Flavoxate Tablets
Action and use
Anticholinergic.
Definition
Flavoxate Tablets contain Flavoxate Hydrochloride. They are coated.
Content of flavoxate hydrochloride, C24H25NO4,HCl
95.0 to 105.0% of the stated amount.
Identification
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 1 volume of 18m ammonia, 80 volumes of propan-2-ol and 200 volumes of ethyl acetate as the mobile phase. Apply separately to the plate (1) 50 µL of a solution prepared by shaking a quantity of the powdered tablets containing 0.2 g of Flavoxate Hydrochloride with 10 mL of chloroform and filtering, (2) 10 µL of a 0.030% w/v solution of 3-methylflavone-8-carboxylic acid BPCRS in chloroform, (3) 10 µL of a 0.015% w/v solution of 3-methylflavone-8-carboxylic acid ethyl ester BPCRS in chloroform, (4) 25 µL of a solution obtained by diluting one volume of solution (1) to 500 volumes with chloroform, (5) 10 µL of a solution obtained by diluting 1 volume of solution (1) to 20 volumes with chloroform and (6) 10 µL of a 0.1% w/v solution of flavoxate hydrochloride BPCRS in chloroform. After removal of the plate, allow it to dry in air and examine under ultraviolet light (254 nm). Any spot corresponding to 3-methylflavone-8-carboxylic acid ethyl ester in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (3) (0.15%) and any other secondary spot in the chromatogram obtained with solution (1), other than the spot corresponding to 3-methyflavone-8-carboxylic acid, is not more intense than the spot in the chromatogram obtained with solution (4) (0.1%).
3-Methylflavone-8-carboxylic acid
Carry out the method for thin-layer chromatography, Appendix III A, using a TLC silica gel GF254 plate (Merck silica gel 60 F254 plates are suitable) and a mixture of 4 volumes of glacial acetic acid, 25 volumes of ethyl acetate and 70 volumes of cyclohexane as the mobile phase. Apply separately to the plate 50 µL of each of the following solutions. For solution (1) shake a quantity of the powdered tablets containing 0.2 g of Flavoxate Hydrochloride with 10 mL of chloroform and filter. Solution (2) is a 0.010% w/v solution of 3-methylflavone-8-carboxylic acid BPCRS. After removal of the plate, allow it to dry in air and spray with dilute potassium iodobismuthate solution. Any spot corresponding to 3-methylflavone-8-carboxylic acid in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (2) (0.5%).
Assay
Weigh and finely powder 20 tablets. To a quantity of the powdered tablets containing 1 g of Flavoxate Hydrochloride add 600 mL of 0.1m hydrochloric acid and disperse with the aid of ultrasound for 10 minutes. Place in a water bath at 70° for 90 minutes, cool, add sufficient 0.1m hydrochloric acid to produce 1 litre and filter. Dilute 5 mL to 250 mL with 0.1m hydrochloric acid and measure the absorbance of the resulting solution at 293 nm, Appendix II B. Calculate the content of C24H25NO4,HCl from the absorbance obtained by repeating the measurement using a 0.002% w/v solution of flavoxate hydrochloride BPCRS in 0.1m hydrochloric acid and from the declared content of C24H25NO4,HCl in flavoxate hydrochloride BPCRS.
Storage
Flavoxate tablets should be protected from light.