Tablet Coating Team Leader Kamlesh R Dandghval Team

Tablet Coating Team Leader- Kamlesh R. Dandghval Team Member- Mr. Sahebrao Boraste Gokhale Education Society Sir Dr. M. S. Gosavi College of Pharm. Edu. & Research Nashik-05 1

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. 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

Equipments for tablet coating: 1. The standard coating pan: 2. Perforated coating pan 3. Fluidized bed coater( Air suspension) 1. 2. 4. 5. The standard coating pan (conventional pan) It consist of circular metal pan mounted somewhat angularly on a stand. The pan is 8 -60 inches in diameter and rotates on its horizontal axis by a motor. 3. Heated air is directed in to pan to the tablet surface. The air is exhausted by means of ducts positioned through front of the pan. Coating solution can be applied to tablet by ladling( pouring) or by spraying, but spraying reduces drying time 7

Conventional coating pan 8

Disadvantages of conventional pan: 1. Drying take place at the surface of material and therefore drying efficiency is low. 2. Mixing efficiency is poor. 3. Dead spots are seen in the product bed. 4. Improper balance between inlet & exhaust can lead to solvent vapor leak in coating area, so may cause heath hazards & risk of explosion. Modified conventional coating pans: Glat immersion sword coating pan: 1. In this air is introduced through perforated metal sword. 2. The air flows upward from sword through tablet bed. 3. This cause intimate mixing of air with wet tablet, thus increasing efficiency. 4. Coating solution is sprayed on tablets by atomized spray system 9

Immersion sword coating pan Glatt immersion tube coating pan: 1. Drying air is immersed through tube that is immersed in tablet. 2. Air flows through tablet bed. 3. A spray nozzle is built at the tip of the tube, which simultaneously sprays coating solution. 10

Glatt immersion tube pan 11

Perforated coating pans: In this system the pan is a perforated or partially perforated drum and is rotated on its horizontal axis in an enclosed housing. Examples: 1. Accela Cota: Air flow through pan is facilitated by fully perforated cylindrical portion of pan. Air is introduced by plenum attached to top of pan and is circulated through pan and tablet bed. The air passed through perforated bed and is exhausted outside through plenum located on the exterior of the pan 12

Accela cota system 13

2. Hicoater: • It has four perforated segments located at 90 degree to each other in the pan. • Each of this perforated section acts as the opening to exhaust air duct fixed to outside of rotating pan. • Each duct makes contact with an exhaust plenum as pan rotates. • The exhaust plenum is design to permit venting when pan rotates. • Drying air is introduced through an opening located above the door. Hi-coater system 14

Driacoater: Driacoater is nonagonal in shape. In this nine flat sections is perforated rib. The air handling system in driacota can produce both positive or negative air flow i. e. it can blow air or exhaust air away. Flow patterns in driacota: Direct air flow: air enters the top through perforated ribs & out through ribs located below the bed. Reverse air flow A: air gets in through ribs located below and out through ribs at the top of pan. 15

Reverse flow B air gets in through ribs located below tablet bed and out through plenum connected to opening at the back of pan. Diagram: 16

Fluidized bed coating/ air suspension system 1. These are highly efficient drying system 2. In this fluidization of tablet mass is achieved in a columnar chamber by upward flow of drying air. 3. When the air enters centre of column , causing tablet to rise in the centre. 17

The tablet move upward & fall downward towards to re-enter the air stream at the bottom of chamber. Coating solutions are continuously applied from spray nozzle to tablet bed. Wurster fluidized bed coater is modified type of air suspension method. 18

FLUIDIZED BED COATING SYSTEMS : 19

SPECIAL COATINGS : Electrostatic coating is a manufacturing process that employs charged particles to more efficiently coat a tablet. Dip coating is a popular way of creating thin films for research purposes. Uniform films can be applied onto flat or cylindrical substrates. 20

FORMULATION OF COATING MATERIAL : Synthetic Polymers Solvents Plasticizers Colorants Opaque Extenders Miscellaneous Coating Solutions 21

IDEAL CHARACTERS OF COATING MATERIAL : Solubility of 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. 22

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. 23

TYPES OF COATING PROCESSES : 1. Sugar Coating 2. Film Coating 3. Compression Coating 24

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. 25