Chlorphenamine Tablets
Action and use
Histamine H1 receptor antagonist; antihistamine.
Definition
Chlorphenamine Tablets contain Chlorphenamine Maleate.
Content of chlorphenamine maleate, C16H19ClN2,C4H4O4
92.5 to 107.5% of the stated amount.
Identification
Comply with the test described under Chlorphenamine Injection using as solution (1) a solution prepared in the following manner. Extract a quantity of the powdered tablets containing 5 mg of Chlorphenamine Maleate with chloroform, filter, evaporate to dryness and dissolve the residue in 1 mL of chloroform.
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 10 volumes of diethylamine, 40 volumes of chloroform and 50 volumes of cyclohexane as the mobile phase but allowing the solvent front to ascend 12 cm above the line of application. Apply separately to the plate 10 µL of each of the following solutions. For solution (1) extract a quantity of the powdered tablets containing 50 mg of Chlorphenamine Maleate with chloroform, filter, evaporate the filtrate to dryness and dissolve the residue in 1 mL of chloroform. For solution (2) dilute 1 volume of solution (1) to 500 volumes with chloroform. After removal of the plate, allow it to dry in air and examine under ultraviolet light (254 nm). Any secondary spot in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (2) (0.2%). Disregard any spot remaining on the line of application.
Assay
Weigh and powder 20 tablets. Shake a quantity of the powder containing 3 mg of Chlorphenamine Maleate with 20 mL of 0.05m sulfuric acid for 5 minutes, add 20 mL of ether, shake carefully and filter the acid layer into a second separating funnel. Extract the ether layer with two 10-mL quantities of 0.05m sulfuric acid, filter each acid layer into the second separating funnel and wash the filter with 0.05m sulfuric acid. Make the combined acid extracts and washings just alkaline to litmus paper with 1m sodium hydroxide, add 2 mL in excess and extract with two 50 mL quantities of ether. Wash each ether extract with the same 20 mL of water and extract with successive quantities of 20, 20 and 5 mL of 0.25m sulfuric acid. Dilute the combined acid extracts to 50 mL with 0.25m sulfuric acid, dilute 10 mL to 25 mL with 0.25m sulfuric acid and measure the absorbance of the resulting solution at the maximum at 265 nm, Appendix II B. Calculate the content of C16H19ClN2,C4H4O4 taking 212 as the value of A(1%, 1 cm) at the maximum at 265 nm.