إبراهيم عبدالله منصور الجبيري الشهري معيد بكليةالصيدلة قسم الصيدلانيات استخدام الحاسب لتقديم محاضرة في موضوع مختص بالبوربوينت 1

TABLET COATING PROCESS 2

COATING PROCESS : PRINCIPLE :  Tablet Coating is the process of a coating composition to a moving bed of tablets with the concurrent use of heated air to facilitate evaporation of solvent.  The distribution of coating is accomplished by the movement of tablets either perpendicular or vertical to the application of the coating composition. 3

OBJECTIVES OF TABLET COATING : 1. To mask taste,odour and colour of the drug. 2. To provide physical and chemical protection to the drug. 3. To control release of drug from the tablet. 4. To protect the drug from gastric environment of stomach. 5. To improve pharmaceutical elegance by use of special colours. 4

COMPONENTS OF TABLET COATING : 1. Tablet Properties 2. Coating Process : Coating Equipment Parameters of coating Process Facility and ancillary equipments Automation in coating process 3. Coating Compositions 5

TABLET PROPERTIES :  Tablets must posses proper physical characteristics.  Tablets must be resistant to abrasion and chipping.  Tablets must have smooth surface and proper shape.  Tablets in coating pan become covered with tacky polymeric films and before surface dries ‘ the applied coating changes from a sticky liquid to a tacky semisolid and eventually to a non-sticky dry surface. So tablets must be in constant motion during early drying phase or else agglomeration may occur.  Coating surface must be wet enough to coat the entire tablet surface. 6

FORMULATION OF COATING MATERIAL :  Synthetic Polymers  Solvents  Plasticizers  Colorants  Opaque Extenders  Miscellaneous Coating Solutions 7

IDEAL CHARACTERS OF COATING MATERIAL :  Solubility in coating material.  Capacity to provide elegant looking dosage.  Stability in presence of water, heat & moisture.  Compatibility with other additives.  Non-toxic and easy to apply.  Should form resistance against cracking.  No bridging should occur.  Low cost. 8

 SOLVENTS : To disperse polymers and other substances on the substrate surface. Eg. Water, ethanol, methanol, etc.  PLASTICIZERS : They are of two types :  Internal Plasticizers : Modify chemical properties of polymers  External Plasticizers :These are film formers and change the flexibility, tensile strength and adhesion properties.  Examples : Castor oil, Tweens, Spans, PEG.  COLORANTS : Provide colour and elegance to dosage form. Eg. Carotenoids, chlorophyll, iron oxides, etc. 9

TYPES OF COATING PROCESSES : Sugar Coating 2. Film Coating 3. Compression Coating

SUGAR COATING :  Sugar coating is the process of coating tablet core with sucrose syrup and consequently evaporating the solvent of syrup with the help of hot air. 11

SUGAR COATING–MULTISTAGE PROCESS : 1. Sealing tablet core- application of a water impermeable polymer such as Shellac, cellulose acetate phthalate and polyvinyl acetate phthalate, which protects the core from moisture, increasing its shelf life. 2. Sub coating -by adding bulking agents such as calcium carbonate or talc in combination with sucrose solution. 3. Smoothing process -remove rough layers formed in step 2 with the application of sucrose syrup. 4. Colouring - for aesthetic purposes often titanium based pigments are included. 5. Polishing - effectively polished to give characteristic shine, commonly using beeswax, carnauba wax. 6. Printing -indelible ink for characterisation. 12

FILM COATING :  It is a single step process of coating tablet core with polymeric film.  The solution is sprayed onto a rotating tablet bed followed by drying, which facilitates the removal of the solvent leaving behind the deposition of thin film of coating materials around each tablet.  The vast majority of film coated tablets are produced by a process which involves spraying of the coating material on to a bed of tablets. Accela Cota is one example of equipment used for film coating.  The thickness of such a coating is usually between 20 and 100 μm. 13

COMPRESSION COATING :  This method uses compression to form a coat on the surface of a preformed tablet.  It is mainly used to incorporate two or more chemically incompatible drugs in a single tablet by placing one or more ingredient in the core and other in the coating material.  It is also used for modified release tablets as the coating is done with granules.  ADVANTAGES :  Single step process  Less time consumed  DISADVANTAGES :  Highly expensive  Organic solvent is used so harmful to environment. 14

TABLET COATING EQUIPMENTS : 15  Three general types of equipments are available  1.Standard coating pan  e.g., Pellegrino pan system  Immersion sword system  Immersion tube system  2.Perforated pan system  e.g.,Accela cota system  Hicoater system  Glattcoater system  Driacoated system  3.Fluidized bed coater

CONVENTIONAL COATING PANS :  It consists of a circular metal pan placed angularly on a stand rotated on its horizontal axis by motor.  Heat is directed in the pan on the tablet bed surface and is exhausted by means of ducts. 16

PERFORATED PANS : 17 Accela cota system Hi-coater system

PERFORATED PANS : 18 Dria coater pan Glatt coater

FLUIDIZED BED COATING SYSTEMS : 19

FLUIDIZED BED COATING SYSTEMS :  In fluid bed coating, particles are fluidized, coating fluid is sprayed on and dried.  3 types :  Top spray coating  Bottom spray coating  Tangential coating 20

SPECIAL COATINGS :  Electrostatic coating Electrostatic coating is a manufacturing process that employs charged particles to more efficiently coat a tablet.  Dip coating Dip coating is a popular way of creating thin films for research purposes. Uniform films can be applied onto flat or cylindrical substrates. 21

SPECIAL COATINGS :  Vacuum film coating Vacuum coating is a mechanized process for applying coatings to lengths of materials. The product to be coated is motivated or conveyed in a lengthwise fashion at a constant speed, and these speeds can be as high as 500 feet per minute. 22

COATING DEFECTS : 23 PICKING & STICKING This is when the coating removes a piece of the tablet from the core. It is caused by over wetting the tablet or by poor tablet quality BRIDGING This occurs when the coating fills in the lettering or logo on the tablet and is typically caused by improper application of the solution, poor design of tablet embossing, high viscosity, high %age of solids in the solution etc. CAPPING This is when the tablet separates in laminar fashion. This occurs due to improper tablet compression

COATING DEFECTS : 24 EROSION This can be the result of soft tablets, an over wetted tablet surface, inadequate drying or lack of tablet surface strength TWINNING 2 tablets stick together. Common problem with capsules. Reduce spray rate or increase the pan speed. PEELING & FROSTING The coating peels away from the tablet surface in a sheet. This indicates the coating solution didn’t lock into the tablet surface. Due to over wetting, defect in coating solution or high moisture content in the tablet core.

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