Excipients are crucial to within the body. Generally, an excipient has no medicinal properties. Its standard purpose is to streamline the manufacture of the drug product and ultimately facilitate physiological absorption of the drug. Excipients might aid in lubricity, flowability, disintegration, taste and may confer some form of antimicrobial function. Selecting the appropriate excipient to support the design of our pharmaceutical formulation is an important step in the drug manufacturing process. Different types of excipients used are:-
DILUENT: – 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.
Commonly used tablet diluents: –
- Lactose-anhydrous and spray dried lactose
2. Directly compressed starch-Sta Rx 1500
3. Hydrolysed starch-Emdex and Celutab
4. Microcrystalline cellulose-Avicel (PH 101and PH 102)
5. Dibasic calcium phosphate dehydrate
6. Calcium sulphate dihydrate
9. Sucrose- Sugartab, DiPac, Nutab
BINDERS & ADHESIVES: – 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
Gelatin- 10-20% solution
Glucose- 50% solution Polyvinylpyrrolidone (PVP)- 2% conc. Starch paste-10-20% solution. Sodium alginate, Sorbitol
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 coloured tablet only.
Cellulose derivatives- Ac- Di-Sol (sodium carboxy methyl cellulose)
PVP (Polyvinylpyrrolidone), cross-linked
SUPERDISINTEGRANTS:- Swells up to ten fold within 30 seconds when contact water.
Example:Crosscarmellose- cross-linked cellulose, Crosspovidone- cross-linked povidone (polymer),
Sodium starch glycolate- cross-linked starch. These cross-linked products swell upto 10n fold with in 30 seconds when in contact with water.
A portion of disintegrant is added before granulation and a portion before compression, which serve as glidants or lubricant. Evaluation of carbon dioxide in effervescent tablets is also one way of disintegration
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.
LUBRICANTS:- Stearic acid
Stearic acid salt – Stearic acid, Magnesium stearate, Talc, PEG (Polyethylene glycols), Surfactants
GLIDANTS:- Corn Starch – 5-10% conc., Talc-5% conc.
Silica derivative – Colloidal silicas such as Cab-O-Sil, Syloid, Aerosil in 0.25-3% conc.
COLOURING AGENTS:- The use of colours and dyes in a tablet has three purposes:
(1) Masking of off colour drugs
(2) Product Identification
(3) Production of more elegant product
All colouring agents must be approved and certified by FDA. Two forms of colours 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 colouring.
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
D & C red 3- Erythrosine
D & C red 22 – Eosin Y
FLAVOURING AGENTS:- For chewable tablet- flavour oil are used
SWEETENING AGENTS:- For chewable tablets: Sugar, mannitol.
Saccharine (artificial): 500 time’s sweeter than sucrose.
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