Lamination:
Lamination is the separation of a tablet into two or more distinct layers.
Reason: Air–entrapment during compression and subsequent release on ejection.
The condition is exaggerated by higher speed of turret.
Picking:
‘Picking’ is the term used when a small amount of material from a tablet is sticking to and being removed off from the tablet-surface by a punch face.The problem is more prevalent on the upper punch faces than on the lower ones. The problem worsens, if tablets are repeatedly manufactured in this station of tooling because of the more and more material getting added to the already stuck material on the punch face.
Reason: Picking is of particular concern when punch tips have engraving or embossing letters, as well as the granular material is improperly dried.
Sticking/ Filming:
‘Sticking’ refers to the tablet material adhering to the die wall.Filming is a slow form of sticking and is largely due to excess moisture in the granulation.
Reason: Improperly dried or improperly lubricated granules.
Cracking:
Small, fine cracks observed on the upper and lower central surface of tablets, or very rarely on the sidewall are referred to as ‘Cracks’.
Reason: It is observed as a result of rapid expansion of tablets, especially when deep concave punches are used.
Mottling:
‘Mottling’ is the term used to describe an unequal distribution of colour on a tablet, with light or dark spots standing out in an otherwise uniform surface.
Reason: One cause of mottling may be a coloured drug, whose colour differs from the colour of excipients used for granulation of a tablet.
Double impression:
Double Impression’ involves only those punches, which have a monogram or other engraving on them. If the letters on the tablet are impressed twice, then they are known as double impression.
Reason: At the moment of compression, the tablet receives the imprint of the punch. Now, on some machines, the lower punch freely drops and travels uncontrolled for a short distance before riding up the ejection cam to push the tablet out of the die, now during this free travel, the punch rotates and at this point, the punch may make a new impression on the bottom of the tablet, resulting in ‘Double Impression’.
If the upper punch is uncontrolled, it can rotate during the short travel to the final compression stage and create a double impression.
Binding:
‘Binding’ in the die, is the term used when the tablets adhere, seize or tear in the die. A film is formed in the die and ejection of tablet is hindered. With excessive binding, the tablet sides are cracked and it may crumble apart.
Reason: Binding is usually due to excessive amount of moisture in granules, lack of lubrication and/or use of worn dies.
Weight variation:
a. Unequal size distribution of granules.
b. Poor flow property of granules.
c. Poor mixing
Hardness:
The applied force, which is required for crushing the tablets is called hardness. Hardness depends on-
a. The weight of material
b. The space between the upper and lower punches at the moment of compression.
Cause: Amount of binder.
Remedy:
Adjusting the amount of binder.
Classification of coating
02. Enteric coating
Steps of FILM coating
01. Core Drying02. Spray of Coating Solution
03. Polishing
