aluminium magnesium silicate(2:1:2)

Description

Aluminum magnesium silicate is a white powder, granules or plates. It can be used as an excipient, such as adsorbent, stabilizer, suspending agent, disintegrant for tablet and capsule, binder for tablet, thickener. Incorporation of MAS into the diclofenac sodium (DS) aqueous gels caused a statistical increase in viscosity and a shift from Newtonian flow to pseudoplastic flow with thixotropic property.

Chemical Properties

Almost white powder, granules or plates.

Chemical Properties

The USP32–NF27 describes magnesium aluminum silicate as a blend of colloidal montmorillonite and saponite that has been processed to remove grit and nonswellable ore components. Four types of magnesium aluminum silicate are defined: types IA, IB, IC, and IIA. These types differ according to their viscosity and ratio of aluminum and magnesium content. The PhEur 6.3 describes magnesium aluminum silicate (aluminium magnesium silicate) as a mixture of particles with colloidal particle size of montmorillonite and saponite, free from grit and nonswellable ore.
Magnesium aluminum silicate occurs as off-white to creamy white, odorless, tasteless, soft, slippery small flakes, or as a fine, micronized powder. Flakes vary in shape and size from about 0.3 0.4mm to 1.0×2.0mm and about 25–240 mm thick. Many flakes are perforated by scattered circular holes 20–120 mm in diameter. Under dark-field polarized light, innumerable bright specks are observed scattered over the flakes. The powder varies from 45 to 297 mm in size.

Uses

Aluminium magnesium silicate is used as an Antacid Raw material in a specific antacid formulations, Ceramics, Suspending Agent, Thickning agent etc.

Production Methods

Aluminium magnesium silicate is obtained from silicate ores of the montmorillonite group, which show high magnesium content. The ore is blended with water to form a slurry to remove impurities and separate out the colloidal fraction. The refined colloidal dispersion is drum-dried to form a small flake, which is then micro-atomized to form various powder grades.

Pharmaceutical Applications

Aluminium magnesium silicate has been used for many years in the formulation of tablets, ointments, and creams. It is used in oral and topical formulations as a suspending and stabilizing agent either alone or in combination with other suspending agents. The viscosity of aqueous dispersions may be greatly increased by combination with other suspending agents, such as xanthan gum, owing to synergistic effects; see Xanthan Gum. In tablets, magnesium aluminum silicate is used as a binder and disintegrant in conventional or slow-release formulations.
Magnesium aluminum silicate may cause bioavailability problems with certain drugs.

Safety

Aluminium magnesium silicate is generally regarded as nontoxic and nonirritating at the levels employed as a pharmaceutical excipient. Subacute animal feeding studies in rats and dogs fed magnesium aluminum silicate at 10% of the diet, for 90 days, were negative, including autopsy and histopathological examinations.
LD50 (rat, oral): > 16 g/kg

storage

Magnesium aluminum silicate is stable indefinitely when stored under dry conditions. It is stable over a wide pH range, has baseexchange capacity, absorbs some organic substances, and is compatible with organic solvents.
Magnesium aluminum silicate should be stored in a well-closed container, in a cool, dry place.

Incompatibilities

Owing to its inert nature, magnesium aluminum silicate has few incompatibilities but is generally unsuitable for acidic solutions below pH 3.5. Magnesium aluminum silicate, as with other clays,may adsorb some drugs. This can result in low bioavailability if the drug is tightly bound or slowly desorbed, e.g. amfetamine sulfate, tolbutamide, warfarin sodium, diazepam, and diclofenac sodium.

Regulatory Status

Included in the FDA Inactive Ingredients Database (oral granules, solutions, suspensions and tablets; rectal; and topical preparations; vaginal preparations). Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Nonmedicinal Ingredients.