1. Prepared by: ZaraSheikh

2.  Coating is a process by which an essentially dry, outer layer of coating material is applied to the surface of a dosage form in order to confer specific benefits that broadly range from facilitating product identification to modifying drug release from the dosage form.

3. 1. Providing a means of protecting the drug substances from the environment, particularly from the light and moisture, and thus potentially improving product stability. 2. Masking the bitter or unpleasant taste of drug substance. 3. Improving the ease of swallowing large dosage forms, especially tablets. 4. Masking any batch differences in the appearance of raw materials.

4. 5. Providing a means of improving product appearance. 6. Aiding in brand identification. 7. Facilitating the rapid identification of product by the manufacturer, the dispensing pharmacist and the patient( color and efficient labelling). 8. Enabling the coated product to be more easily handled on high speed automatic filling and packaging equipment by improving product flow, mechanical strength and reducing the risk of cross-contamination by minimizing dusting problems.

5. 9. Imparting modified release characteristics that allow the drug to be delivered in a more effective manner.

6.  Tablets must be resistant to abrasion and chipping.  Tablets should have smooth surface for proper coating.  The tablets must be in constant motion during the early drying phase to prevent tablet agglomeration.  The spherical shape of tablet is preferable for coating process. This will allow the tablets to roll freely in the coating pan with minimal tablet-to-tablet contact.

7. Tablet coating Sugar coating Film coating Compression coating

8.  Most popular technique and virtually all new coated products introduced to the market are film coated.  Involves the deposition, usually by a spraying method of a thin film of polymer formulation surrounding a tablet.

9.  Most contemporary and thus commonly used process for coating oral solid dosage forms.  It involves the deposition of a thin film of a polymer formulation to the surface of a tablet, capsule or multiparticulate core.  Now all newly launched coated products are film coated rather than sugar coated.

10. 1. Solubility in solvent of choice for coating preparation. 2. Solubility required for the intended use eg, pH- dependent solubility (enteric coating) 3. Capacity to produce an elegant looking product 4. Stability in the presence of heat, light, moisture, air, and the substrate being coated. The film properties should not change with aging. 5. Essentially no color, taste, or odor. 6. Compatibility with common coating solution additives.

11. 7. Nontoxicity with no pharmacological activity, and ease of application to the particles or tablets. 8. Resistance to cracking, and provision of adequate moisture, light, odor, or drug sublimation barrier when desired. 9. No bridging or filling of the debossed tablet surfaces by the film former. 10. Ease of printing procedure on high-speed equipment.

12. Types Immediate release film coatings Modified release film coatings

13. Immediate release coatings Cellulose derivatives (HPMC) Vinyl derivatives (PVP) Aminoalkyl methacrylate copolymers Modified release coatings Cellulose derivatives (EC, CA) Methylmetha crylate copolymers Methacrylic acid copolymers Phthalate esters (HPMCP, CAP, PVAP)

14.  Immediate release film coatings:  Also known as non-functional coatings.  It is used to imply that the coating has no effect on biopharmaceutical properties but a coating, as explained, has many other properties and functions.  Modified release film coatings:  also knows as functional coatings, which may be further categorized as either delayed release (or enteric) or extended release coatings.

15.  Immediate release coatings are usually readily soluble in water, while  enteric coatings are only soluble in water at pH values in excess of 5-6 and are intended to either  Protect the drug while the dosage form is in stomach ( in the case of acid labile drug) or  Prevent release of the drug in the stomach (in the case of the drugs that are gastric irritants)

16.  Currently, the majority of film-coating processes involves the application of a coating liquid where a significant proportion of a major component (the solvent/vehicle) is removed by means of a drying process that is concurrent with the application of that coating liquid.  Aqueous Film-coating formulations typically contain: 1. Polymer 2. Plasticizer 3. Colourants 4. Solvent/vehicle

17. Film coating solution Aqueous solution Non-aqueous solution

18. Contain the following types of materials:  A film former capable of producing smooth, thin films reproducible under conventional coating conditions and applicable to a variety of tablet shapes. Example: cellulose acetate phthalate.  An alloying substance providing water solubility or permeability to the fi lm to ensure penetration by body fluids and therapeutic availability of the drug. Example: polyethylene glycol.

19.  A plasticizer to produce flexibility and elasticity of the coating and thus provide durability. Example: castor oil.  A surfactant to enhance spreadability of the film during application. Example: polyoxyethylene sorbitan derivatives.

20.  Opaquants and colorants to make the appearance of the coated tablets handsome and distinctive. Examples: Opaquant, titanium dioxide; colorant, FD&C or D&C dyes.  Sweeteners, flavors, and aromas to enhance the acceptability of the tablet by the patient. Examples: sweeteners, saccharin; flavors and aromas, vanillin.

21.  A glossant to provide luster to the tablets without a separate polishing operation. Example: beeswax.  A volatile solvent to allow the spread of the other components over the tablets while allowing rapid evaporation to permit an effective yet speedy operation. Example: alcohol mixed with acetone.

22.  Tablets are film coated by application or spraying of the coating solution on the tablets in ordinary coating pans.  The volatility of the solvent enables the film to adhere quickly to the surface of the tablets.

23.  Because of both the expense of the volatile solvents used in the film-coating process and the environmental problem of the release of solvents, pharmaceutical manufacturers generally favor the use of aqueous solutions.  One of the problems attendant to these, however, is slow evaporation of the water base compared to the volatile organic solvent–based solutions.

24.  One commercial water-based colloidal coating dispersion called Aquacoat (FMC Corporation) contains a 30% ethyl cellulose pseudolatex.  Pseudolatex dispersions have a high solids content for greater coating ability and a relatively low viscosity.  The low viscosity allows less water to be used in the coating dispersion, requiring less evaporation and reducing the likelihood that water will interfere with tablet formulation.  In addition, the low viscosity permits greater coat penetration into the crevices of monogrammed or scored tablets.

25.  A plasticizer may be added to assist in the production of a dense, relatively impermeable film with high gloss and mechanical strength.  Other aqueous film- coating products use cellulosic materials such as methylcellulose, hydroxypropyl cellulose, and hydroxypropyl methylcellulose as the film-forming polymer.

26. 1. Film-forming polymer (7% to 18%). Examples: cellulose ether polymers such as hydroxypropyl methylcellulose, hydroxypropyl cellulose, and methylcellulose. 2. Plasticizer (0.5% to 2.0%). Examples: glycerin, propylene glycol, polyethylene glycol, diethyl phthalate, and dibutyl subacetate. 3. Colorant and opacifier (2.5% to 8%). Examples: FD&C or D&C lakes and iron oxide pigments. 4. Vehicle (water, to make 100%).

27.  the appearance of small amounts (picking) or  larger amounts (peeling) of film fragments flaking from the tablet surface,  roughness of the tablet surface due to failure of spray droplets to coalesce (orange peel effect),  An uneven distribution of color on the tablet surface (mottling),  filling-in of the score line or indented logo on the tablet by the fi lm (bridging), and  Disfiguration of the core tablet when subjected for too long to the coating solution (tablet erosion).

28.  Solubility:  For conventional film coating the polymer should have good solubility in aqueous fluids to facilitate the dissolution of the active ingredient from the finished dosage form. However, where a modified-release action is required then a polymer system of low water solubility or permeability will be chosen.

29.  Viscosity:  In general, polymers should have a low viscosity for a given concentration.  This will permit the easy, trouble-free spraying of their solutions in industrial film coating equipment.

30.  Permeability:  Film coating can be used to optimize the shelf-life of a tablet preparation, as some polymers are efficient barriers against the permeability of water vapour or other atmospheric gases.  These properties vary widely between the individual polymers.

31.  Mechanical properties:  The particular polymer chosen for a film coat formulation must be one with adequate strength to withstand the impact and abrasion encountered in normal handling.  Insufficient coating strength will be demonstrated by the development of cracks and other imperfections in the coating.

32. Standard (conventional) coating pan Perforated coating pan Fluidized bed (air suspension) coater Immersion Sword System Immersion Tube System Accela-Cota System Pellegrini Pan System Driacoater System Glatt Coater System Hi-Coater Systems Air Suspension System