Tablet_Coating1

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By: ramuanuddep (94 month(s) ago)

pl send this ppt . mail id; [email protected]

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Tablet Coating Madhuri A. Wanare M.Pharm (Q.A.) Government college of Pharmacy,Amravati

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Objetives of tablet coating The tablet coating depends on the various objectives as follows : ◙ To mask the taste, odor, or color of the drug. ◙ To provide chemical and physical protection to the drug. ◙ To control the release of the drug from tablet ie; control release. ◙ To protect drug from the gastric environment of the stomach with an acid-resistant enteric coating.

Types of Coating:

Types of Coating • Sugar coating • Film coating • Particulate/pellet coating • Compression coating.

There are three primary components involved in tablet coating::

There are three primary components involved in tablet coating : 1. Tablet properties. 2. Coating process. → Coating equipment. → Parameters of coating process. → Facility and ancillary equipment. → Automation in coating process. 3. Coating composition.

(A). Tablet properties::

(A). Tablet properties: □ For coating tablet must posses the proper physical characteristic. □ In coating process, the tablets roll in a coating pan or cascade in the air stream of an air suspension coater as coating composition is applied. □ Tablets must be resistant to abrasion and chipping. ( ie; to tolerate intense attrition of tablet – tablet and tablet and wall of equipment )

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□ In addition to smooth surface, the physical shape of tablet is important. □ 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 non-sticky dry surfaces.

(B). MATERIALS USED IN FILM COATING::

(B). MATERIALS USED IN FILM COATING: □ A film coating is a thin polymer-based coat applied to a solid dosage form such as a tablet, granule or other particle. The thickness of such a coating is usually between 20 and 100 μm. Coating materials may be a physical deposition of the materials on tablet surface or they may form a continuous film depending on composition of coating formulation.

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□ The different type of coating materials are: ► Synthetic polymers ► Solvents ► Plasticizer ► Colorants ► Opaquant extenders ► Miscellaneous coating solution

FILM-COATING FORMULAE EXAMPLES:

FILM-COATING FORMULAE EXAMPLES Basic cellulosic formula % w / w Function HPMC 5 mPa s 7.5 Polymer PEG 400 0.8 Plasticizer Iron oxide yellow 0.6 Pigment/opacifier Titanium dioxide 3.1 Pigment/opacifier Purified water 88.0 Polymer solvent and coating medium vehicle

Ideal characters of coating material are::

Ideal characters of coating material are: □ Solubility in the coating solution. □ Solubility required for intended use: Ex : Free water solubility. Slow water solubility. pH- dependent solubility. □ Capacity to produce elegant looking product. □ Stability in presence of water, heat, moisture, air, and substrate being coated and no change properties with aging.

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□ Essentially no color, odor, or taste. □ Compatibility with common coating solution additives. □ Nontoxic and ease of application. □ Resistance to cracking and should act as barrier. □ No bridging or filling of the debossed tablet surfaces by the film former. □ Ease of printing procedure on high-speed equipment. □ Low cost. □ Ease of application without specialized equipment.

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(A). Film Formers Polymer: ► Non-enteric Materials : 1. Hydroxy propyl methylcellulose, USP: 2. Methyl Hydroxy ethyl Cellulose: 3. Ethyl Cellulose, NF: 4. Povidone, USP: 5. Sodium Carboxy Methyl Cellulose, USP: 6. Polyethylene Glycol,: 7. Acrylate Polymer:

POLYMERS FOR MODIFIED RELEASE APPLICATION:

POLYMERS FOR MODIFIED RELEASE APPLICATION 1. polymers Eudragit RS and RL, 2. Ethyl Cellulose 3. polyethylene glycol

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Reasons for enteric coating are; ▪ To protect acid-labile drugs. ▪ To prevent gastric distress or nausea due to irritation from a drug. ▪ To deliver drugs intended for local action in the intestine. ▪ To deliver drugs that are absorbed in the small intestine to their primary absorption site in their most concentrated form. ▪ To provide a delayed-release component for repeat-action tablets.

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Types of enteric`coating materials are : ◊ Water-resistant ◊ pH-sensitive materials. ◊ Digestible materials ◊ Emulsified by intestine ◊ Some slowly solvated.

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ENTERIC MATERIALS A.POLYMER 1.Cellulose Acetate Phthalate 2.Acrylate Polymer 3.Hydroxy Propyl Methyl Cellulose Phthalate 4.Polyvinyl Acetate Phthalate B. SOLVENT 1.Should dissolve or disperse polymer system 2.Should dissolve other coating solution component 3.Should not create processing problem. EX: water, ethanol , methanol ,chloroform.

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( C). Plasticizers : The two types of the plasticizers are: ►Internal ►External ▪ INTERNAL MATERIALS : They modify/change the chemical properties of the polymer ▪ EXTERNAL MATERIALS : Changes the flexibility, tensile strength, or adhesion properties of the resulting film. D.COLORANT 1.Lake colors: Alumina, Talc. 2.Iron of oxide E.OPACIFYING AGENT 1.High light the product 2.In, crease film coverage. Ex :silicates, carbonates, oxides .

TABLET:SUGAR COATING:

TABLET:SUGAR COATING The basic sugar coating process involve, 1.Sealing 2.Subcoating 3.Syruping/smoothing 4.Coloring 5.Finishing 6.Polishing

STAGES IN SUGAR COATING:

STAGES IN SUGAR COATING

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MATERIALS AND EQUIPMENT : Coating pans : Stainless steel – 40 inches in diameter, with variable speed control, with 2 to 3 atomizing nozzles. Tablet core : 55 to 70 kg of 3/8-inch standard convex tablets.

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SEAL COATING SOLUTIONS FORMULA VARIATION - I FORMULA VARIATION – II. Cellulose acetate phthalate. ------------ 175 g. Zein 480 g ---------- Oleic acid, USP 60g Propylene glycol, USP ----------- 52.5 g. Polyethylene glycol 4000 144 g. ---------- Methylene chloride 480 ml. 840 ml. Alcohol SD 3A 200-proof. q.s. to 2.4 L q.s. to 1.75 L.

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Film defects Sticking and picking Roughness Orange –peel effects Bridging and filling Blistering Hazing/Dull film Colour variation Cracking

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Sticking and picking - Over wetting or excessive film thickness causes tablets to stick each other or to the coating pan. - On drying at the point of contact, a piece of film may remain adhere to pan or tablet. - Giving “picked” appearances to the tablet surface. - Resulting in a small exposed area of the core.

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Remedies - Reduction in liquid application rate. - Increase in drying air temperature and air volume.

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Roughness A rough or gritty surface observed when the coating is applied by spray. Some of the droplets may dry too rapidly before reaching the tablet bed and deposits on tablet surface. On tablet surface spray- dried particles of finely divided droplets of coating solution. Surface roughness also increases with pigment concentration and polymer concentration in the coating solution.

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Remedies Moving the nozzle closer to the tablet bed. Reducing the degree of atomization can decrease the roughness due to spray drying

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Orange –peel effects Inadequate spreading of coating solution before drying causes a bumpy or Orange –peel effects On the coating.

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Causes Indicates that spresding is impaired by rapid rate of drying or by high solution viscosity. Remedies Thinning of coating solution with additional solvents may correct this problem.

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Bridging and filling During drying film may shrink and pull away from the sharp corners of bisect, resulting in a “Bridging” of surface dispersion. These defects can be so severe that the monogram or bisect is completely obscured.

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Remedies Increase in plasticizer contents or change in plasticizer concentration can decrease the bridging

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Filling Applying too much solution, resulting in thick film, causes filling. That fills and narrows the monogram or bisects. In addition, if solution applied too fast, over wetting may cause the liquid to quickly fill and be retained in the monogram. Remedies Judicious monitoring of the fluid application rate . Thorough mixing of tablets in the pan prevent filling.

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Blistering Evaporation of solvents from the core in the oven. And effect of high temperature on the strength, elasticity and adhesion of the film may results in blistering. Remedies Controlled drying conditions.

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Hazing/Dull film Also called as bloom. It can occur when too high a processing temperature is used for a particular formulation. Dulling is particularly evident when cellulosic polymers are applied out of aqueous media at high processing temperature. Also occur if the coated tablets are exposed to high humidity conditions and partial solvation of film results.

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Colour variation Problem caused by process conditions or the formulation Improper mixing, uneven spray pattern and insufficient coating may results in colour variation. The migration of soluble dyes, plasticizer and other additives give the coating a mottled or spotted appearance. Remedies Use of lake dyes eliminates dye migration. A reformulation with different plasticizer and additives is the best way to solve film instability.

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Cracking Cracking occurs if internal stresses in the film exceed the tensile strength of the film. The tensile strength of the film can be increased by using higher molecular –weight polymers or polymer blends. Remedies Adjusting the plasticizer types and concentration can minimize internal stresses Also adjusting the pigment types and concentration can minimize internal stresses

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Thank you

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