Evaluation of tablet

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Evaluation of tablet

Hello bloggers here I present a blog on evaluation of tablets,

In this blog I shall be giving an outline about different evaluation methods for a tablet.


Before a tablet is released out into the market it has to pass a few quality checks, which is mandatory. Evaluation of tablet includes the assessment of tablets physical, chemical and biological properties. To studies them the following test are formulated


* General appearance is the physical appearance of the tablet it has two aspects to address

* First one is the patient compliance, if the tablet is appearance is legible and good, it improves the patient compliance.

* The second one Is for the manufacturer, it helps him in trouble free manufacturing if there is tablet to tablet, batch to batch and lot to lto uniformity of tablet.

* General appearance would include a number of aspects like, size, shape, odor, taste, texture, legibility, identifying marks.



* Different shapes and sizes of tablet are available in the market they are manufactured in order to differentiate them based on their purpose of use and quantity of active ingredient, and the age group of the patient who is going to be administered with the drug.

* Heart shape tablet signify that they are for the cardiac problems, small toy shape, tablet are manufactured in order to attract children etc.

* The shape and size of a tablet would vary based on tooling used in the tablet manufacturing.

* The prime consideration here would be the crown size, because if the concavity is very high it many lead to capping, or chipping problem.

* The crown size is measured by using micrometer, and sliding caliper scale is used to measure the size of 5 to 10 tablets at a time.


* Pharmaceutical manufacturers in order to differentiate their product from the other manufacturers emboss a special marking g on the tablet. The marking can be an embossing, engraving or printing.

* Apart from the company marking there can be imprints which include product code, product name, product potenct,

* But care must be taken that the letters that are embossed on the tablet are properly printed without double impression.


* For rapid identification of the tablet and consumer acceptance the tablet are given a specific colour, the colour of the tablet will enable the manufacturer form differentiating the tablet lot.

* The uniformity of the colour is important parameter here, the tablet should be free form mottling.

* The colour uniformity and gloss of the tablet is evaluated by using reflectance spectrophotometer, tristimulus colorimetric measurement, microreflectance photometer.

* The odour of the tablet indicate the stability of the tablet, for example, the smell of acetic acid in aspirin tablet indicates that the tablet is degraded

* The taste of the tablet is also an important factor, every company has a taste panel which enalise the taste of the tablet, machines are yet to be discovered which can provide the report of the taste.


* Tablet hardness and strength are the essential to see that the tablet can with the shock and stress during manufacturing packing and transportation, and while handled by the patient.

* To test the hardness of the tablet Monsanto tester, Strong-cobb tester, the Pfizer tester, the Erweka tester, the Schleuniger tester are used.

(3) Pfizer tester

(4)Monsanto tester

(5) Erweka tester

(6) Schleuniger tester

* Friability is the tested for a tablet to see weather the tablet is stable to abrasion or not, it is tested by using Roche friabilator. This is made up of a plastic drum fixed with a machine which rotated at 25 rpm for 100 revolutions. And then the twenty tablets which were weighed prior to the test are taken out of the drum and cleaned with a cloth and weighed once again, the weight variation must not be less than 0.5 to 1.0% for an conventional tablet.




* Weight variation test is performed to check that the manufactured tablets have an uniform weight.

* As per USP twenty tablets are weighed individually and an compendia weight is taken, the average weight is obtained by dividing the compendia weight by 20, now the average weight is compared to the individual weight of the tablet,

* For a tablet to pass the test not more than 2 tablets should lie out of the specified percentage and if no tablet differs by more than two times the percentage limit.


Average weight

Maximum percentage difference allowed


130 or less






More than 324



* Disintegration is the first physical change observed for a drug when it enters into the body, thus to see simulate the disintegration of the tablet in the body the disintegration test is performed.

* As per USP the disintegration apparatus consist of 6 glass tubes with a 10 number mesh at the bottom, each tube is 3 inch long.

* This arrangement of 6 tubes is placed in a medium simulated to the disintegration environment. Which is maintained at 37oc +/- 2oc, in 1 liter vessel.

* This system is made to move up and down through a distance of 5 to 6 cm at a frequency of 28 to 32 cycles per minute.

* The disintegration time of the tablet is compared with the values in the monograph.


* The rate and extent of drug release form the tablet is estimated by dissolution test

* Different types of apparatus are used to study the dissolution test of the tablet. As per IP apparatus I (paddle) and apparatus II(basket) are used.

* But as per USP dissolution apparatus used are

USP 30 classification

i. Rotating Basket (Ph.Eur./BP/JP)

ii. Paddle (Ph.Eur./BP/JP)

iii. Reciprocating Cylinder (Ph.Eur.)

iv. Flow Through Cell (Ph.Eur./BP/JP)

v. Paddle Over Disk (Ph.Eur.)

vi. Rotating Cylinder (Ph.Eur.)

vii. Reciprocating Holder

* The dissolution time and rate is compared to the values mentioned in the monograph.

(8) basket dissolution apparatus

(9) paddle dissolution apparatus

This blog is free from plagiarism


1) The theory and practice of industrial pharmacy by Leon Lacman, Herbert A Lieberman, Joseph L.Kang third edition, Varghese publishing house page no -296-303

2) Photograph captured by K.Rajakrishna during his visit to IPC 2010.

3) http://www.exhibitorindia.com/product/Pharmacy/PH-20.jpg

4) http://www.labscientificequipments.com/product/Laboratory%20Testing%20Instruments/TABLET-HARDNESS-TESTER-(MON.jpg

5) http://2.imimg.com/data2/JF/SY/MY-2629441/strong-cobb-type-tablet-hardness-tester-250x250.jpg

6) http://www.capplustech.com/images/schleuniger.jpg

7) http://www.globepharma.com/assets/images/Friabilator_EF-2.jpg

8) http://www.tabletdissolution.com/images/static_pages/baskets_and_shafts/diagram_small.gif

9) http://www.tchpc.tcd.ie/system/files/schematic_pos_centre12_mono_0.jpg

About the Author

Satheesh Babu's picture
Author: Satheesh Babu


G.Sailesh's picture

Can you please tell me the general limits for dissolution test? How to decide whether a batch pass the dissolution test in a quality control laboratory?

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