Name: Magnesium Silicate
CAS No: Silicic acid, magnesium salt [1343-88-0]
JP: Magnesium Silicate USP-NF: Magnesium Silicate
E553a; synthetic magnesium silicate.
Silicic acid, magnesium salt [1343-88-0]
MgOSiO2xH2O
Magnesium silicate is a compound of magnesium oxide and silicon dioxide. See also Section 17. The JP XV states that magnesium silicate contains not less than 45.0% of silicon dioxide (SiO2: molecular weight 60.08) and not less than 20.0% of magnesium oxide (MgO: 40.30), and the ratio of percentage (%) of magnesium oxide to silicon dioxide is not less than 2.2 and not more than 2.5. The USP32–NF27 describes magnesium silicate as a compound of magnesium oxide (MgO) and silicon dioxide (SiO2) that contains not less than 15.0% of MgO and not less than 67.0% of SiO2 calculated on the ignited basis
Magnesium silicate is used in oral pharmaceutical formulations and food products as a glidant and an anticaking agent.
Magnesium silicate occurs as an odorless and tasteless, fine, whitecolored powder that is free from grittiness
See Table I.
Moisture content Magnesium silicate is slightly hygroscopic. Solubility Practically insoluble in ethanol (95%), ether, and water.
Magnesium silicate should be stored in a well-closed container in a cool, dry place.
Magnesium silicate may decrease the oral bioavailability of drugs such as mebeverine hydrochloride,(1) sucralfate, and tetracycline, via chelation or binding, when they are taken together. The dissolution rate of folic acid,(2) erythromycin stearate,(3) paracetamol(4) and chloroquine phosphate(4) may be retarded by adsorption onto magnesium silicate. Antimicrobial preservatives, such as parabens, may be inactivated by the addition of magnesium silicate.(5) Magnesium silicate is readily decomposed by mineral acids
Magnesium silicate may be prepared from sodium silicate and magnesium sulfate. The silicate also occurs in nature as the minerals meerschaum, parasepiolite, and sepiolite.
Magnesium silicate is used in oral pharmaceutical formulations and is generally regarded as an essentially nontoxic and nonirritant material. Orally administered magnesium silicate is neutralized in the stomach to form magnesium chloride and silicon dioxide; some magnesium is absorbed. Caution should be used when greater than 50 mEq of magnesium is given daily to persons with impaired renal function, owing to the risk of hypermagnesemia. Reported adverse effects include the formation of bladder and renal calculi following the regular use, for many years, of magnesium silicate as an antacid.(6,7)
Observe normal precautions appropriate to the circumstances and quantity of material handled. Eye protection is recommended.
GRAS listed. Accepted for use as a food additive in Europe. Included in the FDA Inactive Ingredients Database (oral tablets). Included in the Canadian List of Acceptable Non-medicinal Ingredients
Magnesium aluminum silicate; magnesium metasilicate; magnesium orthosilicate; magnesium trisilicate; talc. Magnesium metasilicate Comments Magnesium metasilicate (MgSiO3) occurs in nature as the minerals clinoenstatite, enstatite, and protoenstatite. Magnesium orthosilicate Comments Magnesium orthosilicate (Mg2SiO4) occurs in nature as the mineral forsterite.
A specification for magnesium silicate is contained in the Food Chemicals Codex (FCC).(8) The EINECS number for magnesium silicate is 215-681-1. The PubChem Compound ID (CID) for magnesium silicate includes 518821 and 14936.