EXPERIMENT 3: UNIFORMITY OF WEIGHT OF TABLETS AND CAPSULES

OBJECTIVE

To determine the uniformity of dosage and weight of tablets and capsules.

INTRODUCTION

The uniformity of the dosage units can be demonstrated by either content uniformity or mass variation.

Weight variation (WV) test can be done only on certain unit dose as shown in Table 1. Other unit dose will need to undergo content uniformity (CU) test.

In weight variation test, measurement of contents is done by estimation of contents based on weight. Pharmacists often use and misuse this WV test by doing this test on all dosage units. If it is used correctly, this WV test can be used to measure content uniformity (CU). There are some conditions in which the weight difference can determine the percentage difference in the API in the individual dosage units. Hence this WV test can be useful in the quality control of drug production.

MATERIALS AND APPARATUS

Apparatus :Weighing balance, weighing boat

Material : 20 Tablets and 20 capsules

A.                Tablets: Ettracin tablet

PROCEDURES

1. 20 tablets were selected randomly and weighed. The average weight was determined.

2. The tablets were weighed individually and for each tablet, the percentage deviation of its weight from the average weight was determined.

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

No.	Individual weight of tablets(g)	Percentage of deviation(%)
1	0.6564	-2.28
2	0.6749	0.48
3	0.6772	0.82
4	0.6617	-1.49
5	0.6749	0.48
6	0.6461	-3.81
7	0.6974	3.83
8	0.6681	-0.54
9	0.6805	1.31
10	0.6930	3.17
11	0.6740	0.34
12	0.6709	-0.12
13	0.6627	-1.34
14	0.6825	1.61
15	0.6824	1.59
16	0.6570	-2.19
17	0.6709	-0.12
18	0.6779	0.92
19	0.6748	0.46
20	0.6504	-3.17

Total weight of 20 tablets =13.4337g

Average weight :  13.4337g / 20

                  =0.6717g

Percentage of deviation =  x 100%

B.CAPSULES: AMPILIN ANTIBIOTIC CAPSULE 250MG

PROCEDURE

1. 20 capsules were selected at random.

2. One capsule was weighed. The capsule was then opened and the contents were removed as completely as possible. The emptied shells were weighed. The net weight of its contents was determined, that is by subtracting the weight of the shells from the weight of the intact capsule.

3. The procedure was repeated with the other 19 capsules.

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

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

No	Individual weight of capsules(g)	Weight of emptied shells(g)	Net weight of the contents(g)	Percentage deviation(%)
1	0.3596	0.0640	0.2956	0.24
2	0.3425	0.0636	0.2789	-5.43
3	0.3651	0.0672	0.2979	1.02
4	0.3447	0.0660	0.2787	-5.49
5	0.3633	0.0647	0.2986	1.25
6	0.3454	0.0690	0.2764	-6.27
7	0.3595	0.0624	0.2971	0.74
8	0.3629	0.0627	0.3002	1.80
9	0.3714	0.0626	0.3088	4.71
10	0.3676	0.0623	0.3053	3.53
11	0.3409	0.0625	0.2784	-5.60
12	0.3752	0.0635	0.3117	5.70
13	0.3561	0.0653	0.2908	-1.39
14	0.3637	0.0651	0.2986	1.25
15	0.3629	0.0627	0.3002	1.80
16	0.3582	0.0647	0.2935	-0.47
17	0.3576	0.0645	0.2931	-0.61
18	0.3758	0.0637	0.2941	-0.27
19	0.3766	0.0634	0.3132	6.21
20	0.3524	0.0651	0.2873	-2.58

Total net weight of the content of 20 capsules = 5.8984 g

Average net weight  = 5.8984 g / 20

                                =0.2949 g

DISCUSSION

Since our average weight of the tablets exceed 250mg so the deviation should be±5.0 % for maximum eighteen tablets and only±10.0 % for minimum two tablets. From the results, we can see that all the 20  Ettrocin tablets are having standard deviation of ±5.0%. There is no tablets of having the ±10.0 standard deviation. Hence this indicate that the production of uniform tablets.

If there are more than two tablets of exceeding the ±10.0 standard deviation, this may indicate the ununiformed weights of the tablets and at the same time may indicate the occurrence of errors. The errors might include the presence of tablet fragments or dust on the tablets when weighed. It can also be the systematic error caused by the inaccuracy of the weighing balance. Environmental factors such as vibration of the table or wind from the air-conditioning may also cause the fluctuation in the value presented by the weighing balance.

However, the variation in the weight of the tablets may be explained by the following. Factors such as the flowing properties of the powder, the speed of tableting machine, the pressure used in compression and the type of machines used in tableting may affect the weight of a tablet. However the two most common causes of weight variation are the differences in the bulk densities and particle size distribution during compression.

For capsules, since our average weight is 295 mg, the deviation of individual net weight should not exceed the limits given below:

From the results, all our capsules are having a deviation of ±10%, which means that all capsules have uniform weights. This may indicate the uniformity of the capsules production. At the same time, this uniformity may also be caused by the usage of a good weighing balance. The weighing balance used for measuring the weight of capsule is more accurate as it is a more advanced balance.

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 of the upper and lower capsule segments or problem in filling the capsule with the target fill weight.

CONCLUSION

The tablets and capsules tested have passed in the test of weight uniformity. This means that both the tablets and capsules tested in this experiment have uniformity in weight production of them.

REFERENCES

1. http://www.pharmainfo.net/files/idownloads/pharmacoeialtestfoDF.pdf

1.Donald K. Lightfoot. (n.d.) Answers To 10 Common Questions About Capsule Filling. Retrieved date. 21st December 2013. From http://capsugel.com/media/library/answers-to-10-common-questions-about-capsule-filling.pdf

2.Dshravani. (2013) Citing Websites. Quality Control Of Capsules. Retrieved date. 21st December 2013. From http://www.pharmainfo.net/quality-control-capsules