Tablets are solid dosage forms that contain medicinal ingredients. They have advantages like ease of administration and stability. Tablet production involves blending active ingredients with excipients using processes like wet or dry granulation. Tablets are evaluated for properties such as uniform weight, disintegration time, dissolution rate and mechanical strength. Proper formulation and processing are necessary to minimize defects and ensure tablets have acceptable quality.

1. Tablet
Mr. G.A.Shete

2.  Tablet:
 Tablets are solid unit dosage form containing medicament or medicaments usually
circular in shape and may be flat or biconvex.
 Advantages of tablets:
Easy to administered.
Easy to dispense.
More stable.
Accuracy in dose.
Bitter and nauseous substance can be easily dispensed.
Light and compact.
Economical.

3.  Disadvantages of tablets:
Problem with compression to crystalline drug.
Hygroscopic drugs are not suitable for compressed tablets.
Drugs with low or poor water solubility, slow dissolution, may be difficult to
formulate.
Cost of production may be increase because of coating and encapsulation to remove
bitter and unpleasant taste.
Swallowing is difficult especially for children and ill (unconscious) patients.

4.  Types of Tablets

5.  Excipients
Diluents: e.g. lactose, sorbitol, starch etc.
Granulating agents:. e g. water, alcohol, starch mucilage, acacia mucilage, tragacanth
mucilage, gelatin solution, isopropyl alcohol, etc.
Binding agents: e.g. gum acacia powder, gum tragacanth, gelatin, sucrose, methyl
cellulose, etc.
Disintegrating agents: e.g. starch, sodium bicarbonate, citric acid and tartaric acid.
Glidants & lubricants: e.g. talc and magnesium stearate.
Colours, flavours and sweetening agents:

6.  Granulation Methods
 Slugging process
 Moist Granulation
 Dry Granulation
 Slugging process (Preliminary Compression)
i) Sieving
ii) Weighing
iii) Blending
iv) Slugging
v) Screening
vi) Blending
vii) Compression Or.
 Drug + Excipients → Blending → Slugging(formation of big size tablet) →
Screening → Blending → Compression.

7.  Slugging method is used in those cases where the medicament is unstable in
presence of moisture. In this process, dry powder is compressed into large tablets or
slugs. These slugs are then broken into small pieces which are passed through a
specified sieve to collect the granules of suitable size. A lubricating agent &
disintegrating agent are mixed with these granules before compression into the
tablet machine.
 Moist Granulation :
 This is the most widely used method. The powdered medicaments along with other
excipients, such as diluent, binding agent & a part of the disintegrating agent are
moistened with a sufficient quantity of granulating agent in order to make a
coherent mass. Coherent mass is then passed through sieve no 8 or 10. if the mass
sticks to the wire of the wire of the sieves it indicates over moistening. The wet
granules are spread in trays & dried at 60 c in hot air oven. The dried granules are
passed through a sieve no 20 to collect the granules of uniform size. The lubricating
agent, any volatile substances & remaining part of the disintegrating are mixed.
These granules are then ready for compression.

8.  Dry Granulation :
 The medicaments which are available in crystalline form or in the form of
granules having its own binding property. Such medicaments are passed through
sieve no 20 or any other specified sieve & the mixed with any additional
excipient. This method is used for making tablets of Aspirin, Sodium bromide,
Potassium chlorate & dried yeast etc.

9.  Method of preparation of Compressed Tablets
Single Punch Tablet Machine
Multipunch Tablet Machine
Rotary Tablet Machine
Dry Cota Tablet Machine
 Single Punch Tablet Machine :
It consists of following major parts:
Hopper Shoe: To supply the granules to the Die & remove the tablet after its
compression.
Lower Punch
Upper Punch
Capacity Regulator: To adjust the position of lower punch to accommodate the
required quantity of granule by the die.

10. Ejection Regulator: To adjust the position of lower punch.
Die: it allows the lower & upper punch to come close together for compression.
Fig: Single punch tablet machine

11.  Working:
 The upper punch rises to allow the hopper shoe to move over the die. The lower
punch drops & granules feed from shoe into the die. The shaking movement of
shoe helps in the flow of granules. The shoe moves aside & the upper punch drops,
thus compressing the granules into a tablet. The upper punch rises upward & the
lower punch rises up to the surface of dies to eject the tablet. The hopper shoe
again moves forward over the dies, pushing aside newly formed tablet. The lower
punch drops & the cycle is restarted.

12.  Defects in tablet manufacturing
 Capping: There is partial or complete removal of top or bottom portion of the tablet.
Lamination: is whenever tablet is breaking or separating anywhere rather than top.
Reason: Excessive fines,
Defective punches and dies,
High speed of the machine,
Too dry granules, or high degree of compaction.
Remedies: Setting the die and punch properly,
Reduce % of fine,
Punches should be polished,
Maintain the desire moisture in granules,
Maintain the speed at optimum,
Regulate the pressure of punches.

13.  Picking and sticking: In picking, the material is removed or picked up by the
upper punch from the upper surface of the tablet.
In sticking, the material sticks to the wall of the die.
Reason: Due to worn out dies and punches,
Small quantity of lubricants,
Presence of moisture in granules,
Excess powder in granules,
Scratches on the surface of face of punch or
Defects in the formulation.
Remedies: Using new set of die.
Adding proper quantity of lubricants in granules.
Dry granules.

14.  Mottling: Mottling means an unequal distribution of colour on the surface of coloured
tablets.
Reason: Migration of dye in the granules during drying,
Use of different colour of medicament and excipients.
Remedies: Drying the granules at a low temperature,
Using the dye which can mask the colour of all the ingredients of tablet formulation.
 Weight variation: During compression of granules in a tablet machine, the tablets do
not have a uniform weight.
Reasons: Granules not uniform in size,
Excess powder in granules,
No proper mixing of lubricants,
No uniform flow of granules from hopper to die,
Variation in speed of machine.

15. Remedies: By Making the granules of uniform size
Use only required quantity of powder ,
By proper mixing of lubricants &
Maintaining the proper speed of machine.
 Hardness variation: Causes same as weight variation. Hardness depends upon
weight of material and space between upper and lower punches during compression.
If any of these varies the hardness will vary.
 Double impression: This defect occurs when the lower punch has a monogram or
some other engraving on it. During compression, the tablet receives an imprint on the
punch. Due to some defect in the machine, the lower punch moves slightly upward
before ejection of a tablet and gives a second though light imprint on the tablet.

16.  Evaluation test for tablet
Shape of Tablets
Appearance
Content of Active ingredient in tablets
Uniformity of Weight
Disintegration test
Dissolution Test
Mechanical strength (Monsanto & Pfizer hardness tester)
Friability test

17.  Disintegration
Disintegration of a tablet means to break a tablet into smaller particles after
swallowing.
The time required to disintegrate the tablet is called disintegration time.
 Method: The apparatus consists of a rigid basket-rack assembly supporting 6 cylindrical
glass tubes placed with one tablet in each tubes. The assembly should be raised and
lowered between 28 and 32 times per minute in the liquid medium at 37 C. The
assembly is suspended in the liquid medium in a 1000 ml beaker. The apparatus is
operated generally for 15 minutes and observed for disintegration of tablets.
 Result: The tablets pass the test if all the tablets disintegrate. In case one or two tablets
fail to disintegrate, repeat the test on 12 additional tablets. The tablets pass the test if
not less than 16 of the total 18 tablets tested have disintegrated.

18. Fig: Disintegration test apparatus

19.  Dissolution test: The test is done for measuring the amount of time required for a
given percentage of drug substance in a tablet to go into solution under specified
condition in vitro.
 The apparatus consists a cylindrical covered vessel made of glass or other transparent
material having 1000 ml capacity. The vessel is fitted with a lid having 4 holes, one
for shaft of stirrer, second for placing thermometer and remaining two for removing
the sample.
 An electric motor which is capable of rotating the basket (woven wire cloth having
aperture size 425 micrometer) in the vessel at varied speed between 25 and 150
revolutions per minute. 1000 ml of water at 37  ± 0.5  C in placed and specified
number of tablets are placed in the dry basket. The motor is started and the rotation
speed is adjusted to 100 rpm or as directed in the monograph. Withdraw the stated
volume of solution from the vessel after 45 minutes or after the time specified in the
monograph. Filter and determine the amount of active ingredient present in it. The
tablets pass the test if for each of the five replicates; the amount of active ingredient
in solution is not less than 70% of the stated amount.

20. Fig: Dissolution Apparatus Fig: Single Tablet Dissolution Apparatus

21.  Friability
 Friability test is performed to evaluate ability of the tablet to with stand wear and tear
in Packing, handling, and transporting. The apparatus used to perform this test is
known as "Friabilator".
 The apparatus: consists of a plastic chamber, which is divided into two parts and it
revolves at a speed of 25 rpm. Twenty tablets are weighed and placed in a plastic
chamber. The chamber is rotated for 4 minutes or 100 revolutions. During each
revolution the tablet falls from a distance of 6 inch. The tablets are removed from the
chamber after 100 revolutions and weighed. Loss in weight indicates the friability.
 Result: The tablets are considered to be of good quality if the loss in weight is less
than 0.8%.

22.  Mechanical strength:
Monsanto hardness tester: It has designed spring-pressure device to test the
hardness of a tablet. It gives reading in Kg/Sq cm. The tablet to be tested is
placed between Spindle & Anvil. The desired pressure is applied by moving the
screw knob in clockwise direction. The scale is moved so that the indicator is
fixed at zero. The pressure is then applied till the tablet breaks. The reading is
noted which indicates the pressure which is needed to break the tablet.
Fig: Monsanto hardness tester

23.  Pfizer hardness tester:
Its working is based on the principle of ordinary plier. In this, plier is fitted
with a pressure dial. The tablet is placed between the jaw of the plier &
pressure is applied by pressing the handles with hand unit until the tablet
breaks. The reading of the dial indicates the pressure needed to break the
tablet.
Fig: Pfizer hardness tester

24.  Coating of Tablets
 Reasons for Coating of Tablets
To mask the unpleasant taste & odour of the tablet.
To offer a physical and/or chemical protection to the drug.
To protect drug from the deterioration effect of external environment.
Increasing the mechanical strength of the dosage form.
To improve the appearance of tablets
To produce the sustained released product.
 Tablet coating is done by following methods:
Pan Coating
Press Coating

25.  Sugar Coating of Tablet
It is done by the pan coating method
 Sieving :- The tablets to be coated are shaken in a suitable sieve to remove the fine
powder or broken pieces of tablets
 Sealing :- Sealing is done to ensure that a thin layer of water proof material, such as ,
shellac or cellulose acid phthalate is deposited on the surface of the tablets. The
shellac or cellulose acid phthalate is dissolved in alcohol or acetone & its several coats
are given in coating pan. A coating pan is made up of copper or stainless steel. The
pan is rotated with the help of an electric motor.
 Sub coating :- In sub coating several coats of sugar & other material such as Gelatin,
Acacia etc. are given to round of tablet and to help in building up to tablet size.
Several coats of concentrated syrup containing acacia or gelatin are given. After each
addition of the syrup, dusting powder is sprinkled. The dusting powder is a mixture of
starch, talc & powdered acacia.

26.  Syrup coating :- This is done to give sugar coats, opacity & color to tablets Several
coats of the syrup are applied Coloring materials & opacity agent are also added to the
syrup The process of coating is repeated until uniform colored tablets are obtained
 Finishing :- Three to four coats of sugar are applied in rapid succession without
dusting powder and cold air is circulated to dry each coat. Thus forms a hard smooth
coat
 Polishing :- Beeswax is dissolved in volatile organic solvent & a few coats of it are
given, The finished tablets are transferred to a polishing pan is rotated at a suitable
speed so the wax coated tablets are rubbed on the canvas cloth. This gives a proper
shining to the tablets.

27.  Enteric Coated tablet:
These tablets are coated with the material which does not disintegrate in stomach but
passes through as it is i.e. enteric polymer e.g.: Hydroxy propyl methyl cellulose
phthalate etc.
These tablets dissolve in intestine.
These are site specific.
 Enteric coating is given to the tablets when:
Medicaments produce severe irritation in stomach.
Action required in intestine.
Medicament may decompose or destroyed by stomach pH.
Drug absorption is better in intestine.
Delayed action is needed.

28. Thank You