EXPERIMENT 4: UNIFORMITY OF WEIGHT OF TABLETS AND CAPSULES.
OBJECTIVE:
To determine the uniformity of weight of tablets and capsules
MATERIAL/APPARATUS:
20 tablets, 20 capsules, weighing boat, weighing balance.
PROCEDURE:
Tablets
1. 20 tablets selected at random are weighed. The average weight is determined.
2. Tablets are individually weighed and for each tablet, the percentage deviation of its weight from the average weight is determined.
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
|
Minimum 18
|
± 20.0
|
Maximum 2
| |
80 mg to 250 mg
|
± 7.5
|
Minimum 18
|
± 15.0
|
Maximum 2
| |
More than 250 mg.
|
± 5.0
|
Minimum 18
|
± 10.0
|
Maximum 2
|
Capsules
1. 20 capsules are selected at random.
2. One capsule is weighed. Capsule is opened and the contents are removed as completely as possible. The emptied shells are also weighed. The net weight of its content is weighed, that is by subtracting the weight of the shells from the weight of the intact capsule.
3. The procedure is repeated with other 19 capsules.
4. The average net weight from the sum of the individual net weights is weighed.
5. The percentage deviation is determined from the average net weight for each capsule. 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
|
Minimum 18
|
± 20.0
|
Maximum 2
| |
300 mg or more
|
± 7.5
|
Minimum 18
|
± 15.0
|
Maximum 2
| |
RESULTS
Total weight of 20 tablets: 13.4523 g
Average of net weight = 13.4523 g
20
= 0.6726 g
|
Percentage deviation = (weight of individual tablet – average weight )
Average weight
Tablets
Tablet
|
Individual weight (g)
|
Percentage deviation (%)
|
1
|
0.6727
|
0.01
|
2
|
0.6791
|
0.97
|
3
|
0.6738
|
0.18
|
4
|
0.6514
|
-3.15
|
5
|
0.6740
|
0.21
|
6
|
0.6776
|
0.74
|
7
|
0.6605
|
-1.80
|
8
|
0.6506
|
-3.27
|
9
|
0.6731
|
0.07
|
10
|
0.6633
|
-1.38
|
11
|
0.6943
|
0.03
|
12
|
0.6719
|
-0.10
|
13
|
0.6731
|
0.07
|
14
|
0.6724
|
-0.03
|
15
|
0.6805
|
1.17
|
16
|
0.6740
|
0.21
|
17
|
0.6686
|
-0.59
|
18
|
0.6723
|
-0.04
|
19
|
0.6851
|
1.86
|
20
|
0.6864
|
2.05
|
Capsules
Total net weight of 20 capsules: 7.8212 g
Average of net weight= 7.8212 g
20
= 0.3911 g
|
Percentage deviation = (net weight of individual capsule – average net weight )
Average net weight
Capsule
|
Weight of individual capsule (g)
|
Weight of empty shell (g)
|
Net weight of individual capsule (g)
|
Percentage deviation (%)
|
1
|
0.4696
|
0.0734
|
0.3962
|
1.30
|
2
|
0.4623
|
0.0760
|
0.3863
|
-1.23
|
3
|
0.4650
|
0.0765
|
0.3885
|
-0.66
|
4
|
0.4352
|
0.0437
|
0.3915
|
-0.10
|
5
|
0.4705
|
0.0750
|
0.3955
|
1.13
|
6
|
0.4575
|
0.0721
|
0.3954
|
1.10
|
7
|
0.4475
|
0.0725
|
0.3750
|
-4.12
|
8
|
0.4699
|
0.0752
|
0.3947
|
0.92
|
9
|
0.4684
|
0.0752
|
0.3932
|
0.54
|
10
|
0.4701
|
0.0756
|
0.3945
|
0.87
|
11
|
0.4678
|
0.0745
|
0.3922
|
0.28
|
12
|
0.4590
|
0.0762
|
0.3828
|
-2.12
|
13
|
0.4692
|
0.0734
|
0.3958
|
1.20
|
14
|
0.4761
|
0.0774
|
0.3987
|
1.94
|
15
|
0.4774
|
0.0742
|
0.4032
|
3.09
|
16
|
0.4655
|
0.0796
|
0.3859
|
-1.33
|
17
|
0.4625
|
0.0764
|
0.3861
|
-1.28
|
18
|
0.4557
|
0.0745
|
0.3812
|
-2.53
|
19
|
0.4681
|
0.0763
|
0.3918
|
0.18
|
20
|
0.4725
|
0.0798
|
0.3927
|
0.41
|
DISCUSSION
Based on the results obtained, the average weight of tablet is 0.6726 g / 672.6 mg which is more than 250 mg. Hence the percentage deviations should have a minimum of 18 tablets within the range of ± 5.0 and maximum of 2 tablets within the range of 10.0. From the data obtained, it shows that the percentage deviations of all 20 capsules are between the range of ± 5.0 with the highest value of -3.27 %(capsule 8). This indicates that the tablets have a uniform and consistent weight.
The average net weight of capsules is 0.3911 g/ 391.1 mg which is more than 300 mg. Thus, the percentage deviation should have a minimum of 18 capsules and maximum of 2 capsules in the range of ± 7.5 and ± 15.0 respectively. From the data obtained, no capsule reached ± 15.0 of standard deviation as the highest value is 3.09 %(capsule 15). The percentage deviation of all capsules lies between the ranges of ± 7.5 which indicates that the capsules have a uniform and consistent weight.
There are some possible errors that might occur while conducting the experiment which may affect the accuracy of the readings. Some of it is vibration of table or in the floor and air current can cause fluctuations in the weighing balance. There might also some solids or dust on the weighing balance that is not removed before weighing procedure continued. The content of the capsules also might not completely remove thus decrease the accuracy of readings.
CONCLUSION
Uniformity test of tablets and capsules weight and content is important to ensure the consistency of dosage units of each tablet and capsule. In this experiment, both preparations comply with the test as all percentage deviation is between the range that is determined in the British Pharmacopoeia.
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