Magnesium trisilicate is also known as “magnesium orthosilicate”. The chemical formula is Mg2Si3O8•nH2O and white orthorhombic crystal with melting point of 1910℃ and relative density of 3.21. This product is insoluble in water or ethanol. It is decomposed into Mg(OH)2 in concentrated alkali or decomposed into silicic acid and magnesium chloride in hot hydrochloric acid. It can be decomposed by hydrofluoric acid. It exists as forsterite mineral in nature. Due to the openness of its crystal structure, it contains holes and channels which are connected with each other as well as the outside world, and has a more developed pore structure and a large specific surface area, thus it has better adsorption performances and molecular sieve functions, which can provide specific acting force of the molecular field. In medicine, it has a lesser effect on neutralizing gastric acid, but slow and lasting, up to 4~5 hours. It is suitable for the treatments of stomach and duodenal ulcer. It also can relieve symptoms caused by hyperacidity. In addition, it can be used as processing aid or polyether adsorbent, which has the function of adsorption and decolorization. The product has broad application prospects in the pharmaceutical intermediates, food additives, rubber filling agent, deodorant, ceramic industry, and other fields.
A certain concentration of Na2O•nSiO2 solution and Mg(NO3)2 solution are respectively prepared by using sodium silicate with chemically pure modulus of 3.34 and chemically pure Mg(NO3)2 as raw materials. According to n(Si):n(Mg)=2:1, Mg(NO3)2 solution is dripped into Na2O•nSiO2 solution at a speed of 5 ml /min and stirred at the same time with the appearance of white precipitate. The mixture solution is aged after 1.0h’s standing after dropping. Then this product can be obtained through preparation of filtering, washing, precipitating to a neutral stance and oven drying.
The product is antacid with slow and long-lasting effect, it does not produce any gas thus protecting the gastric mucosa, and it has the function of light diarrhea and adsorption. Insoluble in water. It can absorb the free acid in stomach, so it plays the role of making acid. The function of neutralizing peptic acid is weak, slow but long-lasting, up to 4~5 hours. The hypocatharsis of antacids containing magnesium can lead to defecation. About 10 % of magnesium can be absorbed by the intestine. In the process of neutralizing gastric acid, there is no carbon dioxide but colloidal silica, which is covered on the surface of ulcer and has protective effects. It can also absorb enterotoxins, bacteria and harmful gases. Large doses have the function of light diarrhea. It is clinically used for hyperacidity and peptic ulcer.
It is used medicinally as an antacid. It can neutralize the stomach acid and protect the ulcer with slow and lasting effects, up to 4~5 hours. It does not produce the gas to protect the gastric mucosa, and it has the function of light diarrhea and adsorption. It can be used to treat stomach, duodenal ulcer and relieve symptoms caused by hyperacidity. It can be used as antioxidant, deodorizer, decolorizer, TLC adsorbent, column chromatography adsorbent and so. It can also be used in ceramics and rubber industry. Food grade products are used as anti-caking agent, filter aid and film agent. According to regulations formulated by FAO / WHO (1984), the maximum amount of anti-caking agent used in powdered dairy products ( milk powder, cream powder, high fat milk powder and half cream powder ) is 10 g / kg.
Long-term use of this product may cause renal tubular silicon stones, thereby damaging the renal tubules. Therefore, in the treatment of gastric ulcer, its potential toxicity should be noted. Vertigo, convulsions, arrhythmia, mental symptoms and abnormal fatigue may occur in patients with renal insufficiency or a large number of long-term use.
- It is contraindicated in patients allergic to the product.
- It is not recommended for children.
- It should be carefully used during the first three months of pregnancy.
- When combined with atropine, digoxin, diazepam and isoniazid, it may affect curative effect of the latter due to the decrease of absorption. When combined with levodopa, the absorption may increase; chlorpromazine drugs can inhibit the absorption of this product.
In the complex decomposition method, the reaction is used to produce magnesium trisilicate precipitation after the pretreatment of magnesium sulfate and magnesium sulfate. Then the finished product of magnesium trisilicate is prepared through washing, filter pressing, drying and crushing. As follows:
2Na2O•3SiO2•5H2O+2MgSO4→Product+2Na2SO4
White or almost white powder.
The USP 32 describes magnesium trisilicate as a compound of
magnesium oxide and silicon dioxide with varying proportions of
water. It contains not less than 20.0% of magnesium oxide and not
less than 45.0% of silicon dioxide. The PhEur 6.0 similarly
describes magnesium trisilicate as having a variable composition
corresponding to the approximate formula Mg2Si3O8·xH2O. It
contains not less than 29.0% of magnesium oxide and not less than
the equivalent of 65.0% of silicon dioxide, both calculated with
reference to the ignited substance.
Magnesium trisilicate occurs as an odorless and tasteless, fine,
white-colored powder that is free from grittiness.
Industrial odor absorbent, decolorizing agent,
antioxidant, medicine (antacid).
USP specifies not less
than 20% magnesium oxide and 45% SiO2, similar
to the FCC requirements for magnesium silicate.
See talc.
Magnesium trisilicate may be prepared from sodium silicate and
magnesium sulfate. It also occurs in nature as the minerals
meerschaum, parasepiolite, and sepiolite.
Trimax (Sterling
Winthrop).
Pharmaceutical Applications
Magnesium trisilicate (Mg2Si3O8) can be used in antacid preparations especially in the treatment of peptic ulcers. The mode of action includes the increase of the pH of the gastric fluid together with the formation of a colloidal silica precipitate,which forms a protection for theGImucosa. Magnesium trisilicate reduces the absorption of iron products, certain antibiotics (such as Nitrofurantoin) or antimalarial drugs (such as Proguanil).
Pharmaceutical Applications
Magnesium trisilicate is used in oral pharmaceutical formulations
and food products as a glidant. It is also used therapeutically as an
antacid, and also for the treatment of ciprofloxacin overdose or
toxicity.
Magnesium trisilicate is used in oral pharmaceutical formulations
and is generally regarded as an essentially nontoxic and nonirritant
material.
When administered orally, magnesium trisilicate is neutralized in
the stomach to form magnesium chloride and silicon dioxide; some
magnesium may be absorbed. Caution should be used when
concentrations greater than 50 mEq of magnesium are given daily
to persons with impaired renal function, owing to the risk of
hypermagnesemia.
Therapeutically, up to about 2 g of magnesium trisilicate may be
taken daily as an antacid.
Reported adverse effects include the potential for osmotic
diarrhea in the elderly using antacids containing magnesium
trisilicate;and the potential for the formation of bladder and
renal calculi following the long-term use of magnesium trisilicate as
an antacid.
Magnesium trisilicate is stable if stored in a well-closed container in
a cool, dry place.
Magnesium trisilicate, when taken with drugs such as mebeverine
hydrochloride,proguanil,norfloxacin,sucralfate, and tetracycline,
may cause a reduction in bioavailability via binding or
chelation. The dissolution rate of folic acid, erythromycin
stearate,paracetamol, and chloroquine phosphate may be
retarded by adsorption onto magnesium trisilicate. Antimicrobial
preservatives, such as the parabens, may be inactivated by the
addition of magnesium trisilicate.
Magnesium trisilicate is also readily decomposed by mineral
acids.
GRAS listed. Accepted for use as a food additive in Europe.
Included in the FDA Inactive Ingredients Database (oral tablets).
Included in nonparenteral medicines licensed in the UK. Included in
the Canadian List of Acceptable Non-medicinal Ingredients.
