Nitrofurantoin Tablets
Action and use
Antibacterial.
Definition
Nitrofurantoin Tablets contain Nitrofurantoin.
Content of nitrofurantoin, C8H6N4O5
90.0 to 110.0% of the stated amount.
Identification
The light absorption, Appendix II B, in the range 220 to 400 nm of the final solution obtained in the Assay exhibits two maxima, at 266 nm and 367 nm.
Related substances
Carry out the method for thin-layer chromatography, Appendix III A, using silica gel HF254 as the coating substance and a mixture of 10 volumes of methanol and 90 volumes of nitromethane 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 0.1 g of Nitrofurantoin with 10 mL of a mixture of 1 volume of dimethylformamide and 9 volumes of acetone and filter. For solution (2) dilute 1 volume of solution (1) to 100 volumes with acetone. After removal of the plate, allow it to dry in air, heat at 100° to 105° for 5 minutes and examine under ultraviolet light (254 nm). Spray the plate with phenylhydrazine hydrochloride solution and heat it at 100° to 105° for a further 10 minutes. By each method of visualisation, any secondary spot in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (2) (1%).
Assay
Carry out the following procedure in subdued light. Weigh and powder 20 tablets. To a quantity of the powder containing 0.12 g of Nitrofurantoin add 50 mL of dimethylformamide, shake for 5 minutes, add sufficient water to produce 1000 mL and mix. Dilute 5 mL to 100 mL with a solution containing 1.8% w/v of sodium acetate and 0.14% v/v of glacial acetic acid and filter. Measure the absorbance of the filtrate at the maximum at 367 nm, Appendix II B, using the sodium acetate-acetic acid solution in the reference cell. Calculate the content of C8H6N4O5 taking 765 as the value of A(1%, 1 cm) at 367 nm.
Storage
Nitrofurantoin Tablets should be protected from light.