Cellulose, silicified microcrystalline

• USP–NFSilicified Microcrystalline Cellulose

SMCC; Prosolv SMCC 50; Prosolv SMCC 90; Prosolv SMCC HD 90

Co-processed microcrystalline cellulose and colloidal silicon dioxide (about 2% w/w) · [—]

Polymer, mixture or material of variable composition — no single molecular formula applies.

Diluent (filler)

Typical concentrations: — · Dosage forms: Solid

A filler–binder for tablets and capsules, used particularly in direct compression but also in wet granulation, dry granulation and capsule filling. Like microcrystalline cellulose it is used over a wide range, typically about 20–90% of the formulation weight, and it is especially helpful for high-dose drugs and formulations with poor flow.

A fine, white or almost white, odourless and tasteless, free-flowing powder made of agglomerated particles of microcrystalline cellulose with colloidal silicon dioxide distributed over their surface.

Composition

microcrystalline cellulose with about 2% w/w colloidal silicon dioxide

Particle size

grades with nominal mean sizes of about 50 µm (SMCC 50) and about 90–125 µm (SMCC 90); high-density grades are also available

pH

about 5.0–7.5 (aqueous dispersion supernatant)

Specific surface area

considerably higher than that of microcrystalline cellulose because of the silica

Solubility

practically insoluble in water, dilute acids and most organic solvents

Stable, although hygroscopic. Store in a well-closed container in a cool, dry place.

Incompatible with strong oxidising agents, as for microcrystalline cellulose.

Made by co-processing: colloidal silicon dioxide is dispersed in an aqueous slurry of microcrystalline cellulose and the mixture is spray-dried, so the silica becomes intimately associated with the cellulose particle surface rather than simply blended.

Both components are widely used in oral products and foods and are regarded as non-toxic and non-irritant; the co-processed material is not absorbed after oral administration.

Observe normal precautions for the quantity handled. The dust may irritate the eyes and respiratory tract; gloves, eye protection and a dust mask are recommended.

Described in a USP–NF monograph. Its components, microcrystalline cellulose and colloidal silicon dioxide, are both GRAS-listed food ingredients and are included in the FDA Inactive Ingredient Database for oral products; the co-processed material is used in oral medicines marketed in the USA and Europe.

Microcrystalline cellulose; colloidal silicon dioxide; powdered cellulose; microcrystalline cellulose and carboxymethylcellulose sodium.

Compared with ordinary microcrystalline cellulose, silicified grades flow better, give stronger tablets at the same compression force, lose less compactibility after wet granulation and are less sensitive to over-lubrication with magnesium stearate. The silica does not change the chemical identity of the cellulose; physical blends of the two components do not reproduce these benefits.