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Thursday, February 21, 2013

Film coating Problems and Remedies


Film coating Problems and Remedies

1.Blistering
2.Blushing
3.Bridging(of the intagliations)
4.Hipping
5.Cracking
6.Cratering
7.Flaking
8.Infilling
9.Orange peel
9.Peeling
10.Picking
11.Pimpling
12.Pitting
13.Pulling out(of a intagliation)
14.Splitting
15.Wrinkling
16.Blooming



1. Blistering:
Film becomes detached from substrate forming a blister
Cause: Over heating during spraying of at end of coating run
Remedy: Milder drying condition.

2. Blooming:
Coating becomes dull immediately or after a prolong storage. Film becomes detached from substrate forming a blister
Cause: due to low molecular weight plasticizers included in the coating formulation
Remedy: Decrease plasticizer concentrations and increase molecular weight of plasticizer..


3. Chipping:
Film becomes chipped and dented, usually at the edges of the tablet
Cause: Excessive attrition during coating process.
Remedy: ↑hardness of the film by increasing the molecular grade of polymer.

4. Cracking:
Films cracks or splits
Cause: high internal stresses in film (more than the tensile strength of the film)
Remedy: Adjusting the plasticizer type and concentration; Pigment type and concentration. Use lower molecular weight polymers or polymeric blends.


5. Flaking:
Film flakes off exposing the tablet surface.
Cause: Associated with cracking and splitting.
Remedy: Adjust the spray rate with drying temperature.


6. Infilling:
Intagliation filled with either particles of dried polymer or solidified foam.
Cause: bubble or foam formation because of air spraying of polymer solution. Over drying of spray or excessive foaming of coating solution.
Remedy: Add alcohol or use spray nozzle capable of finer atomization.

7. Orange peel/ Roughness:
Surface appearance similar to that of an orange or lemon
Cause: poor spreading or spreading of spray droplets associated with non-optimum spray atomization.
Remedy: Thinning the solution with additional solvent; use mild drying conditions


8. Peeling:
Film peels off exposing the best tablet surface
Cause: Associated with cracking and splitting.
Remedy:Adjust molecular grade of polymer. Balance spraying and drying rate


9. Splitting:
Film splits usually around the edges of the tablet
Cause: High internal stress in film.
Remedy:Use lower molecular weight polymers or polymeric blends. And/or adjust plasticizer type and concentration.

**Labels: Coating Tablet Defects, Cause and Remedies, Formulation, Solution, Tablet coating Problems, Tablet properties, polymers, plasticizers

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