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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