Title
Uniformity of
weight of tablets and capsule
Objective
Determine whether the uniformity of weight of tablets
and capsules studied comply with the standard of British Pharmacopoeia or not.
Introduction
Uniformity of weight of tablets and capsules is an
important quality assessment to ensure that each of the tablet and capsule
produced meets the requirement of pharmacopoeia standard and also manufacturing
standard. Uniformity of weight test is not applicable to tablets and capsules
required to comply with the test for uniformity of content. Uniformity of
tablets and capsules ensure that patient will get accurate dose of drug in
tablet or capsule form to prevent the toxic effect or getting no therapeutic
effect. Therefore, uniformity test of weigh of tablets and capsules is carried
out in manufacturing process to make sure those produced tablets and capsules
fit the requirements.
Apparatus
Weighing balance, weighing boat
Material
20 Tablets and 20 capsules
Procedures
Tablets
1)
20 tablets previously selected at random
were 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 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
|
80-250
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 was weighed. The capsule was
opened and the contents were removed as completely as possible. The emptied
shells were then weighed. The net weight of its content 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 was determined
from the sum of the individual net weights.
5)
The percentage deviation from the
average net weight for each capsule was determined. The deviation of individual
net weight should not exceed the limits given below:
Average net weight of
capsule
|
Deviation
(%)
|
Number
of capsules
|
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 and Calculations
Paralgin tablets:
Tablet
|
Individual
weight (g)
|
Difference
between individual weight and average weight (g)
|
%
of deviation
|
1
|
0.6376
|
0.0101
|
1.48
|
2
|
0.7115
|
0.0278
|
4.07
|
3
|
0.6921
|
0.0084
|
1.23
|
4
|
0.7057
|
0.0220
|
3.22
|
5
|
0.7053
|
0.0216
|
3.16
|
6
|
0.7163
|
0.0326
|
4.77
|
7
|
0.6636
|
0.0201
|
2.94
|
8
|
0.6701
|
0.0136
|
1.99
|
9
|
0.6811
|
0.0026
|
0.38
|
10
|
0.6810
|
0.0027
|
0.39
|
11
|
0.6706
|
0.0131
|
1.92
|
12
|
0.6900
|
0.0063
|
0.92
|
13
|
0.6745
|
0.0092
|
1.35
|
14
|
0.6594
|
0.0243
|
3.55
|
15
|
0.7102
|
0.0265
|
3.88
|
16
|
0.6992
|
0.0155
|
2.27
|
17
|
0.7147
|
0.0310
|
4.53
|
18
|
0.7021
|
0.0185
|
2.71
|
19
|
0.6583
|
0.0254
|
3.72
|
20
|
0.6558
|
0.0279
|
4.08
|
i.
Average weight = 13.6736g =
0.68368g
20
ii.
Since the average weight is 683.68mg which is more than 250mg, so the
deviation are ±5% and ±10% ,
a.
% deviation ±5% =
95% ≤ X ≤ 105%
= 649.50 mg ≤ X ≤ 717.86 mg
b.
% deviation ±10% = 90%
≤ X ≤ 110%
= 615.31 mg ≤ X ≤ 752.05 mg
iii.
No tablets deviate from the weight so
this product passed the uniformity of weight test.
Mefenamic Acid Capsules:
Capsules
|
Individual weight (g)
|
Weight of the emptied shells (g)
|
Net weight of the contents (g)
|
Difference between individual weight and
average weight (g)
|
% of deviation
|
1
|
0.4608
|
0.0766
|
0.3842
|
0.0031
|
0.80
|
2
|
0.4547
|
0.0733
|
0.3814
|
0.0059
|
1.52
|
3
|
0.4528
|
0.0704
|
0.3824
|
0.0049
|
1.27
|
4
|
0.4752
|
0.0786
|
0.3966
|
0.0093
|
2.40
|
5
|
0.4675
|
0.0710
|
0.3965
|
0.0092
|
2.38
|
6
|
0.4610
|
0.0782
|
0.3828
|
0.0045
|
1.16
|
7
|
0.4567
|
0.0751
|
0.3816
|
0.0057
|
1.47
|
8
|
0.4578
|
0.0732
|
0.3846
|
0.0027
|
0.70
|
9
|
0.4690
|
0.0739
|
0.3951
|
0.0078
|
2.01
|
10
|
0.4706
|
0.0793
|
0.3913
|
0.0040
|
1.03
|
11
|
0.4684
|
0.0756
|
0.3928
|
0.0055
|
1.42
|
12
|
0.4094
|
0.0718
|
0.3376
|
0.0497
|
12.83
|
13
|
0.4709
|
0.0752
|
0.3957
|
0.0084
|
2.17
|
14
|
0.4728
|
0.0826
|
0.3902
|
0.0029
|
0.75
|
15
|
0.4680
|
0.0728
|
0.3952
|
0.0079
|
2.04
|
16
|
0.4756
|
0.0740
|
0.4016
|
0.0143
|
3.70
|
17
|
0.4662
|
0.0716
|
0.3946
|
0.0073
|
1.89
|
18
|
0.4620
|
0.0749
|
0.3871
|
0.0002
|
0.05
|
19
|
0.4492
|
0.0695
|
0.3797
|
0.0076
|
1.96
|
20
|
0.4682
|
0.0732
|
0.3950
|
0.0077
|
1.99
|
i.
Average net
weight of content = 7.7460 g =
0.3873 g
20
ii.
Since the average weight is 387.30 mg which is more than 300mg, so the
deviation are ±7.5% and ±15% ,
a.
% deviation ±7.5% =
92.5% ≤ X ≤ 107.5%
= 358.25 mg ≤ X ≤ 416.35 mg
b.
% deviation ±15% = 85%
≤ X ≤ 115%
= 329.21 mg ≤ X ≤ 445.40mg
iii.
Only one tablet deviates from the weight
so this batch of products still considers to pass the uniformity of weight
test.
Discussion
According to the results obtained, the average weight of the tablet Paralgin
tablets is 0.68368 g (683.68 mg) which
means the range of more than 250 mg is the suitable range chosen from the table
of the deviation limits. From the data obtained, it is found that all tablets
follow the limits. This shows that almost all tablets tested in this experiment
are uniform in the aspect of weight.
According to the
results obtained, the average weight of the capsules is 0.3873 g ( 387.3 mg) which
means the range of 300 mg and more is the suitable range chosen from the table
of the deviation limits. From the data obtained, it is found that only one
capsule has deviation from the weight. This shows that almost all capsules
tested in this experiment are uniform in the aspect of weight.
Furthermore, errors might also due to the air flow or
wind around the weighing balance to influence the reading of weighing balance.
All these errors will lead to inaccuracies of measurement of weight.
The lid of weighing balance should be closed to
minimize the error occurred.
Conclusion
The uniformity of weight of tablets and capsules test
is useful in quality control during the production of tablets and capsules. In
this experiment, it is found that all tablets and capsules used are uniform.
References
Florence E. Eichie, Ikhuoria M. Arhewoh and Oliver C.
Ezeobi, 13 August 2009. In- vitro evaluation of the pharmaceutical quality of
some ibuprofen tablets dispensed in Nigeria.
African Journal of Pharmacy
and Pharmacology Vol. 3 (10).
Questions:
1 3. Give reasons for
the non-compliance to test for uniformity of weight.
The reasons included poor in-process control during manufacturing of tablet and capsule as well as inaccurate weighing and mixing during preparation. During manufacturing, granules may fed unevenly into the die or/ and lower punch moves irregularly which cause variation in capacity of die space, resulting in different weight of tablets or capsules.
4.
Why does
dissolution test suitable to be used for batch to batch quality control?
Dissolution test is used to assess the in vivo
performance of products. Biopharmaceutical aspects are as important for
stability concerns as they are for batch release after production, in vitro
dissolution being of high relevance in quality control and quality assurance.
In vitro dissolution data will be of great importance when assessing changes in
production site, manufacturing process or formulation and assist in decisions
concerning the need for bioavailability studies. Thus, dissolution test is suitable
to be used for batch to batch quality control.
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