Oral solid dosage forms Tablets Solid pharmaceutical dosage

Oral solid dosage forms

Tablets • Solid pharmaceutical dosage forms containing drug substances with or without suitable diluents & have been traditionally prepared by either compression, or molding methods.

Types of tablets Types of tablet Abbreviations Compressed tablets CT Sugar coated tablets SCT Film coated tablets FCT Enteric coated tablets ECT Multiple compressed tablets -layered tablets -press coated tablets MCT Controlled Release Tablets CRT Tablets for solution CTS Effervescent tablets Compressed suppositories or inserts Buccal or sublingual tablets Molded tablets or tablet triturate -Dispensing tablets -Hypodermic tablets TT DT HT

Compressed tablets • These are small compressed masses containing a medicament or medicaments. • Officially circular in shape, also may be flat or bi-convex. • Contain no special coating. • Made from powdered, crystalline or granular materials, alone or in combination with binders, disintegrants, controlled release polymers, lubricants, diluents, coloring agents.

CT ingredients • Active or therapeutic ingredients. • Inert materials –excipients. – Excipients that impart satisfactory processing and compression properties to the formulation. Diluents, Binders, Glidants, Lubricants. – Excipients that give additional desirable physical properties to the finished tablets –disintegrants, surfactants, colors, flavors, sweetening agents, antioxidants, etc.

Diluents • Single dose of the active ingredient is small. • Diluents –inert substance is added to increase the bulk to make the tablet a practical size for compression. • Dicalcium phosphate, calcium sulphate, lactose, cellulose, kaolin, mannitol, sodium chloride, dry starch, powdered sugar.

Binders • Impart cohesiveness to the tablet formulation. – Ensures tablet remain intact after compression, as well as improving the free flowing qualities by the formulation of granules of desired hardness and size. • Starch, gelatin, sugars like sucrose, glucose, dextrose, lactose; natural and synthetic gums like acacia, sodium alginate, extract of Irish moss, mucilage of isapol husks, carboxymethylcellulose, polyvinylpyrrolidine,

Lubricants • Prevent adhesion of tablet material to the surface of the dies and punches. • Reduce interparticle friction. • Facilitate ejection of tablets from the die cavity. • Improve rate of flow of tablets granulation. • E. g. , talc, magnesium stearate, calcium stearate, stearic acid, hydrogenated vegetable oils and polyethylene glycol.

Glidants • Improve the flow characteristics of a powder mixture. • Added in the dry state just prior to the compression ( at lubrication step). • Colloidal silicon dioxide -1% or less.

Disintegrants • Substance or a mixture of substance added to a tablet to facilitate its breakup or disintegration after administration. • E. g. , starch, clays, cellulose, algins, gums, cross -linked polymers.

Coloring agents • Helps the manufacturer to control the product during its preparation. • Means of identification by the user. • All colorants must be approved by FDA. • Most common method of adding color to tablet formulation is to dissolve the dye in the binding solution prior to the granulating process.

Color Other name FD & C Red 40 Allura red D&C Red 33 Acid fuchsin D FD&C Yellow 6 Sunset yellow FCF FD&C Blue 1 Brillant blue FCF Cochineal extract Natural red 4

Flavoring agents • Adds flavors & sweetness to the tablet formulation. • Volatile oils, volatile substances, fruit flavors.

Sweetening agents • Added to the tablets which are required to be dissolved in the buccal cavity. • Impart sweetness to the preparation to a varying degree. • Mannitol, lactose, sucrose.

Methods of preparation of CT • Dry granulation. • Moist granulation. • Granulation by preliminary compression.

Dry granulation • Slugging or pre-compression or double compression method. • Method: – The blend of powders are compressed into slugs on specially designed tablets machines. – Slugs are flat faced large size tablets which are prepared under heavy pressure on tablet press. – Slugs are then broken to suitable size granules by passing through an oscillating granulator fitted with no 10 or no 20 sieve. – Resultant granules are mixed with lubricants are other necessary additives , then compressed into finished tablets

Moist / wet granulation • Most widely and generally used method. • Granulation meets all the qualities required for a good tablet. • Drawback – – Materials which are destroyed by moisture or excessive heat can not be prepared by this method. – Time consuming process. – Requires number of persons as many different steps are involved in the preparation.

• Steps involved – – Weighing. – Mixing. – Granulation. – Sieving the wet mass. – Drying. – Sieving the dried mass. – Lubrication. – Compression.

• Method– Crystalline substances are reduced to fine powder, mixed with other ingredients, major portion of disintegrating agent is incorporated & mixed uniformly. – Mixed powders are passed through sieve no 30 to 60. – Dry binding agent if necessary is added, followed by careful addition of granulating agent or binding solution.

• Less quantity of granulating agent may cause poor adhesion, soft tablets, capping. • Excessive quantity of binding agent may cause – Formation of very hard tablets , which will take a longer disintegration time. – May be more difficult to pass the excessive wet mass through the sieves to get proper granules.

• Mix continuously until uniform mass is obtained. • Wet mass so obtained is passed through sieve no 6 to 20. • Wet granules obtained after passing through the various sieves are spread in thin layers in trays & dried in oven at temp not exceeding 60 °c. • Dried granules are broken up. • Passed through a proper screen to obtain granules of proper size. • Granules mixed with other additives : second portion of disintegrants, lubricants, flavoring agents. • Blended granules are ready for compression.

Granulation by preliminary compression. • Direct compression method. • For -crystalline material, having free flowing and binding properties. • Drugs that can be compressed directly – – Sodium chloride, sodium bromide, sodium salicylate, acetyl salicylic acid crystals. • To favor disintegration property –vehicle like spray dried lactose, anhydrous lactose, calcium phosphate, compressible sugar, mannitol , micro crystalline cellulose is added.