Bentonite

Synonyms: Albagel; bentonitum; E558; mineral soap; Polargel; soap clay; taylorite; Veegum HS; wilkinite.

Description: Bentonite is a crystalline, claylike mineral, and is available as an odorless, pale buff, or cream to grayish-colored fine powder, which is free from grit. It consists of particles about 50–150 mm in size along with numerous particles about 1–2 mm. Microscopic examination of samples stained with alcoholic methylene blue solution reveals strongly stained blue particles. Bentonite may have a slight earthy taste.

Chemical Name: Bentonite

Adsorbent; stabilizing agent; suspending agent; viscosity increasing
agent

• Bentonite is a naturally occurring hydrated aluminum silicate used primarily in the formulation of suspensions, gels, and sols, for topical pharmaceutical applications.
• It is also used to suspend powders in aqueous preparations and to prepare cream bases containing oil-in-water emulsifying agents.osmetics, and food products, see Section 18. In oral preparations, bentonite, and other similar silicate clays, can be used to adsorb cationic drugs and so retard their release.
• Adsorbents are also used to mask the taste of certain drugs. See Table II.
• Bentonite has been investigated as a diagnostic agent for magnetic resonance imaging.
• Therapeutically, bentonite has been investigated as an adsorbent for lithium poisoning

Aqueous bentonite suspensions retain their viscosity above pH 6, but are precipitated by acids. Acid-washed bentonite does not have suspending properties. The addition of alkaline materials, such as magnesium oxide, increases gel formation. Addition of significant amounts of alcohol to aqueous preparations will precipitate bentonite, primarily by dehydration of the lattice structure

Bentonite is mainly used in topical pharmaceutical formulations but has also been used in oral pharmaceutical preparations, food products, and cosmetics. Following oral administration, bentonite is not absorbed from the gastrointestinal tract. Bentonite is generally regarded as a nontoxic and nonirritant material.

Observe normal precautions appropriate to the circumstances and quantity of material handled. Eye protection, gloves, and a dust mask are recommended. Bentonite should be handled in a wellventilated environment and dust generation minimized.

Bentonite magma; kaolin; magnesium aluminum silicate; magnesium trisilicate; purified bentonite; talc.