Tablet presentation by Ankita Yagnik

All about tablets you need to know. As per syllabus of GTU semester 8.
it includes introduction, types of tablets, evaluation parameters etc.

1. Prepared by: Ankita Yagnik Assistant professor Akshar-preet Institute of pharmacy, Jamnagar Tablet

2. Definition Tablet is defined as a compressed solid dosage form containing medicaments with or without excipients. According to the Indian Pharmacopoeia Pharmaceutical tablets are solid, flat or biconvex dishes, unit dosage form, prepared by compressing a drug or a mixture of drugs, with or without diluents. 2

3. Advantages: They are unit dosage form and offer the greatest capabilities of all oral dosage form for the greatest dose precision and the least content variability. Cost is lowest of all oral dosage form. Lighter and compact. Easiest and cheapest to package and strip. Easy to swallowing with least tendency for hang-up. Sustained release product is possible by enteric coating. Objectionable odour and bitter taste can be masked by coating technique. Suitable for large scale production. 3

4. Greatest chemical and microbial stability over all oral dosage form. Product identification is easy and rapid requiring no additional steps when employing an embossed and/or monogrammed punch face. Disadvantages : Difficult to swallow in case of children and unconscious patients. Some drugs resist compression into dense compacts, owing to amorphous nature, low density character. Drugs with poor wetting, slow dissolution properties, optimum absorption high in GIT may be difficult to formulate or manufacture as a tablet that will still provide adequate or full drug bioavailability. Bitter testing drugs, drugs with an objectionable odor or drugs that are sensitive to oxygen may require encapsulation or coating. In such cases, capsule may offer the best and lowest cost. 4

5. Different types of Tablets (A) Tablets ingested orally: 1. Compressed tablet, e.g. Paracetamol tablet 2. Multiple compressed tablet 3. Repeat action tablet They are one type of extended or modified release tablet. Usually contain two single doses of medication one for immediate and one for delayed release. 4. Delayed release tablet, e.g. Enteric coated Bisacodyl tablet 5. Sugar coated tablet, e.g. Multivitamin tablet 6. Film coated tablet, e.g. Metronidazole tablet 7. Chewable tablet, e.g. Antacid tablet 5

6. (B) Tablets used in oral cavity: 1. Buccal tablet, e.g. Vitamin-c tablet These tablets are placed in side of the cheek for slow release of the medicament. 2. Sublingual tablet, e.g. Vicks Menthol tablet These tablets are placed below the tongue. 3. Troches or lozenges These tablets should not disintegrate but dissolve slowly in the mouth to provide continuous effect. 4. Dental cone Minor tablet form that is designed to place in empty socket following tooth extraction. Main purpose is to prevent multiplication of bacteria. 6

7. (c) Tablets administered by other route: 1. Implantation tablet These are tablets meant for insertion under the skin 2. Vaginal tablet, e.g. Clotrimazole tablet (D) Tablets used to prepare solution: 1. Effervescent tablet, e.g. Dispirin tablet (Aspirin) 2. Dispensing tablet, e.g. Enzyme tablet ( Digiplex ) 3. Hypodermic tablet Tablet that dissolves completely in water to form injectable solution 4. Tablet triturates e.g. Enzyme tablet ( Digiplex ) 7

8. Tablet Ingredients (Excipients) Excipients are substances, other than the active drug substance or finished dosage form, that have been appropriately evaluated for safety and are included in drug delivery systems They are used in preparations; To aid in the processing of the drug delivery system during its manufacturing; To protect, support, or enhance stability, bioavailability or patient acceptability; To assist in product identification; To enhance any other attribute of the overall safety, effectiveness, or delivery of the drug during storage or use. 8

9. To Impart weight, accuracy, & volume(its allow acccuracy of dose) To Improve solubility To Increase stability To Enhance bioavailability To Modify drug release To Increase patient acceptability To Facilitate dosage form design Criteria for tablet excipients; They must be non-toxic. They must be commercially available in acceptable grades. They must be chemically inert. 9

10. List of excipients used; 1.) Diluents 2.)Binder and adhesive 3.) Disintegrents 4.) Lubricants and glidants 5.) Colouring agents 6.) Flavoring agents 7.) Sweetening agents They must be physically and chemically stable. They must be free from any unacceptable microbiologic load. They must be color compatible. They must have no deleterious effect on the bio-availability of the drug. 10

11. 11

12. 1. Diluents: Diluents are fillers used to make required bulk of the tablet when the drug dosage itself is inadequate to produce the bulk. Secondary reason is to provide better tablet properties such as improve cohesion, to permit use of direct compression manufacturing or to promote flow. A diluent should have following properties: 1. They must be non toxic 2. They must be commercially available in acceptable grade 3. There cost must be low 4. They must be physiologically inert 5. They must be physically & chemically stable by themselves & in combination with the drugs. 6. They must be free from all microbial contamination. 7. They do not alter the bioavailability of drug. 8. They must be color compatible. 12

13. Commonly used tablet diluents 1. Lactose-anhydrous and spray dried lactose 2. Directly compressed starch- Sta Rx 1500 3. Hydrolyzed starch- Emdex and Celutab 4. Microcrystalline cellulose- Avicel (PH 101and PH 102) 5. Dibasic calcium phosphate dehydrate 6. Calcium sulphate dihydrate 7. Mannitol 8. Sorbitol 9. Sucrose- Sugartab, DiPac, Nutab 10. Dextrose 13

14. 2. Binders and Adhesives: Binders promote the adhesion of particles of the formulation.These materials are added either dry or in wet- form to form granules or to form cohesive compacts for directly compressed tablet. Example: Acacia, tragacanth - Solution for 10-25% Conc. Cellulose derivatives- Methyl cellulose, Hydroxy propyl methyl cellulose, Hydroxy propyl cellulose, Ethyl cellulose Gelatin- 10-20% solution Glucose- 50% solution Polyvinylpyrrolidone ( PVP )- 2% conc. Starch paste-10-20% solution Sodium alginate Sorbitol 14

15. 3. Disintegrants : Added to a tablet formulation to facilitate its breaking or disintegration when it contact in water in the GIT . Example: Starch- 5-20% of tablet weight. Starch derivative – Primogel and Explotab (1-8%) Clays- Veegum HV , bentonite 10% level in colored tablet only Cellulose Cellulose derivatives- Ac- Di-Sol (sodium carboxy methyl cellulose) Alginate PVP ( Polyvinylpyrrolidone ), cross-linked 15

16. 4. Lubricants and Glidants : Lubricants are intended to prevent adhesion of the tablet materials to the surface of dies and punches, reduce inter particle friction and may improve the rate of flow of the tablet granulation. Glidants are intended to promote flow of granules or powder material by reducing the friction between the particles. Example: Lubricants - Stearic acid, Stearic acid salt - Stearic acid, Magnesium stearate , Talc, PEG ( Polyethyleneglycols ),Surfactants Glidants - Corn Starch – 5-10% conc., Talc-5% conc., Silica derivative - Colloidal silicas such as Cab- OSil , Syloid, Aerosil in 0.25-3% conc. 16

17. 5. Coloring agent: The use of colors and dyes in a tablet has three purposes: (1) Masking of color drugs (2) Product Identification (3) Production of more elegant product All coloring agents must be approved and certified by FDA. Two forms of colors are used in tablet preparation –FD &C and D & C dyes. These dyes are applied as solution in the granulating agent or Lake form of these dyes. (Lakes are dyes absorbed on hydrous oxide and employed as dry powder coloring.) Example: FD & C yellow 6-sunset yellow,FD & C yellow 5- Tartrazine ,FD & C green 3- Fast Green,FD & C blue 1-Brilliant Blue ,FD & C blue 2 - Indigo carmine 17

18. 6. Flavoring agents: For chewable tablet flavor oil are used 7. Sweetening agents: For chewable tablets: Sugar, mannitol . Saccharine (artificial): 500 time’s sweeter than sucrose Disadvantage: Bitter aftertaste and carcinogenic Aspartame (artificial) Disadvantage: Lack of stability in presence of moisture. 18

19. Granulation techniques: In the pharmaceutical industry, granulation refers to the act or process in which primary powder particles are made to adhere to form larger, multi-particle entities called granules. 1. Dry granulation: The dry granulation process is used to form granules without using a liquid solution because the product to be granulated may be sensitive to moisture and heat. Forming granules without moisture requires compacting and densifying the powders. In this process the primary powder particles are aggregated under high pressure. 19

20. Dry granulation can be conducted under two processes; either a large tablet (slug) is produced in a heavy duty tablet press or the powder is squeezed between two rollers to produce a sheet of materials (roller compactor, commonly referred to as a chilosonator ). Advantages: Avoid exposure of the powder to moisture and heat. Used for powders of very low bulk density to ↑ their bulk density. Disadvantages: Tablet disintegration and dissolution may be retarded due to double lubrication and compaction 20

21. Steps of Dry Granulation 1. The blend of finely divided powders is forced into the dies of a large capacity tablet press. 2. Then, compacted by means of flat faced punches (Compacted masses are called slugs and the process is slugging) or roll compactor to produce sticks or sheets. 3. Slugs or sheets are then milled/screened to produce granules(flow more than the original powder mixture). 21

22. Methods of Dry Granulation A. Slugging technique If a tablet press is used for the compaction process, the term slugging is used. But since particles with a small particle size do not flow well into the die of a tablet press, the results are weight differences from one tablet (slug) to another. This in turn causes large fluctuations in the forces applied onto the individual slugs,with translates in variations of the slug’s mechanical strength. Therefore, the properties of these granulates obtained by milling the slugs cannot be controlled well either. This is one of the main reasons why slugging is hardly used any more as a dry granulation method. 22

23. B. Roller compaction technique A Roller compactor generally consist of three major units: A feeding system, which conveys the powder to the compaction area between the rolls A compaction unit, where powder is compacted between two counter rotating rolls to a ribbon by applying a force A size reduction unit, for milling the ribbons to the desired particle size. 23

24. Wet granulation: Wet granulation is a process of using a solution binder to the powder mixture. The amount of liquid can be properly managed; O ver-wetting = the granules to be too hard, U nder-wetting =too soft and friable. Aqueous solutions are safer than other solvents. Steps involved in wet granulation: Mixing of the drugs and excipients Preparation of binder solution Mixing of binder solution with powder mixture to form wet mass Coarse screening of wet mass using suitable sieve 24

25. Drying of moist granules. Screening of granulea through suitable sieve. Mixing of screened granules with disintegrant , glidant and lubricant. Limitations of wet granulation: Multiple separate steps are involved. Not suitable for heat and moisture sensitive drugs 25

26. List of equipment used for wet granulation: A) High Shear granulation: Little ford Lodgie granulator Little ford MGT granulator Diosna granulator Gral mixer B) Granulator with drying facility: i ) Fluidized bed granulator ii) Day nauta mixer processor iii) Double cone or twin shell processor iv) Topo granulator C) Special granulator: i ) Roto granulator ii) Marumerizer 26

27. Special wet granulation techniques: A) High shear mixture granulation: Widely used in pharmaceutical industries. Blending and wet massing accompanied by high mechanical agitation by an impeler and a chopper Mixing achieved through shear and compaction through impeller. Advantages: Short proccesing time Less amount of binder required Highly cohesive material can be granulated 27

28. 28 B) Fluid bed granulation: Fluid bed granulation is process by which granules are produced in a single equipment by spraying a binder solution onto fluidized powder bed Advantage: The material processed by FBG are finer, free flowing and homogeneous. C) Extrusion and spheronization : It is multiple step process capable of making uniform sized spherical particles. Advantages: Applicable for both immediate and controlled releases dosage form

29. 29 D) Spray drying granulation: It is special techniques that directly convert liquids in to solid (dry powder) in single step and removes moisture instantly. Advantages: Rapid process Ability to be operated continuosly Suitable for heat sensitive products

30. Physics of tablet making: 30 Compressibility: It is the ability of a powder to decrease the volume under pressure. Compression: Compression of a powder means reduction in bulk volume of material as a result of displacement of gaseous phase under pressure. Compaction: It is general term used to describe situation in which powder material is subjected to some level of mechanical force. The physics of compaction may be simply stated as the compression and consolidation of two phase systems due to applied force.

31. 31 Consolidation: It is an increase of material resulting particle particle interaction Decompression: During tablet manufacturing the compressional process is followed by a decompression stage in which applied force is removed to eject the tablet from the die. Deformation: It is referred to as change of geometry of a solid when it is subjected to opposing forces.

32. Process of compression: 32 Transitional repacking Deformation at the point of contact Fragmentation and deformation Bonding Deformation of the solid body Decomposition Ejection

33. Tablet processing problems & remedies: 33 1. Binding in the die 2. Picking 3. Sticking 4. Capping 5. Lamination 6. Excessive weight variation 7. Fissured or pitted surface 8. Soft tablets 9. Protracted disintegration 10. Mottled tablets 11. Drug instability 12. Variation of medicament content

34. In-process controls: 34 IPC are checks that are carried out before the manufacturing process is completed. This may include control of equipment and environment too. In process material should be tested for identity, strength, quality and purity. Objective of in-process control are both quality control and process control.

35. Evaluation test for tablets: 35 Hardness Thickness Size Shape Diameter Disintegration rate Dissolution rate Percentage of medicament(assay) Friability

36. Mouth dissolving tablets (MDT): 36 Definition: These are the dosage forms that rapidly disintegrate and/or dissolve to release medicament as soon as they come in contact with saliva. Synonyms: Fast melting tablets Fast dissolving tablets ( FDT ) Oral disintegrating tablets ( ODT ) Oro-dispersible tablets ( ODT )

37. Advantages: 37 Ease of administration Patient compliance Convenience of administration More rapid drug absorption from pre-gastric area Disadvantages: Insufficient mechanical strength Careful handling required It may leave unpleasant taste in mouth if not formulated properly

38. Method of mfg. of MDT: 38 1) Freeze drying or lyophillization : It is the process in which water is sublimed from the product after it is frozen to create amorphous porous structure that can dissolve rapidly. Active drug is dissolved in aqueous solution The mixture is done by weight and poured in wells of preformed blister packs Trays holding this packs are passed through liq. Nitrogen freezing tunnel to froze the drug solution Frozen blisters are placed in refrigerated cabinets After freeze drying the aluminum foil packing is applied Disadvantages: a) time consuming b) expensive c) poor stability

39. 39 2) Tablet molding: Solvent method: Moistening the powder blend with hydro-alcoholic solution Compression at low pressure in molded plates to form wetted mass. The solvent is then removed by air drying. Heat method: Preparations of suspension that contains drug, agar and sugar Suspension is poured in blister packaging wells Solidifying the agar at room temperature to form jelly Drying is done at 30ºC under vacuum. Compared to Lyophilization tablets produced are easy to scale up for industrial manufacture.

40. 40 3) Spray drying: In this process, Gelatin is used as supporting agent and matrix Mannitol as bulking agent Sodium starch glycolate ( SSG ) as superdisintegrants . All these products are used in spray dried form for compression. Tablets manufactured by the spray drying technique have been reported to disintegrate in less than 20 sec .

41. 41 4) Sublimation: To generate porous matrix volatile ingredients are incorporated in the formulation and subjected to sublimation. Highly volatile substances like ammonium bicarbonate, ammonium carbonate, benzoic acid, camphor, naphthalene, urea, phthalic anhydride may be compressed along with other excipients. This volatile material is removed by sublimation. Tablets manufactured by the spray drying technique have been reported to disintegrate in 10-20 sec .

42. 42 5) Direct compression: It is the most cost effective and simplest manufacturing technique. This technique is applied for MDT because of availability of superdisintegrants and sugar based excipients. 6) Mass extrusion: This technology involves softening the active blend using solvent mixture of water soluble PEG and methanol. Then subsequent expulsion of softened mass through extruder to get cylinder of the product in to even segments.

43. Evaluation of MDTs : 43 1) Weight variation 2) Hardness 3) Friability 4) Wetting time 5) In Vitro drug release 6) Crushing strength 7) Friability 8) Modified disintegration test 9) Disintegration in oral cavity 10) Water absorption ratio 11) In Vitro dispersion time

44. Buccal tablets: 44 Buccal region offers an attractive route of administration for controlled systemic drug delivery. Buccal delivery is the administration of drugs through the mucosal membrane lining the cheeks. It is preferred route because buccal mucosa has an expanse of smooth muscle and relatively immobile mucosa which makes it a more desirable region for retentive systems. Advantages: Direct entry of drug in to systemic circulation Easy administration Bypasses first pass metabolism.

45. 45 Disadvantages: Need for the device to maintain its position for many hours. Smaller area of the tissue available for drug administration. Low tissue permeability. Buccal drug delivery system: Hydrogels: They are hydrophilic polymeric matrices that are capable of swelling when placed in aqueous media. They swell infinitely and component molecules dissolve from the surface of matrix. Then drug release occurs through the spaces or channels within the network.

46. 46 Swelling of dried hydrogel (left) to a larger size of the same shape(right) in water.

47. 47 Multilayered tablets: Commonly employed dosage form. Unlike conventional tablets they don't contain disintegrating agent and tend to remain intact during the drug release period. Generally it contains two layers one is drug containing matrix layer and second is impermeable backing layer.

48. 48 Striant: It is monoconvex, tablet like mucoadhesive buccal system. Striant adheres to gum tissue above the incisors with the flat surface facing the cheek mucosa. The active ingredient in striant is testosterone and insertion of striant is done twice a day.

49. 49 Buccal films: These are patches designed either as matrix controlled or membrane controlled devices. They are preferred over buccal tablets because of their flexibility and comfort.

50. Evaluation of buccal tablets: 50 Weight variation Hardness Thickness Friability In vitro dissolution In vitro diffusion/permeability study Mucoadhesive strength Swelling index Surface pH

51. 51 In vitro diffusion/permeability study: The in vitro buccal drug permeation study is carried out through sheep buccal mucosa using at 37±0.2ºC , mucosa mounted between the donor and receptor compartments. The buccal tablet is placed with the core facing the membrane and the compartments clamped together. The donor and receptor compartments were filled with phosphate buffer pH 6.4 and the hydrodynamics in the receptor compartment is maintained by stirring with a magnetic bead at 50 rpm. 1ml sample is withdrawn at predetermined time intervals and analyzed for drug content using UV spectrophotometer.

52. 52 The cumulative amount of permeated drug was plotted versus time and the steady state flux was calculated using the formula: J SS = ΔM /( A.Δt ) Where, ΔM is the amount of drug transported across the membrane Δt is time and A is the diffusional area.

53. 53 Swelling index: The swelling rate of the tablet is evaluated by using pH 6.4 phosphate buffer. The initial weight of tablet is determined ( W1 ). Then tablet is placed in pH 6.4 phosphate buffer (6 ml) in a petridish placed in an incubator at 37 ± 1ºC and the tablet is removed at different time intervals (0.5, 1, 2, 3, 4, 5, 6, 7, 8 hr), blotted with filter paper and reweighted( W2 ). % Swelling index = [( W2-W1 )/ W1 ] x100

54. 54 Surface pH: The surface pH of the tablets is determined in order to investigate the possibility of any side effects on the oral cavity. As acidic or alkaline pH is found to cause irritation to the buccal mucosa, hence an attempt has been made to keep the surface pH close to the neutral pH. A combined glass electrode is used for this purpose. Buccoadhesive tablets are left to swell for 2 hr on the surface of 1 ml of distilled water at room temperature. The surface pH is measured by means of electrode by bringing it in contact with the tablet surface and allowing to equilibrate for 1 min.

55. 55 Bio adhesive/mucoadhesive strength: A modified balance method is used to determining the ex vivo mucoadhesive strength. Fresh sheep buccal mucosa is obtained and the mucosal membrane is separated by removing underlying fat and loose tissues. The membrane is washed with distilled water and then with phosphate buffer (pH 6.4) at 37ºC . The sheep buccal mucosa is cut into pieces and washed with phosphate buffer ( pH6.4 ). A piece of buccal mucosa is tied to glass slide which was fixed on plank and the plank is assembled with a crown block.

56. 56 After hydrating the mucosa with distilled water, the tablet is brought in contact with the mucosa by applying little force for minute. After initial contact the tablet is encircled by a thread which fastened a light plastic beaker through the crown block. Then water is dropped in to beaker until the tablet and sheep mucosa are pulled apart by the gravity of water. The beaker containing water is weighed and minimum detachment force was calculated accordingly. This detachment force gives the mucoadhesive strength of the buccal tablet in grams. Force of detachment (dynes) = Actual wt for detachment (gm) × g Where g= acceleration due to the gravity ( 980cm / sec 2 )

57. Laboratory scale arrangement: 57

58. Floating tablets: 58 Floating drug delivery systems ( FDDS ) They have a bulk density less than gastric fluids and so remain buoyant (floating) in the stomach without affecting the gastric emptying rate for a prolonged period of time. Advantages: Improved drug absorption, because of increased GRT and more time spent by the dosage form at its absorption site. Delivery of drugs for local action in the stomach. Minimizing the mucosal irritation due to drugs, by drug releasing slowly at a controlled rate. Treatment of gastrointestinal disorders such as gastro-esophageal reflux. Simple and conventional equipment for manufacture.

59. 59 Limitations: Floating systems require high level of fluid in the stomach for the delivery system to float and work efficiently. These systems also require the presence of food to delay their gastric emptying. There are limitations to the applicability of floating system for drugs that have solubility or stability problem in the highly acidic gastric environment or that are irritants to the gastric mucosa. Drugs such as nifedipine as well as isosorbide dinitrate , which are well absorbed along the entire GI tract and undergoes significant first pass metabolism may not be desirable candidate since the slow gastric emptying may lead to reduced systemic bioavailability.

60. Factors controlling gastric retention time of dosage form: 60 Density of Dosage Form: Dosage forms having density lower than that of the gastric fluids experience the floating behavior and hence the gastric retention. A density of <1.0 gm/ml is required to exhibit the floating property. Size of the Dosage Form: The mean gastric residence times of the non-floating dosage forms are highly variable and greatly dependent on their size. In most cases, the larger the size of the dosage form, the greater will be the gastric retention time, because the larger size would not allow the dosage form to quickly pass through the pyloric antrum into the intestine.

61. 61 Food Intake and Nature of the Food Food intake, the nature of the food, caloric content, and frequency of feeding have profound effect on the gastric retention of the dosage form. Usually the presence of food increases the GRT (Gastric retention time) of the dosage form and increases drug absorption by allowing it to stay at the absorption site for a longer time. Food containing high calorific value and certain foodstuffs, especially fats, appear to have an inhibitory effect on gastric emptying.

62. 62 Approaches for FDDS Hydrodynamically balanced systems ( HBS ) Gas-generating systems Raft-forming systems Low-density systems

63. Hydro-dynamically balanced systems: 63 These are single-unit dosage forms, containing one or more gel-forming hydrophilic polymers. The formulation method includes a simple approach of thoroughly mixing the drug and the gel-forming hydrocolloid. After oral administration this dosage form swells in contact with gastric fluids and attains a bulk density of < 1. The air entrapped within the swollen matrix imparts buoyancy to the dosage form. The so formed swollen gel-like structure acts as a reservoir and allows sustained release of drug through the gelatinous mass.

64. 64 Figure shows the HBS by mixing the polymer with drug and usually administered in a gelatin capsule. The capsule rapidly dissolves in the gastric fluid then hydration and swelling of the surface polymers produces a floating mass. Drug release is controlled by the formation of a hydrated boundary at the surface. Continuous erosion of the surface allows water penetration to the inner layers, maintaining surface hydration and buoyancy.

65. Gas generating system: 65 These buoyant systems utilise matrices prepared with swellable polymers ( methocel ), polysaccharides (chitosan), effervescent components like sodium bicarbonate, citric acid and tartaric acid or chambers containing a liquid that gasifies at body temperature In single unit systems, effervescent substances are incorporated in the hydrophilic polymer, and CO 2 bubbles are trapped in the swollen matrix. (Fig . a) Bilayer or multilayer systems have also been designed. Drug and excipients can be formulated independently and the gas generating unit can be incorporated into any of the layers . (Fig. b,c )

66. Raft forming system : 66 The mechanism involved in this system includes the formation of a viscous cohesive gel in contact with gastric fluids, wherein each portion of the liquid swells, forming a continuous layer called a raft. This raft floats on gastric fluids because of low bulk density created by the formation of CO 2 . Raft-forming systems have received much attention for the delivery of antacids and drug delivery for gastrointestinal infections and disorders. Because raft-forming systems produce a layer on the top of gastric fluids, they are often used for gastroesophageal reflux treatment.

67. Low density system: 67 Low-density systems have density less than 1 g/ cm 3 with immediate buoyancy. They are made from low-density materials, entrapping oil or air. Polycarbonate, Eudragit S, cellulose acetate, calcium alginate, agar and low methoxylated pectin are commonly used as polymers. The single unit, floating system, consisting of low-density polypropylene foam powder, matrix-forming polymers ( HPMC , polyacrylates , sodium alginate, corn starch, carrageenan , agar, guar gum, arabic gum), drug and filler.

68. Matrix tablets: 68 These are the formulations in which drug is uniformly dissolved or dispersed in release retarding material. Such devices can be formulated as conventional or bi-tri layered matrix systems. Manufacturing method: Hydrophilic matrix: The release retarding material is water swellable or swellable erodible hydrocolloid such as high mol. w t HPMC , HPC , xanthan gum, sodium alginate, guar gum and cross linked polymers of acrylic acid. Hydrophilic matrices are porous systems.

69. 69 Depending upon the behavior of hydrophilic polymer two types of matrices are possible; Free swelling matrix Restricted-swelling matrix Hydrophobic matrix: In this matrix release retarding material is used that is either slowly soluble, erodible or digestible e.g. waxes such as cetyl alcohol etc. Insoluble or non-digestible e.g. EC, polymethacrylates Depending upon the method of incorporation of drug into matrix hydrophobic matrices further classified as porous and non-porous matrix..

70. 70 i ) Porous matrix: This matrix is one where drug and matrix is simply mixed and compressed into tablets or the drug dispersed in the polymer solution followed by evaporation. ii) Non porous matrix: This matrix is one where matrix material is first melted and then drug is incorporated in it through mixing followed by congealing the mass with stirring. Two types of non porous system is possible; Dissolved drug non porous system Dispersed drug non porous system Note: Evaluation parameters as per conventional tablets.

71. 71

72. 72 THANK YOU