DEFECTS IN COATED TABLETS
- BLISTERING:- It is the detachment of film from the tablet substrate as the elasticity of surface film compromised.
Cause– generally occur due to higher temperature during various stages of coating.
- CHIPPING: It is generally an edge phenomena in which at the edge of tablet the surface film chipped off.
Cause- decrease in rotation speed of pan, poor coating solution.
- CRATERING: It is defect in which a defect in film coating leads to craters appearing exposing the tablet surface.
Cause- insufficient drying time, high volume of coating solution used.
- PICKING: It is defect where a surface film is pulled away from the surface when the tablet sticks together and then part due to being detached away from the core.
Cause- over wetting of tablets due to polymer solution, improper drying.
- PITTING: It is a defect in which deformation occur or pits formation occur in the surface of a tablet core without any visible disruption of the film coating.
Cause- it generally occurs when the temperature of core of the tablets generally higher than the melting points of material used in it.
- BLOOMING: It is defect where dullness in coating color of tablet occur after prolonged storage at high temperatures.
Cause- use of low molecular weight plasticizer.
- BLUSHING: It is defect in which whitish specks or haziness occur in the film.
Cause- occur due to the high coating temp. Leads to precipitation of polymers on surface.
- COLOR VARIATION: A defect which involves variation in color of the film.
Cause- poor mixing, uneven spray pattern, migration of dyes during drying etc.
- INFILLING– it refers to filling of intagliations (distinctive words or symbols on tablet surface)
Cause- due to accumulation or settling of foam in intagliations caused due to air spraying.
- ORANGE PEEL EFFECT: It is surface defect resulting in appearance of an orange peel having rough and non-glossy texture.
Cause- too high spray pressure, poor tablet composition, rapid drying etc.
- CRACKING/SPLITTING: It is defect in which the cracks in the films occur across the crown of the tablet (cracking) or splits around the edges of the tablet (Splitting).
Cause- occur when the internal stress of the film exceeds the tensile strength of film, use of high molecular weight polymers.
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