Pyridoxine Tablets

General Notices

Action and use

Vitamin B6.

Definition

Pyridoxine Tablets contain Pyridoxine Hydrochloride.

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

Content of pyridoxine hydrochloride, C8H11NO3,HCl

90.0 to 110.0% of the stated amount.

Identification

A. Shake a quantity of the powdered tablets containing 0.1 g of Pyridoxine Hydrochloride with 50 mL of methanol for 15 minutes, warming occasionally, filter and add sufficient 13.5m ammonia to make the filtrate alkaline. Evaporate the resulting solution to dryness, dissolve the residue as completely as possible in 15 mL of chloroform and filter. To the filtrate add 2 mL of a solution prepared by carefully adding 2 mL of acetyl chloride drop wise to 8 mL of cooled methanol and evaporate the resulting solution to dryness. The infrared absorption spectrum of the residue, Appendix II A, is concordant with the reference spectrum of pyridoxine hydrochloride (RS 308).
B. Shake a quantity of the powdered tablets containing 20 mg of Pyridoxine Hydrochloride with 50 mL of 0.025m standard phosphate buffer for 15 minutes and dilute to 100 mL with the same solvent. Mix, filter and dilute 5 mL of the filtrate to 100 mL with the same solvent. The light absorption of the resulting solution, Appendix II B, in the range 230 to 350 nm exhibits two maxima, at 254 nm and 324 nm.
C. Triturate a quantity of the powdered tablets containing 20 mg of Pyridoxine Hydrochloride with 50 mL of water and allow to stand. To 1 mL of the supernatant liquid add 10 mL of a 5% w/v solution of sodium acetate, 1 mL of water and 1 mL of a 0.5% w/v solution of 2-6-dichloroquinone-4-chloroimide in ethanol (96%) and shake; a blue colour is produced which fades rapidly and becomes brown. Repeat the operation but adding 1 mL of a 0.3% w/v solution of boric acid in place of the 1 mL of water; no blue colour is produced.

Tests

Related substances

Carry out the method for thin-layer chromatography, Appendix III A, using silica gel G as the coating substance and a mixture of 9 volumes of 13.5m ammonia, 13 volumes of tetrahydrofuran, 13 volumes of dichloromethane and 65 volumes of acetone as the mobile phase. Apply separately to the plate 10 µL of each of the following solutions. For solution (1) shake a quantity of the powdered tablets containing 40 mg of Pyridoxine Hydrochloride with 10 mL of water for 15 minutes, filter and use the filtrate. For solution (2) dilute 1 mL of solution (1) to 200 mL with water. After removal of the plate, allow it to dry in air and spray with a 5% w/v solution of sodium carbonate in ethanol (30%). Allow the plate to dry in air, spray with a 0.1% w/v solution of 2,6-dichloroquinone-4-chloroimide in ethanol (96%) and examine immediately. 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%). Disregard any spot remaining on the line of application.

Assay

Weigh and powder 20 tablets. To a quantity of the powdered tablets containing 25 mg of Pyridoxine Hydrochloride add 50 mL of 0.1m hydrochloric acid and heat on a water bath for 15 minutes, swirling occasionally. Cool, dilute to 100 mL with 0.1m hydrochloric acid and filter, discarding the first 20 mL of filtrate. Dilute 5 mL of the filtrate to 100 mL with 0.1m hydrochloric acid and measure the absorbance of the resulting solution at the maximum at 290 nm, Appendix II B. Calculate the content of C8H11NO3,HCl taking 430 as the value of A(1%, 1 cm) at the maximum at 290 nm.

Storage

Pyridoxine Tablets should be protected from light and stored at a temperature not exceeding 30°.

When vitamin B6 tablets are prescribed or demanded, Pyridoxine Tablets shall be dispensed or supplied.