Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Anticholinergic.
DEFINITION
Flavoxate Tablets contain Flavoxate Hydrochloride. They are coated.
The tablets comply with the requirements stated under Tablets and with the following requirements.
Content of flavoxate hydrochloride, C24H25NO4,HCl
95.0 to 105.0% of the stated amount.
IDENTIFICATION
A. Extract a quantity of the powdered tablets containing 0.2 g of Flavoxate Hydrochloride with 10 mL of dichloromethane, filter and evaporate the filtrate to dryness. The infrared absorption spectrum of the residue, Appendix II A, is concordant with the reference spectrum of flavoxate hydrochloride (RS 143).
B. In the test for Related substances, the principal spot in the chromatogram obtained with solution (5) corresponds to that in the chromatogram obtained with solution (6).
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 0.2 g of Flavoxate Hydrochloride with 10 mL of chloroform and filter.
(2) 0.03% w/v of flavoxate impurity A EPCRS in chloroform.
(3) 0.015% w/v of flavoxate impurity B EPCRS in chloroform.
(4) Dilute 1 volume of solution (1) to 500 volumes with chloroform.
(5) Dilute 1 volume of solution (1) to 20 volumes with chloroform.
(6) 0.1% w/v of flavoxate hydrochloride BPCRS in chloroform.
CHROMATOGRAPHIC CONDITIONS
(a) Use as the coating silica gel GF254.
(b) Use the mobile phase as described below.
(c) Apply 50 μL of solution (1). Apply 10 μL of solutions (2), (3), (5), and (6). Apply 25 μL of solution (4).
(d) Develop the plate to 15 cm.
(e) After removal of the plate, allow it to dry in air and examine immediately under ultraviolet light (254 nm).
MOBILE PHASE
1 volume of 18M ammonia, 80 volumes of propan-2-ol and 200 volumes of ethyl acetate.
LIMITS
Any spot corresponding to impurity B in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (3) (0.15%);
any other secondary spot in the chromatogram obtained with solution (1), other than the spot corresponding to impurity A, is not more intense than the spot in the chromatogram obtained with solution (4) (0.1%).
Impurity A
Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.
(1) Shake a quantity of the powdered tablets containing 0.2 g of Flavoxate Hydrochloride with 10 mL of chloroform and filter.
(2) 0.01% w/v solution of flavoxate impurity A EPCRS in chloroform.
CHROMATOGRAPHIC CONDITIONS
(a) Use as the coating silica gel GF254 (Merck silica gel 60 F254 plates are suitable).
(b) Use the mobile phase as described below.
(c) Apply 50 μL of each solution (1).
(d) Develop the plate to 15 cm.
(e) After removal of the plate, allow it to dry in air and spray with dilute potassium iodobismuthate solution.
MOBILE PHASE
4 volumes of glacial acetic acid, 25 volumes of ethyl acetate and 70 volumes of cyclohexane.
LIMITS
Any spot corresponding to impurity A 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.
IMPURITIES
The impurities limited by the requirements of this monograph include impurities A and B listed under Flavoxate Hydrochloride.
