Amilorideand Frusemide Tablets 

Amiloride Hydrochloride and Furosemide Tablets; Amiloride and Furosemide Tablets; Amiloride Hydrochloride and Frusemide Tablets; Frusemide and Amiloride Hydrochloride; Frusemide and Amiloride Tablets; Furosemide and Amiloride Hydrochloride; Co-amilofruse.

Amiloride Hydrochloride and Frusemide Tablets contain not less than 95.0 per cent and not more than 105.0 per cent of the stated amount of anhydrousamiloride hydrochloride,C6H8ClN₇O, HCl and frusemide,C12H11ClN₂O5S.

Usual strengths. Amiloride Hydrochloride 5 mg and Frusemide 20 mg; Amiloride Hydrochloride 5 mg and Frusemide 40 mg;

Identification

1. In the Related substance, the principal spots in the chromatogram obtained with the test solution (b) corresponds to the corresponding principal spot in the chromatogram obtained with the reference solution (b) and (c).
2. In the Assay, the principal peaks in the chromatogram obtained with the test solution corresponds to the principal peaks in the chromatogram obtained with the reference solution (c).

Tests

Related substances.Determine bythin-layer chromatography (2.4.17), coating the plate with silica gel GF254.

Mobile phase. A mixture of 5 volumes of glacial acetic acid, 5 volumes of methanol and 90 volumes of chloroform.

Test solution (a). Weigh a quantity of the powdered tablets containing 80 mg of Frusemide, add 16 ml of methanol and disperse with the aid of ultrasound for 5 minutes, centrifuge and use the clear supernatant liquid.

Test solution (b). Dilute 1.0 ml of the test solution (a) to 10.0 ml with methanol.

Reference solution (a). Dilute 1.0 ml of test solution (b) to 20.0 ml with methanol.

Reference solution (b).A 0.05 per cent w/v solution of frusemide RS in methanol.

Reference solution (c).A 0.00625 per cent w/v solution of amiloride hydrochloride RS in methanol.

Reference solution (d).A 0.0025 per cent w/v solution of 4-chloro-5-sulfaamoylanthranilic acid RS in methanol.

Reference solution (e). A 0.00031 per cent w/v solution of methyl 3,5-diamino-6-chloropyazine-2-carboxylate RS in methanol.

Apply to the plate 20 µl of each solution. Allow the mobile phase to rise 15 cm. After development, dry the platein a current of warm air and examine under ultraviolet light at 254 nm and 365 nm.

At 254 nm

In the chromatogram obtained with test solution (a) any secondary spot other than any spot remaining on the line of application or any spots corresponding to either of the named impurities is not more intense than the spot in the chromatogram obtained with reference solution (a) (0.5 per cent, with reference to the content of frusemide).

At 365 nm

Spray the plate with ethanolicsulphuric acid (20 per cent), heat at 105 for 30 minutes and immediately expose to nitrous fumes in a closed glass tank for 15 minutes (the nitrous fumes may be generated by adding 7M sulphuric acid dropwise to a solution containing 10 per cent w/v of sodium nitrite and 3 per cent w/v of potassium iodide). Place the plate in a current of warm air for 15 minutes and spray with a 0.5 per cent w/v solution of N-(1-naphthyl)ethylenediaminedi hydrochloride in ethanol(95 per cent). If necessary, allow to dry and repeat the spraying.

In the chromatogram obtained with test solution (a) any spot corresponding to methyl 3,5-diamino-6-chloropyrazine-2-carboxylate is not more intense than the spot in the chromatogram obtained with reference solution (e) (0.5 per cent, with reference to the content of anhydrous amiloride hydrochloride) and  any spot corresponding to 4-chloro-5-sulfamoylanthranilic acid is not more intense than the spot in the chromatogram obtained with reference solution (d) (0.5 per cent, with reference to the content of frusemide).

Assay. Determine by liquid chromatography (2.4.14).

Solvent mixture. A mixture of 4 volumes of water and 6 volumes of methanol adjusted to pH 2.0 with orthophosphoric acid.

Test solution. Weigh and powder 20 tablets. Disperse a quantity of the powdered tablets containing 40 mg of Frusemide in 70 ml of solvent mixture, mix with the aid of ultrasound for 20 minutes, dilute to 100.0 ml with the same solvent mixture, mix, filter and dilute 20.0 ml of the filtrate to 50.0 ml with the same solvent mixture.

Reference solution (a).A 0.04 per cent w/v solution of amiloride hydrochloride RS in the solvent mixture.

Reference solution (b).A 0.16 per cent w/v solution of frusemide RS in the solvent mixture.

Reference solution (c).Dilute reference solution (a) and (b) in the solvent mixture to obtain a solution having a known concentration similar to the test solution.

Chromatographic system

    –  a stainless steel column 25 cm x 4.6 mm, packed with octadecylsilane bonded to porous silica (10 µm),

    –  mobile phase: a 0.02 M solution of sodium hexanesulphonate in a mixture of 4 volumes of water and 6 volumes of methanol, the pH adjusted to 4.0 with 1 M acetic acid.

    –  flow rate: 1.2 ml per minute,

    –  spectrophotometer set at 361 nm,

    –  injection volume: 20 µl.

Inject reference solution (c). The test is not valid unless the resolution between the peaks due to frusemide and amiloride is not less than 2.5.

Inject reference solution (a) and (b) for peak identification.

Inject reference solution (c) and the test solution.

Calculate the content of C6H8ClN₇O, HCl and C12H11ClN₂O5S.

Storage. Store protected from light.

Labelling. The label states the strength in terms of the equivalent amount of amiloride hydrochloride.