Excipients in Pharmaceuticals

Excipients :

Excipients are inert substance used to give a preparation a suitable form or consistency. Or

More of less inert any substance added to a drug to give suitable form to the drug. Excipients may function as –

For solid dosage form:

Diluents / Filler:

Diluents are added to tablet formulations to increase the bulk of individual tablet to a practical,convenient and workable size

For example – Lactose, sucrose, glucose, mannitol, sorbitlol, starch, kaolin, Di-calcium phosphate, calcium carbonate, calcium sulphate.

Binder : 

 Binders are adhesive materials used to hold powders together as granules & to assist in ultimately holding the compressed tablet together.

Binder is of two types-

-         Solution binder

-         Dry binder.

Solution binders –

-         Starch paste (10-17%)

-         Gelatin solution (10-20%)

-         Sucrose syrup (50-85%)

-         Glucose solution (50% alcohol, 25% glucose and 25% water)

-         Methyl cellulose 4% in alcohol.

-         Ethyl cellulose 5% in alcohol.

-         Starch- acacia paste( starch 5%, acacia 2% in water)

-         Sodium CMC.

-         PVP in aqueous, alcoholic and hydro alcoholic solⁿ

-         Polyethylene glycol.

Dry binder –

-         Cellulose

-         Methyl cellulose

-         PVP

-         Polyethylene Glycol.

Disintegrators: 

Disintegrators are substance which is added to tablet formulations, when needed to induce the tablet to disintegrate after administration.

For example- Dried corn / Potato starch / Starch / Cellulose / Sodium starch glycolate / Cross linked polyvinyl pyrrolidone / Sodium CMC

*Dried corn or potato starch and cellulose derivatives are the most popular disintegrating agent.

Lubricants (0.5-3% of tablet weight): Lubricants are added to tablet granulation when needed, to-

Lubricants may function as –

-         The flow property of granules is increase as well as to reduce the internal friction

-         Eliminate adhesion to the surface of punch and die

-         To reduce the wall friction and this facilitate the ejection of finished tablet

-         Reduce or scale back excessive punch and die wear

For example – Magnesium stearate / Stearic acid / Polyethylene glycol / Sodium lauryl sulphate / Sodium stearyl fumarate / Liquid paraffin

Glidants: Excipient that added to tablet formulations to promote the flow of granulation by reducing friction between particles (use to improve flow property)

For example – Silica / Magnesium / Stearate / Calcium stearate / Starch / Talc

Coloring agents: It is an agent that use for increasing physical appearance & compatibility & the pharmaceutical dosage form.

Color from plant – Chlorophyll (Green) / -carotene (Yellow / Orange)

Color is normally added by –

-         Dissolving the dye in the binding solution

-         Spraying the granules with a special solution of the dye

-         Distributing the dye with the dry mix and then employing wet granulation.

Flavoring agents – Pharmaceutical necessity added to oral dosage form to musk the test unpleasant flavor of the drug.

For example –Banana flavor, Strawberry flavor, mango flavor etc.

For liquid Dosage form :

Preservative – which prevent microbial growth?

For example – Benzyl alcohol / Phenol / Benzyl conium chloride / Methyl paraben, Propyl paraben / Butyl paraben / Boric acid / Sodium salicylate / Thimersal

Emulsifying agent / Surface active agents (reduce surface tension) :

To reduce internal phase into small globules / Stabilizer of the droplet form of the internal phase of an emulsion. Emulsifiers are also used as a wetting agents & Surfactant.

*Surface tension – Interfacial tension at an air liquid interface. Surface tension causes fluids to assume spherical shape.

For example – Egg yolk, Agar, honey, gelatin, Na Alginate,Polysorbate (80, 60, 20) / Potassium oleate / Sodium dodecyl (lauryl) suphate / Povidone / Propylene glycol / Theophylene / Propylene glycol / Ethyl alcohol / Glycerin

: Anti-oxidant : It helps to prevent oxidation

For example –

Anti-oxidant (reducing agents) – Sodium bi sulphate / Butylated anisole / Thiourea /

Anti-oxidant (blocking agents) – Tocopherol / Ascorbic acid esters

Synergist –Ascorbic acid (vitamin – C) / Phosphoric acid / Tartaric acid / Citric acid

Suspending agents: 
 Agents used in pharmaceutical suspensions to impart viscosity

For example – Gelatin / Methyl cellulose / Sobitol solution / Polyethylene glycol 4000