M1L12 - Tablet excipients

Bulking agent

This is a type of excipient used to form a tablet suitable for handling

Calcium hydrogen phosphate dihydrate

This is a non-hygroscopic bulking agent with good flow properties but incompatible with drugs unstable in alkaline environments, unstable in lots of water and, and forms weaker tablets

Microcrystalline cellulose

This is a bulking agent used in direct compression tabletting, plastically-deforming and inert but hygroscopic, insoluble, and expensive, with poor flow properties

Lactose

This is a bulking agent with good flow properties, low hygroscopicity, and good aqueous solubility, but which forms weaker tablets vulnerable to the Maillard reaction

Adhesive

This is an excipient used to bind in the absence of solution, often: cellulose, methylcellulose, PVP, and PEG are used

Solution binder

This is a class of adhesive excipients used to bind tablet formulations in solution

Starch

This is used 5-10% w/v, forms tablets with good disintegration properties

Gelatine

This is used 2-20% w/v, forms strong adhesive for lozenge formation

Acacia mucilage

This is used 10-20% w/v, forms hard granules for lozenge formation

Polyvinyl pyrollidone (PVP)

This is used 0.5-5% w/v in water or ethanol, forms tablets with good hardness and disintegration and is often used for granulating water-sensitive drugs

Polyvinyl acetate (PVA)

This is used 10% w/v in ethanol solution, produces prolonged disintegration

Carboxymethyl cellulose

This is used 5% w/v in water, anionic and incompatible with cationic substances

Methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose

These are solution binders used 2-8% w/v in aqueous solution

Granulating fluid

This is a fluid in which granules of a drug formulation can be formed, often water or organic

Disintegrant

This is an excipient which breaks up into small fragments in liquid, increasing surface area and promoting dissolution

Type-I disintegrant

This is a disintegrant class which promotes water uptake, e.g. sodium dodecyl sulphate

Type-II disintegrant

This is a disintegrant class which produces gas when in contact with moisture, e.g. tartaric acid and sodium bicarbonate to produce carbon dioxide

Type-III disintegrant

This is a disintegrant class which swells upon contact with water, e.g. starches

Glidant

This is an excipient used to improve the flow properties of a powder mixture

Colloidal silica

This is the most commonly used glidant, used at concentrations 0.2% w/v

Lubricant

This is an excipient used to facilitate the ejection of the tablet by reducing external friction

Magnesium stearate

This is a lubricant used <1% w/v, the most frequently employed lubricant

Anti-adherent

This is an excipient used to reduce adhesion between powder and the punch surface, often talc, starch, or magnesium stearate

Buffering agent

This is an excipient which changes the dissolution rate by altering chemical stability in solution depending on pH

Flavouring agent

This is an excipient which gives a tablet a more pleasant taste or masks an unpleasant one

Colouring agent

This is an excipient which colours the tablet to provide greater aesthetic appeal and/or increase the stability of photosensitive elements in the formulation