Pharmaceutical Excipient Types

Suspending agent are viscosity-increasing agent used to reduce sedimentation rate of particles in a vehicle in which they are not soluble; suspension may be formulated for oral, parenteral, ophthalmic, topical, or other route.

Stiffening agent is used to increase thickness or hardness of a preparation, usually an ointment.

Examples

Cetyl alcohol
Cetyl esters wax

Solvent is used to dissolve another substance in preparation of a solution; may be aqueous or not (e.g., oleaginous). Cosolvents, such as water and alcohol (hydroalcoholic) and water and glycerin, may be used when needed. Sterile solvents are used in certain preparations (e.g., injections).

Examples

Alcohol

Plasticizer is a component of film-coating solutions to make film more pliable, enhance spread of coat over tablets, beads, and granules.
Examples
• Diethyl phthalate
• Glycerin

Ointment base is semisolid vehicle for medicated ointments.

Examples

Lanolin
Hydrophilic ointment
Polyethylene glycol ointment
Petrolatum
Hydrophilic petrolatum

Levigating agent liquid is used as an intervening agent to reduce the particle size of a powder by grinding, usually in a mortar.
Examples
• Mineral oil
• Glycerin
• Propylene glycol

Humectant is used to prevent drying of preparations, particularly ointments and creams.

Examples

Glycerin
Propylene glycol
Sorbitol

Flavorant is used to impart a pleasant flavor and often odor to a preparation. In addition to the natural flavorants  listed, many synthetic ones are used.

Examples

Anise oil
Cinnamon oil
Cocoa

Encapsulating agent is used to form thin shells to enclose a drug for ease of administration.
Examples
• Gelatin

Emulsifying agent is used to promote and maintain dispersion of finely  subdivided particles of liquid in a vehicle in which it  is immiscible. End product may be a liquid emulsion  or semisolid emulsion (e.g., a cream).

Examples

Acacia
Cetomacrogol

Clarifying agent is used as a filtering aid for its adsorbent qualities.

Examples

Bentonite

Colorant is used to impart color to liquid and solid (e.g., tablets and capsules) preparations.

Examples

FD&C Red No. 3
FD&C Red No. 20
FD&C Yellow No. 6
FD&C Blue No. 2

Buffering agent is used to resist change in pH upon dilution or addition of acid or alkali.

Examples

Potassium metaphosphate
Potassium phosphate,monobasic
Sodium acetate

Chelating agent is substance that forms stable water-soluble complexes (chelates) with metals; used in some liquid pharmaceuticals as stabilizers to complex heavy metals that might promote instability. In such use, they are also called sequestering agents

Examples

Edetic acid

Antioxidants are used to prevent deterioration of preparations by oxidation

Examples

Ascorbic acid
Ascorbyl palmitate
Butylated hydroxyanisole
Butylated hydroxytoluene