Tablet coating process in Pharmaceutical Chemistry
−Tablet coating is the process of evenly covering tablets with a substance by applying a series of thin layers. These coaters differ in their function and application.
−Commonly used coaters are natural or synthetic resins, gums, inactive and insoluble filler, sugar, plasticizer, polyhydric alcohol, waxes, authorized coloring material and some times flavoring material .
−Coating may also contain active ingredient.
−Substances used for coating are usually applied as solution or suspension under conditions where vehicle evaporates.
Aspects of tablet coating
- Avoid irritation of oesophagus and stomach
- Avoid bad taste
- Avoid inactivation of drug in the stomach
- Improve drug effectiveness
- Prolong dosing interval
- Improve dosing interval
- Improve patient compliance
- Reduce influence of moisture
- Avoid dust formation
- Reduce influence of atmosphere
- Improve drug stability
- Prolong shelve life
|Blistering, chipping, cratering, picking, pitting
|Pan (standard/perforated) Coating Machines
Fluidized Bed Coating Machines
Spray Coating Machines
Vacuum, Dip & Electrostatic Coating Machines
|Enhance appearance and color
Mask taste and odor (film/sugar)
Improve patient compliance
Impart enteric, delayed, controlled release properties
The general methods involved in coating tablets
- Sugarcoating tablets
- Film-coating tablets
- Enteric coating
- Pan coating
- Fluid-bed or air suspension coating
- Compression coating
Film coating is more favored over sugar coating:
The disadvantages of sugarcoating process :
b) requiring the expertise of highly skilled technicians
c) doubling the size and weight of the original uncoated tablets
d) may vary in size from batch to batch and within a batch
e) large tablets are not as easily swallowed as are small tablets.
The advantages of film-coating process :
a) coated tablets having essentially the same weight, shape, and size as the originally compressed tablet
b) The coating is thin enough to reveal any identifying monograms.
c) far more resistant to destruction by abrasion than are sugar-coated tablets
d) the coating may be colored to make the tablets attractive and distinctive.