Magnesium Compounds: Inorganic compounds that contain magnesium as an integral part of the molecule.Magnesium: A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.Magnesium Sulfate: A small colorless crystal used as an anticonvulsant, a cathartic, and an electrolyte replenisher in the treatment of pre-eclampsia and eclampsia. It causes direct inhibition of action potentials in myometrial muscle cells. Excitation and contraction are uncoupled, which decreases the frequency and force of contractions. (From AMA Drug Evaluations Annual, 1992, p1083)Magnesium Deficiency: A nutritional condition produced by a deficiency of magnesium in the diet, characterized by anorexia, nausea, vomiting, lethargy, and weakness. Symptoms are paresthesias, muscle cramps, irritability, decreased attention span, and mental confusion, possibly requiring months to appear. Deficiency of body magnesium can exist even when serum values are normal. In addition, magnesium deficiency may be organ-selective, since certain tissues become deficient before others. (Harrison's Principles of Internal Medicine, 12th ed, p1936)Magnesium Oxide: Magnesium oxide (MgO). An inorganic compound that occurs in nature as the mineral periclase. In aqueous media combines quickly with water to form magnesium hydroxide. It is used as an antacid and mild laxative and has many nonmedicinal uses.Magnesium Hydroxide: An inorganic compound that occurs in nature as the mineral brucite. It acts as an antacid with cathartic effects.