1 tablet must be an elegant product with an appropriate shape and appropriate size. Size and shape of tablets influence the passing of the product through the pharynx and esophagus. Larger tablets have a prolonged esophageal transit time. This can lead to disintegration of the product in the esophagus and cause injury to the esophagus resulting in pain. 2, It should be free from all defects like flaws, chipping, capping and lamination, ete. 3. The tablet must be sufficiently strong and resistance to shock and abrasion so that it can withstand during manufacturing, packing, shipping, and use. 4. The tablet must be uniform in weight and in drug content. 5. Tablet should be able to release its content in a Predictable and reproducible manner and get absorbed into the systemic circulation. 6. The tablet should be chemically stable so that there should be no alteration of the medicinal agent with time. Itis a unit dosage form and offers greatest dose precision. Itis convenient to administer or swallow with less chances of hang-up . | Itis light in weight. It is cheapest oral dosage form which is easy to handle., Itis attractive and elegant in appearance It provide protection of medicaments from atmospheric conditions like air, moisture and light by coating. The manufacturing cost is low as compare to other solid dosage forms. 8. The Unpleasant or bitter taste can be masked by sugar coating. 9. It can be easily formulate as a special release products such as enteric or delayed release products 10. For storage not so much space is required. It is easiest and cheapest to package. 11. Itis suitable for large scale production. 12, Tablets are tamper proof dosage form. ape pe x1, There are chances of loss of ingredients of tablets during manufacturing because involvement of several unit operation. 2, Some drugs such as highly amorphous substances and low density character are very Aifficult to compress. 3. Drugs with poor wetting properties and slow dissolution rate are difficult to dispenseg in the form of tablets. 4. Drugs with objectionable odor and bitter tasting substances need special treatment for compression. They require encapsulation or special type of coating to enhance the stability of finished tablet. Therefore cost of production get increased. 5, Hygroscopic drugs are not suitable for compressed tablets. 6. Itmay be problematic for children and elders due to difficulties in swallowing. 7. Some solids such as aspirin when formulated into tablet may cause irritant effect on Gl mucosa 8, The absorption of therapeutic agents from tablets is dependent on gastric emptying rate and shows interpatient variation. 9, Bioavailability problem may arise due to slow disintegration and dissolution. ‘There are many types of tablets according to their use, route of administration and manufacturing process. ‘Table 2.1: Classification of tableta SSR uldable, compactable mass. This mass was forced into holes of mold board made of wood oP jc. Then tablets are ejected using peg board and then dried and dispensed. or plastic. ing formulation of tablet, Inspite of active therapeutic agents, many materials which are known as additives or excipients, are usually combined at various quantities to produce a standard tablet. The type and quantity of excipients used are dependent on the intended tablet type and formulation technique. Tablet Excipients include Diluents, binders, Slidants, disintegrants, lubricants, colors, sweeteners and flavours ete, 2.6.1 DILUENTS They are also known as fillers or bulking agents. When dose of the active ingredient is very small or drug dose itself is not sufficient to produce the bulk, in that case diluents are used. Diluents are the inert substance that are added to increase the bulk in order to prepare the tablet of suitable size for compression. Example: anhydrous lactose, spray dry lactose, microcrystalline cellulose, corn starch, dicalcium phosphate, calcium sulfate, lactose, cellulose, kaolin, mannitol, sodium chloride, etc. Should be physiologically inert ‘Must be physically and chemically stable Should be compatible with drug Should be free from microbial contamination Should not affect the bioavailability of drug Should be of low cost Should be non toxic Should be easily availableSS diluents: “ne mast widely used dent TES availabe iy wee wo. pads of loses Fe COMMEay 0 mesh — regula grade ferred beca readily dissolve in water, non reactive e ese disintegration time and 10W cost diluent. The main i of alkaline lubricants and release rate, set reacts with amine Sn 1 produce discolouration ( v haime. This reaction is called Maillard reaction, 12. Spray dried lactose: Now @ days spray dried lactose are ‘used because it permit direct compression. Due 10 conesive wrrare, spray died lactose also as good flow Sharaceristcs. But Spray-dried lactose is susceptible to darkening in the Presence of excess moisture, amines, and other ‘compounds. ie available in two forms: hydrates and anhydrous 44, Dextrose (D-Glucose): This diluent forms, Dextrose may sometimes Be eanbined ina formulation to replace a portion of the spray dred lactose, which may reduce the darkening tendency ofthe resulting tablet. 4, Starch: Starch is occasionally used as @ tablet diluent. Starch is obtained from corn, wheat or potatoes. The starch which is specially dried have a standard moisture level of 34% but costly. USP grade of starch have ‘moisture content 4500 is used which is free flowing and directly compressi Jdrolyzed starches which diluent, binder, disintegrant. Emdex and Celutab are two hy ‘contains dextrose (90-92%) and maltose (@-5%). They are used in chewable tablets pecause of their sweetness and smooth feling in the mouth. 5, Mannitol: It is widely used in chewable tablets. It is non-hygrosc carcinogenic. Its trade name i cerelose is disadvantage is that it is costly. 6 Sorbitol: It is an optical isomer of mannitol Its ‘combined with mannitol formulations to decrease the diluent cost. The major limiation of sorbitol is that it is hygroscopic at humidities above 65%. 1, Suerose : They ae suitable for direct compression. They are available as Sugar tab (90 to 93% sucrose & 7 to 10% invert sugar), Di Pac (97% sucrose & 3% modified dextrins) and Nu Tab (95% sucrose & 4% invert sugar & small amount of corn starch & Magnesium- t between 11 to 14%. Sta-Rx ible. They are also used as pic and non- stearate) 8 Microcrystalline Cellulose (MCO): It is used as diluent and disintegrating agents. Its rade nasne is Avicel. There are two grades of MCC are available one is PH 101 (powder)Ce a es 7 and PH 102 (granules). The disadvantage of MCC is that itis costly and used with other material. 9 Dibasic calcium phosphate and Calcium Phosphate: Calcium phosphate is incompatible with drugs sensitive to alkaline condition. Dibasic calcium phosphate is an {inorganic substance which is available in both fine form and aggregate form. 2.6.2 BINDERS Binet! are the material which are used to produce granules or tablet of the suitable parnine Strength. They are available in dry or liquid form. They enhance the free-flowing aon wae Sranules of desired size and hardness. The selection of binder depends gest wha toe 2 formulated. For example Lozenges require very high amount of binding Nery quickiy, hematin of binders are used in those tablets which has to disintegrate Example: Acaci : a ces pote tragacanth, gelatin, starch paste, Methyl celluose, hydroxypropyl methyl ‘Sinates, polyvinyl pyrolidine (PVP). Table 22: Classification of Binders ‘tis used as the concentration of 10 20% aqueous solution + It should be prepared freshly and ‘added in warm condition to avoid solidification + Com starch is selected in the ‘concentration of 10-20%. + Starch paste is prepared by dispersing starch into cold purified ‘water and then warming in water both with continuous stirring until a translucent paste is formed. During, heating hydrolysis of starch takes place,2.6.3 LUBRICANTS Lubricants are used to lessen the friction between tablet and the wall of die cavity during the ejection of tablet from the tablet machine. It works by coating on the surface of the particles, They are helpful to prevent sticking of tablet formulation to the dies and punches. They also ‘improve granules flow from the hopper to die cavity. They also give shine to the finished tablet. Exampl Talc, magnesium stearate, calcium stearate, stearic acid, hydrogenated vegetable oils and polyethylene glycols (PEG). Lubricants are of two type: Water soluble and water insoluble. Water soluble lubricants are Sodium benzoate (mixture of sodium benzoate and sodium acetate), Sodium chloride, boric acid, sodium lauryl sulphate. Water insoluble lubricants are Talc, stearic acid, Magnesium stearate.Table 23: Classification of commonly used Tubricans Itis water insoluble lubricant. Ttmay cause dissolution problems, These stearates are alkaline in reaction and cannot be used with some acidic drugs like ASA. Itis water insoluble lubricant. 13% 4000 ~ 8000 mol.wt It is used as a water-soluble lubricant for some water soluble and effervescent tablet for lations ted 25% Its water insoluble lubricant, It is solid at room temperature. They melt at compression pressures and temperatures and produce lubricating effect. Light mineral oil is an efficient lubricant. But it ‘an cause mottling or spotting on tablet surfaces ‘Antiadherents: They are used to reduce the sticking or adhesion between tablet ingredients to the faces of the punches orto the die wall. Glidants: They are used to improve granules flow from the hopper to die cavity. 2.6.4 DISINTEGRANTS ‘These substance are added to tablet formulation so that tablet get breakup into small fragments after administration in the GIT. Example: Starches, clays, celluloses, alginates, gums and cross-linked polymers. Croscarmelose, Crospovidone, Sodium starch glycolate are known as Super disintegrants ‘The disintegrants are usually mixed with active ingredients and diluents prior to granulation. For example Starch is divided into two portions. One part is added prior to granulation while remaining partis added prior to compression.Sora err toting gets when come i cot i ae Peers tcl tone. Cramer wel 20814 ee gS seconds, Sodium starch glycolate swells 7 to 12 folds in less than 30 seconds, ropa Soumuac semen Tale at tounge Name Concentration ‘Starch ‘Used in concentration of 5-20% of tablet wag Modified starch Primogel& Expotab) ‘Used in concentration of 18%, ~ ‘Clay (veegum & bentonite) Used in concentration of 10% 2.6.5 COLOURING AGENT Colouring agents are added to the preparation to make the tablet more aesthesc appearance. Colour is also used to identify the product. The colour from natura, and synthetic origin are preferred. All colorants used in pharmaceuticals must be and certified by the FDA (food & Drug Administration). Dyes are generally (food, Drug & Cosmetic Dyes) dyes and D&C (Drug & Cosmetic Dyes) Colorants are obtained in two forms dyes and lakes. Dyes are applied by dissolving inte binding solution before the granulating process. Color lakes are dyes which aze ads ‘onto a hydrous oxide of a heavy metal (ike aluminium) and a mine approved listed as Fou produce insoluble form of te dye. Table 2.5: List of coloring agents Colour Other Name D&C Red 22 Eoin ¥ [FD&C Yeliow Tartrazine FD&C Yellow 6 4 Sunset Yellow FCF FDKCBlue 1 Yellow Orange “Titanium dioxide Burnt sugar a 2.6.6 FLAVOURS AND SWEETEN Flavours are added in the formula chewable tablets, lozenges and ef 0,001- 0.1%. Flavouring agents ar con granules. flavors are added to ‘The Sweetener used are: Sugar Sweeteners such as Saccharin, artificial sweetener which is 500 carcinogenic. Cyclamate can by “Aspartame can be used in plac moisture. In pharmaceutical industry, gra to form large entities called gr. and developing bond between binding agents. Granulation is used in mana it flow evenly through hoppe tablet. Granules are also unifr Granules are prepared by thre a. Wet granulation meth b. Dry granulation methi Direct compression 2.7.1 WET GRANULATION | Wet granulation method of tz 1. Weighing and mixing lubricant. In this step weighing, sf filler or diluent, and dis mixed using mixerto get(a 1 2.6.6 FLAVOURS AND SWEETENERS, Favours are added in the formulation to mask unpleasent taste of drug, Flavours are used in chewable tablets, lozenges and effervescent tablet.. Flavours are used at the concentration of 0.001- 0.1%. Flavouring agents are dissolved in organic solvent and the solution is sprayed on granules, flavors are added to granules just before the compression of tablet The Sweetener used are: Sugar, Mannitol, lactose and sucrose. Now a days Artificial Sweeteners, uch: a8) Sacchariny:Cyclamate-and, espartame, are aloo used. Seocharin’ is a autifcial sweetener which is 500 times sweeter than sucrose. But itis biter after taste and carcinogenic: Cyclamate can be used either alone or with saccharin but it is banned. ‘Aspartame can Pe used in place of saccharin, But aspartame is not stable in presence of ‘moisture. Granulation is used in manufacturing of tablets and pellets. The advantage of granule is that it flow evenly through hopper of tablet machine. On compression, granules form a sound tablet. Granules are also uniform in composition, Granules are prepared by three methods . a. Wet granulation method | b. Dry granulation method ©. Direct compression 2.7.1 WET GRANULATION METHOD Wet granulation method of tablet production involves the following processing steps: 1, Weighing and mixing of formulation ingredients with excipients (excluding the lubricant). In this step weighing, sifting and drug substance(s) and excipients (euch as bulking agent, filler or diluent, and disintegrant are mixed into a powder mixer. These ingredients are mixed using mixer to get uniform powdermix.LK Table 2.6: Machine Tooling 2.40.4 CAPPING Capping happens when a fracture occurs at the top of the tablet and there is partial or complete detachment of top or bottom part of tablet. Figure 213: Capping Causes and remedies 1. Air entrapment is one of the cause of capping. Air entrapment can be reduced by pre compression or by increasing dwell ime and by increasing punch tip- die clearance Too much of fines in granules is also responsible for capping. The defect can be overcome by reducing the amount of fines in granules Over drying of granules also cause capping. If the granules are too dry, they tend to cap of laminate. This problem can be overcome by adding sufficient amount of moisture to granules. Tt is necessary to moisten the granules suitably by adding hygroscopic substance eg. sorbitol, methyl- cellulose or PEG-4000. 4. Capping occur if granules are not thoroughly dried. So dry the granules properly. 5. Insufficient amount of binder or improper binder also cause capping, This can be resolved by adding dry binder such as pre-gelatinized starch, gum acacia, powdered sorbitol, PVP, hydrophilic silica or powdered sugar.3 6 Insufficient or improper lubricant is a reason of capping, This can be overcome by increasing the amount of lubricant or change the type of lubricant. 7. Punch design is also responsible to cause capping. So use flat punches instead of dep concave or bevelled edge punches. 8. Low dwell time also cause capping. Therefore speed. 4, Incorrect adjustment of sweep-off blade cause capping. Adjust sweep-off lade comecty to facilitate proper ejection. increase dwell time by decreasing tum, 2.40.2 LAMINATION It is the segregation of a tablet into two or more layers. Figure 2.14: Lamination Causes and remedies 1. Higher speed of turret lamination. This problem can increasing dwell time and also by: 2. Oily or waxy materials in granules bby adding adsorbent or absorbent. 5, The large amount of hydrophobic lubricant cause lamination. Therefore use Jess amount of lubricant or change the type of lubricant. ‘cause air-entrapment during compression which cause ‘be overcome by carry out precompression and by {increasing punch die clearance. also cause lamination. So modify the mixing process 2.10.3 CHIPPING ‘This is the defect where the film on the edges ofthe tablet is chipped or dented. | Figure 2.15: Chipped tablet Causes and remedies 1. Too dry granules cause substance. chipping. So moisten the granules by adding hyBrosoPess :: | r Large amount of iso cause chipping, Therefore use dy binder or binder in appropriate amount. 3, Ifthe Exit chute is not placing the tablet properly correct machine setting. 4, If the edge of punch face tured inside it cause chi polishing the punch edges. 2.40.4 CRACKING Properly in Deduster, it may cause chipping. So ipping, This problem is resolved by This isthe defect where upper and lower central surface of tablets get cracked. Figure 2.16: Cracking Causes And Remedies 1. Ifthe size of the granules is large. Because of this air get entrapped between the created cavities and during compression cause cracking, This can be overcome by reducing the granule size or by adding fines. 2. Too dry granules also cause cracking. Therefore, Moisten the granules properly and add proper amount of binder. 3. Always compress granules at room temperature to avoid cracking. 4. Deep concave punches also cause cracking during the ejection of tablets. Therefore replace them. 2.10.5 STICKING AND PICKING Figure 2.17: Sticking and pickingi. TT i .dhere to the die wall while Pig tablet material get a ceparareaanee I a i vmateral from a tablet surface get Temoved off by. pie amount : ‘a ee ae punch tips have engraving or embossing letters and whey te face. Picl nas ed ‘ular material is improperly dri : ane cccur due to Improperly dried or improperly lubricated granules which an, ’ eee by drying the granules properly or by changing the lubricant. 2. Addition of colloidal silica as polishing agent avoid sticking, 4. Fast Compressing process also cause sticking, Therefore reduce speed of compresog ‘machine. ; ; 4. Low melting point substances lead to picking. This can be overcome Py using hig, meting point lubricants. ; 5, Compression of too warm granules cause picking. Therefore Refrigerate granules ang ‘Compress them at room temperature. 6. Rough punch faces cause picking. Plate the punch faces with chromium to produce ¢ smooth and non-adherent face. 2.40.6 MOTTLING Itrefers to uneven distribution of the colour on the surface of the coloured tablet. Figure 2.18: MOTTLING Causes and remedy 1. This defects occurs due to Migration of dye to the surface during the process of drying, This can be overcome by changing solvent system, and by decreasing dryi temperature. q os Variation in the colours of medicament and excipis i ipients. This can be overcom: selecting appropriate colourants. E a Improper mixing of a coloured binder solution. This problem can be overcome by reais oy oe excipients during powder blending step, then add fine adhesives such as acacia and tragacanth i ee igacanth and mix well and finally adda °* 2.10.7 DOUBLE IMPRESSION Double impression is the defect where the shape of monogram or other engraving appears stamped twice on the tablet. This is due to free rotation of elther upper punch ot lower punch during eection of a tablet. During compression, the tablet receives the imprint of the 2.40.8 WEIGHT VARIATION When the bless do not have uniform weight, it i known as weight variation. Weight variation of tablet is major in proces control meseure 1. These type of variations occur when granules @ granule size change the weight of fil in each ai amount of granules in die cavity produce lese granules should be used. not uniform in size. The variation in lie. Large size granules or very small ‘weight of tablet. Hence uniform size deposited over the inner walls of the hopper channel, it obstructs the smooth flow of powder, this phenomenon is called as RAT-HOLING. These problems can be overcome by attaching vibrators to hopper to accelerate flow of granules, Figure 2.19: Rat holing ae: alProcess parameters 4. 1: 2 3. ‘Spray rate ‘The spray rate affect the o, 1. tate causes incomplete oY 4 unit : Hy of the film. A coating guid sree ae ef Jow coating liquid spray % Tate 4 Polymer du _ Shighand te tncenens? tno ey St atcent weting. high high face tablet surface. al Alaa ap ens wt win Prin ne in nee : If spraying air pressure; s IE is ex, coalescence. If there is low ae “ssive, it will cause inadequate droplet spreading and Inlet air temperature NB ai Pressure then the tablets get stick to each other The inlet air temperature increases the drying win, eae the VME eine. High inlet air temperature temperature decreases the coating effieney. Mm costing proces. Too much ar Rotating speed of pan The pan speed affects the time the tablets spend on t the spra m rotating speed of the pan cause stillness en ying zone. Too much Sugar coating OG Film coating Enteric coating 2.13.1 SUGAR COATING It is the process of depositing sugar layer that can either be colored or uncolored to the tablets. It is done to mask unpleasant taste of drug and enhance appearance of tablet. The various steps involved in sugar coating are Water proofing or sealing: It is done to provide moisture barrier to the core tablet and harden the tablet surface. This helps to maintain physical and chemical stability of finished product. Polymers that are used for sealing are generally water insoluble. Somet . or se cellulose, polyvinyl agente nS ed are icetate Phthalate, zein, Hydroxypropyl methyl cell a ranch . Hydroxypropyl yl cellulose = sidiibLin cellulose (HPC). Shellac is effective sealant but no wage ; on disintegration and dissolution time due to its polymerization, ~ Coating Process: The tablets are placed in pan and allowed to rotate at the Speed of 1pm. The air is supplied at 30° C. For water proofing or sealing apply three. application Zein solution (800 ml/ application). Allow sufficient time (15-20 minutes) in bet” applications to ensure proper drying of tablets. Tac is used ifthe tablet get stickeq ote wall of the pan or to each other. shellac, cellulose acid phthalate b. Sub coating: It is done to round up the edges of tablet. It act as base for the smoo, coating and coloring, There are two methods used for subcoating. One is Application g Sum based solution followed by dusting of sub coating powder and then drying. Thy step is repeated to achieve desired shape. The dusting powder used are calcium carbonate (30-50% w/w), titanium dioxide (2-10% w/w), powdered sucrose (25.5% w/w) and powdered gum acacia (1-5% w/w), Another method is application of suspension of dry powder in gum /sucrose solution followed by drying, Coating process: Turn off heat and inlet air. Use only exhaust system. Rotate pan at speed of 10 rpm. Use 1.5 liters of warm geatin or acacia solution. Apply 3 to 9 coats to the tablets. Adjust the coating to get desired thickness. Allow sufficient time (15-20 minutes) in between applications to ensure proper drying of tablets. © Syruping or smooth coating: This process is done for smoothing and filling roughness of surface generated during subcoating. Several coats of a simple syrup solution (60-70%) are applied. It increase the tablet dimension to predetermined level. The syrup solution contain pigment, starch, gelatin or acacia. Coating process: Tum on the exhaust outlet air to remove excess dust. Inlet air temperature to be set to get exhaust temperature of 45-489 C. The pan speed is adjusted at 12 rpm. Apply 5 to 15 coats of grossing syrup and dry it quickly. Apply several coats of heavy colored syrup until specific tablet volume is obtained. Tum off the Keat. To achieve final smoothness, size and colour, several coats of regular coloured syrup solutions are applied. Coloring: It gives the color and finished size to the tablet. A thin sucrose syrup containing the requisite coloring materials is used. Water soluble dyes or water insoluble pigments may be used. Water insoluble pigments are preferred over water soluble dye because during drying water soluble dye get migrated on surface.61 . Rotate Coating process: The pan should be clear. Turn off the heat with no supply ofa woe Ban at speed of 12 rpm. 34 coats of regula Colored syrup is applied rap ee ; ie last coat should be of regular syrup but withou athe ust air. The mixing should be uniform and then shut o parce Allow tbletsin pan to dry overnight : e. Polishing: After colouring, tablets are Polished to give desired luster to tablet. A thin ind soon ea The wari dicted name ate oa and solution is sprayed tothe tabler Coating Process: For polishing Cleaned canvas lined pans are used. Air is supplied with the exhaust air. Turned off the heat. Rotate pan at speed of 12 rpm. = Seaing Subeoating and Coloured coating Polishing OOO) ‘ee Figure 2.27; Steps involved in sugar coating During Sugar coating some problems such asa dhering of tablets batch to batch, oversize tablets may occur. Therefore skilled coating. 2.13.2 FILM COATING A film coating is a 9 2. Solubility in Gr tract x Capability to obtain an elegant looking procea moisture, air. Stability in the presence of heat, light, No color, taste or odor. 4. 5. 6. 7. Non toxic and inert n 8. Resistant to cracking, and withstand under normal handling. 9. low cost 10. Ease of printing procedure on high-speed equipment: Materials used in Film Coating Film former or polymer Solvent system Plasticizers Colourants * Opaquant-extenders Film former: The vast majority of the polymers used in film coating are used. Th polymer should form a clear, non-tacky, mechanically strong film. It may be Enteric Non enteric type. Example of enteric material are Shellac, cellulose acetate phthalt (CAP), Hydroxypropyl methyl cellulose, polyvinyl acetate phthalate (PVAP). Exampled non enteric materials are Hydroxypropyl methyl cellulose, ethylcellulose, povidone povidone, sodium carboxy methyl cellulose, methyl hydroxyethyl cellulose. 2, Solvent: Solvents are used to dissolve the polymer. Ethanol, Methanol, isopropano, water, chloroform, acetone, methylene chloride, phenylethyl ketones, Chlorinatsi hydrocarbons are used. The selection of the correct solvent is essential. The solver should have rapid drying rate and should be non toxic. 3. Plasticizer: Plasticizers act by reducing film brittleness. They provide elasticity, ani flexibility to coat. They are used to modify the properties of the polymers. Plasticizes are simply relatively low molecular weight material. Plasticizers break down polymer polymer interactions. Therefore more pliable materials is obtained. The amount of plasticizers used is 1-50% by weight of polymer. Example of plasticizers are: glycerol propylene glycol, PEG ( Polyethylene glycol), phthalate esters, citrate esters, triacetit, castor oil ete. Peeps a [Colonments: They are used to enhance visual appeal of the product. Colourants are also used in identification of the product. Inorganic colorants and Natural colorants are used-63 Example: Sunset yellow, tartrazine, ine, Iron oxide yellow, red and black, titanium dioxide, talc, Anthrocyanins, Fbofloavine and carmine, For light shade, the concentration of colourant should be les than 0.01 ‘Yemay be used while for dark shade, concentration of more than 2% is used. ed in formulation to give more pastel colours and le: Titanium dioxide, talc, aluminium silicates, magnesium carbonate, calcium sulphate, » Magnesium oxide ete, 6. Miscellaneous: It include 8 fo mask unpleasant odours or taste. For Aaample, aspartame, various fruit spirits (organic solvent), water soluble pineapple flavour (aqueous solvent) etc, ‘They are added to solubilize insoluble ingredients in the coating. For example, Spans, Tweens ete. he © Antioxidants: They are added to stabilize a 4 change. For example oximes, phenols ete, 4. Antimicrobials: These STepesition especially in case of aqueous eellulog 'ye system to oxidation and colour An ideal enteric coating material 1. Should be resistant to gastric fluid. Should be easily susceptible to intestinal fluid Should be non toxic Easily available Cheap in cost Should be stable Example: salol, cellulose acid phthalate, shellac and its derivative,plied by dipping core tablets in coating liquid, lack of speed. a substrate is present at which rerial containing OPPOsite charge i 2.13.4 MISCELLANEOUS This type o! then dried. But this process ting: In this tyPe vf coating is aI is not reliable due to of coating, while coating mal ‘a. Dip Coating: b. Electrostatic Coa rostatic charge 1S sprayed over itto get uni Compression coating this is generally @ by compression usin iting require specialized masking and to delayed the release of drug. js new coating procedure. It consist ‘of a pan which is hy Frid vacuum is obtained by sealing, Thee ‘a tablet because coating materia), chine. This method is not wide, tablet machine. This method i, tablet within g tablet ma generally used for taste ‘Vacuum Film coating: this a water jacketed. The tablets are place in P2® from pan is removed by using nitrogen. ‘The coating solution is then appli ipplied ty hydraulic spray system. Due to heated Pan evaporation takes place. The vapours ax removed by vacuum. Several defects can arise with coatings 1. Blistering 5 i] Figure 2.28: Blistering ‘The high temperatures that may i at_may occur during the drying process cause evaporatio ‘a faporation of solvent and produce an un-smooth coated surface with SS at uneven spots are called blisters. This problem is resolved by using mild dry conditions or applying moderate temperatures. 2. Chipping s 1 i Figure 2.29: chipping. 7 to the surface of the tablet ca A ofthe eating. Optiis drying onion propeay causing the disruption Picking ess Figure 230: Picking. 1 is a defect where part ofthe film sticks to the pan. This is due to overwetting of {ablets by the polymer solution. This can be avoided by increasing the efficiency of the drying process or decrease the rate of coating solution application, Blooming Blooming is a defect in which film of a tablet become dull or hazed after @ prolonged Period of storage at a high temperature. It is due to using too much plasticiser. This ean be reduced by decreasing, the concentration of the plastciser, . Blushing It is a defect where white specks are precipitated on the film. This is due to excessively high coating temperature. Therefore decrease the drying temperature to avoid precipitation of polymer._ This is due to poor and other additives of tal *. - tion in the colour © wiasticizers otha, adel seis defect related 0 eT ration of SOUR ayes Pe ing and using md drying wen spray OF en geome! ; ye Figure 2.32: Infilling or symbols or monogram formed on the tinctive words lution which ‘This defect occur due to the dist ¥f too much concentration of polymer sol tablet. This is due to application of are unable to disperse and get accumulate within the symbols, The result is that droplets of liquid become concentrated in the intagliations. This problem can be overcome by adding alcohol to the polymer solution to improve dispersion.7 ° 9% 10. range peel (Roughness) Defect Figure 2.33: Orange feel defect decrease the viscosity of the polymer sol Cracking (Splitting) lution, Cracking is a defect where film coating the tablet become cracked around the edges. This is due to use of higher molecular weight polymers or polymeric blends. Hence, use lower molecular weight polymers or polymeric blends. BVI Quality control Analysis is done to evaluate each step of formulation to obtain a good quality of the products. Before the evaluation of tablets, different test are performed to determine the right granule testing procedure to compress the tablets. Particle Size and Shape determination: The size and shape affects the tablet weight, disintegration time, flowability and friability. The methods for determining the shape are: Sieving, Sedimentation rate, Microscopy, Light screening. Surface area of granules: This affects the dissolution rate Density: Density influence the compressibility, porosity and dissolution of tablet, Granular strength : It is evaluated to determine the changes in the particle size distribution of granulations and compressibility. Flow properties: This is done to determine the flow of granule from hopper to die cavity for tablet uniformity. Flow properties of granules are determined by Angle of repose, and Hausner ratio.