1.Capping & Lamination:
Causes:
1. Air entrapment.
2. Deep concave punch.
3. Claw formation of Punch.
4. Wear ring formation in die wall.
5. Incorrect setting of the press.
6. Compression of too dry material
Solutions:
1. Precompression
2. Reduction in speed of machine.
3. Reduction in final compression force.
4. Using flat punches.
5. Using hygroscopic materials to maintain proper moisture level eg. - PEG-4000 and Methyl Cellulose.
2.Picking & Sticking:
Cause:
1. Picking occurs when punch tips are engraving or embossing. Small enclosed areas in letters A.
2. Wear and tear of the machine.
3. Improper cleaning before starting the batch.
Solutions:
1. Periodically checking and changing of punches and dies.
2. Proper cleaning and maintenance of the machine before batch operation.
3.Mottling:
Causes:
1. Use of a drug whose color differs from tablet excipients.
2. Use of a drug whose dehydration products are colored.
Solutions:
1. The use of colorant may solve the problem but can create another Problem.
A dye can cause mottling by migration to the surface of a Granulation during drying to overcome this difficulty. Change the Solvent system, reduce drying temperature.
2. Disperse a dry color additive during powder binding steps.
4. Weight Variation:
Causes:
(a) Granule size & size distribution:
(b) Poor Flow:
(c) Punch Variation:
(d) Poor Mixing:
5.Hardness Variation:
6.Double Impression:
- Complete or partial loss of top and bottom crowns of a tablet from the main body is called capping.
- The separation of a tablet into two or more distinct layers is called lamination.
- These problems occur immediately after compression, however may occur after several hours or days.
Causes:
1. Air entrapment.
2. Deep concave punch.
3. Claw formation of Punch.
4. Wear ring formation in die wall.
5. Incorrect setting of the press.
6. Compression of too dry material
Solutions:
1. Precompression
2. Reduction in speed of machine.
3. Reduction in final compression force.
4. Using flat punches.
5. Using hygroscopic materials to maintain proper moisture level eg. - PEG-4000 and Methyl Cellulose.
2.Picking & Sticking:
- Surface materials from a tablet that is sticking to the punch and being removed from the tablet surface is picking.
- Sticking refers to tablet materials adhering to the die wall.
- When sticking occurs, additional force is required to overcome the friction between the tablet and die wall during ejection.
Cause:
1. Picking occurs when punch tips are engraving or embossing. Small enclosed areas in letters A.
2. Wear and tear of the machine.
3. Improper cleaning before starting the batch.
Solutions:
1. Periodically checking and changing of punches and dies.
2. Proper cleaning and maintenance of the machine before batch operation.
3.Mottling:
- It is an unequal distribution of colors on a tablet.
Causes:
1. Use of a drug whose color differs from tablet excipients.
2. Use of a drug whose dehydration products are colored.
Solutions:
1. The use of colorant may solve the problem but can create another Problem.
A dye can cause mottling by migration to the surface of a Granulation during drying to overcome this difficulty. Change the Solvent system, reduce drying temperature.
2. Disperse a dry color additive during powder binding steps.
4. Weight Variation:
- Variation of tablet weight also causes variation of active medicaments, which changes the bioavailability.
Causes:
(a) Granule size & size distribution:
- Variations in the ration of small to large granules and difference in granule size determine how the void space between particles are filled.
- Since volume of die cavity remain same , different proportions of large and small particles may change the weight of fill in each die.
(b) Poor Flow:
- The die fill process in based on a continuous and uniform flow of granules from the hopper through the feed frame.
- When the granulation does not flow uniformly some dies are incompletely filled.
- Dies are also not filled properly when machine speed is in excess of granulations flow capability.
- For correcting poor flow the addition of a glidant such as talcum or colloidal silica may be helpful.
(c) Punch Variation:
- When length of lower punches is unequal, the fill in each die varies which causes weight variations of tablet.
(d) Poor Mixing:
- Some times lubricants and glidants are not thoroughly distributed.
- The flow of particles then impaired and the granules do not move efficiently into the dies.
5.Hardness Variation:
- Hardness depends on the weight of materials and space between upper and lower punch at the moment of compression.
- If the volume of materials and distance between the punches varies hardness also alters.
6.Double Impression:
- This involves only punches that have monogram or engraving.
- If the monogram present in upper punch, slight rotation of punch after precompression produce double impression. If monogram present in lower punch after compression is over lower punch move slightly downward to free the tablet and produce double impression. This problem can overcome using non-rotating cam track.