EXPERIMENT 2.3 : UNIFORMITY OF WEIGHT OF TABLETS AND CAPSULES

AIM: to assess the uniformity of weight of tablets and capsules

DATE: 4^th December 2014

INTRODUCTION:

To ensure the consistency of dosage units, each unit in a given batch should contain the active drug within a narrow range. The uniformity of dosage units can be evaluated either by measuring the content uniformity or the weight of the tested units. The test for weight variation is applicable for hard capsules, uncoated tablets and film-coated tablets. The test for content uniformity is required for all dosage. These tests are necessary to ensure that patients take a precise pharmaceutical dose. The reasons behind this practice include providing the patient with the desired dose if the product is not available in the required strength, starting therapy with the lowest possible doses to reduce the incidence of side effects of certain drugs, reducing medication costs, and making the swallowing of large tablets easier. If the test failed and not uniform, the whole batch is considered as a failure. In this test, 20 tablets and capsule were weighed singly and the average weight are determined. Next, the percentage deviation of a single weight from the average weight can be determined.

EXPERIMENTAL METHOD:

Apparatus and Materials:

•      Mefenamic acid BP 500mg tablet

•      Capsules

•      Electronic balance

•      Weighing boat

Procedures:

Tablets

1. 20 tablets of mefenamic acid were selected randomly and weighed. The average weight were
determined.

2. The tablets were weighed individually and the percentage deviation of it’s weight from the average weight were determined for each tablet.

3. The deviation of individual weight from the average weight should not exceed the limits given below.

Average weight of tablet	Deviation (%)	Number of tablets
Less than 80 mg	± 10.0 ± 20.0	Minimum 18 Maximum 2
80 mg to 250 mg	± 7.5 ± 15.0	Minimum 18 Maximum 2
More than 250 mg	± 5.0 ± 10.0	Minimum 18 Maximum 2

Capsules

1. 20 capsules were selected at random.

2. One capsule were weighed. The capsule was opened and the contents was removed as completely as possible. The emptied shells was weighed. The net weight of it’s contents was determined  by subtracting the weight of the shells from the weight of the intact capsule.

3. The procedure was repeated with other 19 capsules.

4. The average net weight from the sum of the individual net weights was determined.

5. The percentage deviation from the average net weight for each capsule also determined. The deviation of individual net weight should not exceed the limits given below:

Average net weight of capsule	Deviation (%)	Number of tablets
Less than 300 mg	± 10.0 ± 20.0	Minimum 18 Maximum 2
300 mg or more	± 7.5 ± 15.0	Minimum 18 Maximum 2

 RESULTS:

Tablets

Average weight : 0.3526 g

Tablets	Weight of tablets (g)	Percentage of deviation (%)
1	0.3519	±0.20
2	0.3518	±0.20
3	0.3518	±0.20
4	0.3520	±0.17
5	0.3517	±0.26
6	0.3523	±0.08
7	0.3534	±0.23
8	0.3502	±0.68
9	0.3527	±0.03
10	0.3521	±0.14
11	0.3525	±0.03
12	0.3520	±0.17
13	0.3526	±0.00
14	0.3526	±0.00
15	0.3477	±1.44
16	0.3525	±0.03
17	0.3525	±0.03
18	0.3527	±0.03
19	0.3508	±0.51
20	0.3525	±0.03

Capsules

Capsule	Weight of capsule (g)	Weight of empty capsule (g)	Weight of capsule content (g)	Percentage Deviation (%)
1	0.4780	0.0759	0.4021	±4.03
2	0.4731	0.0784	0.3947	±2.12
3	0.4711	0.0770	0.3941	±2.10
4	04594	0.0728	0.3866	±0.03
5	0.4545	0.0763	0.3782	±2.15
6	0.4448	0.0772	0.3676	±4.89
7	0.4590	0.0766	0.3824	±1.06
8	0.4710	0.0825	0.3885	±0.52
9	0.4569	0.0790	0.3779	±2.23
10	0.4720	0.0774	0.3946	±2.10
11	0.4524	0.0736	0.3788	±1.99
12	0.4714	0.0769	0.3945	±2.07
13	0.4355	0.0778	0.3577	±7.45
14	0.4711	0.0749	0.3962	±2.51
15	0.4655	0.0731	0.3924	±1.53
16	0.4646	0.0850	0.3796	±1.79
17	0.4668	0.0750	0.3918	±1.37
18	0.4627	0.0755	0.3872	±0.18
19	0.4649	0.0731	0.3918	±1.37
20	0.4699	0.0757	0.3942	±1.99
Total			7.7309
Average			0.3865

The formula used in calculating the deviation(%) was: Deviation= I Weight of tablet or capsule – Average Weight I  x 100%                                              Average weight DISCUSSION: Tablets:

For tablets, since our average weight is 352.6 mg, the deviation of individual net weight should not exceed the limits given below:

Average net weight of tablets	Deviation (%)	Number of tablets
More than 250 mg	±5.0 ±10.0	Minimum 18 Maximum 2

From the results, the tablets have deviation below ± 5.0 which means that all tablets were within the limit given. This indicates the tablets produced were uniform in weight. Weighing balance play an important role as it must clean enough and free from any dust and impurities to get more accurate results. If the tablets have above the range of standard deviation, it shows that the production of the tablets is a failure as they may have some mistakes happened during manufacturing the tablets.

 Capsules:

For capsules, since our average weight is 386.5 mg, the deviation of individual net weight should not exceed the limits given below:

Average net weight of capsule	Deviation (%)	Number of capsules
300 mg or more	± 7.5 ± 15.0	Minimum 18 Maximum 2

From the results, the capsules have deviation below ± 7.5%, which means that all capsules were within the limit given. This indicates the capsules produced were uniform in weight. In order to get a good and accurate result, weighing balance play an important role. We have to make sure that the weighing balance is clean enough and free from any dust and impurities. Besides, all sources of air should be removed or turned off because this may affect the reading obtained.

If the weight variation in capsule exceeds the limit, this may be due to the defect of the capsule filling machine. The machine may have misalignment or problem in filling the capsule with the target fill weight.

 CONCLUSION:

As conclusion, manufacturing of tablets and capsules should be done according to the procedure and they must have Good Manufacturing Practice so that results of tablets and capsules formed have all criteria needed before it is being marketed. They must have uniformity in weight so that tablets and capsules form have the same effect for each tablets and capsules.

 REFERENCES:

Smith, K.L. 2011. Journal of Pharmacy and Pharmacology. An Improved Test for Uniformity of Weight of Tablets. http://onlinelibrary.wiley.com/doi/10.1111/j.20427158.1955.tb12099.x/abstract

The International Pharmacopoeia 4^th edition. http://apps.who.int/phint/en/p/docf/

Shravani. Quality Control Tests For Pharmaceutical Capsules. http://www.pharmainfo.net/quality-control-capsules [5 Disember 2014]