Lovastatin Tablets                

Lovastatin Tablets contain not less than 90.0 per cent and not more than 110.0 per cent of the stated amount of lovastatin, C24H36NO5.

Usual strengths. 10mg ; 20 mg ; 40 mg.

Identification

1. In the Assay, the principal peak in the chromatogram obtained with the test solution corresponds to the peak in the chromatogram obtained with the reference solution.
2. Determine by thin-layer chromatography (2.4.17), coating the plate withsilica gel G.

Test solution. Disperse a quantity of powder containing 16 mg of lovastatin, add 0.4 ml of water and 1.6 ml of acetronitrile. Sonicate for 4 minutes. Centrifuge for 4 minutes, and use the clear supernatant.

Reference solution. A 0.8 per cent w/v solution of lovastatin RS in acetonitrile.

Mobile phase. A mixture of 5 volumes of cyclohexane 2 volumes of chloroform and 1 volume of isopropyl alcohol.

Apply to the plate 5 µl of each solution . After development, dry the plate in air and examine under ultraviolet light at 254 nm. The principal spot in the chromatogram obtained with the test solution corresponds to that in the chromatogram obtained with the reference solution.

Tests

Dissolution (2.5.2).

Apparatus No. 1,

Medium. 900 ml of a solution prepared by dissolving 1.38 g of monobasic sodium phosphate and 20 g of sodium lauryl sulphate in 900 ml of water adjust to pH 7.0 with 1M sodium hydroxide  and dilute 1000 ml with water,

Speed and time. 50 rpm and 30 minutes.

Withdraw a suitable volume of the medium and filter.

Determine by liquid chromatography (2.4.14).

Test solution. Use the filtrate.

Reference solution. Dissolve a quantity of lovastatin RS in sufficient methanol and dilute with the dissolution medium to obtain a solution having a known concentration similar to the expected concentration of the test solution.

Chromatographic system

     –   a stainless steel column 5 cm x 4.6 mm, packed with octadecylsilane bonded to porous silica (5 µm),

     –   mobile phase: a mixture of 30 volumes of a buffer solution prepared by dissolving 3.45 g of monobasic sodium phosphate in 900 ml of water and adjusting the pH 4.0 with orthophosphoric acid and dilute with water to 1000 ml, 50 volumes of acetonitrile and 10 volumes of methanol,

     –   flow rate: 2.0 ml per minute,

     –   spectrophotometer set at 230 nm,

     –   injection volume: 10 µl.

Inject the reference solution and the test solution.

Calculate the content of C24H36NO5 in the medium.

5. Not less than 80 per cent of the stated amount of C24H36NO5.

Uniformity of content. Complies with the test stated under Tablets.

Determine by liquid chromatography (2.4.14), using the chromatographic conditions and reference solution as described under Assay.

Test solution. Transfer one tablet in 50.0 ml volumetric flask, disperse in minimum quantity of water and add sufficient quantity of solvent mixture, sonicate and filter. Dilute , if necessary and make a similar concentration as the reference solution.

Calculate the content of C24H36NO5 in the tablet.

Other tests. Comply with the tests stated under Tablets.

Assay. Determine by liquid chromatography (2.4.17).

Solvent mixture. 20 volumes of a buffer solution prepared by dissolving 3 ml of glacial acetic acid in 900 ml of water, adjust to a pH of 4.0 by the addition of sodium hydroxide solution (20 per cent w/v sodium hydroxide in water) dilute in 1000 ml with water and 80 volumes of acetonitrile.

Test solution. Weigh and powder 20 tablets. Shake a quantity of the powder containing 40 mg of Lovastatin, add 150 ml of solvent mixture, and sonicate for 20 minutes cool and stands for 30 minutes, dilute 200.0 ml with same solvent, centrifuge a portion of this solution. Dilute 5.0 ml of this solution to 25.0 ml with same solvent.

 Reference solution. A 0.004 per cent w/v solution of lovastatin RS in the solvent mixture.

Chromatographic system

     –   a stainless steel column 25 cm x 4.6 mm, packed with octadecylsilane bonded to porous silica (5 µm),

     –   column temperature: 45°,

     –   mobile phase: a mixture of 30 volumes of a buffer solution prepared by dissolving 3.45 g of monobasic sodium phosphate in 900 ml of water and adjusting the pH 4.0 with orthophosphoric acid and dilute with 1000 ml of water, 50 volumes of acetonitrile and 10 volumes of methanol,

     –   flow rate: 1.5 ml per minute,

     –   spectrophotometer set at 230 nm,

     –   injection volume: 50 µl.

Inject the reference solution. The test is not valid unless the column efficiency is not less than 3000 theoretical plates, the tailing factor is not more than 2.0 and the relative standard deviation for replicate injections is not more than 2.0 per cent.

Inject the reference solution and the test solution.

Calculate the content of C24H36NO5in the tablets.

Storage. Store protected from light and moisture.