Flucytosine Tablets

General Notices

Action and use

Antifungal.

Definition

Flucytosine Tablets contain Flucytosine.

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

Content of flucytosine, C4H4FN3O

92.5 to 107.5% of the stated amount.

Identification

Shake a quantity of the powdered tablets containing 0.5 g of Flucytosine with 100 mL of methanol for 30 minutes, filter and evaporate the filtrate to dryness. The infrared absorption spectrum of the residue, Appendix II A, is concordant with the reference spectrum of flucytosine (RS 146).

TESTS

Related substances

Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.

(1) Shake a quantity of the powdered tablets containing 0.10 g of Flucytosine with 10 mL of a mixture of equal volumes of 13.5m ammonia and methanol and filter.
(2) Dilute 1 volume of solution (1) to 10 volumes with methanol (60%) and dilute 1 volume of the resulting solution to 100 volumes with methanol (60%).
(3) Dilute 1 volume of solution (1) to 10 volumes and dissolve 5 mg of fluorouracil BPCRS in 5 mL of the resulting solution.
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 12 cm in an unsaturated tank.
(e) After removal of the plate, allow the solvent to evaporate, stand the plate in a tank of chlorine vapour prepared by the addition of hydrochloric acid to a 5% w/v solution of potassium permanganate contained in a beaker placed in the tank and allow to stand for 15 minutes. Remove the plate and place it in a current of cold air until the excess of chlorine is removed and an area of the coating substance below the line of application does not give a blue colour with a drop of potassium iodide and starch solution. Spray the plate with potassium iodide and starch solution and examine the plate in daylight.
mobile phase

1 volume of anhydrous formic acid, 15 volumes of water, 25 volumes of methanol and 60 volumes of ethyl acetate.

system suitability

The test is not valid unless the chromatogram obtained with solution (3) shows two clearly separated spots.

limits

Any secondary spot in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (2) (0.1%).

Assay

Weigh and powder 20 tablets. To a quantity of the powder containing 0.1 g of Flucytosine add 80 mL of 0.1m hydrochloric acid and shake for 15 minutes. Dilute to 100 mL with 0.1m hydrochloric acid and filter. Dilute 10 mL of the filtrate to 100 mL with 0.1m hydrochloric acid and further dilute 10 mL of the solution to 100 mL with 0.1m hydrochloric acid. Measure the absorbance of the resulting solution at the maximum at 286 nm, Appendix II B. Calculate the content of C4H4FN3O taking 709 as the value of A(1%, 1 cm) at the maximum at 286 nm.

Storage

Flucytosine tablets should be protected from light.