What are Common Tablet Defects Appear in the Manufacturing of Tablets

While manufacturing the tablet formulations, there are various common tablet defects occur. Eventually, the reason for these manufacturing defects of tablets is the formulation, the compression equipment, or both of these.

Common Tablet Defects

Capping:

The term capping is defined as the complete separation of the top or bottom crowns of a tablet from the body of the tablet. Whereas, lamination is the separation of a tablet into two or more different layers.

Generally, these tablet processing problems are rarely visible

immediately after the compression, nevertheless, capping and lamination may occur in a few hours or even after a few days.

During the process of compression, the air is mixed with the granules or particles and does not evade until the pressure of compression is released.

The lamination or capping defect in tablets occurs by the pre-compression, slowing the tableting rate, and lowering the final compression pressure.

Due to the deep concave punches, the curved part of the tablet expands radially while the body of the tablet can not, which conforms to the shear stress that causes the fracture. This type of additional shear stress may be eliminated by the flat pinches.

If the granulation is too dry, and also due to the lack of cohesion, tends to the capping or lamination.

The lamination or capping defect in tablets may also differ from the direct compression method of tablet preparation.

Tablet tooling may also be a cause of capping. The wear and tear on tablet tooling increase the hardness of tablet material which is going to be compressed.

Read more: Tablet machines are used in the pharmaceutical Industry

Sticking and Picking Defects in Tablets:

Term Picking is defined as the surface material from the tablet that is sticking to and being removed from the surface of the tablet through a punch.

Term Sticking is defined as the tablet material adhering to the die wall. When the sticking occurs, there are additional force is required in compression to overcome the friction between the die wall and the tablet during the ejection of the tablet.

If the sticking of the tablet is too hard at the ejection point then it can cause chipping of the tablet edges and can produce a rough edge. Tablet materials that stick to the punches can accumulate to a point and erase the tip design.

The sticking also creates a hindrance in the free movement of the lower punch which causes unusual stress on the punch heads and can tracts, ultimately resulting in their damage.

The low melting point material that can either be active ingredients or additives like polyethylene glycol, or stearic acid softens due to the heat of compression causing sticking. Excessive moisture can also be responsible for the sticking, due to this more drying of granulation is required.

Mottling:

The uneven distribution of color (light and dark spots) on the tablet is known as mottling. The cause of mottling is a drug with a different color from its excipients. The use of colorants may rectify this problem but in some cases, other problems occur.

Mottling can be caused by dye due to the migrating to the surface of a granulation during drying. To defeat this problem, one can change the binder, and solvent system, and minimize the drying temperature.

In direct compression formulations, the use of colorants can cause mottling, if the particle size is too large.

Weight Variation:

The variation in the weight of a tablet can occur if the amount of granulation can be altered during the filling of the die due to which the weight of the tablet also alters and ultimately cause variation in the weight of tablets.

Poor Flow:

The process of die-filling is completely based on the uniform granulation flow from the hopper through the feed frame. If the granules do not flow properly, it leads to moving unevenly through the feed frame so that some dies are not filled.

The poor flow from the feed frame shows that the granules are not flowing properly through the hopper which can be controlled by attaching the vibrators at the side of the hopper to maintain the flow of granulation.

Poor Mixing:

When glidants and lubricants are not mixed thoroughly then the flow of the particles gets impaired, and the granules do not flow freely into the die cavity. The improper mixing of granules at this stage can cause poor granulation flow.

Punch Variation:

When the lengths of lower punches are unequal, the amount of fill in each dies varies. The tooling of uniform dimensions should be very important for a good punch and die control program.

Double Impression Tablet Defect:

The double Impression occurs due to the punches that either contains a monogram or something printed on them. During the time of compression, the tablet received the imprint of the punch.

In some machines, the lower punch is free to drop and travel some uncontrolled distance it moves up the ejection cam to push the tablet out of the die. During its free movement, it rotates. At this point, the punch makes an impression on the bottom of the tablet, which results in a double imprint.

The same problems can occur with imprint upper punches and tablet machines that make use of two compression stages to compress a tablet. The first stage, pre-compression, uses a lower compaction force, than the final compression stage, but the tablet does receive the impression of the punch. If the upper punch is uncontrolled, it can rotate during the short distance to the final compression stage and thus create a double imprint or impression.

I hope you like my article Common Tablet Defects Appear in the Manufacturing of Tablets. I give up the information about the types of manufacturing defects of tablets as well as common tablet defects that occur after compression. If you have any questions or queries related to the article then feel free to ask in the comment section.

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