Excipients by function

In addition to the different origins and roles for the formulation of a drug product excipients can differentiated by their function. The major groups of excipients by function are:

• Anti-Foaming Agents / Defoamer
• Antioxidants
• Binders 
• Coatings
• Colorants / Colors
• Disintegrants 
• Emulsifiers / Surfactants
• Excipients for Ointments
• Excipients for Suppositories
• Fillers & Diluents 
• Flavoring Agents / Flavors
• Gelling Agents
• Lubricants & Glidants 
• Plasticizers
• Preservatives
• Solvents
• Suspension & Viscosity Agents 
• Sweetener
• Etc.

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A defoamer or an anti-foaming agent is a chemical additive that reduces and hinders the formation of foam in pharmaceutical process or bioprocesses.  The terms anti-foam agent and defoamer are often used interchangeably.

Commonly used agents are insoluble oils, polydimethylsiloxanes and other silicones, certain alcohols, stearates and glycols. The additive is used to prevent formation of foam or is added to break a foam already formed.

Antioxidant excipients prevent, delay or minimize the oxidation of foods, pharmaceuticals or nutraceuticals to which they are added with the aim of achieve a better and longer stability of the product.

Binders hold the ingredients in a tablet / granule together.  Binders ensure that tablets and granules can be formed with required mechanical strength, and give volume to low active dose tablets. 

A binder is a substance capable of sticking (interacting) with two substances, forming a bridge between both (+ form a network of molecules stabilizing the glued system)