Calcium silicate

• USP–NFCalcium Silicate

Calcium hydrosilicate; calcium metasilicate; calcium monosilicate; Micro-Cel; silicic acid, calcium salt; E552

Hydrated calcium silicate of variable composition · [1344-95-2]

CaSiO3 (nominal; commercial material is hydrated and variable) · 116.16 (CaSiO3)

Glidant, Adsorbent

Typical concentrations: — · Dosage forms: Solid

Used as an anticaking agent and glidant in powders, and as an adsorbent that converts liquids or oily drugs into free-flowing powders for tableting (for example liquisolid systems). Porous grades of low density have been used in floating, gastroretentive dosage forms. It is also used in foods and cosmetics.

A white to off-white, free-flowing, very fine powder of low bulk density and high specific surface area.

Solubility

practically insoluble in water; decomposed by mineral acids with formation of a silica gel

Liquid absorption

very high; porous grades can take up several times their own weight of water or oil and remain free-flowing

Bulk density

low; fluffy, high-surface-area powder

pH

alkaline (aqueous slurry)

Stable. Store in a well-closed container in a dry place.

Decomposed by strong acids. Its alkaline surface may degrade alkali-sensitive drugs, and its large surface area can adsorb drugs and preservatives.

Produced by hydrothermal reaction of lime (calcium oxide or hydroxide) with a reactive silica such as diatomaceous earth, or by precipitation from solutions of sodium silicate and a calcium salt.

Regarded as non-toxic when taken orally at the levels used. As with other fine silicates, inhalation of the dust should be avoided.

Observe normal precautions for the quantity handled. Use with adequate ventilation and wear eye protection and a dust mask.

GRAS listed. Accepted as a food additive in Europe (E552).

Magnesium silicate; magnesium aluminium silicate; silicon dioxide, colloidal.

Its capacity to hold liquids while staying free-flowing distinguishes it from most other glidants and makes it useful for loading oily drugs or lipid formulations into tablets and capsules.