Trihexyphenidyl Tablets

General Notices

Action and use

Anticholinergic.

Definition

Trihexyphenidyl Tablets contain Trihexyphenidyl Hydrochloride.

The tablets comply with the requirements stated under Tablets and with the following requirements.

Content of trihexyphenidyl hydrochloride, C20H31NO,HCl

90.0 to 110.0% of the stated amount.

Identification

A. Shake a quantity of the powdered tablets containing 20 mg of Trihexyphenidyl Hydrochloride with 20 mL of water and filter. The filtrate yields a yellow precipitate with picric acid solution R1 and a white precipitate with 5m sodium hydroxide.
B. Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.
(1) Shake a quantity of the powdered tablets with sufficient chloroform to produce a solution containing 0.2% w/v of Trihexyphenidyl Hydrochloride and filter.
(2) 0.2% w/v of trihexyphenidyl hydrochloride BPCRS in chloroform.
chromatographic conditions
(a) Use as the coating silica gel.
(b) Use the mobile phase as described below.
(c) Apply 10 µL of each solution.
(d) Develop the plate to 15 cm.
(e) After removal of the plate, dry in air and spray with dilute potassium iodobismuthate solution.
mobile phase

10 volumes of methanol and 90 volumes of chloroform.

confirmation

The principal spot in the chromatogram obtained with solution (1) corresponds in position and colour to that in the chromatogram obtained with solution (2).

Tests

Related substances

Carry out the method for liquid chromatography, Appendix III D, using the following solutions.

(1) Mix a quantity of the powdered tablets containing 50 mg of Trihexyphenidyl Hydrochloride with 10 mL of water, add 10 mL of methanol, disperse with the aid of ultrasound for 5 minutes, shake for 15 minutes, add sufficient methanol to produce 25 mL and filter.
(2) Dilute 1 volume of solution (1) to 100 volumes with methanol (60%).
(3) 0.2% w/v of trihexyphenidyl hydrochloride BPCRS and 0.01% w/v of 3-piperidylpropiophenone hydrochloride BPCRS in methanol (60%).
(4) Dilute 1 volume of solution (2) to 10 volumes with methanol (60%).
chromatographic conditions

The chromatographic conditions described under Uniformity of content may be used.

system suitability

The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between the two principal peaks is at least 4.0.

limits

In the chromatogram obtained with solution (1):

the area of any secondary peak is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (1%);

the sum of the areas of any secondary peaks is not greater than twice the area of the principal peak in the chromatogram obtained with solution (2) (2%).

Disregard any peak with an area less than the area of the principal peak in the chromatogram obtained with solution (4) (0.1%).

Uniformity of content

Tablets containing less than 2 mg and/or less than 2% w/w of Trihexyphenidyl Hydrochloride comply with the requirements stated under Tablets using the following method of analysis. Carry out the method for liquid chromatography, Appendix III D, using the following solutions.

(1) Add 5 mL of water to one tablet and mix with the aid of ultrasound for 5 minutes or until the tablet is dispersed. Add 10 mL of methanol, shake for 15 minutes, dilute to 25 mL with methanol, mix and filter through a filter with a maximum pore size of 0.2 µm.
(2) 0.008% w/v of trihexyphenidyl hydrochloride BPCRS and 0.004% w/v of 3-piperidylpropiophenone hydrochloride BPCRS in the mobile phase.
chromatographic conditions
(a) Use a stainless steel column (15 cm × 3.9 mm) packed with octadecylsilyl silica gel for chromatography (5 µm) (Resolve C18 is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 2 mL per minute.
(d) Use an ambient column temperature.
(e) Use a detection wavelength of 210 nm.
(f) Inject 20 µL of each solution.
mobile phase

0.2 volumes of triethylamine, 200 volumes of water and 800 volumes of acetonitrile, adjust the pH of the mixture to 4.0 with orthophosphoric acid.

system suitability

The test is not valid unless, in the chromatogram obtained with solution (2), the resolution between the two principal peaks is at least 4.0.

determination of content

Calculate the content of C20H31NO,HCl in each tablet using the declared content of C20H31NO,HCl in trihexyphenidyl hydrochloride BPCRS.

Assay

For tablets containing less than 2 mg and/or less than 2% w/w of trihexyphenidyl hydrochloride

Use the average of the individual results determined in the test for Uniformity of content.

For tablets containing 2 mg or more and 2% w/w or more of trihexyphenidyl hydrochloride

Weigh and powder 20 tablets. Carry out the method for liquid chromatography, Appendix III D, using the following solutions.

(1) Add 5 mL of water to a quantity of the powdered tablets containing 5 mg of Trihexyphenidyl Hydrochloride and mix with the aid of ultrasound for 5 minutes. Add 10 mL of methanol, shake for 15 minutes, dilute to 25 mL with methanol and filter through a filter with a maximum pore size of 0.2 µm.
(2) 0.02% w/v of trihexyphenidyl hydrochloride BPCRS and 0.01% w/v of 3-piperidylpropiophenone hydrochloride BPCRS in the mobile phase.
chromatographic conditions

The chromatographic conditions described under Uniformity of content may be used.

system suitability

The assay is not valid unless, in the chromatogram obtained with solution (2), the resolution between the two principal peaks is at least 4.0.

determination of content

Calculate the content of C20H31NO,HCl in the tablets using the declared content of C20H31NO,HCl in trihexyphenidyl hydrochloride BPCRS.