Hydrochlorothiazide Tablets
Action and use
Thiazide diuretic.
Definition
Hydrochlorothiazide Tablets contain Hydrochlorothiazide.
Content of hydrochlorothiazide, C7H8ClN3O4S2
92.5 to 107.5% of the stated amount.
Identification
Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.
By each method of visualisation the principal spot in the chromatogram obtained with solution (1) corresponds in colour and intensity to that in the chromatogram obtained with solution (2).
TESTS
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
10 volumes of tetrahydrofuran, 60 volumes of methanol and 940 volumes of phosphate buffer solution pH 3.2 R1.
50 volumes of tetrahydrofuran, 500 volumes of methanol and 500 volumes of phosphate buffer solution pH 3.2 R1.
Equilibrate the column for at least 20 minutes with mobile phase A.
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between the peaks corresponding to chlorothiazide and hydrochlorothiazide is at least 2.5.
In the chromatogram obtained with solution (1):
the area of any secondary peak is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (1%);
the sum of the areas of any secondary peaks is not greater than 2.5 times the area of the principal peak in the chromatogram obtained with solution (2) (2.5%).
Disregard any peak with an area less than 0.1 times the area of the principal peak in the chromatogram obtained with solution (2) (0.1%).
Assay
Weigh and powder 20 tablets. To a quantity of the powder containing 30 mg of Hydrochlorothiazide add 50 mL of 0.1m sodium hydroxide, shake for 20 minutes and dilute to 100 mL with 0.1m sodium hydroxide. Mix, filter, dilute 5 mL of the filtrate to 100 mL with water and measure the absorbance of the resulting solution at the maximum at 273 nm, Appendix II B. Calculate the content of C7H8ClN3O4S2 taking 520 as the value of A(1%, 1 cm) at the maximum at 273 nm.