| English name | Magnesium Oxide |
| Alias in English | Common name BP: Heavy magnesium oxide and Light magnesium oxide JP: Magnesium oxide PhEur: Magnesii oxidum ponderosum and Magnesii oxidum leve USP: Magnesium oxide. Synonym: Calcined magnesia; E530; MagGran MO; magnesia; magnesia usta; periclase. |
| Chemical name | Magnesium oxide |
| CAS No. | 1309-48-4 |
| Molecular formula | MgO |
| Molecular weight | 40.3 |
| Structure | Mg=O |
| Classification | Anticoagulant; Emulsifier; Flow aid; Filler |
| Usage | Tablet and capsule diluents. Magnesium oxide is used as an alkaline diluent in solid preparations. It is also used as a food additive and antacid, alone or in combination with aluminum hydroxide. Magnesium oxide is also used as an osmotic light laxative and magnesium supplement for magnesium deficiency. [1] [1] Raymond C Rowe, Paul J Sheskey and Sian C Owen. Handbook of Pharmaceutical Excipients. Fourth Edition. [M]London, Chicago: Pharmaceutical Press，2003. |
| Route of administration | Oral, usually topical |
| Storage conditions | Magnesium oxide is stable at room temperature and pressure. It forms magnesium hydroxide in the presence of water. Magnesium oxide is hygroscopic and absorbs water and carbon dioxide more rapidly in its light form than in its heavy form when exposed to air. Large volumes of material should be stored in airtight containers in a cool, dry place. [1] [1] Raymond C Rowe, Paul J Sheskey and Sian C Owen. Handbook of Pharmaceutical Excipients. Fourth Edition. [M]London, Chicago: Pharmaceutical Press，2003. |
| Safety | Magnesium oxide is widely used as excipient and therapeutic agent in solid preparations. Therapeutically, as an antacid 250 to 500 mg orally and as an osmotic laxative 2 to 5 g. Magnesium oxide, when applied as an excipient (because of its laxative effect) still produces this undesirable effect if given orally in large doses, but it is usually considered to be a non-toxic substance. [1] [1] Raymond C Rowe, Paul J Sheskey and Sian C Owen. Handbook of Pharmaceutical Excipients. Fourth Edition. [M]London, Chicago: Pharmaceutical Press，2003. |
| Taboo | Magnesium oxide is a basic oxide that in the solid state reacts with acidic compounds to form salts, such as magnesium dibuprofen, or degrades base-unstable drugs. Adsorption of various drugs to magnesium oxide has been reported in the literature, such as antihistamines, antibiotics (especially tetracyclines), salicylates, atropine sulfate, scopolamine hydrobromide and o-aminobenzoic acid derivatives. Magnesium oxide can be complexed with polymers such as osmotic acrylic resin (Eudragit RS) to prolong the release of the drug and can react with sodium phenobarbital in the solid state. Magnesium oxide has an adverse effect on the stability of diazepam. Magnesium oxide affects the bioavailability of trichlormethiazide and antiarrhythmic drugs. [1] [1] Raymond C Rowe, Paul J Sheskey and Sian C Owen. Handbook of Pharmaceutical Excipients. Fourth Edition. [M]London, Chicago: Pharmaceutical Press，2003. |
| Source and Preparation | Magnesium oxide occurs naturally in the mineral magnesite. It can be produced by calcining the mineral magnesite or magnesium hydroxide, which can be obtained by treating seawater or brackish water with limewater. Purification methods include crushing and sieving, heavy media separation and froth flotation. Magnesium oxide can also be obtained by thermal decomposition of magnesium chloride, magnesium sulfate, magnesium sulfite, magnesite hydrocarbide and the alkaline carbonate 5MgO-4CO2- 5H2O. Purification is carried out by filtration or sedimentation. [1] [1] Raymond C Rowe, Paul J Sheskey and Sian C Owen. Handbook of Pharmaceutical Excipients. Fourth Edition. [M]London, Chicago: Pharmaceutical Press，2003. |
| Management | Listed under GRAS. licensed in Europe for use as a food additive. Included in FDA Guidance on Inactive Components (Oral Capsules and Tablets).UK licensed for use in non-injectable formulations. [1] [1] Raymond C Rowe, Paul J Sheskey and Sian C Owen. Handbook of Pharmaceutical Excipients. Fourth Edition. [M]London, Chicago: Pharmaceutical Press，2003. |
