Page 28 - Reference Guide For Foreign Pharmacy Licensing Exam Theory

www.pharmacyexam.com Krisman

Remedies:

This can be prevented by the proper design of letters and by regulating tablet size.

c. Mottling:

It is defined as when the surface of tablets appears with dark or light zones due to uneven distribution of color.

It is normally reported due to:

1. Migration of dye during granule’s drying process.
2. Decomposition or degradation of one or more ingredients of tablet.
3. Color difference between drug additives.

Remedies:

1. Use color-dye which can mask the color of tablet’s ingredients.
2. Try to dry granules at low temperature.

Evaluation of tablet:

The evaluation of a tablet can be done by the following tests:

A. Weight uniformity of tablet
B. Hardness of tablet
C. Thickness of tablet
D. Friability of tablet

A. Weight uniformity: In this type of evaluation study, normally 20 or more tablets are picked randomly from a
single batch. All tablets are weighed individually and collectively. From the collective weight one can calculate
the average weight of the tablet, which is then compared with the individual weight of tablets. The permissible
limit for tablets weighing 130 milligrams or more would be + 10% and for tablets weighing 325 mg or more
would be + 5%. Nonuniformity in weight may lead to dosing variation.

B. Hardness of tablets: It is normally evaluated by hardness testers. Hardness of tablets normally indicates the
tensile strength of tablets. It is normally measured in the load or pressure required to break a tablet. It greatly
affects the dissolution and disintegration time of tablets.

C. Thickness of tablets: This can be easily calculated by a capillary scale. It is normally measured in terms of
micrometers. It should not vary more than + 5% of standard value.

D. Friability: It is normally defined as loss in weight of a tablet due to chipping or fragmentation in the form of
fine particles. It is normally measured by fibrillators. The pre weighed tablets are placed in different
compartments which are rotated at the speed of 25 R.P.M. Normally, 100 revolutions are applied to tablets.
Each tablet is weighed again and loss in weight of tablet can be determined by the difference. The loss in weight
of a tablet should not be more than 1%.

131