Aluminum magnesium silicate

A study was made of the comparative stabilities at various exposures of an upset stomach remedy suspension. This product consisted of a dispersion of bismuth subsalicylate and phenylsalicylate in an aqueous system. Methyl-cellulose and magnesium aluminum silicate were selected as the suspending agents, because the presence of polyvalent metallic ions precluded the use of hydrocolloids affected by these ions. In addition, it was found that methyl-cellulose contributed a demulcent effect. The viscosity, as well as the suspension characteristics of the combination of protective colloids used, was of a synergistic nature. These colloids formed a thixotropic system. The thixotropy undoubtedly aids in stabilizing this system. In order to make this product palatable and impart elegance, color and flavor were added. Sample 1 (with protective colloids) showed no separation, while sample 2 (without... 

The stability characteristics of two different antiperspirant lotion systems were compared. Sample 1 represented an aqueous emulsion containing an aluminum salt. The internal phase consisted of stearyl alcohol and ethylene oxide reaction products, polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan tristearate. Methylcellulose was used as a stabilizer and bodying agent. Sample 2 represented a dispersion of magnesium aluminum silicate in an aqueous system containing aluminum ions. Because of its com-... 

Figure 6. Effect of magnesium aluminum silicate and cellu-losic hydrocolloids on stability of suspensions...

Figure 7. Synergistic stabilizing effect of magnesium aluminum silicate with carboxymethylcellulose on medicated liquid cream...

Finely divided solid particles that are wetted to some degree by both oil and water can also act as emulsifying agents. This results from the fact that they can form a particulate film around dispersed droplets, preventing coalescence. Powders that are wetted preferentially by water form O/W emulsions, whereas those more easily wetted by oil form W/O emulsions. The compounds most frequently used in pharmacy are colloidal clays, such as bentonite (aluminum silicate) and veegum (magnesium aluminum silicate). These compounds tend to be adsorbed at the interface and also increase the viscosity of the aqueous phase. They are frequently used in conjunction with a surfactant for external purposes, such as lotions or creams. 

Kaolin is a naturally occurring hydrated magnesium aluminum silicate (attapulgite), and pectin is an indigestible carbohydrate derived from apples. Both appear to act as absorbents of bacterial toxins and fluid, thereby decreasing stool liquidity and number. They may be useful in acute diarrhea but are seldom used on a chronic basis. A common nonprescription preparation is Kaopectate. The usual dosage is 1.2-1.5 g after each loose bowel movement (maximum 9 g/d). Kaolin-pectin formulations are not absorbed and have no significant adverse effects except constipation. They should not be taken within 2 hours of other medications (which they may bind). 

Cool to 70°C, add the magnesium aluminum silicate, and mix for 30 minutes or until evenly dispersed. 

Naprosyn (naproxen) suspension for oral administration contains 125 mg/5 mL of naproxen in a vehicle containing sucrose, magnesium aluminum silicate, sorbitol solution, and sodium chloride (30 mg/5 mL, 1.5 mEq),... 

Each gram of Plexion (sodium sulfacetamide 10% and sulfur 5%) cleanser contains 100 mg sodium sulfacetamide and 50 mg sulfur in a cleanser base containing water, sodium methyl oleyltaurate, sodium cocoyl isethionate, disodium oleamido MEA sulfosuccinate, cetyl alcohol, glyceryl stearate and PEG-100 stearate, stearyl alcohol, PEG-55 propylene glycol oleate, magnesium aluminum silicate, methylparaben, disodium EDTA, butylated hydroxytoluene, sodium thiosulfate, fragrance, xanthan gum, and propylparaben. Each gram of Plexion (sodium... 

Clays Magnesium aluminum silicate (V eegum) Anionic 0.5-2.5 Disperses and hydrates readily. Hot water increases rate of hydration 3-11 Plastic/ thixotropy Partially flocculated by electrolytes and incompatible with acidic solution [Pg.168]

Amcinonide Cyclocort White petrolatum, magnesium aluminum silicate... 

Emission Decay Time of Rare-Earth-Activated Lithium Magnesium Aluminum Silicate Glasses... 

Other thickeners used include derivatives of cellulose such as methylcellulose, hydroxypropylmethylcellulose, and cellulose gum natural gums such as tragacanth and xanthan (see Cellulose ethers Gums) the carboxyvinyl polymers and the poly(vinyl alcohol)s. The magnesium aluminum silicates, glycol stearates, and fatty alcohols in shampoos also can affect viscosity. 

Bentonite montmorillonite (a magnesium-aluminum silicate) used as a treating... 

Clay mineral attapulgite is an acicular-shaped hydrous magnesium aluminum silicate. Large deposits occur in South Georgia and North Florida. It is receiving increasing use in partial replacement of furafil. 

Thixotropy can be obtained at fairly low loading concentrations with colloidal silica, bentonite, metallic leafing powders, and hydrated magnesium aluminum silicates. If required, thixotropic adhesive pastes may be formulated which will not flow during cure even at elevated temperatures and which are useful for bonding loose-fitting joints. 

Other mineral additives have been used for many years as functional extenders and fillers in adhesives and sealants. These include kaolin (hydrated aluminum silicate), bentonite (hectorite clay), talc (magnesium silicate), and attapulgite (hydrated magnesium aluminum silicate) additives.1213 Kaolin and talc are considered to be viscosity thickeners whereas attapulgite is more of a conventional thixotrope. They are considered to be very cost-effective rheological additives. 

Hydroxypropyl cellulose Hydroxypropylmethyl cellulose Magnesium aluminum silicate 50.000- 1250,000 10.000- 1 00,000... 

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