Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Cyclo-oxygenase inhibitor; analgesic; anti-inflammatory.
DEFINITION
Benzydamine Mouthwash is a solution of Benzydamine Hydrochloride in a suitable flavoured and coloured vehicle.
The mouthwash complies with the requirements stated under Oromucosal Preparations and with the following requirements.
Content of benzydamine hydrochloride, C19H23N3O,HCl
92.5 to 107.5% of the stated amount.
IDENTIFICATION
A. Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.
(1) Dilute the mouthwash, if necessary, with absolute ethanol to contain 0.15% w/v of Benzydamine Hydrochloride.
(2) 0.15% w/v of benzydamine hydrochloride BPCRS in absolute ethanol.
CHROMATOGRAPHIC CONDITIONS
(a) Use a TLC silica gel F254 precoated plate (Merck silica gel 60 F254 plates are suitable).
(b) Use the mobile phase as described below.
(c) Apply 50 μL of each solution.
(d) Develop the plate to 15 cm.
(e) After removal of the plate, dry in air and examine under ultraviolet light (254 nm).
MOBILE PHASE
30 volumes of triethylamine and 80 volumes of toluene.
CONFIRMATION
The principal spot in the chromatogram obtained with solution (1) corresponds to that in the chromatogram obtained with solution (2).
B. In the Assay, the chromatogram obtained with solution (1) shows a peak with the same retention time as the principal peak in the chromatogram obtained with solution (2).
TESTS
Acidity or alkalinity
5.0 to 7.0, Appendix V L.
1-Benzyl-1H-indazol-3-ol
Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.
(1) Extract a quantity of the mouthwash containing 15 mg of Benzydamine Hydrochloride with seven 90-mL quantities of chloroform. Filter each extract through phase separating paper, evaporate the combined extracts to dryness and dissolve the residue in 10 mL of methanol.
(2) 0.0015% w/v of 1-benzyl-1H-indazol-3-ol BPCRS in methanol.
CHROMATOGRAPHIC CONDITIONS
(a) Use a TLC silica gel F254 plate.
(b) Use the mobile phase as described below.
(c) Apply 20 μL of each solution.
(d) Develop the plate to 15 cm.
(e) After removal of the plate, dry in air and examine under ultraviolet light (365 nm).
MOBILE PHASE
10 volumes of glacial acetic acid, 20 volumes of chloroform and 70 volumes of cyclohexane.
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) (1%).
ASSAY
Carry out the method for gas chromatography, Appendix III B, using the following solutions. Prepare a 0.075% w/v solution of 1-benzyl-3-(3-diethylamino-propoxy)-1H-indazole BPCRS (internal standard) in water (solution A).
(1) Add 10 mL of solution A, 5 mL of water, 5 mL of 1M sodium hydroxide and 20 mL of chloroform to a quantity of the mouthwash containing 7.5 mg of Benzydamine Hydrochloride, diluted, if necessary to 5 mL with water, shake for 5 minutes, centrifuge and use the chloroform layer.
(2) Prepare solution (2) in the same manner as solution (1) except using 5 mL of a solution containing 0.15% w/v of benzydamine hydrochloride BPCRS in water in place of a quantity of the mouthwash containing 7.5 mg of Benzydamine Hydrochloride, diluted, if necessary, to 5 mL with water.
CHROMATOGRAPHIC CONDITIONS
a) Use a glass column (2 m × 2 mm) packed with acid-washed, diatomaceous support (80 to 100 mesh) coated with 3% w/w of phenyl methyl silicone fluid (50% phenyl) (OV-17 is suitable).
(b) Use nitrogen for chromatography as the carrier gas at 30 mL per minute.
(c) Use isothermal conditions maintained at 260°.
(d) Use an inlet temperature of 300°.
(e) Use a flame ionisation detector at 300°.
(f) Inject 1 μL of each solution.
DETERMINATION OF CONTENT
Calculate the content of C19H23N3O,HCl from the chromatograms obtained using the declared content of C19H23N3O,HCl in benzydamine hydrochloride BPCRS.
LABELLING
The label states, where appropriate, that the preparation is also suitable for use as a gargle.
