Clonazepam Tablets

Benzodiazepine.

Clonazepam Tablets contain Clonazepam.

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

95.0 to 105.0% of the stated amount.

Extract a quantity of the powdered tablets containing 10 mg of Clonazepam with 25 mL of dichloromethane, centrifuge, filter the supernatant liquid, evaporate to dryness and dry the residue at 60° at a pressure not exceeding 0.7 kPa. The infrared absorption spectrum of the residue, Appendix II A, is concordant with the reference spectrum of clonazepam (RS 432).

Carry out the following procedure protected from light. Comply with the requirements in the dissolution test for tablets and capsules, Appendix XII B1.

(a) Use Apparatus 1, rotating the basket at 100 revolutions per minute.

(b) Use 900 mL of water, at a temperature of 37°, as the dissolution medium.

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

(1) After 45 minutes withdraw a sample of the medium and filter. Use the filtered medium, diluted with water if necessary, to produce a solution expected to contain 0.00005% w/v of Clonazepam.

(2) 0.00005% w/v of clonazepam BPCRS.

(a) Use a stainless steel column (25 cm × 4.0 mm) packed with octadecylsilyl silica gel for chromatography (5 µm).

(b) Use isocratic elution and the mobile phase described below.

(c) Use a flow rate of 1 mL per minute.

(d) Use an ambient column temperature.

(e) Use a detection wavelength of 254 nm.

(f) Inject 100 µL of each solution.

30 volumes of acetonitrile, 30 volumes of methanol and 40 volumes of water.

Calculate the total content of clonazepam, C₁₅H₁₀ClN₃O₃, in the medium from the chromatograms obtained and using the declared content of C₁₅H₁₀ClN₃O₃ in clonazepam BPCRS.

The amount of clonazepam, C₁₅H₁₀ClN₃O₃, released is not less than 75% (Q) of the stated amount.

Carry out the following procedure protected from light and prepare samples immediately before use. Use low-actinic glassware. Prepare a mixture of 10 volumes of tetrahydrofuran, 42 volumes of methanol and 48 volumes of water (solution A). Carry out the method for liquid chromatography, Appendix III D, using the following solutions.

(1) Shake a quantity of the powdered tablets containing 10 mg of Clonazepam with 1 mL of tetrahydrofuran and 4 mL of methanol, add sufficient water to produce 20 mL, mix and filter.

(2) Dilute 1 volume of solution (1) to 100 volumes with solution A and further dilute 2 volumes of this solution to 10 volumes with solution A.

(3) 0.005% w/v each of clonazepam BPCRS and flunitrazepam BPCRS in solution A.

(4) 0.0005% w/v of 3-amino-4-(2-chlorophenyl)-6-nitroquinolin-2(1H)-one BPCRS in solution A.

(5) Dilute 1 volume of solution (2) to 2 volumes with solution A.

(a) Use a stainless steel column (15 cm × 3.9 mm) packed with end-capped octylsilyl silica gel for chromatography (5 µm) (Symmetry C8 is suitable).

(b) Use isocratic elution and the mobile phase described below.

(c) Use a flow rate of 1 mL per minute.

(d) Use an ambient column temperature.

(e) Use a detection wavelength of 254 nm.

(f) Inject 20 µL of each solution.

(g) Allow the chromatography to proceed for 3 times the retention time of clonazepam.

(h) The retention time of clonazepam is about 7 minutes, the retention time of 3-amino-4-(2-chlorophenyl)-6-nitroquinolin-2(1H)-one is about 14.5 minutes and the retention time of (2-amino-5-nitrophenyl)(2-chlorophenyl)methanone is about 17 minutes.

48 volumes of a 0.66% w/v solution of diammonium hydrogen orthophosphate, previously adjusted to pH 8.0 with a 4.0% w/v solution of sodium hydroxide or dilute phosphoric acid, 10 volumes of tetrahydrofuran and 42 volumes of methanol.

The test is not valid unless:

in the chromatogram obtained with solution (3) the resolution factor between the two principal peaks is not less than 1.8;

in the chromatogram obtained with solution (5) the signal-to-noise ratio of the principal peak is at least 10.

In the chromatogram obtained with solution (1):

the area of any peak corresponding to 3-amino-4-(2-chlorophenyl)-6-nitroquinolin-2(1H)-one is not greater than the area of the principal peak in the chromatogram obtained with solution (4) (1%);

the area of any peak corresponding to (2-amino-5-nitrophenyl)(2-chlorophenyl)methanone is not greater than 5 times the area of the principal peak in the chromatogram obtained with solution (2) (1%);

the area of any other secondary peak is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (0.2 %).

The sum of the impurities is not more than 2%.

Disregard any peak with an area less than that of the area of the principal peak in the chromatogram obtained with solution (5) (0.1%).

Tablets containing less than 2 mg and/or less than 2% w/w of Clonazepam comply with the requirements stated under Tablets using the following method of analysis. Prepare a mixture of 10 volumes of tetrahydrofuran, 42 volumes of methanol and 48 volumes of water (solution A). Carry out the following procedure protected from light and prepare the solutions immediately before use. Carry out the method for liquid chromatography, Appendix III D, using the following solutions in solution A.

(1) Shake a whole tablet with 1 mL of tetrahydrofuran and 4 mL of methanol, add sufficient water to produce 10 mL, mix and filter. Dilute the filtrate, if necessary with sufficient solution A to produce a solution expected to contain 0.001% w/v of Clonazepam.

(2) 0.001% w/v of clonazepam BPCRS.

(3) 0.0005% w/v each of clonazepam BPCRS and flunitrazepam BPCRS.

The chromatographic conditions described under Related substances may be used with an injection volume of 100 µL.

The test is not valid unless, in the chromatogram obtained with solution (3), the resolution factor between the two principal peaks is at least 1.8.

Calculate the content of C₁₅H₁₀ClN₃O₃ in the tablets from the chromatograms obtained and using the declared content of C₁₅H₁₀ClN₃O₃ in clonazepam BPCRS.

Use the average of the 10 individual results obtained in the test for Uniformity of content.

Prepare a mixture of 10 volumes of tetrahydrofuran, 42 volumes of methanol and 48 volumes of water (solution A). Carry out the following procedure protected from light and prepare the solutions immediately before use. Carry out the method for liquid chromatography, Appendix III D, using the following solutions.

(1) Shake a quantity of the powdered tablets containing 10 mg of Clonazepam with 10 mL of tetrahydrofuran and 40 mL of methanol, add sufficient water to produce 100 mL, mix and filter.

(2) 0.01% w/v of clonazepam BPCRS in solution A.

(3) 0.005% w/v each of clonazepam BPCRS and flunitrazepam BPCRS in solution A.

The chromatographic conditions described under Related substances may be used.

The test is not valid unless, in the chromatogram obtained with solution (3), the resolution factor between the two principal peaks is at least 1.8.

Calculate the content of C₁₅H₁₀ClN₃O₃ in the tablets from the chromatograms obtained and using the declared content of C₁₅H₁₀ClN₃O₃ in clonazepam BPCRS.

Clonazepam Tablets should be protected from light.

The impurities limited by the requirements of this monograph include:

A. (2-amino-5-nitrophenyl)(2-chlorophenyl)methanone.

B. 3-amino-4-(2-chlorophenyl)-6-nitroquinolin-2(1H)-one.