Flurazepam Capsules

General Notices

Action and use

Benzodiazepine.

Definition

Flurazepam Capsules contain Flurazepam Monohydrochloride.

The capsules comply with the requirements stated under Capsules and with the following requirements.

Content of flurazepam, C₂₁H₂₃ClFN₃O

90.0 to 110.0% of the stated amount.

Identification

A. Shake a quantity of the contents of the capsules containing the equivalent of 0.15 g of flurazepam with 3 mL of chloroform IR and filter. The infrared absorption spectrum of the filtrate, Appendix II A, is concordant with the reference spectrum of flurazepam monohydrochloride (RS 155).

B. The light absorption, Appendix II B, in the range 220 to 350 nm of the final solution obtained in the Assay exhibits two maxima, at 240 nm and 284 nm.

Tests

Related substances

Carry out the method for thin-layer chromatography, Appendix III A, using silica gel GF₂₅₄ as the coating substance and a mixture of 2.5 volumes of diethylamine and 97.5 volumes of ether as the mobile phase. Apply separately to the plate 10 µL of each of the following solutions. For solution (1) shake vigorously a quantity of the contents of the capsules containing the equivalent of 0.1 g of flurazepam with 2 mL of a mixture of 2 volumes of 13.5m ammonia and 98 volumes of methanol and centrifuge. For solution (2) dilute 1 volume of solution (1) to 200 volumes with the same solvent mixture. After removal of the plate, dry it in a current of air and examine under ultraviolet light (254 nm). Any secondary spot in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (2) (0.5%).

Assay

Carry out the following procedure protected from light. Transfer a quantity of the capsule contents containing the equivalent of 0.1 g of flurazepam into about 150 mL of 1m methanolic sulfuric acid, washing the inner surfaces of the capsule shells, shake for 10 minutes and add sufficient 1m methanolic sulfuric acid to produce 250 mL. Further dilute this solution with 1m methanolic sulfuric acid to produce a solution containing the equivalent of about 0.002% w/v of flurazepam and measure the absorbance of the resulting solution at the maximum at 284 nm, Appendix II B. Calculate the content of C₂₁H₂₃ClFN₃O taking 319 as the value of A(1%, 1 cm) at the maximum at 284 nm.

Labelling

The quantity of active ingredient is stated in terms of the equivalent amount of flurazepam.