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TABLET COATING

TABLET COATING. DEPARTMENT OF PHARMACEUTICS CHALAPATHI INSTITUTE OF PHARMACEUTICAL SCIENCES. Mask the unpleasant taste and odour ex; Quinine drugs, vitamins Provide physical and chemical protection Improve patient acceptability

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TABLET COATING

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  1. TABLET COATING DEPARTMENT OF PHARMACEUTICS CHALAPATHI INSTITUTE OF PHARMACEUTICAL SCIENCES

  2. Mask the unpleasant taste and odour ex; Quinine drugs, vitamins Provide physical and chemical protection Improve patient acceptability Control the release of the drug from tablet ex; sustained release.

  3. Improve the chemical stability of the drug by protecting it against light, air , oxidation and moisture. • Protect the drug from gastric environments of stomach • Mechanical strength to the tablet core. • Maintains the shape of the tablet • Identification of a product by the manufacture • Pharmacist and by the patient

  4. Tablet Properties : • Coating tablet must posses the proper physical characteristics (size ,shape) • They should easily cascade in the coating pan . • They should be resistant to abrasion and chipping . • Tablets must be in contact motion during early drying phase .

  5. The film coating adheres to all exposed surfaces surface imperfections are not eliminated sugar coating with high solid content, fills many imperfections.

  6. COATING EQUIPMENTS COATING PANS SPRAY EQUIPMENT FLUIDIZEDBED COATER STANDARD COATING PANS PERFORATED COATING PANS E.g.; accela coater pan hi-coater pan dria coater pan glatt coater pan AIRLESS SPRAY AIR SPRAY E.g.; immersion tube system immersion sword system

  7. Stainless steel – 40 inches in diameter, with variable speed control, with 2 to 3 atomizing nozzles. .

  8. Standard Coating pan

  9. It is large circular pan of about 8 to 60 inch diameter. It mounted angularly at an angle 40˚ The pan is rotated on its horizontal axis by means of motor. Tablets are coated by spraying the coating solution over the rolling Bed of tablets using spray equipment. Coated tablets are dried by passing hot air into pan through hot Air inlet. Exhausted air is removed through vents or ducts.

  10. Immersion Tube System

  11. Tube is immersed in to tablet bed Hot air is passed in to tablet bed Air flows In upward direction Exhaust air removed by exhaust vent or duct. Coating material and drying air is applied Simultaneously

  12. Immersion sword system Drying air is introduced into the pan through a sword like device having perforations It is immersed into the tablet bed Air flows in upward direction Exhaust air removed by exhaust vent or duct.

  13. Accela-Cota System

  14. Drying air is passed in to perforated cylindrical pan Air is drawn into tablet bed Application of coating solution on tablet bed by spraying Exhausted air is passed through a duct located At the bottom of the pan

  15. Hi-Coater System

  16. Function of Hi- Coater is same as accela coater. Drying air is passed in to perforated cylindrical pan through a inlet Coating solution is applied by spraying nozzles Exhausted air is passed through perforated plates present At the bottom of the pan

  17. Hi coater Accela coater

  18. Dria-Coater System

  19. Inside periphery of driacoater is attached with hollow Perforated ribs . It provides multidirectional air flow Direct air flow: Air is passed through the ribs located top of the pan and exhausted through the ribs located below the tablet bed. b) Reverse flow : Air is passed through the ribs located below the tablet bed and exhausted through the outlet at the back Of the pan.

  20. Glatt coater It is latest perforated pan coater Drying air passed through tablet bed from the inner side of the drum Exhaust through the out let . Optional split chambered plenum is used to pass the drying air in reverse Manner through the perforations, for the partial fluidization of tablet bed.

  21. Fluidized bed coater (Air Suspension Coater)

  22. Fluidized bed coaters are highly efficient drying systems. Fluidization of the tablet mass is achieved in a Coating chamber. More air enters into the center of the chamber Causing tablets to rise in the center. Then they fall down towards the chamber wall and re enters into the air stream . Spray solutions are continuously applied from a spray nozzle Located at the bottom of the chamber.

  23. Spray Application systems High – pressure air less system Low – pressure air atomized system Both these systems vary in atomization of liquid. Airless system: liquid is pumped at a high pressure (250-3000psig) through a small orifice (0.009 to 0.020 inch) Degree of atomization depends upon - Fluid pressure - Orifice size - Viscosity of liquid

  24. Air atomized – Liquid is pumped through large orifice • (0.020 to 0.060inch) at low pressure (5-50 psig). Air contacts the liquid stream at the tip of the atomizer to obtain fine spray degree of atomization depends upon - Fluid pressure - Fluid cap orifice - Viscosity of liquid - Air pressure - Air cap design selection of spray system depends upon composition of the coating solution

  25. Types of coating Conventional coating process Specialized coating process Contemporary coating process Compression coating Electrostatic coating Vacuum coating Film coating Sugar coating Enteric coating Non –enteric coating

  26. Sugar coating Sugar coating is an effective process for the application of thick coating layers, primarily for masking taste.

  27. Advantages : Inexpensive and requires simple equipment. Tablets produced are of High quality ,smooth & elegant appearance. Dis advantages: Time consuming and lengthy process ( it requires several hours to days to complete) It requires highly skilled manpower.

  28. Basic steps involved in sugar coating : Sub coating sealing

  29. SEAL COATING • Why seal coating is done ? • Need of the seal coating ? • To prevent the moisture penetration into the tablet core. • It is needed in the pan-ladling process in which localized over wetting of a portion of the tablet bed . Examples: Shellac (natural product derived from scale insects, laccifer lacca) Zein : is an alcohol-soluble protein derivative from corn used as an effective sealant. Lengthening dissolution time not reported

  30. SUBCOATING Why sub-coating is necessary? • It is applied to round the edges and build up the tablet size & weight ( 50 to 100 %) Steps involved in sub-coating: Binder solution and dusting of subcoating powders are alternately applied on tablets and dried. Same procedure is done until the desired thickness is achieved In spray process the subcoating suspension contains both binder and insoluble powders. Subcoating solutions : Gelatin, Acacia in syrup & water Subcoating powders : Kaolin, Dextrin sugars etc

  31. SMOOTHING(SYRUPING OR COLOURING): What is the need of syruping ? • It covers the imperfections on the tablet surface caused by the subcoating and imparts the desired colour to the tablet. First syrup coat contains some suspended powders are called grossing syrups, colourants can be added in this step. In the second step, syrup solution containing the dye is applied until the final size and colour is achieved. In the final step, a few clear coats of syrup may be applied.

  32. POLISHING: Tablets can be polished in clean standard coating pans or Canvas –lined polishing pans, Polishing can be done by applying powdered wax (bees wax, carnauba) or warm solutions of these waxes in naptha or other suitable Volatile solvents.

  33. FORMULATION OF SUGAR COATING SOLUTION :

  34. Enteric coating polymers : Cellulose acetate phthalate , acrylate polymers, hydroxypropyl methyl cellulose phthalate, poly vinyl acetate phthalate, Solvents used for sugar coating : Ethanol , methanol, isopropanol , chloroform, acetone Methylene chloride , methylene ethyl ketone,

  35. Sugar coated pills

  36. FILM COATING Application and deposition of thin film of polymer solution Around the tablet surface Mechanism of Film formation latex particles dispersed in aqueous phase formation of thin film with evaporation of water through film Formation of continuous film

  37. Opaquant extenders colorants

  38. Ideal characters of film coating material: Should be soluble in aqueous fluids Solubility required for the intended use e.g. freely water soluble, Slow water soluble , pH- dependent soluble(enteric coating) Capacity to produce an elegant look Must be stable in the presence of heat, light,moisture,air Should not have color, taste, and odour Non toxic and ease to application Should be resistance to cracking

  39. FILM FORMERS (non – enteric materials ): Hydroxy propyl methyl cellulose(HPMC),USP Soluble in organic , aqueous and gastro intestinal fluids. It has flexibility and chip resistance , Polymer has tendency to bridge or fill the tablet surfaces HPMC+Plasticizers or other polymer = eliminate bridging or filling problem Methyl hydroxy ethyl cellulose : It is soluble in fewer organic solvents.

  40. Ethyl cellulose , NF It is insoluble in water and gastrointestinal fluids. Ethyl cellulose + HPMC = used in tablet coating Ethyl cellulose + water soluble additives are mostly used In preparing sustained released coating for fine particles and tablets. Hydroxy propyl cellulose: It is soluble in water , gastro intestinal fluid and organic solvents at below 40˚c and insoluble at above 45˚c. Hydroxy propyl cellulose + other polymers = improve film character

  41. Povidone ,USP Povidone k30 is mostly used as binder and also as tablet coating polymer It forms a clear ,glossy and hard film. Sodium carboxy methyl cellulose,USP It is easily dispersed in water and form colloidal solutions Insoluble in organic solvents Not used for coating solution.

  42. Poly ethylene glycols Poly ethylene glycols are used as plasticizers in coating solution Poly ethylene glycols combine with cellulose acetate phthalate forms gastro intestinal soluble films

  43. ENTERIC COATING: These are intact with stomach but will dissolve and release the contents of dosage form once it reaches the small intestine. Important reasons for enteric coating: Protects the acid labile drugs from the gastric fluids e.g. enzymes& antibiotics. Prevents gastric distress or nausea due to irritation from a drug e.g. sodium salicylate Intended for local action in the intestine e.g. diclofenac sodium

  44. ENTERIC COATING MATERIALS: Cellulose acetate phthalate (CAP) Widely used in the industry. These films are brittle and formulated with hydrophobic film forming materials to achieve better enteric coating. Acrylate polymers: Two trade forms of resins eudragit L and eudragit S, produce gastric acid resistance films Soluble in intestinal fluid at pH 6 to 7.

  45. Hydroxy propyl methyl cellulose phthalate(HPMCP) These polymers are dissolved at pH at 5 to 5.5. Poly vinyl acetate phthalate (PVAP) These polymers are similar to hydroxy propyl cellulose phthalate. Ideal enteric polymer should dissolve or become permeablenear and above pH 5.0

  46. SOLVENTS: Primary function of a solvent system is to dissolve or disperse the polymers and other additives to substrate surface. • Should dissolve or disperse the polymer system. • Should easily disperse other coating solution components. • Should be colorless, tasteless, odourless, inexpensive, nontoxic,inert. • Should be easily dried. • Should be eco -friendly. Important Characters: Examples: water, ethanol, methanol, isopropanol, chloroform, acetone, methylethyl ketone and methylene chloride.

  47. PLASTICIZERS: These are added to film coating to modify the physical Properties of the polymer. Ability to decrease the film brittleness, polymer- polymer interactions It gives the stability to film and final coated product Concentration of plasticizer is expressed as the amount of Polymer being plasticized. Recommended level of plasticizer – 1 to 50% by weight of film Former.

  48. Examples of plasticizers: • Castor oil, propylene glycol of 200 and 400 series and surfactants e.g. Tweens, Spans and organic acid esters. • Water- soluble plasticizer : PEG, propylene glycol. • Organic- soluble plasticizer : castor-oil and Spans.

  49. COLOURANTS: Used to provide distinctive color and elegance to a dosage form Most of colorants are synthetic dyes (soluble) & lakes ( insoluble)Approved by FD&C, D&C. LAKES : derived from dyes by precipitating with Carriers e.g. alumina, talc Lakes contains 10 to 30 % of pure dye content • For very light shade, concentration : less than 0.01 %. • For dark shade, concentration : more than 2.0 % • Examples • Inorganic materials : iron oxides • Natural coloring materials :Anthocyanins, caramel, carotenoids, chlorophyll, indigo, flavones, turmeric and carminic acid.

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