled amount of C21H29NO·HCl is dissolved in 45 minutes.
Assay—
Phosphate buffer–bromocresol purple solution—
Dissolve 38 g of monobasic sodium phosphate and 2 g of anhydrous dibasic sodium phosphate in water to make 1000 mL. Adjust the pH of the solution to 5.3 ± 0.1, if necessary (Solution A). Dissolve 400 mg of bromocresol purple in 30 mL of water, add 6.3 mL of 0.1 N sodium hydroxide, and dilute with water to 500 mL (Solution B). Mix equal volumes of Solution A, Solution B, and chloroform, shake in a separator, and discard the chloroform. If appreciable color is extracted, repeat with additional portions of chloroform until no color is extracted.
Standard preparation—
Transfer about 80 mg of
USP Biperiden Hydrochloride RS, accurately weighed, to a 100-mL volumetric flask, add methanol to volume, and mix. Transfer 5.0 mL of this solution to a second 100-mL volumetric flask, add 25 mL of water, dilute with methanol to volume, and mix. The concentration of
USP Biperiden Hydrochloride RS in the
Standard preparation is about 40 µg per mL.
Assay preparation—
Weigh and finely powder not less than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 2 mg of biperiden hydrochloride, to a 50-mL volumetric flask, add 12.5 mL of water, and heat on a steam bath for 15 minutes. Cool, dilute with methanol to volume, and mix.
Procedure—
Transfer 5.0 mL each of the
Standard preparation, the
Assay preparation, and a mixture of methanol and water (3:1) to provide the blank, to individual separators each, containing 10.0 mL of
Phosphate buffer–bromocresol purple solution. Extract the solution in each separator with 20.0 mL of chloroform for 2 minutes. After the layers have separated, pass each chloroform extract through filter paper (Whatman No. 31 or equivalent) into separate glass-stoppered, 50-mL volumetric flasks. In the same manner, extract the solution in each separator with another 20.0-mL portion of chloroform, filter, and wash each filter with 8 mL of chloroform, collecting each combined filtrate and washing, respectively, in the 50-mL volumetric flask containing the first extract. Dilute with chloroform to volume, and mix. Concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 408 nm, with a suitable spectrophotometer, using the blank to set the instrument. Calculate the quantity, in mg, of C
21H
29NO·HCl in the portion of Tablets taken by the formula:
0.05C(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Biperiden Hydrochloride RS in the
Standard preparation, and
AU and
AS are the absorbances of the solutions from the
Assay preparation and the
Standard preparation, respectively.
