types of tablet defects, reasons, prevention methods.

1. TABLET DEFECTS
PREPARED BY:
K. ARSHAD AHMED KHAN
M.Pharm, (Ph.D)
Dept. of Pharmaceutics
RIPER.

2. PH 101.76 2
1. Picking & sticking
2. Capping & lamination
3. Mottling
4. Double impression
5. Poor mixing
6. Poor flow
7. Weight variation
8. Hardness variation
9. Punch variation
Manufacturing defects in tablets :

3. PH 101.76 3
Defect Reasons Correction
1. Picking and
sticking
Picking- Material
adherence to punch
face causes removal
of material from
tablet surface.
Sticking - adherence
of tablet material to
the die walls.
Causes difficulty in
ejection of tablet.
1. Improper
designing of
engraved punches.
2. Poor maintenance
of punches
surfaces.
3. Use of worn out
punches and dies.
4. Under dried
granules.
1. Proper designing
of punches.
2. Chrome plating of
punch surfaces.
3. Proper quantity of
anti-adherents.
4. Adequate drying
of granules.

4. PH 101.76 4
Defect Reasons Correction
2. Capping &
lamination:
Capping - partial or
total separation of top
or bottom portions of
the tablet.
Lamination -
separation of tablet in
two or more layers.
1. entrapment of air
in granules.
2. excess fines in
granules.
3. excessive drying
of granules.
4. use of defective
punches and dies.
1. reduce the
percentage of
fines in granules.
2. maintenance of
desired amount of
moisture in
granules.
3. replacement of
defective punches
& dies.

5. PH 101.76 5
Defect Reasons Correction
3. Mottling:
Uneven distribution
of colour on the
surface of tablets.
1. difference in the
colours of drugs &
additives.
2. migration of colour
to the surface of
granules during
drying.
3. improper
distribution of
colours in powder
bulk.
4. larger particles of
dye/ lake.
1. using a dye that
can mask the
colours of all
the ingredients.
2. drying the
granules at low
temperature.
3. using the dyes/
lakes of very fine
particle size.

6. PH 101.76 6
4. Double impression:
• Double impression of monogram on lower surface of tablet.
• Occurs where the lower punch have a monogram.
• Reasons-
1. free rotational travel of lower punch after compression causes a
new lighter impression on the bottom of the tablet.
2. Tablet compression machines using 2 compression stages.
• Correction-
1. By controlling the undesirable movement of punches.
2. Using new punches with anti-turning devices.

7. 5. Poor mixing:
Reason:
1. Ununiform distribution of lubricant and glidant.
2. Reduced mixing time during lubricant addition.
Prevention:
Adequate mixing of lubricant.

8. 6. Poor Flow:
Improper flow of powder from hopper to die cavity leading to
incomplete filling of die cavity.
Reasons:
1. Particulate solids moving under gravity are subjected to uneven
pressure form mass above and along side.
2. Hopper vibration/ mixing action leading to segregation of
particles (large particle on top & small particle in bottom)
3. Arching/ Bridging/ Rat holing.
Prevention:
1. Addition of glidant (talc, colloidal silica)
2. Using induced die feeders
3. Restricting the flow of hopper.

9. PH 101.76 9
7. Weight variation:
• Tablets will not have uniform weight.
• Reasons-
1. poor flow of granules.
2. non-uniform particle size distribution of granules.
3. presence of excessive fines.
• Correction-
1. using proper concentration of lubricants and glidants.
2. by uniform size distribution of granules.
3. decreasing the proportion of fines.

10. PH 101.76 10
8. Hardness variation:
• Tablets do not have uniform hardness.
• Reasons-
1. If volume & material varies in die cavity.
2. Distance between punches varies hardness will vary.
9. Punch variation:
Differences in punch lengths.
Reason:
Lower punches of unequal lengths changes die cavity fill volume.
Prevention:
Using good punches with uniform dimension and die control
program.