## STP FOR AMLODIPINE TABLETS

1.0) Description: Visual

2.0)  Average Weight: Check weight of 20 tablets at randomly and calculate the average weight by formula :

wt of 20 tablets (gm) x 1000 / 20. found avg. wt in mg

3.0)   Uniformity of weight:

Weigh 20 tablets selected at random and calculate the average weight. Not more than two of the individual weights deviate from the average weight by more than the percentage shown in table.

Tablets were weighed individually and the percentage of deviation of its weight from the average weight was determined for each tablet. Formula for calculate the percentage of deviation = (experimental weight – theoretical weight)    x 100

Theoretical weight

 Average weight of tablets Percentage deviation More than 80mg but Less than 250mg 7.5% 250mg or More 5%

4.0)      Identification Test:

In the assay, the principal peak in the chromatogram obtained with the test solution (b) corresponds to the peak in the chromatogram obtained with the reference solution (a).

5.0)      Hardness:

The standard method used for tablet hardness testing is compression testing. The tablet is placed between two jaws that crush the tablet. The machine measures the force applied to the tablet and detects when it fractures. Although compressive force is applied to the tablet, along the diameter of the tablet at right angles to the applied force.

6.0)      Disintegration Time:

Unless otherwise stated in the individual monograph, introduce one tablet into each tube and add a disc to each tube. The assembly is suspended in the liquid medium in a suitable vessel, preferably a 1-litre beaker. The volume of liquid is such that the wire mesh at its highest point is at least 15mm below the surface of the liquid, and at its lower point is at least 25mm above the bottom of the beaker. At no time should the top of the basket-rack assembly become submerged. There is a thermostatic arrangement for heating the liquid and maintaining the temperature at 37±2°.

If 1 or 2 tablets fail to disintegrate, repeat the test on 12 additional tablets; not less than 16 of the total of 18 tablets tested disintegrate.

If the tablets adhere to the disc and the preparation under examination fails to comply, repeat the test omitting the disc. The preparation complies with the test if all the tablets in the repeat test disintegrate.

7.0)      Dimension of Tablet:

Length, breadth and thickness are determined by vernier in mm

8.0)      Friability:

The test is applicable to compressed tablets and is intended to determine the physical strength of tablets. Tablets with a unit weight equal to or less than 650 mg, take a sample of whole tablets corresponding as near as possible to 6.5g. For tablets with a unit weight of more than 650mg, take a sample of 10 whole tablets. The tablets should be carefully dedusted prior to testing. Accurately weigh the tablet sample, and place the tablets in the drum. Rotate the drum 100 times and remove the tablets. Remove any loose dust from the tablets as before, and accurately weigh.

The test is run only once unless the results are difficult to interpret or if the weight loss is greater than the target value, in which case, the test is repeated twice and the mean of the three tests is determined.

Formula: initial wt. – after friability wt. x100 / initial wt.

A maximum loss of weight (From a single test or from the mean of three tests) not greater than 1.0 percent is acceptable for most tablets.

If obviously cracked, chipped or broken tablets are present in the sample after tumbling, the sample fails the test.

9.0)      Dissolution:

Medium: 500ml of 0.01 M Hydrochloric acid

Time: 30 minutes

Speed: 75 rpm

Limit: NLT 80% of the stated amount of Amlodipine.

Withdraw a suitable volume of the medium and filter. Measure the absorbance of the filtered solution, suitably diluted with the medium if necessary, at the                   maximum at about 239nm. Calculate the content of Amlodipine in the medium from the absorbance obtained from a solution of known concentration of                       Amlodipine Besilate reference standard in the same medium.

10.0)    Leak test:

The apparatus is used to test for the integrity of packed strips, blisters and Alu-Alu Blister pack containing tablets. Ensure apparatus bath is filled with purified water upto mark indicated and add 0.5% crystal violet solution in water. Samples are placed into the desiccators and the lid is placed in position. The pump starts to produce a vacuum 15inHg inside the desiccators and the vacuum is held for 1 minute. The sample remains at the required vacuum level for given time interval buzzer will sound after time is over and will cut off the vacuum pump. As the package is immersed in a colored dye solution the venting of the desiccators will allow any holes to be penetrated by the dye and the contents of the flexible packaging will also be stained with the same coloring material.

Examine all the strips for any leakage by opening the pockets manually. If anyone pocket shows evidence of leakage, reject the sample, stop the Blister / Strip machine and immediately take corrective action.

11.0)    Related substance:

Determined by liquid chromatography.

Test solution (a): Weigh and powder 20 tablets. Weigh a quantity of the powder containing 50mg amlodipine, dissolve in the mobile phase, dilute to 50.0ml with the mobile phase and centrifuge.

Test solution (b): Dilute 5ml of the test solution (a) to 100ml with mobile phase.

Reference solution (a): A solution of amlodipine besilate reference standard containing 0.005 per cent w/v of amlodipine in the mobile phase.

Reference solution (b): Dilute 5.0ml of test solution (a) to 100ml with the mobile phase. Dilute 5ml if this solution to 50ml with the mobile phase.

Reference solution (c): Dissolve 5mg of amlodipine besilate reference standard in 5ml of strong hydrogen peroxide solution. Heat at 70° for 45 minutes and centrifuge.

Chromatographic system:

• A stainless steel column 15cmX3.9mm packed with octadecylsilane bonded to porous silica (5µm),
• Mobile phase: a mixture of 15 volumes of acetonitrile, 35 volumes of methanol and 50 volumes of a solution prepared by dissolving 7.0ml of triethylamine in 1000ml water, adjusted to pH 3.0 with O.P.A.
• Flow rate: 1ml per minute,
• Spectrophotometer set at 237nm,
• Injection volume: 10µl

The relative retention time between amlodipine and amlodipine impurity D (3-ethyl 5-methyl2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-6-methylpyridine-3,5-dicarboxylate) is about 0.5.

Inject reference solution(c). The test is not valid unless the resolution between the peaks corresponding to amlodipine and impurity D is at least 4.5.

Inject test solution (a) and reference solution (b). Continue the chromatography for 3 times the retention time of amlodipine. The area of any peak corresponding to amlodipine impurity D multiplied by 2 is not more than the area of the principal peak in the chromatogram obtained with reference solution (b) (0.5 per cent). The sum of the area of all the other secondary peaks is not more than the area of the principal peak in the chromatogram obtained with reference solution (b) (0.5 per cent) Ignore any peak due to benzene sulphonate (relative retention about 0.2) and any peak with an area 0.1 times the area of the principal peak in the chromatogram obtained with reference solution (b) (0.05 per cent).

12.0)    Uniformity of content:

Determine by liquid chromatography

Test solution: Powder one tablet and dissolve in 50ml of the mobile phase, dilute with sufficient mobile phase get a solution containing 0.002 per cent w/v of amlodipine, shake for 10 minutes and filter through a glass- fibre filter paper.

Reference solution: A solution of amlodipine besilate reference standard in mobile phase equivalent to 0.002 per cent w/v of amlodipine.

Chromatographic system:

• A stainless steel column 15cmX3.9mm packed with octadecylsilane bonded to porous silica (5µm),
• Mobile phase: a mixture of 15 volumes of acetonitrile, 35 volumes of methanol and 50 volumes of a solution prepared by dissolving 7.0ml of triethylamine in 1000ml water, adjusted to pH 3.0 with O.P.A.
• Flow rate: 1ml per minute,
• Spectrophotometer set at 237nm,

Injection volume: 10µl

Calculate the content of Amlodipine in the tablet.

13.0)    Assay: Determined by liquid chromatography.

Test solution (a): Weigh and powder 20 tablets. Weigh a quantity of the powder containing 50mg amlodipine, dissolve in the mobile phase, dilute to 50.0ml with the mobile phase and centrifuge.

Test solution (b): Dilute 5ml of the test solution (a) to 100ml with mobile phase.

Reference solution (a): A solution of amlodipine besilate reference standard containing 0.005 per cent w/v of amlodipine in the mobile phase.

Chromatographic system:

• A stainless steel column 15cmX3.9mm packed with octadecylsilane bonded to porous silica (5µm),
• Mobile phase: a mixture of 15 volumes of acetonitrile, 35 volumes of methanol and 50 volumes of a solution prepared by dissolving 7.0ml of triethylamine in 1000ml water, adjusted to pH 3.0 with O.P.A.
• Flow rate: 1ml per minute,
• Spectrophotometer set at 237nm,
• Injection volume: 10µl

Inject reference solution (a) and test solution (b).

Calculate the content of Amlodipine in tablets.

Formula:

Area of Test      STD Wt.(mg)      5                 50                  100           Potency

—————–X————–X——-X—————–X——–X—————-X Average wt.

Area of STD        100                  50          Test Wt.(mg)         5                100

Alternative Method: By UV Spectrophotometer

Test Solution: Weigh and powder 20 tablets. Weight sample equivalent to 5mg of Amlodipine 100ml volumetric flask add 20ml 0.1M HCl into it and sonicate to dissolve the test sample. Make up to mark with 0.1 M HCl. Filter and check absorbance.

Reference Solution: Weigh 30mg of reference standard of Amlodipine besilate in 50ml of volumetric flask. Add 20ml 0.1 M HCl into it and sonicate to dissolve. Make up to mark with 0.1 M HCl. Dilute 5ml of this solution to 50ml with same solvent.

Check Absorbance of test as well as reference standard at about 362nm in UV Spectrophotometer.

Calculate the content of Amlodipine in the tablets.

Formula:

Area of Test      STD Wt.(mg)  5              100                 Potency

—————–X————–X——-X——————–X———–X Average wt.

Area of STD        50               50        Test Wt.(mg)          100

Acceptance criteria: 90.0%-110.0%

14.0)    MICROBIOLOGICAL PURITY:

Perform the test according to requirements of IP,

Total aerobic Microbial count (TAMC): NMT 103 CFU/g

Total combined yeasts/Moulds count (TYMC): NMT 102 CFU/g

Pathogens: in 1gm drug.

Escherichia Coli – Should be absent

Pseudomonas aeroginosa – Should be absent

Salmonella – Should be absent

Staphylococcus aureus– Should be absent

Abbreviations:

Wt.: Weight

mg: Miligram

ml: Milileter

STD: Standard

inHg: Inch of Mercury

rpm: Rounds per minute

CFU: Colony forming unit

O.P.A: Orthophosphoric acid

HCl: Hydrochloric acid